A brief introduction to the manufacturing of plastics and the synthesis of resins

The basic raw materials for the manufacture of plastics were initially based on agricultural and sideline products, shifted to coal and coal tar products from the 50s of this century, and gradually shifted to oil and gas from the <>s.

The plastics industry consists of three production systems: the production of plastic raw materials (resins or semi-finished products and additives), the production of plastic products, and the manufacture of plastic molding machinery (including molds).

(1) Synthesis method of resin <>. Polycondensation reaction. Chemical reactions in which water or other simple molecular bonds are removed from monomers to synthesize polymers. It can be divided into homopolycondensation reaction and co-polycondensation reaction.

(1) Homopolymerization: Polycondensation reaction of a monomer with two functional groups.

(2) Cocondensation reaction: Polycondensation reaction performed by two or more bifunctional monomers.

2. Polyaddition reaction. A chemical reaction in which unsaturated or cyclic monomer molecules are added and polymerized to produce polymers. There is no release of water or other low-molecular by-products in the reaction, and the polymer element composition produced is the same as that of the original monomer. According to the type of monomer participating in the reaction and the configuration of the polymer itself, it can be divided into homopolymerization reaction, copolymerization reaction and directional polymerization reaction.

(1) Homopolymerization reaction: a polymerization reaction between unsaturated or cyclic monomer molecules. Such as polyethylene, polypropylene, polyvinyl chloride, etc.

(2) Copolymerization reaction: polymerization reaction of two or more unsaturated or cyclic monomer bonding. Such as acrylic ester-butadiene-styrene copolymer (ABS). Copolymers obtained from two monosystems can have the following four arrangements in the polymer chain:

Alternating copolymers ... - A-B-A-B-A-A-A-B-B-A-B-A-B-A-B-A-A-B-A-B- Random copolymers ... -A-A-B-B-B-B-A-A-A-B-A A-B-A A... Block copolymers ... -A-A-A-B-B-B-B-B-B-A-A... Grafted copolymers ... -A-A-A-A-A-A-A-A... └-B-B-B └-B-B-B(3) Directional polymerization reaction: In the polymerization process, the reaction conditions are controlled so that the monomer polymerizes into a reaction with directional regular structural products, that is, a polymerization reaction with a fully homotic configuration or an inter-isometric configuration. Its polymerization products are called directed polymers.

First, the definition of plasticPosted: 2006-1-23 9:12:26Plastic refers to resin (or direct polymerization with monomer in the processing process) as the main component, plasticizers, fillers, lubricants, colorants and other additives as auxiliary components, in the process of processing can flow molding materials.

Plastics mainly have the following characteristics: (1) most plastics are lightweight, have good chemical stability, and will not rust; (2) Good impact resistance; (3) It has good transparency and wear resistance; (4) Good insulation and low thermal conductivity; (5) Good formability, colorability, low processing cost; (6) Most plastics have poor heat resistance, large thermal expansion rate and easy combustion; (7) Poor dimensional stability and easy deformation; (8) Most plastics have poor low temperature resistance and become brittle at low temperatures; (9) Easy aging; (10) Some plastics are soluble in solvents.