cassava

Cassava starch as an effective component

for Ideal Biodegradable Plastics

An Investigatory Project submitted to

the High School Department of

St. Paul College, Pasig

in partial fulfillment of the

requirements in Chemistry

Submitted by:

Group Number 9

Dianne Marie C. Roxas

Karla Angela P. Sese

Jannica Sibal

Mariel P. Sta. Ana

Teacher: Ms. Mendiola

Date of Submission: December 7, 2009

Abstract

The purpose of this experiment is to be able to help the society with its environmental issues by

creating a biodegradable plastic out of Cassava Starch. The researchers will use environment-friendly

materials which can be made into biodegradable plastics that will not harm the environment and will not

add to pollution problems. Cassava Tubers were ground and squeezed to extract its starch. Starch

obtained was weighed and divided into three equal parts; 80 grams in trial 1, trial 2 and trial 3. T1, T2 and

T3 also consisted of 60 ml Polyester resin and 50 grams of Polymer MEKP Hardener for T1, 75 grams for

T2 and 125 grams in T3. The components in every treatment or trial were mixed, stirred and then poured

in 3 different shirts with Petroleum Jelly and then sun-dried. Afterwards, different methods were used to

test the effectivity of the plastic. T1, T2 and T3 were sun-dried but they did not look like a plastic at all.

The researchers observed the product while waiting for it to dry but there were no signs of turning into a

plastic. The Cassava starch was too thick and the researchers realized that it would not turn into a plastic

because of its heavy weight and it would take more time before it would dry because of its thickness.

After letting T1, T2 and T3 dry under the sun, it became hard. Although the researchers had unexpected

results and the Cassava starch did not turn into plastic, studies have already proven that Cassava starch

could be used for making various types of packaging products. Cassava is a promising raw material for

the development of biodegradable plastics. The research activities have shown and proven that cassava

starch is effective in the development of biodegradable packaging materials such as plastics. Studies

determined the effectiveness of cassava starch as component of biodegradable plastic. Results confirmed

that cassava starch is ideal as tests proved its worth. Therefore, Cassava Starch is an effective component

for Biodegradable plastic.

Table of Contents

Introduction…………………………………………………………………………………………………1

Significance of the Study…………………………………………………………………………………...2

Review of Related Literature……………………………………………………………………………….3

Scope and Limitation……………………………………………………………………………………….5

Definition of Terms…………………………………………………………………………………………5

Methodology……………………………………………………………………………………………….7

Data and Results……………………………………………………………………………………………8

Discussion and Analysis…………………………………………………………………………………..12

Conclusion………………………………………………………………………………………………...13

Recommendations…………………………………………………………………………………………13

Bibliography………………………………………………………………………………………………14

Acknowledgment………………………………………………………………………………………….15

I. Introduction

Plastics are used because they are very useful, cheap, manageable and handy. Plastics have been

the fastest growing basic material because they are versatile, light weight, energy saving, durable and

recyclable. It has become a popular material used in a wide variety of ways. Plastics can last a long time

but unfortunately, this same useful quality can make plastic a huge pollution problem. Its long life means

it survives in the environment for long periods where it can do great harm. Non-biodegradable plastics are

durable but they degrade very slowly; molecular bonds that make plastic so durable make it equally

resistant to natural process of degradation. Plastic packaging provides excellent protection for the

product, it is cheap to manufacture and seems to last forever. Lasting forever, however, is proving to be a

major environmental problem. Plastics are also a huge problem in waste disposal and studies have been

made to find a substitute material which can be used in making biodegradable plastics. Because plastic

does not decompose, and requires high energy ultra-violet light to break down, the amount of plastic

waste in our oceans is steadily increasing. Studies that have been done locally show about 3, 500 particles

of plastic per square kilometer of sea off the southern African coast. The world production of plastic is

estimated to be more than 100 million tons per year. Plastics are indeed a threat to wild life. A great proof

for this is that plastics have been found in the stomachs of sea turtles, birds, and fish all over the world.

Tragically, millions of tons of plastic are poisoning our oceans. Plastic pollution harms people, animals,

and the environment because it is non-biodegradable. In the marine environment, plastic breaks down into

smaller and smaller particles that absorb toxic chemicals, are ingested by wildlife, and enter the food

chain that we depend on. People need alternative and effective components of plastic that is safe and

biodegradable which will not harm and pollute the earth.

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II. Problem

Could Cassava Starch be an effective component for ideal Biodegradable plastic?

