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1、 PP (polypropylene)

PP plastic, chemical name: Polypropylene

English Name: polypropylene (PP for short)

Specific gravity: 0.9-0.91g/cm3 molding shrinkage: 1.0-2.5% molding temperature: 160-220 ℃

Features: nontoxic, tasteless, small density, strength and rigidity, hardness and heat resistance are superior to low-pressure polyethylene, which can be used at about 100 degrees. It has good electrical performance and high-frequency insulation, which is not affected by humidity, but brittle, wear-resistant and aging at low temperature. It is suitable for making general mechanical parts, corrosion-resistant parts and insulation parts. Common acid and alkali organic solvents have little effect on it and can be used for tableware.

Forming characteristics:

1. The crystalline material has small hygroscopicity and is easy to crack and decompose in long-term contact with hot metal

2. Good fluidity, but large shrinkage range and shrinkage value, easy to cause shrinkage cavity, dent and deformation

3. The cooling speed is fast, the pouring system and cooling system should slowly dissipate heat, and pay attention to control the molding temperature. When the material temperature is low temperature and high pressure, it is easy to be oriented. When the mold temperature is lower than 50 degrees, the plastic parts are not smooth, it is easy to produce poor fusion, flow marks, and warpage and deformation above 90 degrees

4. The wall thickness of the plastic must be uniform to avoid lack of glue and sharp corners, so as to prevent stress concentration

2、 PVC (polyvinyl chloride)

Basic characteristics:

It is one of the largest plastic products in the world. It is cheap and widely used. PVC resin is white or light yellow powder. Different additives can be added according to different uses, and PVC plastics can present different physical and mechanical properties. A variety of hard, soft and transparent products can be made by adding a proper amount of plasticizer into PVC resin.

The density of pure PVC is 1.4g/cm3, and the density of PVC parts with plasticizer and filler is 1.15-2.00g/cm3.

UPVC has good tensile, flexural, compressive and impact resistance, which can be used as structural materials alone.

The softness, elongation at break and cold resistance of soft PVC will increase, but the brittleness, hardness and tensile strength will decrease.

PVC has good electrical insulation performance, can be used as low-frequency insulation material, and its chemical stability is also good. Due to the poor thermal stability of PVC, long-time heating will lead to decomposition, release HCl gas, make PVC discoloration, so its application range is narrow, and the use temperature is generally between - 15 and 55 degrees.

Main purpose:

Because of its high chemical stability, it can be used to make anticorrosive pipes, pipe fittings, oil pipelines, centrifugal pumps and blowers. PVC rigid board is widely used in the chemical industry to make various tank linings, building corrugated boards, door and window structures, wall decorations and other building materials. Due to the excellent electrical insulation, it can be used in the electrical and electronic industries to manufacture plugs, sockets, switches and cables. In daily life, PVC is used to make sandals, raincoats, toys and leatherette!

Polyvinyl chloride (PVC)

PVC is synthesized from acetylene and hydrogen chloride to vinyl chloride and then polymerized. It has high mechanical strength and good corrosion resistance. It can be used to make waste gas emission and detoxification tower, gas and liquid delivery pipe in chemical industry, textile industry, etc. it can also replace other corrosion-resistant materials to make storage tanks, centrifugal pumps, ventilators and joints, etc. When the amount of plasticizer is 30% - 40%, soft PVC is prepared. It has high elongation, soft products, good corrosion resistance and electrical insulation. It is often made into film, which is used in industrial packaging, agricultural seedling raising, daily raincoat, tablecloth, etc. it can also be used to make acid and alkali resistant hose, cable sheath, insulation layer, etc.