Environmental Engineering Reference
In-Depth Information
5
, reducing weight, especially in vehicles, is particularly profitable
because of savings in fossil fuel use and related GHG emissions.
2. Moldability into complex shapes
Advanced molding techniques allow both thermoplastic and thermoset
materials to be fabricated into complex 3D objects. This has the
engineering advantage where, unlike with materials such as steel (used
in aircraft construction, for instance), individual pieces need not be
fastened together to create such shapes. Large objects like hot tubs,
shower stalls, or marine vessels can be fabricated easily as a single piece
with no joints that can fail during use. These can be colored in any hue
desired and in some instances even coated with a protective surface
layer.
3. Durability can be designed into the material
Depending on the specific application, the plastic material can be
compounded with antioxidants, light stabilizers, and flame retardants
to ensure that the service requirements of products are met. For
instance, the same plastic can be compounded for durability or long
service lifetimes as well as degradability or controlled loss of properties
(as with enhanced photodegradable plastics) using appropriate
additives.
4. Biological and chemical inertness
Common plastics are not affected by aggressive chemicals, and some
(such as bleach, lubricant oils, solvents, and acids) are even safely
packaged in plastic bottles. It is their bio-inertness that allows them to
be extensively used in food packaging and medical devices. Common
plastics do not support the growth of microorganisms. In cases where
this sometimes is seen to occur (such as in PVC shower curtains), it is
the additive plasticizer that supports the growth, rather than the PVC
plastic material.
5. Electrical and thermal insulators
hardware such as switches and household power outlets. However,
where needed, conductive fillers such as metal whiskers or carbon
nanotubes can be used as fillers in the plastic to impart electrical
conductivity at the desired level. As they are good thermal insulators as
