Transcript
SEMESTER –VII
THESIS TITLE
“STUDY OF PET WASTE RECYCLING“
PROJECT ADVISOR
ASSOCIATE PROFESSOR ARSHAD FARUQUI
GROUP MEMBERS
QASIR NAZIR 16-PE-12
YASIR ABBAS 16-PE-18
ADIL HANIF KALWAR 16-PE-20
ISRAR AHMAD 16-PE-22
IJAZ HUSSAIN 16-PE-07
FARAZ ALI KHAN 16-0-PE-05
MUHAMMAD FAIZAN KHALID 16-0-PE-12
SALEEM SIDDIQUI 16-0-PE-18
ACKNOWLEDGEMENT
In the name of Allah, the Most Gracious and the Most Merciful Alhamdulillah, all praises to Allah for the strength and blessing in completing this thesis. Special appreciation goes to Professor Dr. Naim Masood Hasan , Associate Professor Zaheer Ahmed Chaugtai , Associate Professor Tariq Jamal . Associate Professor Arshad Faruqui for his supervision and constant support. We also wish to acknowledge Laboratory & Technical staff for helping us. Sincere thanks to all our seniors for their support during the study.
Last but not least, deepest gratitude goes to our beloved parents for their endless love, prayers and encouragement. To those who indirectly contributed in this research, your kindness means a lot to us. Thank you very much.
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TABLE OF CONTENT
ACKNOWLEDGEMENT………………………………………………….………………………………….i
INTRODUCTION...................................................................................................1
CHAPTER 1. Literature Survey……………………………………....……………………………...2
Poly(ethylene terephthalate)……………………………………………………….……………………………………….2
History of PET……………………………………………………………………………….………………………………………2
Chemistry of PET………………………………………………………………………….….……………………………………3
Formation of PET………………………………………………………………………….………………………………………3
Morphology of PET……………………………………………………………………….………………………………………5
Properties of PET………………………………………………………………………….…………………………………..….6
Process ability of PET…………………………………………………………………….…………………………………..…6
Application of PET………………………………………………………………………….………………………………….…6
CHAPTER 2. Recycling of PET Plastics……………………...........................................9
Introduction……………………………………………………………………………….……..…………………………………9
PET Recycling…………………………………………………………………………….……………………………………….11
History of PET Recycling…………………………………………………………….……………………………………….11
Effect of Contaminants of PET…………………………………………………....………………………………………11
CHAPTER 3. Physical Recycling Techniques…………………………….…………………….13
Flotation or Hydrocyclone Process…………………………………………….……………………………………….13
Water Bath / Hydrocyclone Process………………………………………….…………………….………………….14
Solvent /Floatation Process……………………………………………………….……………………………………….14
Physical Recycling of PET bottle to Form Fibre………………………….…………………….………………….15
PET bottles recycling in Pakistan…………………………………………………………………….………………....19
CHAPTER 4. Chemical Recycling to form Unsaturated Polyester Resin ………..22
Glycolysis………………………………………………….…………………………………………………………….………….22
Hydrolysis………………………………………………….……………………………………………………….………………24
Methanolysis…………………………………………….……………………………………………………….……………….25
Chemical Recycling Of Pet on Laboratory Scale…………………..………………………………………………25
Formulation of Recycled Unsaturated Polyester ……..…………………………………………………………26
CHAPTER 5. Applications of Recycled PET……………………………..………………………27
Unsaturated Polyester Products…………………………………………………………………………………………29
a. GRP Pipes ……….………………………………………………………………………………………………………29
b. GRP SHEETS…………………………………………………………………………………………………………….29
c. GRP Houses…………………………………………………………………………………………………………….30
d. Cultured Marble……………………………………………………………………………………………………..30
CHAPTER 6. Testing………………………………………………………………..…………….………33
Fibre Testing…………………………………………………………………………………………………….………………..33
Description of Test for Fibre…………………………………………………………………….…………………………33
a. Denier Testing…………………………………………………………….……………….………………………….33
b. Cut Length………………………………………………………………………………….…………………………..34
c. Friction Measurement……………………………………………………………….……………………………34
d. Draw Ratio…………………………………………………………….………………….…………………………….34
e. Thermal Shrinkage…………………………………………………….…………….……………………………..35
f. Tensile Strength And Elongation at Break for Fibre………..…….………………..….….……….37
Comparison Test Report of Virgin Unsaturated Polyester Resin with Recycled
Unsaturated Polyester Resin (8THSemester) .…………………………………………..….……………….…38
Description of Test for Unsaturated Polyester Resin…………….……………………………….……………39
a. Density…………………………………………………………………….……………………………………………..39
b. Acid Value……………………………………………………………….………………………….…………………..39
c. Viscosity………………………………………………………………….………………………...……………………39
d. Gel Time………………………………………………………………….……………………………………………..39
e. Exothermic Temperature……………………………………….……………………………………………….39
f. Peak Time………………………………………………………………..................................................39
CHAPTER 7. Market Survey…………………………………..………………………..…………….40
Local Market Survey………………………………………………………………………………………….……………….42
International & Local Manufacturer, Supplier & World Scenario…………….……………….…………46
CHAPTER 8. Work Plan…………………………………………………………………….……..……………………48
References…………………………………………………………………………………………….……...…………………..49
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INTRODUCTION
Poly (ethylene terephthalate), PET is an important engineering thermoplastic
which is widely used all around the world. The basic sources of raw materials for
PET resin production are crude oil and natural gas. PET is a condensation polymer
derived from terephthalic acid (TPA) or dimethyl terephthalate (DMT) and
ethylene glycol (EG). The great acceptance of PET as a packaging material is due
to its toughness, clarity, capability of being oriented and reasonable cost.
Compared to glass, PET containers are lightweight and shatter-resistance. They
provide an acceptable barrier and they are considered as the most recyclable
plastics in world. Each year millions of tons of PET remain as scrap after being
used in several areas. Because of the governmental and environmental
regulations, PET is being recycled [1].
In this study, bottle grade and fibre grade Polyester was recycled by two different
methods, such as physical recycling and chemical recycling. In physical recycling
the PET bottle were crushed washed and extruded to get fibre but In Chemical
recycling PET bottle flakes were used, there are different methods in chemical
recycling such as, Glycolysis, Hydrolysis, Methanoylsis etc. However, in industry
glycolysis method is used for chemical recycling.
