Study on Effect of Reinforcement of Keratin Fiber

Study on effect of Reinforcement of Keratin Fiber (human hair)

on HDPE

Bachelor of Technology

In

Plastic Technology

Central Institute of Plastics Engineering & Technology, Lucknow UP 226008

Study on effect of Reinforcement of Keratin Fiber (Human Hair) on HDPE

Bachelor of Technology

In

Plastic Technology

UNDER SUPERVISION OF: SUBMITED BY:

Mr. SANJAY CHAUDHARY SHUBHAM KR. GAUTAM

Mr. CHANDRASHEKHAR SHARMA

Central Institute of Plastics Engineering & Technology, Lucknow UP 226008

ACKNOWLEDGEMENT

We avail this opportunity to extend my hearty indebtedness to my guide

Prof. Sanjay Chaudhary for their invaluable guidance, motivation, untiring

efforts and meticulous attention at all stages during Our course of work.

We also express my sincere gratitude to Mr. Maan Singh, Mr. Ravi Shukla, Testing Department for their timely help during the course of work.

Our special thanks to Prof. Chandrashekhar Sharma for his support. I am also grateful to all staff members of Processing department at C.I.P.E.T. Lucknow for their co-operation.

ABSTRACT

Natural fibers have recently attracted the attention of scientists and

technologists because of the advantages that these fibers provide over

conventional reinforcement materials, and for which the development of natural

fibers composites has been a subject of interest for the past few years. These

natural fibers are low-cost fibers with low density and high specific properties.

These are biodegradable and non-abrasive, unlike other reinforcing fibers.

However certain drawbacks such as incompatibility with the hydrophobic

polymer matrix, the tendency to form aggregates during processing and poor

resistance to moisture greatly reduce the potential of natural fibers to be used as

reinforcement in polymer matrices.

The primary purpose of the study is to investigate the reinforcement

effect of Keratin Fiber (Human Hair) on High Density Polyethylene (HDPE).

In the present piece of research work, we have used Keratin fiber(Human

Hair) which are light. Short fibers obtained from human hair are found to

possess high impact resistance, strength, stiffness and hydrophobic nature.

Their low cost, low density and large aspect ratio can make them good

reinforcing materials in polymer matrix to make composites. Randomly

oriented short Keratin fibers with 1% weight percentage are reinforced into

HDPE matrix to prepare composite sheet. Flexural strength, Tensile strength of

keratin fiber composite are also evaluated.

Keywords: Natural fiber, Keratin fiber, Polymer Composite

TABLE OF CONTENT

LIST OF TABLES

LIST OF FIGURES

Chapter 1. Introduction

1.1 Motivation

1.2 Relevance of the Present Study

1.3 Background

1.4 Types of Composite Materials

1.5 Reinforcement

1.6 Types of Polymer Composites

1.7 Bio Fiber Reinforced Composites

1.8 Bio Fibers

1.9 Types of Bio Fibers

1.10 Mechanical Properties of Bio Fibers

1.11 Matrix Resins

Chapter 2. Literature Review

2.1 Natural Bio-Fiber Reinforced Composites

2.2 Keratin fiber

2.3 Structure and Properties

2.4 Polymer Keratin based fiber Composite

Chapter 3. Materials & Methods

3.1 Matrix Materials

3.1.1 Low Density Polyethylene

3.1.2 High Density Polyethlene

3.2 Composite Processing

3.2.1 Compression Molding

Chapter 4. Experimental Details & Results

4.1 Tensile Test of LDPE Film ASTM D882

4.2 Tensile Test of HDPE Sheet ASTM D638

4.3 Flexural Test of Reinforced HDPE Sheet ASTM D790

Chapter 5. Conclusions

5.1 Conclusions

5.2 Recommendation for future work

REFERNCES

LIST OF TABLES

1.4 Comparative properties of metals and polymeric matrix compositesa (Mallick, 1993, p. 13)

1.10 Mechanical Properties of Bio Fibers (Source Ref. 9).

1.11 Property/process characteristics for thermoplastic and thermosetting

matrix systems.

1.11c Typical unfilled thermoplastic resin properties (Mazumdar, 2002, p. 53).

1.11b Typical unfilled thermosetting resin properties (Mazumdar, 2002, p. 48).

LIST OF FIGURES

2.3 Structure of hair at various length-scales.

4.1a Sample 1 of LDPE Reinforced film

4.1b Sample 2 of LDPE Reinforced film

4.1c Sample 3 of LDPE Reinforced film

4.1d Sample 4 of LDPE film

Chapter 1

Introduction

Chapter 1

Introduction

1.1 Motivation

Until the beginning of the nineteenth century, the materials developed,

manufactured and used, whether homogeneous or composite, were basically

inorganic in nature. Complex organic substances such as coal and oil were

subjected to destructive processes to produce simpler chemicals such as coal

gas and gasoline. However, during the twentieth century, organic chemists have

developed the means of reversing this destructive process and of creating from

the by-products materials that do not occur naturally. Most important among

these new substances are the ‘super-polymers’, commonly called ‘plastics’, a

term which in many cases is misleading, and the production of these materials

has increased dramatically since the Second World War.

The possibilities of using these plastic materials in engineering situations

are now being extensively examined, and in the field of structural engineering

such development is taking place mainly in their use as glass fiber-reinforced

plastics, the plastic material most widely used being polyester resin. A large

number of materials, e.g. jute, asbestos, carbon and boron, have been used for

the fiber reinforcement of the plastic matrix, the main function of the fibers

being to carry the majority of the load applied to the composite and to improve

the stiffness characteristics of the polymer matrix. The most widely used

material for the reinforcement of polymer is glass fiber in all its various forms,

partly because of its high strength and its low specific gravity, partly because of

its chemical inertness, and partly because of its being relatively inexpensive to

produce. Notwithstanding these, development of new higher modulus fibers

such as boron, graphite, silicon carbide, and beryllium gives us reinforcements

having several times the modulus of elasticity of glass fibers with densities as

low as or lower than glass and strengths close to that of glass fibers. In addition

to having available new chemical types of fibers, there are also a number of

options with regard to fiber diameter, fiber length, and grouping of filaments

into strands, roving, and yarn. These types and forms of fibers give us a new

degree of freedom in terms of being able to select the most appropriate type

fiber for a given application.

1.2 Relevance of the Present Study

A key feature of fiber composites that makes them so promising as

engineering materials is the opportunity to tailor the materials through the

control of fiber and matrix combinations and the selection of processing

techniques. Matrix materials and fabrication processes are available that do not

significantly degrade the intrinsic properties of the fiber. In principle, an infinite

range of composite types exists, from randomly oriented chopped fiber based

materials at the low property end to continuous, unidirectional fiber composites

at the high-performance end. Composites can differ in the amount of fiber, fiber

type, fiber length, fiber orientation, and possibly fiber hybridization. In general,

short-fiber composites are used in lightly loaded or secondary structural

applications, while continuous fiber-reinforced composites are utilized in

primary applications and are considered high-performance structural materials.

By nature, continuous-fiber composites are highly anisotropic. Maximum

properties can be achieved if all the fibers are aligned in the fiber-axis direction.

The properties, such as modulus and strength, decrease rapidly in directions

away from the fiber direction.

