The concept of plastic materials 1. The main component […]
The concept of plastic materials
1. The main component of plastic raw materials is graphite
2. Plastic raw material: It is made of high molecular synthetic resin (polymer) as the main component, infiltrated with various auxiliary materials or additives, has plasticity and fluidity under a specific temperature and pressure, and can be molded into a certain shape, and A material that maintains its shape under certain conditions.
3. Polymer: refers to the pure material or polymeric material produced during the polymerization process. Both natural and synthetic resins are polymer polymers, referred to as polymers.
4.Plastic has good insulation against electricity, heat and sound: electrical insulation, arc resistance, heat preservation, sound insulation, sound absorption, vibration absorption, and excellent noise reduction performance.
Most of the plastic raw materials are extracted from some oils. The most familiar PC material is extracted from petroleum. PC material has a gasoline smell when it is burned; ABS is extracted from coal, and ABS is extracted from coal. When burned out, it will be soot-like; POM is extracted from natural gas, and POM will have a very smelly gas when burned out.
Simple identification method for plastic raw materials
The identification methods of plastics usually adopt appearance and use, density test, softening point or melting point, combustion test, and comprehensive identification method to identify. The following introduces several commonly used techniques for everyone to learn:
◎Use of plastic products
Qualitative identification without background knowledge is very difficult. However, if the source of the sample and other background knowledge of the use situation are known, the scope of identification will be greatly reduced.
◎The flammability of the material is related to the contained elements.
Combustible elements-carbon, chlorine, sulfur and other non-combustible elements-halogen, phosphorus, nitrogen, silicon, boron, etc.
The color of the flame is usually related to the element
Yellow-plastics containing only carbon and hydrogen, such as PS
Blue-Oxygen-only plastic, such as POM
Green-chlorinated plastics, such as PVC
White-burning fierce plastic, such as nitrocellulose, etc.
Characteristics of general plastic materials
a. Plastic raw materials expand by heat, and the coefficient of linear expansion is much larger than that of metals;
b. The rigidity of general plastic materials is one order of magnitude lower than that of metals;
c. The mechanical properties of plastic raw materials will decrease significantly under long-term heating;
d. General plastic materials will undergo permanent deformation if they are subjected to a long-term force at room temperature and under a stress lower than their yield strength;
e. Plastic raw materials are very sensitive to notch damage;
f. The mechanical properties of plastic raw materials are usually much lower than that of metals, but some composite materials have higher specific strength and specific modulus than metals. If the product design is reasonable, it will be more advantageous;
g. Generally, the mechanical properties of reinforced plastic raw materials are anisotropic;
h. Some plastic materials will absorb moisture and cause size and performance changes;
i. Some plastics are combustible;
j.The fatigue data of plastic raw materials is still very small, and it needs to be considered according to the use requirements.
Plastic raw materials classification
According to the molecular structure of synthetic resin, plastic raw materials are mainly divided into thermoplastic and thermosetting plastics: for thermoplastics, plastics that are still plastic after repeated heating: mainly PE/PP/PVC/PS/ABS/PMMA/POM/PC/PA Commonly used raw materials. Thermosetting plastics mainly refer to plastics made of synthetic resins that are hardened by heating, such as some phenolic plastics and amino plastics, which are not commonly used.
According to the scope of application, there are mainly general plastics such as  PE/PP/PVC/PS, etc., and engineering plastics such as ABS/POM/PC/PA. There are also some special plastics such as high temperature and humidity resistance. Corrosion and other plastics modified for special purposes.
Material utilization and color treatment
1. Most of the plastic raw materials can be recycled, but because the plastic (nozzle material) used is more brittle than the general raw materials, it can only be used with new materials (raw materials). The maximum proportion should not exceed 25%. It should be based on customer requirements. Standards are the principle. Various types of plastic materials require different melting points and different injection pressures, so they must not be confused in production.
2. Since plastic products need to be matched with colors, plastic raw materials can be divided into: pumped pellets, color powder, color materials, and the recent appearance of adding liquid to color in plastic raw materials. The pumping raw materials are already mixed with pigments In the raw materials, each plastic material has been colored, so the color of the product is stable and uniform. Toner materials and color materials are mixed materials of color types or toners, and the cost is low, and there is no need to store a large amount of colored materials. But the color Unstable, it is difficult to control uniformity in production.
According to thermal performance and processing performance
Thermoplastics: softened by heat and can be repeatedly heated for molding
Such as polyvinyl chloride plastic, polypropylene plastic
Thermosetting plastics: can not be heated and melted after being cured and shaped by heat
Such as phenolic plastics, urea-formaldehyde plastics
According to purpose
General-purpose plastics: large output
Such as polyethylene, polypropylene, polyvinyl chloride
Such as polycarbonate, polysulfone, polyphenylene ether, polyamide, polyoxymethylene
Such as medical plastics, conductive plastics, high temperature resistant plastics