The main objective of this study is to obtain fibre and unsaturated polyester resin
from recycling of PET. In addition to this main objective is to reduce the
manufacturing cost of fibre and to manufacture unsaturated polyester resin from
bottle grade PET to reduce the manufacturing cost of UP resin and improve the
physical and chemical properties of UP resin[2].
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CHAPTER 1
LITERATURE SURVEY
1.1. Poly(ethylene terephthalate)
Poly (ethylene terephthalate), PET, is one of the most commercially used
thermoplastic. PET is a linear condensation polymer that has been used in
applications that have seen rapid growth especially as packaging material for
carbonated beverages since it was introduced as a container resin. Prior to this
surge in use, PET was used as food packaging film, including boil-in-bags for
frozen vegetables, and most commonly for the production of fiber for clothing
and other applications. The structure of PET is as follows [3].
Figure. Chemical structure of PET
1.1.1. HISTORY OF PET
PET has been well known under the name of polyester for more than 60 years.
The following milestones mark the development from polyester fibres in the
early 1940ies to modern PET bottles. Calico Printers Association [4], a small
English company, developed the first laboratory samples of poly (ethylene
terephthalate) in fiber form in 1941. Polyester research began in the United
States after World War II. Nathaniel C. Wyeth is a inventor of PET bottle. In the
1950s, this research was based on textiles such as DuPont's Dacron™ and ICI's
Terylene™. In 1962, the first polyester tire cord was manufactured by Goodyear
[4]. In 1977, PET was produced commercially for packaging applications such as
film, sheet, coatings, and bottles - although oriented PET film was available in the
1950s. Since then due to the new improvements in mechanical and barrier
properties, the consumption of the resin has grown rapidly, primarily for
carbonated beverage bottles.
1941: production of first polyester Fibres.
1950s: production of textile fibres (brand names: “Trevira”,
“Dralon”)
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1950-60s: extended use in textile industry
1970s: first production of packaging containers
End of 1980s: first refillable beverage containers
1.1.2. CHEMISTRY OF PET
PET is made industrially by two methods, the first step in each of which involves
conversion of the TPA and DMT feed stock with ethylene glycol (EG) into bis
(hydroxyethyl) terephthalate (BHET). In the early stages, polymer technology was
not developed to produce TPA with sufficient purity. In the early 1960s, pure TPA
was produced directly from p-xylene with bromide-controlled oxidation. DMT
was made by esterification of terephthalic acid. However, a different process
involving two oxidation and esterification stages is now used to produce most
DMT. The intermediate product, ethylene oxide is produced by oxidation of
ethylene. Then ethylene glycol is obtained by reaction of ethylene oxide with
water.
1.1.3. FORMATION OF PET
PET is a step-growth (condensation) polymer derived from terephthalic acid
(TPA) or dimethyl terephthalate (DMT) and ethylene glycol (EG) according to the
following chemical reactions
Figure 2.2 PET formation via acid route
Figure 2.3 PET formations via ester interchange
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In condensation polymerization, if the system is heated with antimony catalyst, a
reversible reaction takes place between two polyfunctional molecules to produce
one larger polyfunctional molecule, with the possible elimination of a small
molecule such as water or methanol. The polycondensation rate is heavily
dependent on the type and concentration of the catalyst. The reaction continues
until almost all of one of the reagents is used up; an equilibrium is established
which can be shifted at high temperatures by controlling the amounts of the
reactants and products. “Copolyesters, which are produced commercially to
reduce the crystallinity of PET, are made by replacing the TPA or EG portion with
another dibasic acid or glycol or both. The step growth polymerization occurs in
two steps: First, a low molecular weight precursor is formed (BHET), which is
then transesterified to form a high molecular weight reactor grade resin. To
achieve very high molecular weights
(I.V.: 0.72-0.84) and thus avoid thermal degradation in the melt, condensation is
also performed in solid phase in a vacuum or under nitrogen. The molecular
weights of the PET are adjusted to the intended application area”[5], which were
given in
Table 2.1 Application areas and molecular weights of PET
PET Application IVDCA
(dl/g) MW Range
Fibers 0.57 – 0.65 38500 - 46000
Fibers, low pilling 0.39 – 0.51 23000 – 32000
Filaments, textile 0.65 – 0.68 46000 – 49000
Filaments, technical
0.65 – 1.00 46000 – 84000
Bottles 0.70 – 1.00 51000 – 84000
Films 0.59 – 0.69 41000 – 51000
Solid State Polymerization:
Dry monomers can be submitted to solid state polymerization as well as
solid prepolymers (i.e., low-molecular-weight polymers derived from
conventional polymerization techniques). The former process is usually referred
as direct SSP; meanwhile, in the latter case, post-SSP (SSP finishing) is used to
further increase the molecular weight and to improve processability and end-
product properties, respectively [26–28]. To the same perspective, SSP is proved
to be an efficient recycling technique [29,30], through which the molar mass of
the post consumer material is increased, thus permitting processing without
severe recycled material deterioration.
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1.1.4. MORPHOLOGY OF PET
PET is a linear molecule that exists either in an amorphous or in a crystalline
state. In the crystalline state, the molecules are highly organized and form
crystallites, which are crystalline regions that extend no more than a few
hundred angstrom units. The maximum crystallinity level that can be achieved is
probably no more than 55 %. The crystallinity in the PET soft drink bottle is
normally about 25 % [4]. PET produced by solid stating comes from the reactor in
crystalline form. It is shipped to the fabricator in this form. Polymers in either
amorphous or crystalline form can be uniaxially or biaxiallly oriented. In either
case, orientation greatly increases the strength of PET; because strain induced
orientation usually imparts some crystallinity. As the crystalline state is the
normal state for PET, the amorphous PET is produced deliberately. Amorphous
PET is prepared by rapidly cooling the molten resin from a melt temperature of
260 °C to temperature below the glass transition of 73 °C. On the other hand,
slow cooling of the molten resin will produce a crystalline polymer. A recycler of
PET who produces pellets by extrusion will normally produce crystalline polymer.
