the term 'plastics' is used to describe a wide variety of resins or polymers
with different characteristics and uses.
polymers are long chains of molecules, a group of many units, taking its
name from the greek 'poly' (meaning 'many') and 'meros'
(meaning 'parts' or 'units').
while all plastics are polymers, not all polymers are plastic.
for the discussion of recycling, an understanding of two basic types of
polymers is helpful:
* thermoplastic polymers can be heated and formed,
then heated and formed again and again. the shape of the polymer
molecules are generally linear or slightly branched. this means that the
molecules can flow under pressure when heated above their melting point.
* thermoset polymers undergo a chemical change when they are heated,
creating a three-dimensional network. after they are heated and formed,
these molecules cannot be re-heated and re-formed.
comparing these types, thermoplastics are much easier to adapt to recycling.
plastic from a blow mold (the neck of the bottle is narrower than the body)
has a slightly different structure from the exact same plastic used in an
injection mold (where the opening is the widest part of the product).
plastic identification / recycling code
when working with plastics there is often a need to identify which
particular plastic material has been used for a given product.
most consumers recognize the types of plastics by the numerical coding
system created by the society of the plastics industry in the late 1980s.
there are seven different types of plastic resins that are commonly used to
package household products. the identification codes listed below can be
found on the bottom of most plastic packaging.
#1- polyethylene terephthalate (PET)
soda & water containers, some waterproof packaging, tennis balls.
#2 - high-density polyethylene (PE)
milk, detergent & oil bottles. toys and plastic bags.
#3 - vinyl / polyvinyl chloride (PVC)
food wrap, vegetable oil bottles, blister packages.
#4 - low-density polyethylene
many plastic bags. shrink wrap, garment bags.
#5 - polypropylene
refrigerated containers, some bags, most bottle tops,
some carpets, some food wrap, chairs (back/seats).
#6 - polystyrene
throwaway utensils, meat packing, protective packing.
#7 - other. usually layered or mixed plastic.
no recycling potential - must be landfilled.
although all plastic containers bear the chasing arrows symbol with a
number in the middle, suggesting that all such products are recyclable,
it is only 1s and 2s that can be.
there is no market for bottles numbered 3 through 7.
most of the products which are manufactured from what is
recycled, can't be recycled a second time.
so, what you set out at your curb is only one generation away
from a landfill!
recycling PET is similar to the polyethylenes.
bottles may be color sorted and are ground up and washed.
unlike polyethylene, PET sinks in the wash water while the plastic caps
and labels are floated off. the clean flake is dried and often repelletized.
PVC bottles are hard to tell apart from PET bottles,
but one stray PVC bottle in a melt of 10,000 PET bottles can ruin the entire batch.
it's understandable why purchasers of recycled plastics want to make sure that
the plastic is sorted properly.
equipment to sort plastics is being developed, but currently most recyclers are
still sorting plastics by hand (and in the third world)
that's a hard and ugly work, it's expensive and time consuming.
plastics also are bulky and cumbersome to collect.
in short, they take up a lot of space in recycling trucks.
virgin resin production outpaces recycling
currently only about 3.5% of all plastics generated is recycled,
compared to 34% of paper, 22% of glass and 30% of metals.
at this time, plastics recycling only minimally reduces the amount of
virgin resources used to make plastics.
recycling papers, glass and metal, materials that are easily recycled more than
once, saves far more energy and resources than are saved with plastics recycling.
the recycling rate for all PET (polyethylene terephthalate) bottles,
which represent 44 percent of total plastic bottle production,
dropped to 25 percent.
PET soda bottles, which represent one fourth of all plastic bottles produced,
and nearly two thirds of all PET bottles, dropped to 36 percent last year.
plastic bottle recycling has not kept pace with the dramatic increases in
virgin resin PET sales, particularly for PET bottles.
most of the increase in virgin resin sales has been for single-serve PET
soda bottles (under 24 oz) that now make up 60 percent of soda bottle
'bottle to bottle' recycling or downcycling ?
when glass, paper and cans are recycled, they become similar products
which (theoretically) can be used and recycled over and over again.
with plastics recycling, however, there is usually only a single re-use.
some soda bottles make it to a recycler who must scramble
to find a buyer, and often ends up selling the bottles at a loss
to an entrepreneur who makes carpeting or traffic strips,
-- anything but new bottles.
and what is the plastic bottling industry doing to create a stronger
recycling market for its product? nothing.
see soda companies and recycling
if you think the latest fashions on the runway are trashy, you might just be right.
PET can be recycled into fibres that are used for polyester fabrics.
major designers used recycled plastic bottles for haute couture.
the strength, warmth, and durability properties of virgin and recycled yarns are
the same. the only difference is that recycled yarns have a matte rather than the
glossy finish of virgin polyester.
five PET bottles yield enough fiber for one extra-large t-shirt or
twenty-five two-liter bottles can make one sweater.
five two-liter PET bottles yield enough fiberfill for a ski jacket.
carpet companies can often use 100% recycled resin to manufacture polyesther
carpets in a variety of colors and textures.
PET is also spun like cotton candy to makr fiber filling for pillows and quilts.
it takes 35 two-liter PET bottles to make enough fiberfill for a sleeping bag.
PET can also be rolled ito clear sheets or ribbon for VCR and audio cassettes.
the PET bottle is one seventh the weight of a glass bottle of the same size,
and is resealable, unbreakable as well as being recyclable
deutsche gesellschaft für kunststoff-recycling mbH (DKR)
extremely rapid growth of the material PET for non-reusable packaging
german PET forum on recycling
the 'green bottle' is the first commercially-produced bottle in the world made
entirely of 100 percent recycled curbside-collected food grade plastic.
although in theory all plastic is recyclable, market forces, transportation costs and
handling constraints often make recycling plastic prohibitively expensive.
back to PET bottle article
- design and recycling -
|disposal of bottles, unfortunately
the recycling process is messy