There are two kinds hardness of PVC, one is soft PVC (unit: A) and the other is hard PVC (unit: D).
1, soft PVC contains softener, this material is easy to become brittle, not convenient to save, so soft PVC is not used in important places, generally used in the floor, ceiling surface.
2, hard PVC is also called UPVC, or PVC-U products. It does not contain meat software, so it is flexible, easy to shape, not easy to become brittle, long preservation time, so it is often used to manufacture pipes, flame retardant cables, electrical flame retardant switches, sockets, plastic steel, bumpers and so on.
Polyvinyl chloride, PVC for short, is the initiator of vinyl chloride monomer in peroxide, azo compounds; Or under the action of light, heat polymerization polymerization polymerization polymerization of polymer reaction mechanism. Vinyl chloride homopolymer and vinyl chloride copolymer are called vinyl chloride resin.
PVC for amorphous structure of white powder, branched degree is small, relative density 1.4, glass transition temperature of 77 ~ 90 ℃, 170 ℃ or so began to decompose, poor stability to heat and light, in more than 100 ℃ or the sun for a long time, will decompose and produce hydrogen chloride, and further automatic catalytic decomposition, cause discoloration, physical and mechanical properties also fell rapidly, In practical application, stabilizer must be added to improve the stability of heat and light.
PVC molecular weight of industrial production is generally in the range of 50,000 ~ 110,000, with a large polydispersity, molecular weight increases with the reduction of polymerization temperature; Without a fixed melting point, it begins to soften at 80 ~ 85℃, changes to viscoelastic state at 130℃, and changes to viscous flow state at 160 ~ 180℃. Good mechanical properties, tensile strength about 60MPa, impact strength 5 ~ 10kJ/m2; Excellent dielectric properties.
PVC used to be the largest general-purpose plastic in the world and was widely used. It is widely used in building materials, industrial products, daily necessities, floor leather, floor bricks, artificial leather, pipes, wires and cables, packaging film, bottles, foaming materials, sealing materials, fibers and so on.
According to the hardness of PVC and softness of PVC, rockwell hardness tester and Shore hardness tester were used respectively.
Most high performance engineering plastics or harder plastics are determined by Rockwell. Xiao is used to determine the harder plastics, such as general plastics and some engineering plastics.
There is no accurate one-to-one correspondence between P and degree, but the reference values are as follows:
98 ~ 100 20
30 of 97 ~ 96
40 of 95 ~ 94
45, 93 ~ 91
50 of 90 ~ 88
55, 87 ~ 85
60 of 84 ~ 81
80 ~ 79, 65
78 ~ 75, 70
74 ~ 73, 75
72 ~ 69, 80
68 ~ 67, 85
66 ~ 63, 90
59 ~ 57, 100
SHORE A is an international standard. P(Taiwan) number refers to the ratio of plasticizer and PVC oil. According to the hardness of pvc comparing sheet, you can easily find out the hardness.