It is important to do so because the processor, who normally dries the recycled
PET before using it, prefers pellets of crystalline PET. Amorphous resin tends to
soften and stick at elevated temperatures of drying, forming clumps and
adhering to the walls of the drying unit. The crystallization rate of PET is very
important in processing. Crystallinity has a great effect on the product clarity and
process ability. However, if the size of the crystallite is small enough to minimize
light scattering, clarity can be achieved in spite of the crystallinity of the polymer.
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1.1.5. PROPERTIES OF PET The rapid growth of PET is due to the following properties:
can be used as an amorphous or crystalline material,
has good impact strength,
can be made transparent or opaque as required,
permits continuous service temperatures of around 180 °C (partially
crystalline) and 60 °C (amorphous),
is environment-friendly; it can be recycled or incinerated to form carbon
dioxide and water, leaving virtually no residue,
Offers an excellent price/performance ratio.
very good chemical resistance
Some properties are given in the Table [6].
Property Value Units
Specific Gravity 1.37 – 1.38 ---
Crystalline Melting Point 250 – 255 °C
Vicat Softening Point 261 °C
Moisture absorption (in water)
24 h at 23°C 0.02 %
2 h at 100°C 0.1 %
Tensile Strength (at yield) 71.5 MPa
(at break) 52.9 MPa
Flexural Strength 110.3 MPa
Flexural Modulus 2758 MPa
Izod Impact Strength 29 – 38 J/m
Elongation 70 %
1.1.6. PROCESSABILITY OF PET
PET can be processed by different methods such as melt spinning, injection
molding, stretch blow molding, flat-film extrusion, thermoforming, etc. The
resulting products (e.g. fibers, films, injection-molded articles, bottles, and
sheets) can be colored, adhesive bonded, welded, painted and laser marked.
1.1.7. APPLICATTION OF PET
The fact that the mechanical properties of PET, especially its impact resistance,
improved by biaxial drawing have contributed to the success that PET has
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experienced throughout the packaging sector. This trend is continuing and PET is
also expected to expand its future market share. Polyester bottles have gained
wide acceptance as soft drink containers for the following reasons:
93 % weight saving compared to glass,
High barrier properties, especially for oxygen (O2) and carbon dioxide
(CO2)
Excellent transparency and gloss,
Very good mechanical properties,
Shatter-resistance up to drop height of 2.5 m,
Shock-resistant and tough,
Very good chemical resistance,
Approved for food contact (FDA/ BGA),
Readily recyclable.
PET has also gained favor in other food packaging applications other than
carbonated beverage containers. Syrups, oils, and mustard can now be found in
PET bottles. Nonfood packaging items include those for cosmetics, toiletries, and
household products. PET film is used for photographic film and magnetic tapes
[7]. New developments have led to use of PET in manufacturing of beer and
other hot fill applications [8]. Disposable PET containers are now being used in
hospitals for wound drainage systems [9]. The bottles are extrusion blow
molded, radiation sterilized, and they exert and maintain a constant starting
vacuum of 600 mmHg to provide optimum suction for wound drainage. Sekisui
Kaseihin Kogyo Company, Japan [10], has developed foam of crystalline PET,
known as Cell-PET. This foam has high thermal resistance and has good potential
to be used in packaging of foodstuffs. Glass fiber reinforced PET can also be used
in electrical and electronic goods [11]. It can be used in appliances such as
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sandwich toasters, tabletop ovens, cooker components and electric irons. PET
can also be used in electrical components such as power switches, light bulb
bases, and sensor housings, as well as in specialized applications such as housings
for measuring instruments.
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CHAPTER 2
RECYCLING OF PET PLASTICS
2. INTRODUCTION
Although the percentage of refillable PET beverage containers increases in
Europe and North America, the majority of PET bottles worldwide are one-way
bottles which are discarded after use. PET-bottles contribute increasingly to the
generation of waste and litter especially in developing countries [12]. One-way
discarded PET-bottles have a negative impact on the environments because they:
waste resources
pollute soil, rivers, coastal areas
pollute the air when burned
consume a lot of landfill site space
get scattered and make the environment look untidy.
Recycling of PET-bottles
saves 65% of the energy for primary PET-production
Offers jobs and income for low-income groups.
Depending on the type of raw material, three types of recycling are
possible:
Recycling of PET material by re-melting
Recycling of feedstock material
Energy recycling
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FIGURE: - 1
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2.1. PET RECYCLING
Plastics are a small but significant component of the waste stream. Plastics have
become an integral part of our lives. The amount of plastics consumed annually
has been grown steadily. Its low density, strength, user-friendly design and
fabrication capabilities and low cost, are the drivers to such growth [13]. Besides
its wide use in packaging, automotive and industrial applications, they are
extensively used in medical delivery systems, artificial implants and other
healthcare applications, etc.
The main problem during material recycling is the segregation of polymers. A
polymer after segregation is typically not completely pure. The presence of
contaminants generates some problems such as cleavage of chains, an increase
in carboxylic end groups, a reduction in molecular weight, a decrease in intrinsic
viscosity (I.V.) leading to a decrease in mechanical properties of the material. The
main problem in recycling of PET is the elimination of all impurities that may
catalyze hydrolysis [14].
2.2. HISTORY OF PET RECYCLING
The recycling of poly (ethylene terephthalate) soft drink bottles began after their
introduction in 1977 because some states had laws requiring a deposit on all
beverage containers. By 1989, the recycling rate had increased to 23 % up from
only 10 % in 1982. In U.S., more than 90 % of the bottles were collected from
deposit sites in 1989. Over the past decade, the technology for recycling PET soft
drink bottles has been advancing rapidly. However, most commercial recycling
systems depend on some flotation system to separate PET from the high-density
polyethylene (HDPE) base-cup resin, alternative systems have been developed.
One of the serious contaminants in PET recycling is the adhesive used to attach
the base cup and the label to the PET bottle. Today, new technology has
minimized this problem and has allowed the recycling industry to produce a very
pure recycled PET [4]. According to a survey carried by NAPCOR the PET bottle,
industry continued its strong growth in 1997. ASG (Analytical Sciences Group)
determined that 2.551 billion pounds of PET bottles and jars were available for
recycling in 1997 in the U.S., which represents an almost 16 % increase from
1996. The additional new applications, particularly in the area of hot filled bottles
and jars, are expected to lead this continued strong growth in 1998.
