Agriculture Reference
In-Depth Information
Among the most important group of polymers are PA and linear poly-condensates,
which are used in engineering applications, as well as in fibres and films. Due to
hydrogen bonds and aromatic components, some of these materials are resistant
to high temperatures. However, they are hydrophilic polymers known for their
high absorption of water. Linear polyesters are also poly-condensates, which have
gained notoriety only in the form of polyarylesters. Special co-polyesters have such
stiff molecular segments that they exhibit anisotropic behaviour even in the melt state.
Polymers exhibiting such behaviour are called 'liquid crystalline polymers'. Polyimides
are the stiffest molecules. They are conductive and semi-conductive polymers that
are high temperature-resistant with a very high heat-deflection temperature. An
important group of technical thermoplastics are the polyarylethersulfones and
polyarylsulfides. Their unique molecular structure, composed of aromatic and sulfur-
based building blocks, makes them high-strength plastic materials for engineering
designs.
2.3 Properties of Plastics
The properties of plastics can be categorised as:
•
Compatibility of material properties
•
Mechanical properties
•
Friction and wear
•
Environmental properties
•
Water absorption
•
Weathering effects
•
Rheological properties
•
Permeability properties
•
Electrical properties
•
Optical properties
•
Acoustic properties
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