III. Hypothesis

a. If you’d use the starch of Cassava plant as a component of plastic, then the plastic will be

biodegradable.

b. If you’d use the starch of Cassava plant as a component of plastic, then the plastic will be non-

biodegradable.

IV. Significance of the Study

This study is important to be able to help Mother Earth in reducing its pollutants and toxic or

harmful wastes. Through this study, the researchers will be able to help other people, the animals and the

environment. The researchers would like to stop plastic pollution and be part of the solution. Plastic bags

and bottles, like all forms of plastic, create significant environmental and economic burdens. They

consume growing amounts of energy and other natural resources, degrading the environment in numerous

ways. In addition to using up fossil fuels and other resources, plastic products create litter, hurt marine

life, and threaten the basis of life on earth. There is over 45 million tons of plastics per year and nearly

every piece of plastic ever made still exists today because of its long-life properties. Biodegradable

plastics could be an effective solution to all of these problems. Biodegradable plastics are a much better

choice than non biodegradable plastics because they are friendlier to the earth and the environment.

Biodegradable plastics break down faster, can be recycled easier and are non-toxic. With these

characteristics of biodegradable plastics, we could help save lives and the environment as well and reduce

the threat plastics give to marine life. Plastic, the wonder material that we use for everything, is perhaps

the most harmful of this trash because it does not readily break down in nature but if it is biodegradable,

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these plastics break down faster so they have a much shorter effect on the earth, and they will degrade

completely. Normal plastics are manufactured using oil, and this process is very harmful to the

environment by polluting the air and environment, but this is not the case with green biodegradable

plastics. Using biodegradable plastics will minimize the effects that these products have on the earth, and

help eliminate their waste much faster.

V. Review of Related Literature

In the past few decades, there has been a marked advance in the development of biodegradable

plastics from renewable resources, especially for those derived from starch-based materials. The goal of

this development is to obtain biodegradable plastics that perform as well as traditional plastics when in

use and which completely biodegrade at disposal. Several starch-based plastics have been introduced into

the market, and are used in some applications now. Starch foam is one of the major starch-based

packaging materials. It is produced by extrusion or compression/explosion technology. This product has

been developed as a replacement for polystyrene which is used to produce loose-fillers and other

expanded items. Another type of starch-based plastics is produced by blending or mixing starch with

synthetic polyester. For this type of biodegradable plastics, granular starch can be directly blended with

polymer, or its granular structure can be destructurized before being incorporated into the polymer matrix.

The type of starch and synthetic polymer as well as their relative proportions in the blends influence the

properties of the resulting plastics. The last group of starch-based plastics is polyesters that are produced

from starch. The major starch-derived polyesters in the market now are polylactic acid and

polyhydroxyalkanoate. Experimental studies have demonstrated that cassava starch could be used for

making various types of packaging products. As a major source of starch in tropical and subtropical

regions, cassava is a promising raw material for the development of biodegradable plastics in these areas.

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Research has been done on biodegradable plastics that break down with exposure to sunlight

(e.g., ultra-violet radiation), water or dampness, bacteria, enzymes, wind abrasion and some instances

rodent pest or insect attack are also included as forms of biodegradation or environmental degradation. It

is clear some of these modes of degradation will only work if the plastic is exposed at the surface, while

other modes will only be effective if certain conditions exist in landfill or composting

systems. Starch powder has been mixed with plastic as a filler to allow it to degrade more easily, but it

still does not lead to complete breakdown of the plastic. Some researchers have actually genetically

engineered bacteria that synthesize a completely biodegradable plastic, but this material, such as Biopol,

is expensive at present.

The diversity and ubiquity of plastic products substantially testify to the versatility of the special

class of engineering materials known as polymers. However, the non-biodegradability of these

petrochemical-based materials has been a source of environmental concerns and hence, the driving force

in the search for ‘green’ alternatives for which starch remains the frontliner. Starch is a natural

biopolymer consisting predominantly of two polymer types of glucose namely amylose and amylopectin.

