PP physical mechanical properties
The strength and rigidity of PP are better than that of low-pressure PE. Due to the high regularity of PP molecular structure, its impact resistance at fixed, room temperature and low temperature is poor, and its stress-strain relationship depends on the strain rate, molecular weight and crystallinity. The yield value and elastic modulus of PP mainly depend on the degree of crystallinity; the impact strength also varies with the isotactic content of the polymer, and the molecular weight can affect the impact strength, ie, the molecular weight is large and the impact strength is large, but the forming process performance also follows. As it deteriorates, it has a greater bending fatigue life. It has a living hinge that can withstand more than 70,000,000 folding bends with no signs of damage; but its gap is particularly sensitive.
PP has excellent fibrillation, and its tensile properties are very good. When the special temperature exceeds 80°C, the decrease in tensile strength due to temperature increase becomes less, that is, the tensile strength at room temperature still remains at 100°C. Half of it. The PP molecule is oriented in the direction of the melt flow because its strength is also directional, ie the tensile impact strength perpendicular to the orientation direction is 50% lower than the orientation direction, the hardness of PP is lower than that of PS and ABS, but higher than PE and Excellent surface gloss, friction coefficient of 0.12 and nylon similar. Every 15th wear 15~30mg.
Thermal and Electrical Thermal Properties of PP:
PP has good heat resistance, melting point is 164 ~ 170 °C, resistant to temperatures above 100 °C boiled and disinfected, no external force, the temperature is not deformed even to 150 °C, under low load can also be used continuously at 110 °C. The stress relaxation resistance at 90°C is good. Low temperature use -15 ~ -20 °C, embrittlement temperature and isotactic structure content and average molecular weight. With the same isotactic structure content, the lower the melt index, the lower the embrittlement temperature and the higher the isotactic structure content, the higher the embrittlement temperature.
Electrical performance:
PP is a very good electrical insulator, does not absorb water, is not affected by dampness in the air, and has a high breakdown voltage. It is a slow burning material. Low dielectric constant (2.2~2.6), not affected by temperature; Dielectric strength is high in the range of 26*106 V/m, high temperature, high dielectric strength, high volume resistance, different dielectric constant, high temperature The resistance decreases, the volume resistivity at room temperature is 1017 Ω.cm, and the temperature drops to 1013 Ω.cm when the temperature rises to 93°C. Under the allowable high temperature conditions, the current leakage is kept to a minimum.
PP chemical properties and environmental resistance chemical properties:
PP has good resistance to erosion and contamination of chemical agents, especially against environmental stress cracking, inorganic minerals with inorganic salts, dilute or concentrated solutions of alkalis, and even elevated temperatures. Chemicals, but halogens, fuming nitric acid, fuming sulfuric acid and other highly oxidizing agents, will attack PP plastics. There are few solvents that dissolve it at room temperature, only aromatic hydrocarbons, chlorinated hydrocarbons. It can make it soften and swell, especially when the temperature rises more significantly.
Environmental resistance:
At room temperature, PP is completely free from moisture erosion less than a day/0.01% water absorption, water vapor permeability is also very low; when the temperature rises, the life of the plastic will be shortened because the stabilizer is in contact with water. The long molecular chain of the PP molecule contains a tertiary carbon atom of the methyl group, and has weak resistance to depolymerization; it is easily oxidized and depolymerizes under ultraviolet light.
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