2.3. EFFECT OF CONTAMINANTS OF PET
“A major concern during reprocessing of PET is to remove all contaminants that
can catalyze the hydrolysis of PET. Also, the reprocess or must avoid adding such
cleaning agents as caustic soda in the wash step. These compounds are
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sometimes used to help removal of labels. Often, adhesive residues are trapped
in the PET granules and remain there after washing. Since these adhesives
darken when treated at PET extrusion temperatures, the recycled PET becomes
discolored and hazy. During removal of labels, ionic or non-ionic surfactants are
used to prevent the re-sticking of the PVA adhesive on to the flakes. If not
cleaned properly, residual contaminants in recycled PET could be a risk to the
public health, especially when intended to use for direct food contact
applications”. In addition, PVC content exceeding 50 ppm in the scrap PET makes
it worthless for advanced applications such as film forming.
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CHAPTER 3
PET RECYCLIGN TECHNIQUES
3.1. FLOTATION OR HYDROCYCLONE PROCESS
Hydrocyclone is a centrifuge device with a greater gravity force that simply
accentuates the action of a sink-float tank. In this process, PET and high-density
polyethylene (HDPE) are separated by differences in their density. In this process,
the system is fed with crushed, baled bottles with and without caps. If the bales
consist of both green and colorless bottles, the bottles are color sorted by hand
or by photocell (sensors). The dirty, sorted bottles are first reduced to 32-9.5 mm
(0.125-0.375 in.) flake by being processed through a granulator. Labels and loose
dirt are removed by blowing air at low pressure. The contaminated flake is then
metered into an agitated washing tank along with a hot non-foaming detergent
solution. All recyclers have their own detergent recipes, a preferred solids
concentration in the slurry, and a preferred temperature and wash cycle. The use
of caustic soda in the wash solution is not recommended because it facilitates
the hydrolysis of PET chains that results in drop in intrinsic viscosity. The washing
step removes the last traces of label material, disperses, and sometimes
dissolves the adhesives. The polymer flakes are thoroughly rinsed with fresh
water to remove residual wash solution, label and other materials. Now cleaned,
the crude flake or chip moves into hydro-cyclone that separates the heavy PET
from light HDPE in water medium. HDPE floats in water while PET sinks. Ethylene
vinyl acetate (EVA), if present from the cap liner, stays with the HDPE. The
effectiveness of the hydrocyclone depends on the concentration of the solids and
the speed of the centrifuge. The "heavy" and "light" product streams from the
tank or the hydrocyclone are typically flushed once more with fresh water and
processed first through spin dryers and then through hot air dryers. Then the
metal impurities (if any) are removed by feeding the PET flakes into the
multistage electrostatic separator. An interesting variation on the flotation or
hydrocyclone process is the addition of a step that granulates or grinds the PET
bottles cryogenically. Because adhesive contaminants are embrittled at cryogenic
temperatures, whereas PET is not, adhesive contaminants in a cryogenic process
become a fine powder. The fines are easily removed from the coarser PET flake
by screening.
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DIAGRAM OF HYDROCYCLONE
3.2. WATER BATH/ HYDROCYCLONE PROCESS
This process developed by Reko, a division of DSM in Holland, operates either
with PET bottles that have plastics caps or with cap-free bottles. In this process,
bottle components are substantially separated before granulation. Color-sorted
crushed bottles from the bale move continuously through a hot water bath (1 -
1.5 min.) that is at least 70 °C and close to 100 °C. At these temperatures, the PET
bottles, which are blow-molded by a process that orients the PET, shrink. As a
result, the labels and caps, which do not shrink, separate from the PET bottles.
From the immersion tank, the separated components are deposited on a
vibrating screen that removes the detached labels. After washing and rinsing, the
PET flake in water medium moves through a hydrocyclone that removes any
residual polyethylene and adhesives. Finally, the clean and dried recycled PET
passes through a metal detector to ensure the absence of any traces of metal
3.3. SOLVENT / FLOTATION
This system was developed by Dow Chemical. The process begins like the
conventional flotation process, discussed before, but it is followed by a series of
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float/sink steps using chlorinated solvents. After the water-flotation step that
separates the polyethylene and some labels from the PET flakes, the ''heavies"
move first through a float/sink step with 1,1,1-trichloroethane as the solvent and
then through another float/sink step using a mixture of perchlomethylene and
trichlomethane. The trichloroethane dissolves the adhesives and floats any
remaining label materials. Finally, the solvents are removed and recovered in a
closed distillation system and the adhesive free
PET is dried.
3.4. PHYSICAL RECYCLING OF PET BOTTLE TO FORM FIBRE
Recycling is processing used materials (waste) into new products to prevent
waste of potentially useful materials, reduce the consumption of fresh raw
materials, reduce energy usage, reduce air pollution (from incineration) and
water pollution (from land filling) by reducing the need for "conventional" waste
disposal, and lower greenhouse gas emissions as compared to virgin production.
65%
30%
4%
1%
GLOBAL RECYCLED APPLICATION OF PET
Polyester Fibers
PET Bottle Resins
Polyester Film
Others
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FOLLOWING STEPS INVOLVE IN PHYSICAL RECYCLING OF PET BOTTLE TO FORM FIBR Step 1 Bale Breaking Stage
Used plastic bottles are collected from municipal curbside systems and deposit centers and are compressed into half-ton bales for delivery to the Carbon LITE process facility in Riverside CA. A bale-breaking machine de-compresses the
bales back into single bottles. Step 2 Bottle Cleaning Stage
The single bottles are separated from any trash and debris and washed in hot
caustic water.
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Step 3 Bottle Sorting Stage
Automatic sorting equipment segregates the bottles into three streams: clear
PET, green PET and non-PET. The non-PET stream is re-baled and sold to others for subsequent processing into various plastic products.
Step 4
Washing Stage
The clear and green streams of bottles are ground into cornflake-like flakes. These flakes are intensively washed, rinsed and dried.