One of the outstanding characteristics of the rapidly increasing

technology of composite materials is the almost unlimited freedom of choice

that presents itself to the designer. Since not only the number of constituent in a

composite materials but also their distribution and orientation within a given

structural shape are subject to choice and can possibly lead to identical

performance characteristics, it is one of the foremost requirements for

developing the technology to also provide avenues for making this choice an

intelligent one.

1.3 Background

The most primitive composite materials were straw and mud combined to

form bricks for building construction. The ancient brick-making process can

still be seen on Egyptian tomb paintings in the Metropolitan Museum of Art.

The most advanced examples perform routinely on spacecraft in demanding

environments. The most visible applications pave our roadways in the form of

either steel and aggregate reinforced Portland cement or asphalt concrete. Those

composites closest to our personal hygiene form our shower stalls and bath tubs

made of fiberglass. Solid surface, imitation granite and cultured marble sinks

and counter tops are widely used to enhance our living experiences.

The recognition of the potential weight savings that can be achieved by

using the advanced composites, which in turn means reduced cost and greater

efficiency, was responsible for this growth in the technology of reinforcements,

matrices and fabrication of composites. If the first two decades saw the

improvements in the fabrication method, systematic study of properties and

fracture mechanics was at the focal point in the 60’s. There has been an ever-

increasing demand for newer, stronger, stiffer and yet lighter- weight materials

in fields such as aerospace, transportation, automobile and construction sectors.

Composite materials are emerging chiefly in response to unprecedented

demands from technology due to rapidly advancing activities in aircrafts,

aerospace and automotive industries. These materials have low specific gravity

that makes their properties particularly superior in strength and modulus to

many traditional engineering materials such as metals. As a result of intensive

studies into the fundamental nature of materials and better understanding of

their structure property relationship, it has become possible to develop new

composite materials with improved physical and mechanical properties. These

new materials include high performance composites such as Polymer matrix

composites, Ceramic matrix composites and Metal matrix composites etc.

Continuous advancements have led to the use of composite materials in more

and more diversified applications. The importance of composites as engineering

materials is reflected by the fact that out of over 1600 engineering materials

available in the market today more than 200 are composite.

1.4 Types of Composite Materials

Broadly, composite materials can be classified into three groups on the

basis of matrix material. They are:

a) Ceramic Matrix Composites (PMC)

b) Metal Matrix Composites (MMC)

c) Polymer Matrix Composites (CMC)

a) Ceramic Matrix Composites:

Ceramic fibers, such as alumina and SiC (Silicon Carbide) are

advantageous in very high temperature applications, and also where

environment attack is an issue. Since ceramics have poor properties in tension

and shear, most applications as reinforcement are in the particulate form (e.g.

zinc and calcium phosphate). Ceramic Matrix Composites (CMCs) used in very

high temperature environments, these materials use a ceramic as the matrix and

reinforce it with short fibers, or whiskers such as those made from silicon

carbide and boron nitride.

b) Metal Matrix Composites:

Metal Matrix Composites have many advantages over monolithic

metals like higher specific modulus, higher specific strength, better

properties at elevated temperatures, and lower coefficient of thermal

expansion. Because of these attributes metal matrix composites are

under consideration for wide range of applications viz. combustion chamber

nozzle (in rocket, space shuttle), housings, tubing, cables, heat exchangers,

structural members etc.

c) Polymer matrix Composites:

Most commonly used matrix materials are polymeric. The reasons for

this are twofold. In general the mechanical properties of polymers are

inadequate for many structural purposes. In particular their strength and

stiffness are low compared to metals and ceramics. These difficulties are

overcome by reinforcing other materials with polymers. Secondly the

processing of polymer matrix composites need not involve high pressure

and doesn’t require high temperature. Also equipment required for

manufacturing polymer matrix composites are simpler. For this reason polymer

matrix composites developed rapidly and soon became popular for structural

applications. Polymer composites are used because overall properties of the

composites are superior to those of the individual polymers. They have a greater

modulus than the neat polymer but aren’t as brittle as ceramics.

The most significant advantage of polymer matrix composites (PMCs)

derives from the fact that they are lightweight materials with high strength and

modulus values. The light weight of PMCs is due to the low specific gravities

of their constituents. Polymers used in PMCs have specific gravities between

0.9 and 1.5, and the reinforcing fibers have specific gravities between 1.4 and

2.6 (Mallick, 1993). Depending on the types of fiber and polymer used and their

relative volume fractions, the specific gravity of a PMC is between 1.2 and 2,

compared to 7.87 for steel and 2.7 for aluminum alloys. Because of their low

specific gravities, the strength-to-weight ratios of PMCs are comparatively

much higher than those of metals and their composites (Table 2.1). Although

the cost of PMCs can be higher than that of many metals, especially carbon or

boron fibers are used as reinforcements, their cost on a unit volume basis can

be competitive with that of the high performance metallic alloys used in the

aerospace industry.

A second advantage of PMCs is the design flexibility and the variety of

design options that can be exercised with them. Fibers in PMC can be

selectively placed or oriented to resist load in any direction, thus producing

directional strengths or moduli instead of equal strength or modulus in all

directions as in isotropic materials such as metals and unreinforced polymers.

Similarly, fiber type and orientation in a PMC can be controlled to produce a

variety of thermal properties such as the coefficient of thermal expansion.

PMCs can be combined with aluminum honeycomb, structural plastic foam, or

balsa wood to produce sandwich structures that are stiff and at the same time

lightweight. Two or more different types of fibers can be used to produce a

hybrid construction with high flexural stiffness and impact resistance (Mallick,

1997).

There are several other advantages of PMCs that make them desirable in

many applications. They have damping factors that are higher than those of

metals, which means that noise and vibrations are damped in PMC structures

more effectively than in metal structures. They also do not corrode. However,

depending on the nature of the matrix and fibers, their properties may be

affected by environmental factors such as elevated temperatures, moisture,

chemicals, and ultraviolet light.

Table 1.4 Comparative properties of metals and polymeric matrix compositesa (Mallick,

1993, p. 13)

1.5 Reinforcements

The most common reinforcements are glass, carbon, aramid and boron

fibers. Typical fiber diameters range from 5 µm to 20 µm. The diameter of a

glass fiber is in the range of 5 to 25 µm, a carbon fiber is 5 to 8 µm, an aramid

fiber is 12.5 µm. Because of this thin diameter, the fiber is flexible and easily

conforms to various shapes. In general, fibers are made into strands for weaving

or winding operations. For delivery purposes, fibers are wound around a bobbin

and collectively called a “roving”. An untwisted bundle of carbon fibers is

called “tow”. In composites, the strength and stiffness are provided by the

fibers. The matrix gives rigidity to the structure and transfers the load the fibers.

