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PET

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Petrochemical Engineering
Duhok Polytechnic University
Name: Safwan Kamal Askender
Stage: 3
Subject: Petrochemical
Date: 26/4/2021
[1]
Objective:
Recycled polyethylene terephthalate (PET) by a depolymerization
reaction and use of the product for the synthesis of a diester of
high added value.
Highlights:
Plastics are important in our society providing a range of
benefits.
Waste plastics, nowadays, burden the marine and terrestrial
environment.
Additives and PoTSs create complications in all stages of
plastics lifecycle.
Inappropriate use, disposal and recycling may lead to
undesirable release of PoTSs.
Sound recycling of plastics is the best waste management
and sustainable option.
Introduction:
Global plastic demand is dominated by thermoplastic types
of polypropylene (PP) (21%), low -and linear lowdensity polyethylene (LDPE and LLDPE) (18%), polyvinyl
chloride (PVC) (17%), and high-density polyethylene, (HDPE)
(15%). Other plastic types with high demand are polystyrene (PS),
and expandable PS (8%), polyethylene terephthalate (PET) (7%,
excluding PET fibre) and the thermosetting plastic polyurethane.
Plastic polymers are not only used for consumer products but also
to make synthetic fibres, foams, coatings, adhesives and sealants,
[2]
which are used in numerous applications . In Europe, the use of
plastics is mostly dominated by packaging (38%), followed by
building and construction (21%), automotive (7%), electrical and
electronic (6%), and other sectors (28%), such as medical and
leisure, Polyethylene terephthalate (sometimes
written poly(ethylene terephthalate)), commonly
abbreviated PET, PETE, or the obsolete PETP or PET-P, is the most
common thermoplastic polymer resin of the polyester family and
is used in fiber for clothing, containers for liquids and foods,
and thermoforming for manufacturing, The confusion seems
to come from PET's chemical name, polyethylene terephthalate.
Despite the suffix, PET is not a
plasticizer phthalate. Phthalates are low molecular weight
monoesters made from ortho-phthalic acid. PET is a high
molecular weight polyester made from tere-phthalic acid.
Benefit of plastic:
Plastics are important in our society providing a range of benefits for
human health and the environment. For example
Plastic packaging protects food and goods from getting wasted
and/or contaminated, thereby saving resources.
The light weight of plastic packaging compared to other materials
saves fuel and decreases emissions during transportation.
Plastic water supply systems and storage containers/tanks can
provide clean water.
Low-density plastic materials, used as replacements for metals or
ceramics in cars and aircraft, save fuel and decrease emissions.
Plastic protective clothing and safety equipment (e.g. fire proof
materials, helmets, air bags) prevent injuries.
Plastic products for medical applications contribute to improved
heath (e.g. blood pouches, tubings, disposable syringes, prosthesis)
[3]
Reagent & material
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Bottle of water (PET)
pentan1-ol
KOH (0.079 mol)
Water
HCl
Acetone
H2SO4
MeOH
Procedure:
A) Preparation of PET samples From bottles of soda or mineral
water previously cleaned without labels, using scissors, cut plastic
into small pieces to obtain a mass of approximately (5 g).
B) Hydrolysis of PET samples (preparation of Terephthalic Acid)
1. In round-bottom flask, add (35 ml) of pentan-1-ol (mixture of
isomers or pentan1-ol.
2. Add (5 g) of PET (0.052 mol equivalent ester), and (4.4 g) of
KOH (0.079 mol) in the round-bottom flask.
3. Reflux the mixture with magnetic stirring. While at first the
polymer does not dissolve, shortly after dissolution a dense white
emulsion forms. Note (If magnetic stirring is stopped by the
viscosity of the reaction crude, add more solvent in portions of (5
ml) of pentan-1-ol).
4. Once the stirring resumes, maintain the reflux for (1 h)
5. After reflux, cool the reaction to room temperature.
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6. Add (25 ml) of water so that the white solid (terephthalate
potassium salt) is dissolved.
7. Filtration to remove any remaining suspended solid, (it’s
preferred to use Buchner funnel to filtration because the
water/pentan-1-ol mixture filters very slowly by gravity).
8. Transfer the filtrate to a separating funnel. Decant the aqueous
(lower) layer and wash the organic (top) with another (25 ml) of
water.
9. Collect in a beaker both aqueous layers, and add diluted HCl
very slowly with magnetic stirring to neutrality. Polymer synthesis
and characterization (If the acid is added too quickly, a solid
crystal of very small size will form and will be difficult to filter).
10. Once the terephthalic acid has precipitated, filter the crystals
(using Buchner funnel) and wash with of (5-10 ml) of acetone.
11.Weigh, calculate yield, and store for the next step
Producing Dimethyl Terephthalate :
1. In a round-bottom flask, add (2.5 g) of terephthalic acid and (20
ml) MeOH.
2. Cool the mixture in an ice bath and slowly add with a dropper
(3 ml) of concentrated H2SO4. (If the acid is added too quickly, a
solid crystal of very small size will form and will be difficult to
filter). 3. Add a stir bar into the flask and reflux (using a drying
tube) for (60 min).
4. After reflux, cool the reaction to room temperature.
5. Filter the resulting solid (using Buchner funnel).
6. Recrystallize the impure product from dichloromethane.
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7. Weigh, and calculate the yield.
Calculation:
Discussion:
What products are made from polyethylene terephthalate?
Products commonly made from recycled PET include new PET
bottles and jars, carpet, clothing, industrial strapping, rope,
automotive parts, fiberfill for winter jackets and sleeping bags,
construction materials, and protective packaging.
After preparing solution in part (C) we put solution into cold
water during adding H2SO4?
To remove heat from solution cuz the are exothermic solution.
What plastics contain phthalates?
Some phthalates are in polyvinyl chloride plastics, which are used
to make products such as plastic packaging, garden hoses, and
medical tubing. People are exposed to phthalates by eating and
[6]
drinking foods that have contacted products containing
phthalates.
Do plastic water bottles have phthalates?
Most plastic wraps, water bottles, and food containers are
phthalate-free.
Is PET plastic safe?
Previous research has focused on plastics containing the chemical
bisphenol-a (BPA). During that time regular PET plastic water
bottles have maintained a reputation as safe, at least as far as
human health is concerned. But new evidence suggests that PET,
or polyethylene terephthalate, may not be so benign after all.
Chemical recycling can turn plastic back into its original
components?
Chemical recycling can turn plastic back into its original
components, from which new plastic can be made. Chemically
recycled plastic is of high quality and can be a drop-in substitute
for plastic from virgin fossil feedstock even for sensitive
applications, such as food packaging and medical products.
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