Step 5
Solid State De-contamination Stage
The dried clean flakes are heated under vacuum to remove any contaminates that may exist. This system of de-contamination is recognized by the FDA as
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acceptable for subsequent use in direct food packaging. The purified flakes are melted and extruded into pellets. This is our finished product and it is similar in consistency to rice. Step 6 Final Packaging Stage
The food-grade pellets are transported to bottle manufacturers and other customers in bulk hopper road trucks or railcars. Some customers prefer the pellets to be packaged in one-ton plastic bags on pallets. And then these bags of flakes goes to different industries to achieve final production just like these flakes can be use in the production of Synthetic fiber, films, Gel Coats, Coating applications and different other applications. The example of Polyester Synthetic fiber with processing is given bellow:
Synthetic Fibers
Synthetic fibers are "man-made textile fibers produced entirely from chemical substances, unlike those man-made fibers derived from such natural substances as cellulose or protein." The polymers of synthetic fibers do not occur in nature, instead, they are produced from scratch in chemical plants or laboratories, "usually from by-products of petroleum and natural gas." Of these polymers is polyethylene terephthalate/polyester. Synthetic fibers are "spun and woven into huge consumer and industrial products", from garments such as shirts and scarves, home furnishings such as carpets ad drapes, to industrial parts such as flameproof linings and drive belts.
Stages in the Melt Spinning of polyester fibers
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3.5. PET BOTTLES RECYCLING IN PAKISTAN
Bales of used bottles (Post Consumer Bottles for Recycling)
Crusher used for cutting the used bottles into flakes
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Crusher front view
Washing line used for cleaning up the pet flakes
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PET flakes are drying in SUN
Final Recycled PET flakes (Final Product)
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CHAPTER 4
CHEMICAL RECYCLING OF PET TO FORM UNSATURATED POLYESTER
RESIN
Chemical recycling is also an established method for the recovery of process
waste. However, equipment costs are high and require large turnovers to be
economically viable.
4.1. GLYCOLYSIS
Glycolysis is a chemical process of PET waste recycling which required heat for
processing so it is an endothermic reaction. If recycled PET is treated with excess
glycol, a transesterification reaction takes place. The reduction of high molecular
weight PET to short-chain fragments is achieved by heating the PET with a glycol
such as propylene glycol (PG) in the presence of a catalyst. Typical catalysts are
zinc, manganese, or cobalt acetic acid. Typically this glycolysis reaction takes
place over an 8 hour period at 200 °C with a PG/PET and major products are bis-
hydroxyethyl terephthalate, bis-bydroxypropyl terephthalate, and mixed EG/PG
terephthalate diesters, plus some free EG and PG. The reaction is carried out
under continuous nitrogen purge to inhibit degradation of the resulting polyols.
Under these reaction conditions, the resulting polyol has a number average
molecular weight of 480 and a hydroxyl number of 480. If a higher molecular
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weight polyol were desired, the PG/PET ratio is lowered; i.e. less PG is used per
mole of PET. Glycolysis reaction can also be done using glycerol, which produces
a polyol with higher hydroxyl number, or with diethylene or dipropylene glycol
(DEG). [17]
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PIOLET PLANT
4.2. HYDROLYSIS
Treating PET with water in excess at an elevated temperature of 150-250 °C in
the presence of sodium acetate as catalyst produces terephthalic acid (TPA) and
ethylene glycol (EG) in four hours. Catalysts for hydrolysis are either acids (such
as sulfuric) or bases (such as ammonium hydroxide) [16]. An acid catalyst will
promote the hydrolysis in 10-30 minutes at 60-95 °C. Alternatively, PET can be
treated with an excess of methanol, to produce dimethyl terephthalate (DMT)
and EG. A typical PET/methanol ratio is 1:4. [17]
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4.3. METHANOLYSIS
Weighed amounts of PET (w1), methanol and ionic liquids were added in an
autoclave with a stirrer and a thermometer. The mixture was heated up to the
given temperature for certain time. The reaction mixture was filtered to remove
the unreacted PET (w2). The obtained filtrate was diluted with an equal volume
of water and a precipitate was obtained and filtered. The obtained filtrate was
distilled under vacuum to remove water and ethanediol, the residue that is
mainly composed of ionic liquid and catalyst was reused directly as solvent and
catalyst. The filter cake which is mainly composed of dimethyl
terephthalate(DMT) was dried to obtain DMT product . [17]
4.4. CHEMICAL RECYCLING OF PET ON LABORATORY SCALE
It is a process in which polymer chain breakdown into oligomer. Such as PET flakes are converted to BHET (Bis Hydroxyethyl Terephthalate). So this process consists of following Steps. i- First PET bottle Cut into Flakes of size 10mm ii- We take three neck Flask in which we put PET flakes and Diethylene Glycol
(DEG) as we know that glycolysis consist of transesterifaction of PET. As transesterifaction decrease the molecular weight of the polymeric chain.
iii- And then Zinc Acetate is added which is used as a catalyst and temperature is 210oC for 5 hour. And this reaction takes place in three neck round bottle flask.
iv- Nitrogen gas is supplied throughout the reaction. v- After this it is cooled down to 100oC at room temperature.
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vi- Now After this the solution is filtered and again pour it in to the flask vii- Then nitrogen supply is started to the flask to avoid oxygen to react with the
solution. viii- After this heating is started and phthalic anhydride, hydroquinone and maleic
anhydride is added to the flash. Due to which unsaturated polyester resin is formed
ix- After this styrene, monomer is added to the flask because it can start cross linking and stop the pre maturing.
x- And our unsaturated polyester resin is ready to use.
FORMULATION OF RECYCLED UNSATURATED POLYESTER
The Below formulation is approximate by weight.
S.No MATERIALS PERCENTAGE % 1 PET Flakes 24
2 DEG 27
3 MA 18
4 Styrene 28
5 THQ 0.01
6 HQ 0.001
7 WAX 0.05
8 Zn. Act 0.007
9 St. Acid 0.05
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CHAPTER 5
APPLICATION OF RECYCLED PET
Regrind PET can be used for reprocessing into cheap fiberfill for pillows and
sleeping bags or used directly in filled and reinforced PET molding compounds.