Fibers for composite materials can come in many forms, from continuous

fibers to discontinuous fibers, long fibers to short fibers, organic fibers to

inorganic fibers. Some of the common types of reinforcements include:

• Continuous carbon tow, glass roving, aramid yarn

• Discontinuous chopped fibers

• Woven fabric

• Multidirectional fabric (stitched bonded for three dimensional properties)

• Stapled

1.6 Types of Polymer Composites

Broadly, polymer composites can be classified into two groups on the

basis of reinforcing material. They are:

a) Fiber reinforced polymer (FRP)

b) Particle reinforced polymer (PRP)

a) Fiber Reinforced Composite

Common fiber reinforced composites are composed of fibers and a

matrix. Fibers are the reinforcement and the main source of strength while

matrix glues all the fibers together in shape and transfers stresses between the

reinforcing fibers. The fibers carry the loads along their longitudinal directions.

Sometimes, filler might be added to smooth the manufacturing process, impact

special properties to the composites, and / or reduce the product cost.

Common fiber reinforcing agents include asbestos, carbon / graphite

fibers, beryllium, beryllium carbide, beryllium oxide, molybdenum, aluminium

oxide, glass fibers, polyamide, bio fibers etc. Similarly common matrix

materials include epoxy, phenolic resin, polyester, polyurethane, vinyl ester etc.

Among these resin materials, polyester is most widely used. Epoxy, which has

higher adhesion and less shrinkage than polyesters, comes in second for its high

cost.

b) Particle Reinforced Composite

Particles used for reinforcing include ceramics and glasses such as small

mineral particles, metal particles such as aluminum and amorphous

materials, including polymers and carbon black. Particles are used to

increase the modules of the matrix and to decrease the ductility of the matrix.

Particles are also used to reduce the cost of the composites. Reinforcements

and matrices can be common, inexpensive materials and are easily processed.

Some of the useful properties of ceramics and glasses include high melting

temperature, low density, high strength, stiffness, wear resistance, and

corrosion resistance. Many ceramics are good electrical and thermal insulators.

Some ceramics have special properties; some ceramics are magnetic

materials; some are piezoelectric materials; and a few special ceramics are

even superconductors at very low temperatures. Ceramics and glasses have one

major drawback: they are brittle. An example of particle – reinforced

composites is an automobile tire, which has carbon black particles in a matrix

of poly-isobutylene elastomeric polymer.

Over the past few decades, we find that polymers have replaced

many of the conventional metals/materials in various applications. This is

possible because of the advantages polymers offer over conventional materials.

The most important advantages of using polymers are the ease of

processing, productivity and cost reduction. Polymer composites have

generated wide interest in various engineering fields, particularly in

aerospace applications. Research is underway worldwide to develop newer

composites with varied combinations of fibers and fillers so as to make them

useable under different operational conditions. In most of these applications,

the properties of polymers are modified using fillers and fibers to suit the high

strength/high modulus requirements. Fiber-reinforced polymers offer

advantages over other conventional materials when specific properties

are compared. These composites are finding applications in diverse fields from

appliances to spacecraft.

1.7 Bio Fiber Reinforced Composites

A bio-composite is a material formed by a matrix (resin) and a

reinforcement of bio fibers (usually derived from plants or cellulose). With

wide-ranging uses from environment-friendly biodegradable composites

to biomedical composites for drug/gene delivery, tissue engineering

applications and cosmetic orthodontics, they often mimic the structures of the

living materials involved in the process in addition to the strengthening

properties of the matrix that was used but still providing bio

compatibility. Bio-composites are characterized by the fact that the bolsters

(glass or carbon fiber or talc) are replaced by bio fiber (wood fibers, hemp, flax,

sisal, jute...). These bio/bio- fiber composites (bio-Composites) are

emerging as a viable alternative to glass-fiber reinforced composites

especially in automotive and building product applications. The combination of

bio-fibers such as kenaf, hemp, flax, jute, henequen, pineapple leaf fiber, and

sisal with polymer matrices from both nonrenewable and renewable resources

to produce composite materials that are competitive with synthetic composites

requires special attention. Bio fiber–reinforced polypropylene composites have

attained commercial attraction in automotive industries. Bio fiber-

polypropylene or bio fiber- polyester composites are not sufficiently eco-

friendly because of the petroleum-based source and the non-biodegradable

nature of the polymer matrix. Using bio fibers with polymers based on

renewable resources will allow many environmental issues to be solved. By

embedding bio-fibers with renewable resource–based biopolymers such as

cellulosic plastics; polylactides; starch plastics; polyhydroxyalkanoates

(bacterial polyesters); and soy-based plastics, the so-called green bio-

composites are continuously being developed.

1.8 Bio Fibers

Bio fibers have recently attracted the attention of scientists and

technologists because of the advantages that these fibers provide over

conventional reinforcement materials, and the development of bio fiber

composites has been a subject of interest for the past few years. These bio fibers

have low-cost with low density and high specific properties. These are

biodegradable and nonabrasive, unlike other reinforcing fibers. Also, they are

readily available and their specific properties are comparable to those of other

fibers used for reinforcements. However, certain drawbacks such as

incompatibility with the hydrophobic polymer matrix, the tendency to form

aggregates during processing, and poor resistance to moisture limit the potential

of bio-fibers to be used as reinforcement in polymers. Another important aspect

is the thermal stability of these fibers. These fibers are lingo-cellulosic and

consist of mainly lignin, hemi-cellulose, and cellulose. The cell walls of the

fibers undergo pyrolysis with increasing processing temperature and contribute

to char formation. These charred layers help to insulate the lingo- cellulosic

from further thermal degradation. Since most thermoplastics are processed at

high temperatures, the thermal stability of the fibers at processing temperatures

is important. Thus the key issues in development of bio reinforced composites

are

(i) Thermal stability of the fibers,

(ii) Surface adhesion characteristics of the fibers, and

(iii) Dispersion of the fibers in the case of thermoplastic composites.

1.9 Types of Bio Fibers

Bio fibers are grouped into three types: seed hair, bast fibers, and leaf fibers,

depending upon the source. Some examples are cotton (seed hairs), ramie, jute,

and flax (bast fibers), and sisal and abaca (leaf fibers). Of these fibers, jute,

ramie, flax, and sisal are the most commonly used fibers for polymer

composites. On the basis of the source which they are derived from bio fibers

can also be grouped as:

a) Fibers obtained from plant/vegetable. (cellulose: sisal, jute, abaca,

bagasse)

b) Fibers obtained from mineral. (minerals: asbestos)

c) Fibers derived from animal species. (sheep wool, goat hair, cashmere,

rabbit hair, angora fiber, horse hair, human hair)

d) Fibers from bird / aqueous species. (feather, sea snels etc.)

Numerous reports are available on the bio fiber composites. The research

works on development of bio/bio-fiber reinforced polymer composites have

been extensively reviewed also. Many researchers have been conducted to study

the mechanical properties, especially interfacial performances of the

composites based on bio fibers due to the poor interfacial bonding between the

hydrophilic bio fibers such as sisal, jute and palm fibers and the hydrophobic

polymer matrices.

1.10 Mechanical Properties of Bio Fibers

The tensile strength of glass fibers is substantially higher than that of

bio fibers even though the modulus is of the same order. However, when

the specific modulus of bio fibers (modulus/specific gravity) is considered,

the bio fibers show values that are comparable to or better than those of glass

fibers. These higher specific properties are one of the major advantages of using

bio fiber composites for applications wherein the desired properties also include

weight reduction.

Table 1.10 Mechanical Properties of Bio Fibers (Source Ref. 9).

