The so-called "plastic modification" refers to a method of adding one or more other substances to a plastic resin to change its original properties, improve one or more aspects of the properties, and thereby expand its scope of application. The modified plastic materials are collectively referred to as "modified plastics".
There are roughly the following types of plastic modification methods:
1. Reinforcement: By adding fibrous or sheet-like fillers such as glass fiber, carbon fiber, mica powder, etc. to increase the rigidity and strength of the material, such as glass fiber reinforced nylon used in power tools.
2. Toughening: By adding rubber, thermoplastic elastomer and other materials to plastics, the purpose of improving its toughness / impact strength is achieved, such as toughened polypropylene commonly used in automobiles, home appliances and industrial applications.
3. Blending: uniformly mix two or more incompatible polymer materials into a macro-compatible and micro-phase-separated mixture to meet certain physical and mechanical properties, optical properties, processing properties, etc. Required method.
4. Alloy: Similar to blending, but with good compatibility between components, it is easy to form a homogeneous system, and can obtain certain properties that cannot be achieved by a single component, such as PC / ABS alloy, or PS modified PPO.
5. Filling: By adding fillers to plastics, the purpose of improving physical and mechanical properties or reducing costs is achieved.
6. Other modifications: such as using conductive fillers to reduce the resistivity of plastics; adding antioxidants / light stabilizers to improve the weather resistance of materials; adding pigments / dyes to change the color of materials, and adding internal / external lubricants to make materials Improved processing properties, the use of nucleating agents to change the crystalline characteristics of semi-crystalline plastics to improve its mechanical and optical properties, and so on.
In addition to the physical modification methods mentioned above, there are also methods to modify plastics using chemical reactions to obtain specific properties, such as maleic anhydride grafted polyolefins, polyethylene cross-linking, and the use of peroxides in the textile industry. Degrading the resin to improve flowability / fibrillation performance, etc.
In the industry, multiple modification methods are often used together, such as the addition of toughening agents such as rubber in order to not lose too much impact strength in the process of plastic reinforcement modification; or physical mixing in the production of thermoplastic vulcanizates (TPV) And chemical crosslinking and so on.
In fact, at least any plastic raw material contains a certain percentage of stabilizers at the factory to prevent its degradation during storage, transportation and processing. Therefore, "non-modified plastics" in the strict sense does not exist. However, in industry, base resins produced by chemical plants are often referred to as "non-modified plastics," or "pure resins."