Why Recycling Plastics?
With a market demand on
plastic materials and scraps, more plastic recyclables are recovered
from domestic sources for recycling, in addition to plastic scraps from
commercial and industrial sources.
Witama Jaya recycling plant uses seven steps to recycle plastic waste:
Inspection Workers inspect the plastic waste for contaminants like rock and glass, and for plastics that the plant cannot recycle. - Chopping & Washing The plastic is washed and chopped into flakes.
- Floatation Tank If mixed plastics are being recycled, they are sorted in a flotation tank, where some types of plastic sink and others float.
- Drying The plastic flakes are dried in a tumble-dryer.
- Melting The dried flakes are fed into an extruder, where heat and pressure melt the plastic. Different types of plastics melt at different temperatures.
- Filtering The molten plastic is forced through a fine screen to remove any contaminants that slipped through the washing process. The molten plastic is then formed into strands.
- Pelletizing The strands are cooled in water, then chopped into uniform pellets which can be used to make new products. Recycled plastics can be made into many products, including flowerpots, lumber substitutes and carpeting.
Plastic recycling is the process of recovering
scrap or waste plastics and reprocessing the material into useful
products, sometimes completely different from their original state.
Before recycling, plastics are sorted according to their resin identification code. PET, for instance, has a resin code of 1. Processing
When
compared to other materials like glass and metal materials, plastic
polymers require greater processing to be recycled.Plastics have a low
entropy of mixing, which is due to the high molecular weight of their
large polymer chains. A macromolecule interacts with its environment
along its entire length, so its enthalpy of mixing is large compared to
that of an organic molecule with a similar structure. Heating alone is
not enough to dissolve such a large molecule; because of this, plastics
must often be of nearly identical composition in order to mix
efficiently.
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When different types of plastics are melted together
they tend to phase-separate, like oil and water, and set in these
layers. The phase boundaries cause structural weakness in the resulting
material, meaning that polymer blends are only useful in limited
applications.
Another barrier to recycling is the widespread use of dyes, fillers, and other additives in plastics.
The
polymer is generally too viscous to economically remove fillers, and
would be damaged by many of the processes that could cheaply remove the
added dyes. Additives are less widely used in beverage containers and
plastic bags, allowing them to be recycled more frequently.
The
use of biodegradable plastics is increasing. If some of these get mixed
in the other plastics for recycling, the recycled plastic is less
valuable.
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PLASTIC
RECYCLES PELLET
1. HIGH DENSITY
POLYETHYLENE (HDPE) PLASTIC RECYCLE
Overview
High Density Polyethylene (HDPE) recycle grade is the
plastic used mainly to make milk bottles and many other types including liquid
detergent and cleaning
solution bottles. HDPE has the highest amount of usage for any plastic and is
the second most recycle plastics.
HDPE is
more rigid and harder than lower density materials. It also has a higher
tensile strength, four times that of low density polyethylene, and is three
times better in compressive strength .
Characteristics:
·
Excellent
processing and mechanical properties;
·
Excellent
environmental stress crack resistance and chemical resistance;
·
Excellent
electric properties and durability
Grade and
applications:
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Grade
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Applications
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Injection molding grade
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Caps for beverage bottles, pallets for all uses, containers, dust bin,
pails and bottle cap for mineral water, transport and stacking crates, silicon cartridge,
toys complicated parts, light-weight household
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Film grade
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Merchandise bags, consumer trash bags, industrial and institutional
liners
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Blow molding grade
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Small bottles, shampoo and cleaner bottles 20 liter containers, oil
bottle, general purpose containers
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Pipe extrusion molding grade
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Pressure pipes, for water and gas, sewage pipe, cable protection pipe,
corrugated pipes for tele-communication cable, sewage pipe, cable protection
pipe, corrugated pipe for building wire
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Crosslinked pipe grade
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Crosslink pipe, silane crosslinking pipe
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2. LOW DENSITY
POLYETHYLENE (LDPE) PLASTIC RECYCLE
Overview
Low
Density Polyethylene (LDPE) is the plastic used mainly make film for trash
bags, food packaging, shrink films, and construction/agricultural films.
LDPE was
first found by British ICI research team by accident and was commercially
available in 1939. Initially it was used for wire insulation for military
purpose such as radar cable insulation. In the U.S.A it was it was manufactured
by Dupon in 1942 and by UCC in 1943
Characteristics:
·
Super
transparency and processability. These products are suitable for special
agricultural applications such as long-life and anti-fogging films due to their
excellent miscibility characteristic with various master batches.
·
Outstanding
processability and super blending characteristic with additives. Molecular
weight, melt index and density of these products are specially designed to
satisfy the demanding requirements of foaming processes, chemical resistance
·
Superior
transparency, processability and rigidity, which make this grade suitable for
multilayer containers.
Grade
and applications:
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Grade
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Applications
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Film Grade
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General purpose wrapping (shopping bags, food packing film).
Heavy-duty films (resin bags, sugar bags, corn powder bag), shrink wrapping
(bottle box wrapping), pallet shrink coves, thin films, agricultural films
(greenhouse application), tunnel film, mulching film, protective films (gel
free films for lamination, metal substrates)
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Foam Grade
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Packaging materials for consumer electronics, packaging material,
automobile interiors, thermal insulation sheets
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Blow molding grade
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Food containers, squezee
bottle
(mayonnaise bottle, ketchup bottle) and detergent bottle
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Extrusion coating grade
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PET coating, paper coating, craft paper, paper cup, al coating
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Injection molding grade
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Lid, masterbatch, powder coating, artificial flowers, thin wall
products
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3. POLYPROPYLENE (PP)
PLASTIC RECYCLE
Overview
Polypropylene
(PP) recycle grade is a tough, lightweight rigid plastic made by polymerization
of high purity propylene gas in the presence of an organometallic catalyst at
relatively low pressure and temperatures.
Characteristics:
·
Excellent
processing and mechanical properties;
·
Excellent
environmental stress cracking resistance and chemical resistance;
·
Excellent
electric and durability
Grade
and applications:
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CLASSIFICATIONS
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GRADE
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APPLICATIONS
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Injection
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Industrial
products, general purpose injection molding, rigid packaging, general use
housewares, closures, thin wall containers, disposable syringe, transparent
containers
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Extrusion
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Sheet,
thermoforming, pipes, strappings, tubings, blow molded bottles
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HOMOPOLYMER
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Film
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Textile
overwraps, garment bags, cigarette packaging
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Fiber
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Stape
fiber, multifilament yarn, carpets, compact spinning, fine fiber yarn,
non-woven fabric
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Flat
yarn
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Band,
tapes, yarn, straw
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Lamination
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Various
types of lamination
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BLOCK / IMPACT COPOLYMER
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Injection
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Battery
case, crates, furniture, luggage shells, industrial products, automotive
parts, housewares, tub, outer part of washing machines, large injection goods,
inner parts of cars, electric home appliances, general purpose molding,
industrial components, molded luggage, rigid packaging, containers
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Blow
molding
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Vacuum
forming, sheets, (VTR cassette case, binder, box)
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RANDOM COPOLYMER
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Injection
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Table
wares food containers, disposable syringe, rigid containers, housewares,
general purpose housewares, home appliances
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Blow,
extrusion
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Medical
use, cosmetic containers, all transparent bottles, video sheet containers
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Films
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General
food package, metalized CPP films, shrinkage films, CPP films
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