1.11 Matrix Resins

Thermosets Vs Thermoplastics

Nowadays both thermoplastic and thermosetting resins are used as

matrices for composites. Each type exhibits particular advantages and

disadvantages with respect to processability and service performance, as

illustrated in Table 1.11. Although a wide range of different chemistries exists

within each type, some general features can be distinguished, which have

determined their area of application.

Table 1.11a Property/process characteristics for thermoplastic and thermosetting matrix

systems.

Some of the basic properties of selected thermoset and thermoplastic

resins are shown in Table 1.11b and Table 1.11c, respectively.

Table 1.11b Typical unfilled thermosetting resin properties (Mazumdar, 2002, p. 48).

In general the crosslinked structure of thermosetting polymers provides

potential for higher stiffness and service temperatures than thermoplastics. The

upper limit of service temperature for advanced composites is most often

determined by the glass transition temperature.

On the other hand, toughness and elongation to break may be

considerably for thermoplastic resins. This may be a particular advantage in

applications where impact strength is a major requirement. Most high-

performance thermoplastics offer outstanding interlaminar fracture toughness

and acceptable post-impact compression response. This feature of thermoplastic

materials has been the major reason for their increased use in composite

structures.

Table 1.11c Typical unfilled thermoplastic resin properties (Mazumdar, 2002, p. 53).

From a processing viewpoint, the high melt viscosities of thermoplastics

generally create considerable difficulties during fiber wet-out and impregnation.

Thus, thermoplastic based composites generally require higher processing

temperatures and pressures to ensure sufficient flow during the final forming

process.

The higher processing temperatures and pressures needed for the forming

of thermoplastic-based composites generally impose stricter requirements on

the processing equipment, and more advanced engineering is needed

for tool construction. The higher processing temperatures may also induce

considerable difficulties in mismatch of thermal contraction between the matrix

and fibers during the processing cycle.

The longer relaxation times for thermosetting materials may be a

disadvantage, due to a reduced ability to relax process-induced internal stresses.

In anisotropic composites in particular, the potential of the polymer to relax

internal stress fields is important for the elimination of process-induced defects.

Such defects, in the form of voids, microcracking, fiber buckling, warpage, and

residual stresses may diminish the durability and long-term performance of the

composite.

Thermoplastic-based composites offer potential for lower conversion

costs from intermediate material forms into final end-use parts by process

automation. Furthermore, thermoplastics also offer the advantage of having

almost indefinite storage life, which facilitates the logistics of the

manufacturing procedure.

Finally, thermoplastics may be post formed and/or reprocessed by the

reapplication of heat and pressure, which gives a potential for recyclability. The

increased awareness, in these last years, about material Recyclability has

brought about a heightened interest in thermoplastic matrix composites,

especially in large volume areas such as the automobile industry.

Chapter 2

Literature Review

Chapter 2

Literature Review

During the last decades, particulates with fibers and fillers features so

called reinforce plastics are utilized to improve the physical and mechanical

properties of polymers and composites. Among the natural, inorganic and

organic fibers and fillers have been widely studied. In this study, keratin fiber

(human hair) use as organic natural fibers. Both filler and fiber are low cost,

higher thermal stability, excellent mechanical properties and abundance

provoked us to use these with plastics material. Natural fibers have received

much attention as reinforcing materials for polymers because of their

potentially high aspect ratio and unique intercalation / exfoliation

characteristics. Keratin fiber based composites has the lower density and good

mechanical properties as compare to material. Keratin fiber enhance mechanical

properties like impact, tensile, fracture etc, and reduce density.

2.1 Natural Bio-Fiber Reinforced Composites

Synthetic fibers such as glass, nylon, carbon, Kevlar and boron are

generally used to make composite materials for specific purposes even though

they are expensive and are non-renewable resources. This is because of their

very high specific strength properties which do not deteriorate appreciably with

time. On the other hand, there is a growing interest in the development of new

materials which enhance optimal utilization of natural resources, and

particularly, of renewable resources. The natural fibers like Keratin, cotton, jute

and sisal have also attracted the attention of scientists and technologists for

applications in consumer goods, low cost housing and civil structures where the

prohibitive cost of synthetic fibers restricts their use. These natural fiber

composites possess characteristic properties such as high electrical and impact

resistance, good thermal and acoustic insulating properties and high work of

fracture in addition to specific strengths comparable to synthetic fiber

reinforced polymer composites. Accordingly, manufacturing of high-

performance engineering materials from renewable resources has been pursued

by researchers across the world owning to renewable raw materials are

environmentally sound and do not cause health problem.

It is known that natural fibers are non-uniform with irregular cross

sections which make their structures quite unique and much different with man-

made fibers such as glass fibers, carbon fibers etc. Saheb and Jog have

presented a very elaborate and extensive review on the reported work on natural

fiber reinforced composites with special reference to the type of fibers, matrix

polymers, treatment of fibers and fiber-matrix interface. Many researchers have

been conducted to study the mechanical properties.

The matrix phase plays a crucial role in the performance of polymer

composites. Both thermosets and thermoplastics are attractive as matrix

materials for composites. In thermoset composites, formulation is complex

because a large number of components are involved such as base resin, curing

agents, catalysts, flowing agents, and hardeners. These composite materials are

chemically cured to a highly cross-linked, three-dimensional network structure.

These cross-linked structures are highly solvent resistant, tough, and creep

resistant. The fiber loading can be as high as 80% and because of the alignment

of fibers; the enhancement in the properties is remarkable. Thermoplastics offer

many advantages over thermoset polymers. One of the advantages of

thermoplastic matrix composites is their low processing costs. Another is design

flexibility and ease of molding complex parts. Simple methods such as

extrusion and injection molding are used for processing of these composites. In

thermoplastics most of the work reported so far deals with polymers such as

polyethylene, polypropylene, polystyrene, and poly (vinyl chloride). This is

mainly because the processing temperature is restricted to temperatures below

200ºC to avoid thermal degradation of the natural fibers. For thermoplastic

composites, the dispersion of the fibers in the composites is also an important

parameter to achieve consistency in the product.

Thermoplastic composites are flexible and tough and exhibit good

mechanical properties. However, the percentage of loading is limited by the

process ability of the composite. The fiber orientation in the composites is

random and accordingly the property modification is not as high as is

observed in thermoset composites. Properties of the fibers, the aspect ratio of

the fibers, and the fiber–matrix interface govern the properties of the

composites. The surface adhesion between the fiber and the polymer plays an

important role in the transmission of stress from matrix to the fiber and thus

contributes toward the performance of the composite. Another important aspect

is the thermal stability of these fibers. Since most thermoplastics are processed

at high temperatures, the thermal stability of the fibers at processing

temperatures is important. Thus the key issues in development of natural

reinforced composites are

(i) Thermal stability of the fibers,

(ii) Surface adhesion characteristics of the fibers,

(iii) Dispersion of the fibers in the case of thermoplastic composite.