The advantages of starch for plastic production include its renewability, good oxygen barrier in the dry

state, abundance, low cost and biodegradability. The longstanding quest of developing starch-based

biodegradable plastics has witnessed the use of different starches in many forms such as native granular

starch, modified starch, plasticized starch and in blends with many synthetic polymers, both

biodegradable and non-biodegradable, for the purpose of achieving cost effectiveness and biodegradation

respectively. In this regard, starch has been used as fillers in starch-filled polymer blends, thermoplastic

starch (TPS) (produced from the combination of starch, plasticizer and thermomechanical energy), in the

production of foamed starch and biodegradable synthetic polymer like polylactic acid (PLA) with varying

results. However, most starch-based composites exhibit poor material properties such as tensile strength,

yield strength, stiffness and elongation at break, and also poor moisture stability. This therefore warranted

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scientific inquiries towards improving the properties of these promising starch-based

biocomposites through starch modification, use of compatibilizers and reinforcements (both organic and

inorganic), processing conditions, all in the hope of realizing renewable biodegradable substitutes for the

conventional plastics.

VI. Scope and Limitations

This experiment only covers plastic bags, not including other plastic materials such as plastic

containers, plastic cups, straws and other plastic utensils. The experiment can be done in a matter of 2

hours, excluding the sun-drying procedure. Most of the materials used in the experiment are accessible

and can be bought in supermarkets. However, there are a few which are not available in nearby stores.

Premix Polyester Resin and Polymer MEKP Hardener are manufactured by Polymer Products (Phil) Inc.

and can be bought in Bagong Ilog, Pasig City.

VII. Definition of Terms

Biodegradable - able to decompose naturally: made of substances that will decay relatively quickly as a

result of the action of bacteria and break down into elements such as carbon that are recycled naturally

Starch – a white, granular or powdery, odorless, tasteless and complex carbohydrate found chiefly in

seeds, fruits, tubers, roots and stem pith of plants, notably in corn, potatoes, wheat, and rice; an important

foodstuff and used otherwise especially in adhesives and as fillers and stiffeners for paper and textiles.

Plastics – the word plastic is derived from the words plasticus (Latin for “capable of molding”) and

plastikos (Greek “to mold,” or “fit for molding”). Plastics are polymeric, moldable and synthetic materials

which are derived from fossil fuels, such as oil, coal or natural gas. Plastics consist of organic (carbon-

containing) long molecular chains that give them many of their unique properties. They can be made

hard, flexible, strong, transparent, light and elastic.

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Polymer – long-chain molecules that repeat their structures over and over

Polyethylene Bags - the bags that you will see commonly used, such as plastic grocery bags, are made

from petroleum byproducts, which is the root of most all of the environmental problems that they are the

source of. Not only do they take substantially longer to break down or degrade, but as they do they release

highly toxic chemicals.

Resin – It is a hydrocarbon secretion of many plants, particularly coniferous trees. It is valued for

its chemical constituents and uses, such as varnishes and adhesives, as an important source of

raw materials for organic synthesis, or for incense and perfume.

Polymer Methyl Ethyl Ketone Peroxide (MEKP) - The most popular type of hardener because of

its economy and ease of use.

Polyester Resin - Polyester resins are the most commonly used matrix in the marine and

composite industry. These resins are styrene-based, flammable and catalyzed when combined

with Methyl Ethyl Ketone Peroxide(MEKP). Polyester resins are unsaturated resins formed by

the reaction of dibasic organic acids and polyhydric alcohols.

Premix Polyester Resin R10-60 – It is a fast gel premix polyester resin used for wood, kapiz, and

other lamination with cellophane, “Lumirror” or “Mylar” films. It is also used to make

decorative jewels and flowers from ceramic molds, to make small coatings from polyethylene &

silicone rubber molds, and to cast on intrinsic molds such as steel or bass frames.

Plastic Resin Glue – Plastic resins are made by heating hydrocarbons in what is known as the

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"cracking process." The goal here is to break down the larger molecules into ethylene, propylene,

and other types of hydrocarbons. The amount of ethylene produced depends on the cracking

temperature. Once the cracking process has been completed, the compounds are formed into

chains that are known as polymers. Different polymers are combined to make plastic resins that

have the characteristics needed for different applications. Once the plastic resins have been

formed, they are used to make many different kinds of products.

Catalyst - chemical that accelerates chemical reaction: a substance that increases the rate of a chemical

reaction without itself undergoing any change

VIII. Methodology

A. Materials

2 Cassava Tubers

180 ml of Premix Polyester Resin

300 ml of Polymer MEKP Hardener

100 grams Petroleum Jelly

3 old shirts

Measuring cup

Grater

Plastic Spoon

Knife

3 Plastic Containers

Chopping board

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B. Procedure

1. Gather the Cassava Tubers. Ground and squeeze it to extract the starch.

2. Get hold of 240 grams of the starch and divide it into 3 equal parts: 80 grams in trial 1, trial 2 and

trial 3.