Another outlet for used PET is as a fuel source. According to Eastman, PET burns
cleanly to produce carbon, oxygen, and water, and one pound of PET has the
same heating value as one pound of soft coal. There are different uses of waste
PET it will be converted in to UP resin which is thermosetting material and it can
be uses for variety of purposes and PET waste can also be converted to polyols
for use in rigid or flexible urethane foams. Urethane foams made from recycled
PET are relatively cheaper than those made from normal virgin polyols. A variety
of clothing, including uniforms, working wear, T-shirts, polo shirts, sweatshirts
and using filament yarn, sweatshirts (jersey), windbreakers (woven), bags
(woven), tents (woven) and umbrellas (woven), are being manufactured from
recycled PET bottles. Recycled PET is also used as the plastics clamshells for
bakery and deli products.
This clamshell is produced by thermoforming a 3-layer sheet in which the middle
layer contains the recycled PET. Previously recycled PET cannot be used for food
packaging due to the restriction of Food and Drug Association (FDA). Now after
the development of new, advanced and sophisticated recycling processes, the
FDA has started giving approval to recycled PET up to a certain level. This has
opened new doors for the use of recycled PET. As one of the major users of
plastic containers for food use, and as a leader in the beverage industry, The
Coca-Cola Company has been involved in PET recycling from the start and was
one of the first companies to receive a "no-objection" letter from U.S. FDA,
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allowing the use of recycled PET for food-contact application. Since then many
different companies have taken an interest in developing some process for
recycling PET so that it can be used in direct food contact packaging and have
gained success [18]. The market of recycled PET for beer bottles is also igniting
interest of various manufacturers [19].Development in the field of reinforced
recycled PET is also catching up. Glass/mineral filled PET is now being used as
automotive grille opening retainers by Ford Motor Company, Mitsubishi Motors
and Toyoda Gosei Co. Ltd. jointly are now molding car engine covers entirely
from recycled PET soft drink bottles. [20]
RECYCLED PET T SHIRT & Lamp made with recycled PET straps
Extensive research investigated the use of resin based on recycled poly (ethylene
terephthalate) plastics waste for the production of a high performance
composite material, namely polyester concrete, for the construction industry.
Resins using recycled PET offered the lower source cost of materials for forming
good quality polyester concrete. Other applications include polyester resin for
sail boats, shower units, and floor tiles, lumber, floor coverings, corrugated
roofing, home insulation, industrial strapping, rope, non-food containers, light
weight auto body parts, and machine housings.
Athletic shoes made from recycled PET Recycled bottles & Recycled PET Grocery Bag
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UNSATURATED POLYESTER PRODUCTS
GRP PIPE
GRP Pipes are manufactured using filament winding process on computer
controlled machines. By adjusting the relative speed of mandrel rotation and
glass distribution head movement, helical reinforced layers with different angles
can be wound. In order to increase the pipe stiffness, especially on large
diameter pipes, silica sand can be added to parallel layers of wall. Pipes
manufactured using this process are used for aboveground and underground
installations, with gravity flow, medium and high internal pressure.
GRP SHEET
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GRP HOUSE
CULTURED MARBLE
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Building (panels, corrugated/flat sheets, profiles, infrastructure, bridges,
sanitary ware, swimming pools, subsea construction etc.)
Tanks, Containers, Pipes (incl. relining of pipes)
Electrical (wind turbines, appliance)
Marine (pleasure boats, utility vessels)
Automotive (cars, trucks, trains, container panels)
Castings (artificial stone, marble etc.)
Shirt Buttons
Synthetic marble castings Formulated products (gel coats, adhesives, putties)
Air conditional Panels
Air craft Components
Archery Bows
Arrow Shafts
Hoods
Trunk Lids
Floor Pans
Airscoopes
Bathroom Products
Building Panels
Cable Trays
Dish Washer Parts
Furniture
Helmets
Solar Energy Panels
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Unsaturated Polyester Button
Front Panel of Train Cultured marble
CAR Putty
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CHAPTER 6
TESTING
6.1. FIBRE TESTING
6.1.1. DESCRIPTION OF TEST FOR FIBRE
a. DENIER TESTING
TESTING STANDARD: - ASTM D 1059
Scope: To determine the Denier and filament count of all types of yarns.
Measure length of sample Weigh in grams Calculate count Count filaments
DENIER TESING MACHINE
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b. CUT LENGTH
TESTING STANDARD: - ASTM D 5319
c. FRICTION MEASUREMENT
TESTING STANDARD: - ASTM D 3412
METHOD:-
The test yarn is pulled over a friction body at a certain speed and a certain
angle. The tensile force is measured before and behind this friction body. The
friction coefficient is calculated
µ - METER
d. DRAW RATIO
TESTING STANDARD: - ASTM D1708
METHOD:-
During the course of a cycle, machine continuously measures the tension
produced in a sample yarn, which is heated to a certain temperature and
drawn to a certain percentage.
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DRAW TENSION TESTING INSTRUMENT
e. THERMAL SHRINKAGE
TESTING STANDARD: - ASTM D 4974
METHOD:-
Up to 10 samples are heated to a certain temperature for a specified period
of time or they are exposed to a temperature ramp. Either the
samples‘changes in length and/or the forces built up in the samples are
monitored via the connected computer. Since the instrument is computer
controlled, all test parameters are easily set and stored corresponding to
different tested materials. Therefore, once the test configuration is set, the
operator just needs to prepare the samples onto the measuring sensors and
the whole test takes place automatically.
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THERMAL SHRINAGE TESTING INSTRUMENT
f. TESNILE STRENGTH AND ELONGATION AT BREAK FOR FIBRE
TESTING STANDARD: - ASTM D 2343
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UNIVERSAL TESTING MACHINE
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6.2. COMPARISON TEST REPORT OF VIRGIN UNSATURATED POLYESTER
RESIN WITH RECYCLED UNSATURATED POLYESTER RESIN.
(8TH SEMESTER)
S.NO PROPERTIES VIRGIN UP RESIN
VALUE
UP RESIN FROM PET
VALUE
1 Appearance clear -
2 Viscosity 25oC
(DIN CUP) 90-110sec -
3 Density (25oC) 1.15 -
4 Acid Value (mgkoh/g)
35-40 -
5 Gel time 30oC (7-10)min -
6 Exothermic
Temperature (155-170)0C -
7 Peak Time (14-25)min -
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6.2.1. DESCRIPTION OF TEST FOR UNSATURATED POLYESTER RESIN
A. DENSITY TEST ASTM D4052
B. ACID VALUE TEST ASTM D3643
C. VISCOSITY TEST DIN 53211 D. GEL TIME TEST ASTM D3532
E. EXOTHERMIC TEMPERATURE TEST ASTM D2471
F. PEAK TIME TEST ASTM D2499
The above mentioned tests will be performed in semester 8th.
