Typical applications for PC/PBT polycarbonate and polybutylene terephthalate: gearboxes, automotive bumpers and required chemical and corrosion resistance, thermal stability, impact resistance and geometric stability The product.
Injection molding process conditions: drying treatment: recommended 110 ~ 135C, about 4 hours of drying. Melting temperature: 235~300C. Mold temperature: 37~93C.
Chemical and physical properties: PC/PBT has the combined properties of both PC and PBT, such as the high toughness and geometric stability of PC and the chemical stability, thermal stability and lubrication properties of PBT. The shrinkage rate is around 0.5%.
PE-HD High Density Polyethylene Typical applications: refrigerator containers, storage containers, household kitchen utensils, sealing covers, etc.
Injection molding process conditions: Dry: no need to dry if stored properly. Melting temperature: 220~260C. For larger molecules, the recommended melting temperature range is between 200 and 250 °C. Mold temperature: 50~95C. Plastic parts with a wall thickness of 6 mm or less should use a higher mold temperature, and plastic parts with a wall thickness of 6 mm or more use a lower mold temperature. The plastic part cooling temperature should be uniform to reduce the difference in shrinkage. For optimum machining cycle time, the cooling tunnel diameter should be no less than 8 mm and the distance from the mold surface should be within 1.3 d (where "d" is the diameter of the cooling tunnel). Injection pressure: 700~1050bar. Injection speed: High speed injection is recommended. Runners and gates: The runner diameter is between 4 and 7.5 mm and the runner length should be as short as possible. Various types of gates can be used, and the gate length should not exceed 0.75 mm. Particularly suitable for use with hot runner molds.
Chemical and physical properties: The high crystallinity of PE-HD leads to its high density, tensile strength, high temperature distortion temperature, viscosity and chemical stability. PE-HD has stronger resistance to permeation than PE-LD. PE-HD has a low impact strength. The characteristics of PH-HD are mainly controlled by density and molecular weight distribution. The PE-HD molecular weight distribution suitable for injection molding is very narrow. For the density of 0.91~0.925g/cm3, we call it the first type PE-HD; for the density of 0.926~0.94g/cm3, it is called the second type PE-HD; for the density of 0.94~ 0.965g/cm3 It is called the third type PE-HD. The material has good flow characteristics and an MFR between 0.1 and 28. The higher the molecular weight, the worse the flow characteristics of PH-LD, but the better the impact strength. PE-LD is a semi-crystalline material with a high shrinkage after molding, between 1.5% and 4%. PE-HD is prone to environmental stress cracking. Cracking can be mitigated by using materials with very low flow characteristics to reduce internal stresses. PE-HD is easily dissolved in hydrocarbon solvents when the temperature is higher than 60C, but its solubility resistance is better than PE-LD.
PE-LD Low Density Polyethylene Typical Applications: Bowls, Cabinets, Pipe Couplers
Injection molding process conditions: Drying: generally does not require melting temperature: 180~280C Mold temperature: 20~40C In order to achieve uniform cooling and economical heat removal, it is recommended that the cooling channel diameter be at least 8mm and from the cooling channel to the mold surface. Do not exceed 1.5 times the diameter of the cooling channel. Injection pressure: up to 1500 bar. Holding pressure: up to 750bar. Injection speed: It is recommended to use a fast injection speed. Runners and gates: Various types of runners and gates PE can be used, particularly suitable for use with hot runner molds.
Chemical and physical properties: Commercially available PE-LD materials have a density of 0.91 to 0.94 g/cm3. PE-LD is permeable to gases and water vapor. The high coefficient of thermal expansion of PE-LD is not suitable for processing products for long-term use. If the density of PE-LD is between 0.91 and 0.925 g/cm3, the shrinkage is between 2% and 5%. If the density is between 0.926 and 0.94 g/cm3, the shrinkage is 1.5%~4. %between. The current actual shrinkage rate also depends on the injection molding process parameters. PE-LD is resistant to a wide range of solvents at room temperature, but aromatic hydrocarbons and chlorinated hydrocarbon solvents allow it to swell. Similar to PE-HD, PE-LD is prone to environmental stress cracking.
PEI Polyetherimide Applications: Automotive (engine accessories such as temperature sensors, fuels and air handlers), electrical and electronic equipment (printed circuit boards, chip housings, explosion-proof boxes, etc.), product packaging, aircraft interior equipment, Pharmaceutical industry.
Injection Molding Process Conditions: Drying: PEI has hygroscopic properties and can cause material degradation. The required humidity value should be less than 0.02%. Drying conditions of 150 C for 4 hours are recommended. Melting temperature: 340~400C for common type materials and 340~415C for enhanced type materials. Mold temperature: 107~175C, the recommended mold temperature is 140C. Injection pressure: 700~1500bar. Injection speed: Use the highest possible injection speed.
Chemical and physical properties: PEI has a very high temperature stability, even for non-reinforced PEI, it still has good toughness and strength. Therefore, the superior thermal stability of PEI can be used to fabricate high temperature heat resistant devices. PEI also has good flame retardancy, chemical resistance and electrical insulation properties. The glass transition temperature is very high, reaching 215C. PEI also has a very low shrinkage (typically between 0.4% and 0.7%) and good isotropic mechanical properties.