2.2 Keratin fiber

Hair is composed of proteins, lipids, water, and small amounts of trace

elements. All proteins in animal and human bodies are built from permutations

of amino acid molecules in a polypeptide string. The polypeptide chains of

protein keratin are organized into filaments in hair cells. Hair is one of the most

difficult proteins to digest or solubilize. Among the most common dissolving

procedures for hair are acidic, alkaline, and enzymatic hydrolysis. For the

analysis of hair, the solid samples are transferred by solubilization via digestion

into a liquid phase. Small molecular solvents and molecules with hydrophobic

groups appear to have higher affinity for hair. A good solvent attacks the

disulfide bonds between cystine molecules and hydrates the hair shaft.

Consequently, the hair becomes a jelly-like mass.

2.3 Structure and Properties

Hair is a biological material consisting of polypeptide chains of keratin

arranged into filaments. In most mammals, hair increases the sensitivity of the

skin surface and forms an insulating and protective coat. Hair reduces heat loss

from the body and often provides camouflage. For humans, hair is important

only for personal adornment and display. In lower animals (e.g., insects), hairs

(whiskers) have a sensory function. Some stems, leaves, and plants also possess

hairs on their roots. Hair is a complex tissue and grows from the hair follicle

embedded in the inner layer (dermis) in the skin where the germination center is

formed by matrix cells that are in active build-up to layers of the hair shaft,

including the cuticle, cortex, and medulla. The cortex forms the bulk of the hair

shaft and is located immediately beneath the cuticle. The medulla is the

innermost region of hair and consists of scattered cells and hollow space.

Human hair is not homogeneous. In the outer layers of hair, the surface

composition may vary rapidly.

Figure 2.3 Structure of hair at various length-scales: (a) filament protein with globular end

group and alternating helical/linker sections; (b) coiled coil of filament proteins; (c)

intermediate filament with 16 coils; (d) filament embedded in matrix; (e) macrofibril; (f)

cortical call enclosed by cell-membrane complex; (g) cross-section of a hair fiber with cells,

nuclear remnants and pigment granules, enclosed by the cuticle.

The basic elemental composition of hair is:

49.0% carbon

14.5% nitrogen

30.0% oxygen

3.0% sulfur

Trace elements barium, calcium, chromium, copper, iron, manganese,

nickel, lead, titanium, zinc

Hair is a poor electrical and thermal conductor. Hair densities vary from

1.3 to 1.47 g/cm3. Hair diameters have a mean and standard deviation of 67.1 ±

12.0 μm. Protein keratin is made up of chains of amino acids, especially

arginine, cystine, and serine. As noted above, the softer keratins occur in the

external layers of skin, hair, wool, and feathers, while the harder types

constitute nails, claws, and hoofs.

The polypeptide chains of keratin are organized into filaments in hair

cells. Keratin gives a characteristic diffraction pattern. This pattern shows that

hair and wool possess a repeating structural unit along the long axis of the hair.

Consequently, the polypeptide chains in the fibrous proteins are coiled in some

regular way. Four kinds of fibrous proteins (keratins, collagen, and elastin) are

responsible for the structure of cells, tissues, and organisms. The chief

structural component of hair is protein keratin. Keratin in the cortex comprises

85% or more of the mass of the hair shaft. Cortical keratin is composed of two

types of structural proteins: matrix and fibrous. Matrix proteins have a high

sulfur content and contain polypeptides with a molecular weight of

approximately 10–28 kDa. The sulfur content of human hair is high compared

with other animal species. Fibrous proteins are embedded in matrix proteins and

are characterized by a low sulfur content.

Two types of proteins can be classified according to their

structure/shapes: fibrous and globular. The fibrous proteins are long and stringy

molecules with the polypeptide chains extended along one axis rather than

folded into a globular shape. In globular proteins, the polypeptide chains are

tightly folded into compact spherical or globular shapes. Nearly all enzymes,

antibodies, and blood transport proteins are globular proteins. The hydrophilic

or polar groups of globular proteins are exposed on the outer surface and

therefore are soluble in water, e.g., serum albumin.

2.4 Polymer Keratin based Fiber Composite

Polymer composites are widely used in areas of automotive, aerospace,

construction, and electronic industries because of their improved mechanical

(e.g., stiffness, strength) and physical properties over pure polymers. These

composites are made using micron-sized particulates and long fibers to

reinforce the weak polymer matrices. In recent years polymer composites have

drawn a great deal of interest because of a high potential of achieving property

improvement by a small addition of nanoparticles in the polymer matrices.

Furthermore, this significant improvement in variety of properties is achieved

without sacrificing the lightweight of polymer matrices.

Essentially, this technology can be used in any application where

improving polymer properties would be of value – either by improving existing

materials or by reducing the amount of material required to match current

physical capabilities.

Future developments include:

• Adapting the technology for different types of polymers;

• Biodegradable composites;

• Self-healing materials; and

• Potential use for electrical purposes. Many of the electrical and conductive

properties of keratin have not been explored in detail but our work so far

indicates.

Chapter 3

Materials and Methods

Chapter 3

Materials and Methods

This chapter describes the materials and methods used for the processing

of the composites under this investigation.

3.1 Matrix material

3.1.1 Low-Density Polyethylene (LDPE)

LDPE is a semi-rigid, translucent material, and was the first of the

polyethylene to be developed. It is primarily used at ‘normal’ operating

temperatures. Its qualities include toughness, flexibility, resistance to chemicals

and weather, and low water absorption. It is easily processed by most methods

and has a low cost. It is also resistant to organic solvents at room temperature.

Its use is not advisable in situations where extreme temperatures are found. It is

a corrosion-resistant, low density extruded material that provides low moisture

permeability. LDPE has a fairly low working temperature, soft surface, and low

tensile strength. It is an excellent material where corrosion resistance is an

important factor, but stiffness, high temperature, and structural strength are not

important considerations.

LDPE resins are re-emerging as a valuable product family, combining

superior clarity with a stiffness and density favoured by converters for down

gauging. Ease of processing beyond most linear low-density PE (LLDPE)

resins, combined with improved product performance, continues to give cost-

competitive solutions to converters in a wide variety of fi lm applications.

These range from complex food packaging structures to shopping bags, coated

paperboards, liners, overwraps, consumer bags, heavy-duty sacks, clarity shrink

and collation films, lamination films, agricultural films, extrusion coatings, caps

and closures, and a variety of durable products such as power cables and toys.

In packaging applications Dow LDPE resins offer excellent aesthetics,

printability, strength, tear resistance, and elasticity. In cost-sensitive health and

hygiene markets LDPE resins can improve processing efficiencies, and can be

used for wire, cable, pipes, and other goods.

LDPE is lightweight and formable, has a high impact resistance and

excellent electrical properties, and is machinable and weldable. LDPE can be

processed by all conventional methods: hot gas welded fusion and butt welded,

ultrasonically sealed, die cut, machined with wood- or metal-working tools,

vacuum formed, and thermoformed. The long side-chain branching of the

LDPE molecules produces a more amorphous polymer having a lower melting

point and higher clarity compared to LLDPE. LDPE is also differentiated from

LLDPE by poorer physical properties as regards tensile strength, puncture and

tear resistance, and elongation. LDPE has very good flow behaviour and

excellent resistance to chemicals. It is flexible and tough at low temperatures,

transparent in thin films, and has very good environmental stress crack

resistance (ESCR). UV-stabilized LDPE is used in agricultural/building

components and sheeting film.

