First, properties (1) General performance: PPS as a white appearance, high crystallinity, hard and brittle polymer, the relative density of pure PPS 1.3, but the modification will increase. PPS There water absorption is extremely small, generally only about 0.03%. PPS flame is good, its oxygen index is over 44%; compared with other plastics, it is a high fire-retardant plastic materials (PVC pure oxygen index 47%, PSF was 30%, PA66 to 29% MPPO to 28%, PC 25%).
(2) mechanical properties: the mechanical properties of pure PPS is not high, especially low impact strength. Glass fiber reinforced will greatly enhance the impact strength, from 27J / m increased to 76J / m, increased 3 times; tensile strength increases by the 6Mpa to 137Mpa, increased 1-fold. PPS rigid high, rare in engineering plastics. The bending modulus of pure PPS up 3.8Gpa, after modification of inorganic filling up 12.6Gpa, increased 5 times. And to rigid PPO known only 2.55Gpa, PC only 2.1Gpa.
PPS resistance to creep under load, good, high hardness; high wear resistance, abrasion when his 1000 transfer was only 0.04g, molybdenum disulfide filled F4 and will be further improved upon; PPS also has a certain self-Yun sex. The mechanical properties of PPS temperature sensitivity to small (3) Thermal Properties: PPS has excellent thermal properties, short term resistance to 260 ��, and can be 200 ~ 240 �� for long term; its heat resistance and the PI rather, second only in F4 plastic, which is also rare in thermosetting plastics.
(4) Electrical Properties: PPS electrical properties is very prominent, compared with other engineering plastics, the dielectric constant and dielectric loss tangent values are relatively low, and the larger the frequency, temperature and temperature range did not change large; PPS arc resistance, and can be comparable with the thermosetting plastics. PPS commonly used in electrical insulation material, the amount can account for about 30%.
(5) environmental performance: PPS is one of the best features of a good chemical resistance, chemical stability after the F4; PPS on the most acid, ester, ketone, aldehyde, phenol and aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons so stable, intolerance and oxidative chlorinated biphenyl acid, oxidants, concentrated sulfuric acid, concentrated nitric acid, aqua regia, hydrogen peroxide and sodium hypochlorite, etc.. Good radiation resistance of PPS.
(1) Automotive: PPS for the automotive industry accounted for 45%, mainly for automotive functional parts; such as production of discharge pipe loop can replace metal valves and water pump impeller, such as pneumatic signal modem.
(2) Electronics: PPS can be used for electrical and electronic industry, 30%, which is suitable for ambient temperature higher than 200 �� high temperature electrical components; can produce generators and engines on the point of shabu, shabu electric brackets, starter coil , shield and blade; the TV can be used for high voltage shell and socket, binding post and terminal board; in the electronics industry, manufacturing transformers, choke ring and frame relay and housing, integrated circuit carrier; use high-frequency performance, manufacturing H-level routing frame and fine-tuning capacitors.
(3) Mechanical industry: for housing, structural parts, wear parts and sealing materials, specifically a pump, valve, bearing, bearing bracket, piston rings and gears.
Polysulfide diphenyl ether (PPS) of the molding process
1. Processing characteristics
PPS resin provided by the manufacturer as a relatively low quality (4000 ~ 5000), a high crystallinity (75%) of white powder, which can not be directly pure PPS plastics molding, can only be used for spraying. For plastics molding PPS, the need for cross-linking modification, the melt viscosity increased. General crosslinked melt index of 10 to 20 is appropriate; for glass fiber reinforced PPS melt index can be larger, but not greater than 200.
PPS heat cross-linking method and chemical cross-linking cross-linking of two, currently dominated by thermal crosslinking. Thermal cross-linking cross-linking temperature of 150 ~ 350 ��, 150 �� lower than the cross-linking does not occur, higher than the occurrence of highly cross-linked 350 ��, but lead to processing difficulties.
Chemical cross-linking need to be added to promote cross-linking agent, the specific varieties of zinc oxide, lead oxide, magnesium oxide, cobalt oxide, and phenolic compounds, HEXAMETHOXYMETHYL melamine amide, hydrogen peroxide, alkali metal or alkaline earth metal hypochlorite, etc..
PPS Although cross-linking, but little decline in liquidity; Thus, waste can be reused three times; PPS itself with mold release, can not join the release agent; PPS after heat treatment can improve the crystallinity and the heat distortion temperature, post-processing conditions: temperature 204 ��, time 30min.
2. Processing methods
(1) Injection: adopt common injection molding machine, glass fiber reinforced PPS melt index of 50 is appropriate. Injection molding process conditions: barrel temperature, pure PPS to 280 ~ 330 ��, 40% GFPPS to 300-350 ��; nozzle temperature, pure PPS to 305 ��, 40% GFPPS to 330 ��; mold temperature of 120-180 ��; injection pressure ,50-130 MPA.
(2) out of: The exhaust extruder conditions were: feed zone temperature is less than 200 ��; barrel temperature of 300-340 ��, connect the temperature 320-340 ��, the die temperature of 300-320 ��.
(3) Molding: suitable for large products, using two compression, before cooling, after hot pressing. Pressing the preheating temperature of pure PPS is about 360 �� 15min, GFPPS to about 380 �� 20min; molding pressure of 10 ~ 30Mpa, cooled to 150 �� stripping.
(4) spray forming: suspended by suspension spray coating method and mixed with the powder thermal spray are the PPS coating to the metal surface, through the plastics, quenching and by coating; PPS coating treatment temperature at 300 �� more insulation 30min.