Plastic key features:
① most plastic lightweight, chemically stable, will not rust;
② good impact resistance;
③ has good transparency and abrasion resistance;
④ insulation,
and low thermal conductivity;
⑤ general formability, good color, low processing costs;
⑥ most plastics poor heat resistance, thermal expansion, easy to
burn;
⑦ poor dimensional stability, easily deformed;
⑧ most plastics poor low temperature resistance, low temperature
brittle;
⑨ easy to aging;
⑩ certain plastics soluble in solvents.
Plastics can be divided into two types of
thermosetting and thermoplastic, the former can not be re-shape to use, which
can be repetitive.
Plastic polymer structure, there are two
basic types:
The first is a linear structure, a polymer
compound having such a structure is called a linear polymer compound;
The second body structure is a polymer
compound having such a structure is called a polymer compound body. Some
polymer having a branched chain, a branched polymer known as belonging to the
linear structure. Although some polymer intermolecular crosslinking, but
crosslinking less known network structure, body structure belongs.
Two different structures, showing two
opposite properties. A linear structure (including the branched chain
structure) of the polymer molecules due to the presence of a separate, and
therefore, flexibility, plasticity, can be dissolved in a solvent, the heating
can be melted, the hardness and brittleness of smaller features. Since there is
no independent body structure of polymer macromolecules exist, so there is no
elasticity and plasticity, can not dissolve and melt, only swelling, hardness
and brittleness. Polymer plastic has the two structures, made by the linear polymer is a thermoplastic plastic,
a polymer made by the body are thermosetting plastics.
Compared with other plastic materials
<1> resistance to chemical attack
<2> shiny, partially transparent or
translucent
<3> is a good insulator mostly
Light <4> weight and sturdy
<5> can be processed easily
mass-produced, inexpensive
<6> versatile, multi-utility, easy
coloring, and some high-temperature plastic is also divided into pan with
plastic and plastic, the main purpose is to define the breadth, such as PE, PP
cheap, available in a variety of different types of production of the machine.
Plastic is more expensive, but raw material stability
And physical properties are much better, in
general, it also has two characteristics of rigidity and toughness.
Plastic advantages:
1, most of the plastic of the
corrosion resistance, strong acids, bases and the reaction is not.
2, low-cost plastic.
3, durable, waterproof, lightweight.
4, easy to be made into different shapes of plastic.
5, is a good insulator.
6, the plastic can be used in the
preparation of fuel oil and fuel gas, which can reduce oil consumption.
Disadvantages of plastic
1, the recycling of waste plastics,
classification is very difficult and economically viable.
2, plastic is easy to burn, produce toxic
gases when burned. Such as polystyrene produced during combustion of toluene, a
small amount of this substance can cause blindness, vomiting and other symptoms
of inhalation, PVC burning will produce toxic hydrogen chloride gas, in
addition to burning, is a high temperature environment, will lead to plastics
decompose toxic ingredients, such as benzene and so on.
3, the plastic product is made of petroleum refining, petroleum resources are
limited.
4, the plastic can not be natural
decomposition.