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CHAPTER 7
MARKET SURVEY
7.1. LOCAL MARKET SURVEY
PET FLAKES DEALERS
NHN PETRO INDUSTRIES
Contact Person:- Mr. Shareef Siddiqui (PLANT INCHARGE)
Phone No:- 0213-512-1136
Cell No:- 0300-272-7911 / 0313-209-2092
Address:- Plot No:-44, Sector No:-24, Korangi Industrial Area Karachi Pakistan.
PRICE
White Flakes Rs. 96/Kg
Blue Flakes Rs. 94/Kg
Green Flakes Rs. 90/kg
QUALITY TRADER
Contact Person:- Yunus Lodhi
Phone No:- 0213-825-0533
Cell No:- 0334-303-0140
Address:- Plot No:- 120-A, Sector No:- 27, Korangi Industrial Area Karachi Pakistan.
PRICE
White Flakes Rs. 98/Kg
Blue Flakes Rs. 97/Kg
Green Flakes Rs. 89/kg
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SHER SHAH KARACHI
Contact Person:- Mr. Bilal
Cell No:- 0345-256-9235
Address:- Phanka hotel Street near Caltex Petrol Pump Karachi Pakistan.
PRICE
White Flakes Rs. 73-75/Kg
Blue Flakes Rs. 73-74/Kg
Green Flakes Rs. 73-74/kg
IMPORTANT INFORMATION
A. PRICE FLUCATION:-
In summer price per kg 50-55
In winter price per kg 72-75
B. CRUSH SELLING COST:-
In summer Crush = Rs 60/kg
In Winter Crush = Rs (80-85)/kg
C. WASH PRICES:-
Hot wash (SODA CASTIC)= Rs. 10/kg
Cold Wash =Rs. 5/kg
D. OTHER COST:-
Crush (LABOUR COST)= 3/kg
Separation Labor Cost = 2-3/kg
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LOCAL CHEMICAL MARKET SURVEY
AHMED CHEMICAL CO. importer distributor & supplier of chemicals
Phone No:- 0213-243-0561 / 0213-243-7345
E-mail:- ahmedchm@cyber.net.pk
Address:- Daryalall Street, Jodia Bazar, Karachi Pakistan
S.No CHEMICALS PRICES
1 Monoethylene Glycol 140/Kg
2 Diethylene Glycol 135/Kg
3 Propylene Glycol 250/Kg
4 Malic Anhydride 220/kg
5 Phthalic Anhydride N/A
6 Zinc Acetate N/A
7 Hydroquinone 7800/Kg
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COC [CENTER OF CHEMICALS] dealer & importer of chemical Phone No:- 0213-400-6934 / 0213-243-3522
E-mail:- tariq.ikhlas@gmail.com
Address:- Shop # 6, Maryam Manzil, Katchi Gali # 1, Jodia Bazar Karachi-Pakistan.
S.No CHEMICALS PRICES
1 Monoethylene Glycol 140/Kg
2 Diethylene Glycol N/A
3 Propylene Glycol N/A
4 Malice Anhydride 220/kg
5 Phthalic Anhydride 340/Kg
6 Zinc Acetate N/A
7 Hydroquinone 7380/Kg
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ILYAS SONS CORPORATIN HOUSE OF SPECIALTY CHEMICALS (IMPORTER & MANUFACTURES REPRESENTATIVE) Phone No:- 0213-400-6934 / 0213-243-3522
E-mail:- tariq.ikhlas@gmail.com
Address:- 156/3-A, Kutchi Gali No. 1, Jodia Bazar, Karachi-74000
S.No CHEMICALS PRICES
1 Monoethylene Glycol 140/Kg
2 Diethylene Glycol 300/Kg
3 Propylene Glycol 250/Kg
4 Malice Anhydride 220/kg
5 Phthalic Anhydride N/A
6 Zinc Acetate N/A
7 Hydroquinone N/A
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Karachi Scientific Traders (Stockiest & suppliers) of Laboratory Chemicals, Glassware, Scientific Instruments, P.H. & TDS Meters.
Phone No:- 02132513527 / 02132526057
E-mail:- mohsinadeel@yahoo.com
Address:- Shop #. G-13 Union Chamber, North Napier Road, Karachi.
S.No CHEMICALS PRICES
1 Monoethylene Glycol 140/Kg
2 Diethylene Glycol N/A
3 Propylene Glycol 250/Kg
4 Malice Anhydride 220/kg
5 Phthalic Anhydride N/A
6 Zinc Acetate N/A
7 Hydroquinone 8500/kg
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International Chemical Market Survey
CHEMICALS COMPANY PRICE
DEG
Nangong Xihua Felt Co., Ltd. China
US $1200-2000 /
Metric Ton
Adinath Chemicals India
US $1200-1600 /
Ton
YOUNG'S CORPORATION South Korea
US $1.2-1.5 /
Kilogram
MEG
Shanghai Homore Industrial Co., Ltd
China
US $700-1000 /
Ton
Adinath Chemicals India
US $1000-1500 /
Ton
Hana International Trade Co. Iran(Islamic Republic of)
US $1020 / Metric
Ton
PG
Qingdao Baijie International Trade Co., Ltd.
China
US $1500-1800 /
Ton
BeoChems Industrial US
US $3-9 / kg
Fancying Industrial LTD South korea
US $1500-1540 / Metric Ton
MALEIC ANHYDRIDE Zhengzhou Qiangjin Science And
Technology Trading Co., Ltd. China
US $1610-1750 /
Metric Ton
PHTHALIC ANHYDRIDE Shijiazhuang Baicheng Chemical
Co., Ltd. China
US $1535-1800 /
Ton
ZINC ACETATE Tianjin Flourish Chemical Co., US $1846-2153 /
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Ltd. China
Ton
Shijiazhuang Haosheng Chemical Co., Ltd
China
US $1650-1950 /
Metric Ton
Beijing Sanyoujinbiao Chemical Co., Ltd.
