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Generation:
A figure that refers to the amount (weight, volume or
percentage of the overall waste stream) of materials
and products as they enter the waste stream and before
materials recovery, composting or combustion takes place.
(Characterization of Municipal Solid Waste in the United
States: 1995 Update, prepared for U.S. EPA Municipal
and Industrial Solid Waste Division Office of Solid
Waste, March 1996).
Glycolysis:
A process that stops short of complete depolymerization,
but breaks long polymer chains into short-chain oligomers
that are repolymerized into virgin polymer. (Modern
Plastics Encyclopedia 1995).
Granulating:
A size-reduction process used for production scrap,
post-consumer plastic packaging, industrial parts, or
other materials that must be downsized for further processing.
Granulators consist of a feed hopper, cutting chamber,
classifying screen, and rotating knives that work in
concert with stationary-bed knives to reduce the plastic
scrap until it is small enough to pass through the classifying
screen. The resulting particles, called regrind, can
vary in size from 3 mm to 20 mm. (Modern Plastics Encyclopedia
1995).
Green Dot:
Germany's Packaging Ordinance of June 12, 1991, designed
to eliminate any packaging that cannot be reused, recycled
or incinerated for energy recovery. Its aim is to keep
packaging separate from the municipal waste stream by
forcing retailers and distributors to take back used
packaging materials and reuse, recycle or dispose of
it. A private company established by industry to fulfill
obligations under the Ordinance, Duales System Deutshland
(DSD), guarantees that the packaging of participating
members will be collected for reuse or recycling. In
return, the products of DSD members can bear the "green
dot." (Environmental Packaging; U.S. Guide to Green
Labeling, Packaging and Recycling. Thompson Publishing
Group, October 1995).e intensive physical mixing in
a molten polymer that is achieved during extrusion can
homogenize different grades of materials and even some
types and amounts of foreign material that might not
have been removed during the recycling process. (Adapted
from Modern Plastics Encyclopedia 1995).
Gel
Permeation Chromatography (GPC)
GPC is used to separate dissolved polymer molecules
according to their coil diameter in solution. The chromatograms
can be converted to molar mass distributions, which
is an important parameter because it has a significant
effect on the physical, mechanical and rheological properties
of a polymer. It is also possible to calculate the average
molar masses, Mn, Mv, Mw and Mz, and when on-line viscometric
detection is used, to study long chain branching (LCB)
and its distribution.
Grade
The designation given a material by a manufacturer such
that it is always reproduced to the same specifications
established by the manufacturer.
Graft polymer
A substance composed of graft macromolecules
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Plastic
Brief