3. Place 60 ml of the plastic resin glue (Premix Polyester Resin) with 50 grams of flour catalyst for

T1, 75 grams for T2 and 125 grams in T3.

4. Mix and stir the components and pour it in the shirt with Petroleum Jelly and let it dry under the

sun.

5. To test its capacity to carry weight, use the plastic to carry objects.

6. For its ability to hold water, put water inside the plastic.

7. To test its tensile and bending properties, stretch the plastic as far as you can.

8. Repeat steps 5-7 using T2 and T3.

IX. Data and Results

Trial 1 Trial 2

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Trial 3 Materials

Sun – drying procedure

Amount of

Cassava

Starch (g)

Amount of

Plastic Resin

Glue (ml)

Amount of

Polymer

MEKP

Hardener (g)

Did the color

change?

Hardness Can it be peeled

from the shirt

completely?

Texture of

the final

product

T1 80 g 60 ml 50 g No It hardened

but did not

turn into

plastic.

It can be peeled

off the shirt

completely

Rough

T2 80 g 60 ml 75 g No Hardened a

little but did

not turn into

plastic.

It can be peeled

off the shirt but

not completely

Some parts

are smooth

but most of

the parts

are rough.

T3 80 g 60 ml 125 g Yes, it

changed to

color

Yellow.

Did not

harden at all.

It cannot be

peeled off the

shirt at all

Some parts

are rough

but most

parts are

smooth.

The researchers had unforeseen outcomes. The researchers had 3 trials: T1, T2 and T3. The three

trials contained 80 grams of cassava starch and 60 ml of plastic resin glue each. They also put 50 grams of

Polymer MEKP Hardener in T1, 75 grams in T2 and 125 grams in T3. The researchers used plastic resin

glue because plastic resins are made by heating hydrocarbons where larger molecules is breaking down

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into ethylene propylene. Once the process has been completed, the compounds are formed into chains that

are known as polymers. Polymers are combined to make plastic resins. Once the plastic resins have been

formed, they are used to make several varieties of products. Another reason on why the researchers used

plastic resin glue on their experiment because based on studies, plastic resin glue dries to a glass-hard

consistency depending on the ambient temperature. On the other hand, the researchers used Polymer

MEKP Hardener on their research because when it is mixed with the resin, the resulting chemical reaction

causes heat to build up and improve or harden the resin to make the product more effective. They used

different amounts of MEKP so that the researchers would know if what would work the best, the

container with more MEKP or the one with less. After mixing and stirring the treatments, it was

transferred on 3 separate shirts with Petroleum Jelly then sun-dried. After 4 hours of observing the

conducted experiment, their products hardened but did not look like it would turn into plastic like they

have been expecting. T1 is the hardest of them all hence, it can be peeled off the shirt and since T3 did

not harden, its texture is smooth and it cannot be peeled off the shirt in any way. T2 hardened a little but

still did not look like plastic. Some parts are smooth but most parts are rough. It can also be peeled off the

shirt but not completely. In order for us to test its capacity to carry weight, we used the plastic to

carry objects, we also tested its tensile and bending properties, T1 had the best result for both.

We also tested for its ability to hold water by putting water inside the three trials, none of our

trials worked. In view of the fact that the thickness of the cassava starch on the shirt is a factor why the

outcome didn’t work as expected. The cassava starch was not spread evenly making it so thick, thus, the

cassava starch being too thick means it would also be difficult for it to dry.

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X. Discussion and Analysis

The researchers have studied the final product of all three trials and have observed that: In the

first trial, the researchers have observed that among the three trials it was the most successful because of

the hard and sturdy layer it produced. It was strong enough to carry objects but it can also be bent without

breaking. Even when it was peeled from the white cloth it did not break down. The researchers believe

that trial one would be the most reasonable and efficient trial to use for a biodegradable plastic. In the

second trial, the researchers observed that the final product was somewhat not as whole as trial one. It

made a rather sticky substance that was very flimsy and fragile, especially when it was peeled off the

white cloth. In the third trial, the researchers have observed the looseness of the final product. Though it

has been sun dried, it kept its damp and very sticky attribute. It showed since of being very flimsy and

loose. When trial three was peeled of it easily broke down because of its very gooey feature. The

researchers believe that trial three would be the most inefficient trial to use for a biodegradable plastic

because its lack in plastic features.