China
US $1035-1527 /
Metric Ton
HYDROQUINONE
Xi'an Aladdin Biological
Technology Co., Ltd China
US $30-200 /
Kilogram
N.A.K.P. Foto Inc Canada
CA $11.50-12.00 /
Kilogram
Protech Science Corp. US
US $9850.00-
10835.00 / Ton
STYRENE MONOMER
AK-TAS DIS TICARET A. S. Turkey
US $1200-1600 /
Metric Ton
Shandong Hao Na Import & Export Co., Ltd.
China
US $1250-1550 /
Ton
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WORK PLAN
The Strategy for this Project,
PET WASTE RECYCLING
Consist of two sections on which our work is based. The content to be covered in two
sections is summarized below according to the semester.
SEMESTER-7
In this semester our strategy consist of theoretical detail about,
Bottle Grade & Fiber Grade Recycling
Physical Recycling Process
Chemical Recycling Process
Market Survey
Testing Techniques
Application of Unsaturated Polyester Resin
SEMESTER-8
Semester 8th will include brief detail about,
the structural analysis of material on which the PET recycling is based.
Practical work will include physical and chemical recycling to form fiber and
unsaturated polyester (UP) resin respectively.
Testing results and data from recycling process will be obtained and discussed in
detail.
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REFERENCES
*1+ Lubin G., “Handbook of Fiberglass and Advanced Plastics Composites”, Van Nostrand Reinhold Company, New York, (1969) *2+ Chaudhari K. P., Kale D. D., “Impact Modification of Waste PET by Polyolefinic Elastomer”, Polymer International, Vol. 52, p. 291-298 (2003) *3+ Deanin R. D., “The Relationship Between Structures, Properties, and Applications in Polymer Structure, Properties and Application”, Cahners Publishing Company Inc., York, Pennsylvania, (1972) *4+ Ehrig R. J., “Plastics Recycling, Products & Processes”, Hanser Publishers, New York, (1992) [5] Brandrup J., Bittner M., Michaeli W., Menges G., "Recycling and Recovery of Plastics", Carl Hanser Verlag, New York, (1996) *6+ Brydson I. A., “Plastics Materials”, 4th Ed., Buterworth Scientific Press, London, (1982) *7+ Nitschke C., “Modern Plastics Encyclopedia”, McGraw Hill, New York, (1985) [8] KOSA, "Innovative PET Resin for Beer and Hot-Fill Markets", Plastics News International, (2000) *9+ Eastman Chemical Products Inc., “PET Bottles Move Into Medical Care Application”, Modern Plastics International, Vol. 15, p.46 (1985) [10] Sekisui Kaseihin Kogyo Co., Japan, "New Polymer Applications'', Plastics Industry News (Japan), Vol. 39, p. 20-21 (1993) [11] Ticona GmbH, Hoechst GmbH, "Inform Issue 5. Electrical/ Electronics Industry - Celanex - Impet - Vmdar", Frankfurt am Main, p. 28-30 (1997) *12+ Mantia F., “Handbook of Plastics Recycling”, Rapra Technology Limited, Shawbury, (2002) [13] Paci M., La Mantia F., "Influence of Small Amounts of Poly Vinyl Chloride on the Recycling of Polyethylene Terephthalate", Polymer Degradation and Stability, Vol. 63, p. 11-14 (1999) [14] Torres N., Robin J. J., Boutevin B., "Chemical Modification of Virgin and Recycled Poly(ethylene terephthalate) by Adding of Chain Extenders During Processing", Journal of Applied Polymer Science, Vol. 79, p. 1816-1824 (2001) *15+ Pawlak A., Pluta M., Morawiec j., Galeski A., Pracella M., “Characterization of Scrap Poly(ethylene terephtahlate)”, European Polymer Journal, Vol. 36, p. 1875-1884 (2000)
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*16+ Lamparter R. A., Barna B. A., and Jonsrud D. R., “Process for Recovering Terephthalic Acid from Waste Polyethylene Terephthalate”, U.S. Patent 4,542,239, (1985) *17+ Gruschke H., et al. “Process of Depolymerization of Polyethylene Terephthalate to Terephthalic Acid and Dimethyl Ester”, U.S. Patent 3,403,115, (1968) [18] Doba J., "FDA Gives Go-Ahead for Recycled PET Use", Plastics News,Vol. 11, p. 4 (2000) [19] Defosse M., "Promising Beer Bottle Market is Igniting Interest in Recycled PET", Modern Plastics International, Vol. 29, p. 38 (1999) [20] Moore S., "Auto Engine Cover is Made from PET Bottles", Modern Plastics International, Vol. 30, p. 32-36 (2000) *21+ Jang B. Z., “Advanced Polymer Composites: Principles and Applications”, ASM International, Materials Park (1994) [22] http:// www.accessscience.com McGraw-Hill Encyclopedia of Science & Technology Online *23+ Simon G. P., “Polymer Characterization Techniques and Their Applications to Blends”, Oxford University Press, (2003) *24+ Strong A. B., “Plastics, Materials & Processing”, Prentice Hall, New York, (2000) *25+ Yılmazer U., Cansever M., “Effects of Processing Conditions on the Fiber Length Distribution and Mechanical Properties of Glass Fiber Reinforced Nylon-6”, Polymer Composites, Vol. 23, p. 61-71 (2001)
[26]. Dujari R, Cramer G, Marks D. Method for solid phase polymerization (E.I. du Pont de Nemours & Company). WIPO Patent WO 98/23666, 1998.
[27]. Flory P. Polymerization process (E.I. du Pont de Nemours & Company). U.S. Patent 2,172,374, 1939.
[28]. Monroe G. Solid phase polymerization of polyamides (E.I. du Pont de Nemours & Company). U.S. Patent 3,031,433, 1962.
[29]. Cruz S, Zanin M. PET recycling: evaluation of the solid state polymerization process. J. Appl. Polymer. Sci. 2006; 99:2117–2123. [30]. Karayannidis G, Kokkalas D, Bikiaris D. Solid-state polycondensation of poly(ethylene terephthalate) recycled from postconsumer soft-drink bottles: I. J. Appl. Polym. Sci. 1993;50(12):2135–2142.
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