Plastic is a kind of thermosetting relatively strong material, this material after heating, its molecular structure will show a net-like mentality, it is easy to polymerize into a variety of shapes. Plastic can be divided into many categories, can be divided into general-purpose social and engineering use of plastic, general-purpose plastic is generally used in life, engineering use of tree resin general chemical composition will be higher. Here we look at what are the plastic raw materials?
A classification
Polymers are made of many smaller and structurally simple small molecules, by **** valence bonding to combine and form.
(1) According to the cooling of the characteristics of the resin when cooled by heat classification
a, thermosetting plastics: refers to the heating, will make the molecular structure of the combination into a mesh state, but the combination into a mesh polymer, even if re-heating will not be softened, showing what is known as the [non-reversible changes], is the molecular structure of the changes that take place (chemical changes?). This is the result of a change in the molecular structure (chemical change?).
Thermoplastic: refers to the plastic that melts after heating, flows to the mold after cooling, and melts again after reheating, which can be heated and cooled to produce [reversible change] (liquid ←→ solid), which is the so-called physical change.
In accordance with the scope of application of the main general-purpose plastics such as PE/PP/PVC/PS, engineering plastics such as ABS/POM/PC/PA and other commonly used types. In addition, there are some special plastics such as high temperature and high humidity and corrosion resistance and some other special purposes and modified plastic.
(2) by the use of plastics classification
a. General-purpose plastics of this type of plastic when a class of very wide range of plastics, it is a large production, accounting for about three-quarters of the total output of plastics, low prices, a large number of daily necessities used to make the force is not big, such as television housings, telephone housings, plastic pots, plastic buckets and so on. The relationship with people is very close, becoming an important pillar of the plastics industry. Commonly used general-purpose plastics are PE, PVC, PS, PP, PF, UF, MF and so on.
b. Engineering plastics? General-purpose plastics, although inexpensive, but its mechanical properties, temperature resistance, corrosion resistance are difficult to meet the needs of certain projects and equipment used as structural materials, for which engineering plastics came into being, it is high mechanical strength, rigidity, can replace some steel or non-ferrous metal materials, can be manufactured to create a complex structure of the mechanical parts or engineering force parts, many of the use of the effect is also more than the original material, the commonly used engineering plastics are PA, ABS, PSF, PTFE plastic materials, POM plastic materials, PC and so on.
c. Specialty plastic materials? This type of plastic material has a unique function, can be used in some special occasions, such as magnetic conductivity plastic, ionomer plastic, pearlescent plastic, photosensitive plastics, medical plastics and so on.
Second, the material utilization
1. Most of the plastic raw materials can be recycled, but due to the turnover of plastic (water mouth material) than the general raw materials to be brittle, so only can be mixed with new materials (raw materials) used together, the ratio of the maximum can not be more than 25% for the appropriate, should be required by the customer as the principle of the standard. Various types of plastic materials due to the different melting points required, the injection pressure is different, the production must not be confused.
2. Because the plastic product to match the color, so the plastic raw materials can be divided into: drawing grain material, color powder material, color seed material, and the recent emergence of the addition of liquid in the plastic raw material coloring. Drawing granular raw materials is already mixed into the raw material pigments, each grain of plastic materials have been colored, so the formation of product color stability and uniformity. Color powder and color seed material is the color seed or color powder mixed raw materials, low cost, and do not need to store a large number of colored materials. But the color is not stable, it is difficult to control the uniformity in production.
There are many kinds of plastic raw materials, most of them are resin as raw material. Most of the plastic raw materials can be recycled, is a relatively new type of mixed materials. There are many models and toys in our lives that are made of plastic. Injury to this material is not heat-resistant, so we must pay attention to the use of plastic to prevent high temperatures, it is best not to be close to the source of fire. If the plastic is melted by the fire, it is necessary to duck in time to avoid being burned. It is also important to avoid accidental ingestion by small children.