The disadvantages of LDPE are its low strength, stiffness, and maximum

operating temperature, flammability, poor UV resistance, high gas permeability

(particularly CO2), and susceptibility to environmental stress cracking.

3.1.2 High-Density Polyethylene (HDPE)

HDPE is more rigid and harder than lower density materials with a

molecular weight below 300,000 g/mol. It also has a high tensile strength and

has high compressive strength.

The extremely high molecular weight of HDPE combined with its very

low coefficient of friction produces an excellent abrasion-resistant product

which is resistant to gouging, scuffing, and scraping. HDPE has exceptional

impact strength, being one of the best impact-resistant thermoplastics available,

and has excellent machinability and self-lubricating characteristics. Its

properties are maintained even at extremely low temperatures. HDPE has stress

cracking resistance and very good chemical resistance to corrosives (with the

exception of strong oxidizing acids at elevated temperatures). Certain

hydrocarbons cause only a light surface swelling at moderate temperature.

Moisture and water (including saltwater) have no affect on HDPE. It can be

used in freshwater and saltwater immersion applications. HDPE can be hot gas

welded, fusion and butt welded, ultrasonically sealed, die cut, machined with

wood- or metalworking tools, vacuum formed, and thermoformed.

Representing the largest portion of PE applications, HDPE offers

excellent impact resistance, is of low weight, has low moisture absorption, and

has high tensile strength. HDPE is stronger and stiffer but its impact strength is

not as good at low temperatures. It is also more prone to warpage due to its

higher crystallinity, which makes it very sensitive to differential cooling rates

across the walls of rotomoulded products. HDPE also has higher shrinkage than

LDPE.

HDPE does have certain disadvantages. It is susceptible to stress

cracking, has lower stiffness compared to polypropylene (PP), high mold

shrinkage, and poor UV resistance. It is also available in a UV-stabilized form

that has better UV resistance, but the tensile strength and elongation at break

are reduced compared with unmodified HDPE. HDPE may give off dangerous

fumes if strongly heated and dense smoke is formed when it burns. Dust can be

an irritant to the eyes, skin, and respiratory system.

3.2 Composite Processing

3.2.1 Compression Molding

Compression molding is a method of molding in which the molding

material, generally preheated, is first placed in an open, heated mold cavity. The

mold is closed with a top force or plug member, pressure is applied to force the

material into contact with all mold areas, while heat and pressure are

maintained until the molding material has cured. The process employs

thermosetting resins in a partially cured stage, either in the form of granules,

putty-like masses, or preforms. Compression molding is a high-volume, high-

pressure method suitable for molding complex, high-strength fiberglass

reinforcements. Advanced composite thermoplastics can also be compression

molded with unidirectional tapes, woven fabrics, randomly oriented fiber mat or

chopped strand. The advantage of compression molding is its ability to mold

large, fairly intricate parts. Also, it is one of the lowest cost molding methods.

However, compression molding often provides poor product consistency

and difficulty in controlling flashing, and it is not suitable for some types of

parts. Fewer knit lines are produced and a smaller amount of fiber-length

degradation is noticeable when compared to injection molding. Compression-

molding is also suitable for ultra-large basic shape production in sizes beyond

the capacity of extrusion techniques.

Chapter 4

Experimental Details & Result

Chapter 4

Experimental Details & Result

4.1 Tensile Test of 0.5 mm Thick LDPE Sheet prepared by

Reinforcing Keratin Fiber (Human Hair)

Testing standard-ASTM D 882

Significance and Use

Tensile properties determined by this test method are of value for the

identification and characterization of materials for control and specification

purposes. Tensile properties can vary with specimen thickness, method of

preparation, speed of testing, type of grips used, and manner of measuring

extension. Consequently, where precise comparative results are desired, these

factors must be carefully controlled. This test method shall be used for referee

purposes, unless otherwise indicated in particular material specifications. For

many materials, there can be a specification that requires the use of this test

method, but with some procedural modifications that take precedence when

adhering to the specification.

Tensile properties can be utilized to provide data for research and

development and engineering design as well as quality control and

specification. However, data from such tests cannot be considered significant

for applications differing widely from the load-time scale of the test employed.

The tensile modulus of elasticity is an index of the stiffness of thin plastic

sheeting. The reproducibility of test results is good when precise control is

maintained over all test conditions. When different materials are being

compared for stiffness, specimens of identical dimensions must be employed.

The Tensile Energy to Break (TEB) is the total energy absorbed per unit

volume of the specimen up to the point of rupture. In some texts this property

has been referred to as toughness. It is used to evaluate materials that are

subjected to heavy abuse or that can stall web transport equipment in the event

of a machine malfunction in end-use applications. However, the rate of strain,

specimen parameters, and especially flaws can cause large variations in the

results. In that sense, caution is advised in utilizing TEB test results for end-use

design applications. Materials that fail by tearing give anomalous data which

cannot be compared with those from normal failure.

Scope

1.1 This test method covers the determination of tensile properties of Plastics

in the form of thin sheeting and films (less than 1.0 mm (0.04 in.) in thickness).

Note 1—Film is defined in Terminology D883 as an optional term for sheeting

having a nominal thickness no greater than 0.25 mm (0.010 in.).

Note 2—Tensile properties of plastics 1.0 mm (0.04 in.) or greater in thickness

shall be determined according to Test Method D638.

1.2 This test method can be used to test all plastics within the thickness range

described and the capacity of the machine employed.

1.3 Specimen extension can be measured by grip separation, extension

indicators, or displacement of gage marks.

1.4 The procedure for determining the tensile modulus of elasticity is

included at one strain rate.

Note 3-The modulus determination is generally based on the use of grip

separation as a measure of extension; however, the desirability of using

extensometers, is recognized and provision for the use of such instrumentation

is incorporated in the procedure.

1.5 Test data obtained by this test method is relevant and appropriate for use

in engineering design.

1.6 The values stated in SI units are to be regarded as the standard. The

values in parentheses are provided for information only.

1.7 This standard does not purport to address all of the safety concerns, if

any, associated with its use. It is the responsibility of the user of this standard to

establish appropriate safety and health practices and determine the applicability

of regulatory limitations prior to use.

Note 4—this test method is similar to ISO 527-3, but is not considered

technically equivalent. ISO 527-3 allows for additional specimen

configurations, specifies different test speeds, and requires an extensometer or

gage marks on the specimen.

Sample Size for the test sample:

There were four samples out of which three samples are being prepared

by reinforcing hair and one sample is a standard sample for comparison of

tensile and other properties:

S. No. Thickness (mm) Width (mm) Length (mm)

1 0.35 25 150

2 0.24 25 150

3 0.32 25 150

4 0.22 25 150

Specimen Preparation

The specimen is prepared by laying the hair one by one into the plastic

sheet of LDPE. There is no particular gap between two hairs. The hairs are

being arranged in the longitudinal direction. After laying the hair the next step

is to compress the sheet in pneumatic compression molding machine. The

temperature which is set is 180˚C. The sheet is compressed into the machine for

ten minutes and then taken out and the samples of prescribed dimensions are cut

by the cutter.

