1. The origin of the term "resin"
Plastic is a material with high polymer as the main component. It is composed of synthetic resin and fillers, plasticizers, stabilizers, lubricants, pigments and other additives. It is in a fluid state during manufacturing and processing to facilitate modeling , It presents a solid shape when the processing is completed. The main component of plastic is synthetic resin. Resins are originally named after lipids secreted by animals and plants, such as rosin, shellac, etc. Synthetic resins (sometimes simply referred to as "resins") refer to high-molecular polymers that have not been mixed with various additives. The resin accounts for about 40% to 100% of the total weight of the plastic. The basic properties of plastics are mainly determined by the properties of the resin, but additives also play an important role.
2. Why should plastics be modified?
The so-called "plastic modification" refers to the method of adding one or more other substances to the plastic resin to change its original performance, improve one or more aspects, and thus achieve the purpose of expanding its scope of application. Modified plastic materials are collectively referred to as "modified plastics".
Up to now, the research and development of plastics chemical industry has synthesized thousands of polymer materials, of which only more than 100 have industrial value. More than 90% of the commonly used resin raw materials for plastics are concentrated in the five general resins (PE, PP, PVC, PS, ABS) At present, it is very difficult to continue to synthesize a large number of new polymer materials, which is neither economical nor realistic.
Therefore, in-depth study of the relationship between polymer composition, structure and performance, and modification of existing plastics on this basis, to produce suitable new plastic materials, has become one of the effective ways to develop the plastics industry. The sexual plastics industry has also achieved considerable development in recent years.
Plastic modification refers to changing the properties of plastic materials in the direction expected by people through physical, chemical or both methods, or to significantly reduce costs, or to improve certain properties, or to give plastics The new function of the material. The modification process can occur during the polymerization of the synthetic resin, that is, chemical modification, such as copolymerization, grafting, crosslinking, etc., can also be conducted during the processing of the synthetic resin, that is, physical modification, such as filling and co-polymerization. Mixing, enhancement, etc. Reply to "modified plastic" to see more
3. What are the methods of plastic modification?
1. There are roughly the following types of plastic modification methods:
1) Reinforcement: The purpose of increasing the rigidity and strength of the material is achieved by adding fibrous or flake fillers such as glass fiber, carbon fiber, and mica powder, such as glass fiber reinforced nylon used in power tools.
2) Toughening: The purpose of improving the toughness/impact strength of plastics is achieved by adding rubber, thermoplastic elastomers and other substances to plastics, such as toughened polypropylene commonly used in automobiles, home appliances and industrial applications.
3) Blending: uniformly mix two or more incompletely compatible polymer materials into a macro-compatible and micro-phase-separated mixture to meet certain requirements in terms of physical and mechanical properties, optical properties, and processing properties. The required method.
4) Alloy: similar to blending, but with good compatibility between components, it is easy to form a homogeneous system, and certain properties that cannot be achieved by a single component, such as PC/ABS alloy, or PS modified PPO, can be obtained.
5) Filling: The purpose of improving physical and mechanical properties or reducing costs is achieved by adding fillers to the plastic.
6) Other modifications: such as the use of conductive fillers to reduce the electrical resistivity of plastics; the addition of antioxidants/light stabilizers to improve the weather resistance of the materials; the addition of pigments/dyes to change the color of the material, and the addition of internal/external lubricants to make the material The processing performance of the semi-crystalline plastic is improved, the nucleating agent is used to change the crystalline characteristics of the semi-crystalline plastic to improve its mechanical and optical properties, and so on.
In addition to the above physical modification methods, there are also methods to modify plastics by chemical reactions to obtain specific properties, such as maleic anhydride grafted polyolefin, polyethylene crosslinking, and the use of peroxides in the textile industry. Degrade the resin to improve fluidity/fibre-forming properties, etc. . . There are so many different things.
The industry often uses a variety of modification methods together, such as adding rubber and other toughening agents in the plastic reinforcement modification process in order not to lose too much impact strength; or the physical mixing in the production of thermoplastic vulcanizates (TPV) And chemical cross-linking, etc...
In fact, any plastic raw material contains at least a certain proportion of stabilizers when it leaves the factory to prevent it from degrading during storage, transportation and processing. Therefore, "non-modified plastics" in the strict sense do not exist. However, in industry, the basic resin produced in chemical plants is usually referred to as "non-modified plastic" or "pure resin."