The physical properties of plastic include transparency, flexibility, elasticity, permeability,

ductility, electrical resistance and its ability to hold water. The researchers observed that the final

products lack plastic properties. None of the 3 trials were transparent and for its flexibility, it was only T1

that can be bent without getting destroyed. Though T1, T2 and T3 lack those properties, it can still be

considered as an effective component for biodegradable plastics because they are biodegradable.

Studies have already proven that cassava starch is an effective component of biodegradable

plastics. However, the end product of the experiment did not look like a plastic at all. The researchers had

altered the suggested procedure found on the internet. The procedure was not also vey precise and

specific. A factor that might have affected the results was the use of chemicals. The shirts, petroleum

jelly, Polymer MEKP Hardener were only used as substitutes for the actual materials. The shirt was used

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to replace silk screen and Petroleum Jelly was used instead of oil. Polymer MEKP Hardener was used a

substitute for the flour catalyst. Also, the appropriate type of Plastic Resin must be selected to make the

particular type of product needed but in the procedure, no type was specified so the researchers used

Premix Polyester Resin. There were lots of flaws in the experiment which probably was the reason why

the researchers failed in the experiment. The cassava starch was not also ground and it was the reason

why it was thick and it was not also spread thoroughly. The weather was also a factor because sunlight

and heat was really needed for the cassava starch to dry but then, it was not too sunny.

XI. Conclusion

Even though the researchers had unanticipated outcome, they still conclude that Cassava starch

can be used as a biodegradable polymer to replace plastics in packaging materials. Cassava starch can be

applied for the production of biodegradable plastics. Starch can be incorporated into plastics to improve

the biodegradability of the plastic and finished product. According to different studies and research,

cassava starch could be used for making a range of types of plastics and is now being used in the market.

Cassava has a promising raw material and its starch have the characteristic of being able to absorb

humidity, just like normal plastics. It’s also has a low bulk density and only a little modification is needed

to increase its moisture content which is needed in producing plastics. Since starch is a natural polymer

and is biodegradable, it can play as an important role in the biodegradable plastic manufacturing.

Therefore, Cassava starch is an effective component in biodegradable plastics.

XII. Recommendations

Although the researchers were not successful in this experiment and had unexpected results, they

still recommend this topic which can be used in Investigatory Projects. For those who are interested in

this topic and would like to perform this experiment in the future, the researchers are suggesting that you

should follow the right procedure and be accurate with your measurements. People should have sufficient

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background information about the chemicals that they will be using and they make sure that they areusing

the right materials or chemicals. Remember that little factors might affect the outcome so you should be

careful in performing the different steps. Future experimenters should clarify the procedure and make sure

that the ingredients that you will be using as substitutes will be effective in this project.

XIII. Bibliography

Jodee Redmond. (2003) What is Plastic Resin? Retrieved December 2009, from

http://www.wisegeek.com/what-is-plastic-resin.htm

Australian Academy of Science (2002) Making packaging greener – biodegradable plastics Retrieved

December 2009 http://www.science.org.au/nova/061/061key.htm

Cassava and Starch Technology Research Unit (1998) Biodegradable and Physical Properties of

Cassava Starch/Polycaprolactone Blend. Retrieved September 2009 from

http://www.cassava.org/Pub/1998/1998_04.htm

(2007) Cassava starch as an effective component for Ideal Biodegradable Plastic Retrieved September

2009 from

http://www.investigatoryprojectexample.com/biochemistry/cassava-starch-as-biodegradable-plastic.html

Jaarsma, Frank. (2000) Physical And Mechanical Properties of Plastics. Retrieved December 2009 from

http://www.thefreelibrary.com/Physical+And+Mechanical+Properties+of+Plastics.-a067717233

Biodegradable plastic. In Wikipedia. Retrieved September 2009, from

http://en.wikipedia.org/wiki/Biodegradable_plastic#Advantages_and_disadvantages

http://sundoc.bibliothek.uni-halle.de/diss-online/02/02H017/t7.pdf

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http://www.ciat.cgiar.org/asia_cassava/pdf/proceedings_workshop_00/538.pdf

Japan Echo Inc. (2005) Plastic from plants Retrieved December 2009 from,

http://web-japan.org/trends/business/bus050107.html

Biodegradable Plastic. Retrieved December 2009 from,

http://www.mindfully.org/Plastic/Biodegradable-Plastic.htm

XIV. Acknowledgement

The researchers would like to acknowledge Dianne Roxas’ parents for allowing them to work on

the experiment in their house.

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