Machine Used

1. Compression Molding

2. Cutter

Pictures of prepared samples are given below

Sample 1

Fig. 4.1a

Sample 2

Fig. 4.1b

Sample 3

Fig. 4.1c

Sample 4

fig. 4.1d

Procedure Used

The samples are tested in universal testing machine. Two marks of each

50 mm made from both side for gripping the specimen in UTM. The specimens

are then attached in the UTM machine for testing. The operating speed of

machine is 50mm/min .by minutely viewing it can be seen that the load is first

transferred to the keratin (human hair) fiber and then to the sheet. Since these

hairs are embedded into the sheet the hair break in the alignments direction and

then the sheet got stretched.

Data

The following calculations can be made from tensile test results

1. Tensile strength (at yield and at break)

2. Tensile modulus

3. Strain

4. Elongation and percent elongation at yield

5. Elongation and percent elongation at break

The results of the tested samples are as follows

S. No.

Max. Load

Tensile Strength

(PSi)

Modulus (Automatic)

(MPa)

Tensile at Max.

Erosion (%)

Tensile strain at

Max. Load (%)

Speed (mm/min)

1. 68.23 7.8 76.41 366.31 43.49996 50

2. 40.88 6.81 145.84 87.83985 16.33353 50

3. 82.31 10.29 105.66 160.5266 44.16673 50

4. 49.27 8.96 109.24 158.21327 62.16672 50

-20

0

20

40

60

80

-10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190

Load

(N)

Extension (mm)

Specimen 1 to 1

Specimen #

1

-20

0

20

40

60

0 10 20 30 40 50

Load

(N)

Extension (mm)

Specimen 2 to 2

Specimen #

2

-50

0

50

100

-10 0 10 20 30 40 50 60 70 80 90

Load

(N)

Extension (mm)

Specimen 3 to 3

Specimen #

3

-20

0

20

40

60

0 10 20 30 40 50 60 70 80

Load

(N)

Extension (mm)

Specimen 4 to 4

Specimen #

4

S. No. Data Avg. values of Hair reinforced

sheet

Avg. values of sheet w/o Hair

1. Max. Load (N) 63.80 49.27

2. Tensile Strength (PSi)

8.3 8.96

3. Modulus 109.30 109.24

4. Tensile Strain at Max. Extension

(%)

204.80 158.213

5. Tensile Strain at Max. Load (%)

34.66 62.1672

6. Speed 50 50

Thus from the compared data it is clear that after reinforcing the keratin

fiber of length 15 mm, the values of load, modulus, tensile strain at maximum

extension got increased by a considerable amount. And the load is first

transferred to the hair which break at some stage of stretching of the sheet and

the main load is transferred to the sheet after breaking of the hairs.

4.2 Tensile Test of the Plastic Sheet (3-4 mm) Thick made from

HDPE Material reinforced with disintegrated Human Hair

Standard- ASTM D638

Scope

Tensile tests measure the force required to break a specimen and the

extent to which the specimen stretches or elongates to that breaking point.

Tensile tests produce a stress-strain diagram, which is used to determine tensile

modulus. The data is often used to specify a material, to design parts to

withstand application force and as a quality control check of materials. Since

the physical properties of many materials (especially thermoplastics) can vary

depending on ambient temperature, it is sometimes appropriate to test materials

at temperatures that simulate the intended end use environment.

Test Procedure

Specimens are placed in the grips of the Instron at a specified grip

separation and pulled until failure. For ASTM D638 the test speed is

determined by the material specification. For ISO 527 the test speed is typically

5 or 50mm/min for measuring strength and elongation and 1mm/min for

measuring modulus. An extensometer is used to determine elongation and

tensile modulus.

Elevated or Reduced Temperature Test Procedure

A thermal chamber is installed on the Instron universal test machine. The

chamber is designed to allow the test mounts from the base and crosshead of the

Instron to pass through the top and bottom of the chamber. Standard test

fixtures are installed inside the chamber, and testing is conducted inside the

controlled thermal environment the same as it would be at ambient temperature.

The chamber has internal electric heaters for elevated temperatures and uses

external carbon dioxide gas as a coolant for reduced temperatures. The size of

the chamber places a limitation on the maximum elongation that can be

reached, and extensometers are generally limited to no more than 200° C.

Specimen Size

The most common specimen for ASTM D638 is a Type I tensile bar.

Whose dimensions are as per standard, and is being prepared by punch die.

Data

The following calculations can be made from tensile test results:

1. Tensile Strength (at yield and at break)

2. Tensile Modulus

3. Strain

4. Elongation and % Elongation at yield

5. Elongation and % Elongation at break

Machine used in the Preparation of Sample

The machine used in the preparation of material for specimen is two toll mill .the material preparation conditions are given below:

1. Two Roll Mill

Front roll mill temp-180˚C

Load - 1.4 rpm

S .V- 15.0

P.V- 15.0

Rear roll mill temp- 200˚C

Load - 1.5 rpm

S.V-12.0

P.V- 12.0

Nip Gap (roll gap): 0.58 mm

1: Extensometers

2: Instron Universal Tester

Procedure

A fixed amount of material is taken (200 gm) and taken in two roll mill in order to melt the material and also to disperse the hair of size about 1mm. The conditions used or employed are given above.

S. No. Wt. of HDPE (gm) % of Hair

1. 200 1

2. 200 0

After proper dispersion of disintegrated hair the material is being ready

for preparing for the sheet. The sheet is prepared by compression molding at a

temperature of 180ºC. When the sheet is prepared then the final testing sample

are cut with the help of punch and die assembly.

Test Details

Results of Tensile Test of Hair Reinforced HDPE Material

S. No.

Max. Load (N)

Tensile Strength (MPa)

Modulus (Automatic)

(MPa)

Tensile Strain at

Max. Extension

(%)

Tensile Strain at

Max. Load (%)

Speed (mm/min)

Tensile Stress at

Yield (Zero slope) (MPa)

1. 515.10 22.36 449.56 688.85932 14.66589 50 22.35693

2. 481.79 24.11 472.22 170.04633 14.33346 50 24.11366

3. 693.49 24.08 414.21 160.00697

1

16.66668 50 24.07948

4. 686.55 23.69 417.11 60.31994 16.33353 50 22.35693

Graphs for the Tests

Sample 1

-200

0

200

400

600

-10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180

Load

(N)

Extension (mm)

Specimen 34 to 34

Specimen #

34

Sample 2

-200

0

200

400

600

-10 0 10 20 30 40 50

Load

(N)

Extension (mm)

Specimen 37 to 37

Specimen #

37

Sample 3

0

200

400

600

800

-10 0 10 20 30 40 50

Load

(N)

Extension (mm)

Specimen 36 to 36

Specimen #

36

Sample 4

0

200

400

600

800

-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Load

(N)

Extension (mm)

Specimen 35 to 35

Specimen #

35

The sample number 1 & 2 are the samples which are hair reinforced and

sample number 3&4 are the samples which are prepared by pure HDPE

material. The thicknesses of samples are given below:

Sample 1. 3.84 mm

Sample 2. 3.33 mm

Sample 3. 4.805 mm

Sample 4. 4.83 mm

Comparission of Values

S. NO. Data Avg. Value for Sample w/o Hair

Avg. Value for Sample with

Hair1. Maximum Load (N) 498.44 690.02

2. Tensile Strength (MPa) 23.235 23.885

3. Modulus (Automatic) (MPa) 460.89 415.66

4. Tensile strain at Maximum

Extension (%)

429.44 110.16

5. Tensile strain at Maximum

Load (%)

14.49967 16.50554

6. Speed (mm/min) 50 50

7. Tensile stress at Yield

(Zero Slope) (MPa)

23.235 23.250

Thus from above compared results it is clear that the value of maximum

load, tensile strength and tensile strain at maximum load got increased in the

case of hair reinforced composite with HDPE material. While the value of

tensile stress at yield remained almost constant and the value of modulus and

tensile strain at maximum extension got decreased in the case of reinforced hair

composite.

