This document discusses polymers and their uses in daily life. It begins by defining polymers as large molecules composed of repeating structural units. Common synthetic polymers mentioned include polyethylene, polypropylene, polyvinyl chloride, and nylon. The document then focuses on poly lactic acid (PLA), describing its production from renewable resources like corn starch, its properties, and its biodegradability. PLA has various applications in agriculture, medicine, packaging and textiles. While PLA production reduces fossil fuel usage, it also releases carbon dioxide and methane during degradation. Overall, the document provides an overview of polymers with a detailed focus on production, properties and uses of the biodegradable polymer PLA.
1. POLYMERS IN DAILY LIFE
BY
VIGNESH PRABHU.T
SCHOOL OF SCIENCE AND HUMANITIES
KONGU ENGINEERING COLLEGE
(AUTONOMUS)
PERUNDURAI-638052.
2. CONTENT
What is a Polymer ?
Classification
Poly lactic acid
Preparation
Properties
Applications
Degradation
Drawbacks
Benefits
Future works
3. WHAT IS A POLYMER ?
Polymers are substances whose molecules have
high molar masses and are composed of a large
number of repeating units. There are both naturally
occurring and synthetic polymers. Among naturally
occurring polymers are proteins, starches,
cellulose, and latex.
Polymers are studied in the fields
of biophysics and macromolecular science,
and polymer science which includes
polymer chemistry and polymer physics.
4.
5. SOME COMMON EXAMPLES OF SYNTHETIC
POLYMERS
POLY ETHYLENE
Polyethylene or polyethene is the most common
Plastic
Its primary use is in packaging.
Melting point: 115–135 °C
Density: 0.91–0.96 g/cm
3
Chemical formula: (C2H4)n
o POLY PROPYLENE
Polypropylene is a thermoplastic polymer used in a wide variety of
applications including packaging and labeling, textiles, stationery,
plastic parts and reusable containers.
Density: 946 kg/m³
Melting point: 130 °C
Formula: (C3H6)n
6. POLY VINYL CHLORIDE
Polyvinyl chloride, more correctly but unusually
poly(vinyl chloride), commonly abbreviated PVC, is the
third-most widely produced synthetic plastic polymer
Density[g/cm3] :1.3–1.45
Chemical formula: (C2H3Cl)n
Melting point :100–260 °C
7. NYLON
Nylon is a generic designation for a family of
synthetic polymers, more specifically aliphatic or
semi-aromatic polyamides. They can be melt-
processed into fibers, films or shapes.
o BAKELLITE
Bakellite first plastics made from synthetic
components, Bakelite was used for its electrical
nonconductivity and heat-resistant properties in
electrical insulators, radio and telephone casings, and
such diverse products as kitchenware, jewelry, pipe
stems, children's toys, and firearms.
8. POLY LACTIC ACID
Polylactic acid (PLA) is a rigid thermoplastic
polymer that can be semicrystalline or totally
amorphous, depending on the stereopurity of the
polymer backbone.
Highly versatile thermoplastic material
Made from 100% renewable resources
PRODUCTION
SOLVENT METHOD
NON SOLVENT METHOD
9. SOLVENT METHOD
Producers have several industrial routes to usable
(i.e. high molecular weight) PLA. Two main
monomers are used: lactic acid, and the cyclic di-
ester, lactide.
NON SOLVENT METHOD
Start with starch from renewable resource
Renewable resources used : corn starch ,
tapioca roots, chips or sugarcane.
Unrefined dextrose processed from starch
Dextrose fermented into lactic acid
Lactide produced through condensation
Purification through vacuum distillation
10. PROPERTIES:
PLLA has a crystallinity of around 37%, a glass
transition temperature 60–65 °C, a melting
temperature 130°–230°C and a tensile modulus
2.7–16 GPa.
Heat-resistant PLA can withstand temperatures of
110 °C.
It is upto 7 times recycleable.
11. PROPERTIES(CONT’)
Below Tg, PLA behaves as a glass with the ability
to creep until cooled to its transition temperature of
approximately _45°C.
Below this temperature PLA will only behave as a
brittle polymer.
Polylactic acid can be processed like most
thermoplastics into fiber (for example, using
conventional melt spinning processes) and film
12. APPLICATIONS
In agriculture :
Coating of seeds can be done with the help of poly
lactic acid
Prevents the seeds from damage during
transportation and sowing
Withstands mechanical pressure
When sown into the soil
this PLA coating gets degraded
easily
Food products too can be coated
with PLA which gets degraded
easily
13. In medicine :
Being able to degrade into
innocuous lactic acid, PLA is used
as medical implants in the form of
anchors, screws, plates, pins, rods,
and as a mesh.
Depending on the exact type used, it
breaks down inside the body within
6 months to 2 years.
This gradual degradation is
desirable for a support structure,
because it gradually transfers the
load to the body (e.g. the bone) as
that area heals.
PLA is also used in cosmetics
14. In industrial field :
PLA can also be used as a decomposable packaging
material, either cast, injection-molded, or spun.
Cups and bags have been made from this material.
In the form of a film, it shrinks upon heating, allowing it
to be used in shrink tunnels.
It is useful for producing loose-fill packaging, compost
bags, food packaging, and disposable tableware.
In the form of fibers and non-woven textiles, PLA also
has many potential uses, for example as upholstery,
disposable garments.
15.
16. DEGRADATION
Fully combustible in
composting facilities
Can be converted back to
monomer
Can be completely
broken down to H20,
CO2, and organics
Degradation time: weeks
to months
17. DRAWBACKS
PLA releases carbon dioxide and methane during
the biological breakdown phase
Fossil fuels still needed to produce PLA
Some believe that PLA will degrade too slowly to
make a difference in waste streams
18. BENEFITS
Biodegradable: Less
landfill space!
1500 pounds of waste per
year for every person
Plastic materials account
for 20% (vol.) of landfills
20-50% less fossil fuels
used in production than
in petroleum based
polymers
No net increase in CO2
emissions