4.3 Flexural Test of Reinforced Sheet of HDPE Material

Standard- ASTM D790

Scope

The flexural test measures the force required to bend a beam under three

point loading conditions. The data is often used to select materials for parts that

will support loads without flexing. Flexural modulus is used as an indication of

a material’s stiffness when flexed. Since the physical properties of many

materials (especially thermoplastics) can vary depending on ambient

temperature, it is sometimes appropriate to test materials at temperatures that

simulate the intended end use environment.

Test Procedure

Most commonly the specimen lies on a support span and the load is

applied to the center by the loading nose producing three point bending at a

specified rate. The parameters for this test are the support span, the speed of the

loading, and the maximum deflection for the test. These parameters are based

on the test specimen thickness and are defined differently by ASTM and ISO.

For ASTM D790, the test is stopped when the specimen reaches 5% deflection

or the specimen breaks before 5%. For ISO 178, the test is stopped when the

specimen breaks. Of the specimen does not break, the test is continued as far a

possible and the stress at 3.5% (conventional deflection) is reported.

Elevated or Reduced Temperature Test Procedure

A thermal chamber is installed on the universal test machine. The

chamber is designed to allow the test mounts from the base and crosshead of the

universal tester to pass through the top and bottom of the chamber. Standard

test fixtures are installed inside the chamber, and testing is conducted inside the

controlled thermal environment the same as it would be at ambient temperature.

The chamber has internal electric heaters for elevated temperatures and uses

external carbon dioxide gas as a coolant for reduced temperatures.

Specimen Size

A variety of specimen shapes can be used for this test, but the most

commonly used specimen size for ASTM is 3.2 mm x 12.7 mm x 125 mm

(0.125" x 0.5" x 5.0") and for ISO is 10 mm x 4 mm x 80 mm.

Data

Flexural stress at yield, flexural strain at yield, flexural stress at break,

flexural strain at break, flexural stress at 3.5% (ISO) or 5.0% (ASTM)

deflection, flexural modulus. Stress/Strain curves and raw data can be provided.

Equipment Used

1. Universal Tester

2. Flexural test fixtures

Procedure for Sample Preparation

The sheet which is used for preparing the tensile test is also used for

preparing the flexural test sample.

A fixed amount of material is taken (200 gm) and taken in two roll mill

in order to melt the material and also to disperse the hair of size about 1mm.the

conditions used or employed are given above.

S. No. Wt. of HDPE (gm) % of Hair

1. 200 1

2. 200 0

After proper dispersion of disintegrated hair the material is being ready

for preparing for the sheet. The sheet is prepared by compression molding at a

temperature of 180ºC. When the sheet is prepared then the final testing sample

are cut with the help of punch and die assembly.

Test Details

S. No. Max. Flexural

Load

Modulus (Automatic) (MPa) Flexural Stress at Max. Flexure

Load (MPa)1. 52.15 737.56835 20.41042

2. 53.45 756.14239 20.91792

3. 37.91 861.05640 21.38298

4. 41.63 877.53622 23.48303

Graphs of Flexural Test

Sample 1

0

2

4

6

0 1 2 3 4 5 6 7 8 9 10 11

Flex

ure

load

(kg

f)

Flexure extension (mm)

Specimen 1 to 1

Specimen #

1

Sample 2

0

2

4

6

0 1 2 3 4 5 6 7 8 9 10 11

Flex

ure

load

(kgf

)

Flexure extension (mm)

Specimen 2 to 2

Specimen #

2

Sample 3

-1

0

1

2

3

4

0 1 2 3 4 5 6 7 8

Flexu

re lo

ad (k

gf)

Flexure extension (mm)

Specimen 3 to 3

Specimen #

3

Sample 4

0

1

2

3

4

5

0 1 2 3 4 5 6 7 8

Flexu

re lo

ad (k

gf)

Flexure extension (mm)

Specimen 4 to 4

Specimen #

4

The sample number 1 & 2 are the samples which are hair reinforced and

sample number 3&4 are the samples which are prepared by pure hdpe material.

The thicknesses of samples are given below:

Sample 1. 4.83 mm

Sample 2. 4.68 mm

Sample 3. 3.35 mm

Sample 4. 3.40 mm

The length and width of the sample are as per the standard.

Comparison of Values

S. No. Data l Avg. Value for w/o

Hair HDPE

Material

Avg. Value for w/o

Hair Reinforced

HDPE Material

1. Max. Flexure

Load (N)

39.77 52.80

2. Modulus

(Automatic)

(MPa)

869.29631 746.85537

3. Flexure Stress at

Max. Flexure

Load (MPa)

22.43305 20.66417

From the above results it can be seen that the maximum flexure load

wear by the virgin material i.e. HDPE is 39.77 and by the composite prepared

by reinforcing 1% keratin fiber(human hair) material is 52.80.thus it is clear

that the flexure load wearing capacity of reinforced material is more as

compared to virgin material.

The value for modulus of the virgin material is more than that of

reinforced composite and also the flexure stress at maximum flexure load is

also more than that of with hair composite.

Chapter 5

CONCLUSIONS

Chapter 5

CONCLUSIONS

5.1 Conclusions

The experimental investigation and statistical analysis on Keratin fiber

reinforced HDPE matrix composites has led to the following conclusions:

Keratin fibers (Human Hair) bears high aspect ratio and hence are good

reinforcement material for fabrication of randomly oriented short fiber

reinforced HDPE composites. By incorporating Keratin fiber, density of the

composites decreases and possess very low amount of porosity. However,

Flexural strength and hardness of these composite increases with weight % of

feather fiber, but not aggressively.

5.2 Recommendation for Future Work

The present work leaves a wide scope for future investigators to explore

many other aspects of bio-fiber reinforced polymer composites. Some

recommendations for future areas of research include:

1. To increase mechanical strength of these composites for their use in

different sectors can be studied.

2. Environmental study of Keratin fiber reinforced polymer composites i.e.

the effect of different environmental conditions like alkaline medium,

acidic medium, freezing temperature etc. on the properties and/or

degradation of these composites is to be evaluated.

3. Possible use of other fibers/flakes obtained from bio-wastes in the

development of new composites.

4. Other polymers can be tried as the matrix material for fabrication of

Human Hair reinforced composites.

References

1. Brown J. R. and Mathys Z., (1997). “Reinforcement and matrix effects on the combustion properties of glass reinforced polymer composites”, Composites Part A: Applied Science and Manufacturing. Vol. 28, Issue 7, pp: 675-681.

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