PPA plastic introduction
PPA Plastics is: high temperature resistant nylon PPa has a heat distortion temperature of over 300 °C and a continuous use temperature of 170 °C to meet your short-term and long-term thermal performance.
Also known as high temperature resistant nylon heat distortion temperature above 300 °C Features Superior mechanical properties Continuous use temperature up to 170 ° C
Maintains superior mechanical properties - strength, hardness, fatigue resistance and creep resistance - over a wide temperature range and in high humidity environments. Toughened grade PPA combines superior toughness with a range of hardness and flexibility, and requires a one-time rigidity in fasteners and a good choice for flexibility in repetitive use.
Polyphthalamide (PPA) resin is a semi-aromatic polyamide based on terephthalic acid or phthalic acid. Both semi-crystalline and non-crystalline, the glass transition temperature is around 255 °F. Amorphous PPA is mainly used in applications requiring barrier properties; semi-crystalline PPA resin is mainly used for injection molding, and is also used in other melt processing processes. The latter mainly introduces the latter - semi-crystalline PPA resin, specially noted except. The semi-crystalline PPAS has a melting point of about 590 °F and is supplied as an opaque rectangular section.
PPA resins are stronger and harder than fatty polyamides such as nylon 6,6; less sensitive to moisture; better thermal properties; and much better creep, fatigue and chemical resistance. For example, a PPA resin containing 45% glass short fibers has a tensile strength of about 276 MPa, a flexural modulus of more than 13,786 MPa, and a heat distortion temperature (HDT) of 549 °F. Even with mineral filler grade PPA, the tensile strength can reach 117 MPa. PPA resins are less ductile than nylon 6,6, however, unreinforced impact modified grade PPA resins have been developed with a notched Izod impact strength of up to 20 ft • lb/in.
All polyphenolamines absorb certain moisture, causing plasticization and dimensional changes. For example, nylon 6,6, at 23 °F, with a relative humidity of 100%, can absorb 8.9% of water, which reduces its glass transition temperature from 6.5 ° C to 20 ° C, and increases the size by 2. 3%. Under the same conditions, the PPA resin can absorb about 6% of water, but its glass transition temperature Tg is not lower than 40 ° C, and the accompanying dimensional growth does not exceed 1.0%.
As mentioned earlier, glass-reinforced PPA resins have high HDT values and can withstand short-term effects at very high temperatures, such as in a furnace or in a vapor phase and in an infrared countercurrent solidification process. The thermal oxidative stability of PPA resin makes it resistant to long-term high temperature. Glass reinforced grade PPA has a continuous use temperature of 330 °F in 20,000 hours.
Under normal environmental conditions, PPA resins generally exhibit excellent resistance to aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons, esters, ketones, alcohols, and most aqueous solutions. Such resins cannot withstand the action of very strong acids and strong oxidizing agents. Soluble in phenol and cresol. PPA is not inherently flame retardant. According to the UL94 standard, flame retardant grade resins are rated VO up to 0.031 inch thickness.
Although other melting processes can be used, most PPA resins are processed by conventional injection molding. The PPA material is pre-dried to a moisture level of less than 0.1% and then placed in a heat-sealed metal village bag or box that ensures that the PPA material does not need to be dried before processing. The acceptable humidity level for the processing process is 0.15% or less. The processing of wet resins results in a decrease in molecular weight, resulting in a corresponding loss of mechanical properties. Using a desiccant bucket dryer, it is easy to dry the resin to a dew point humidity of 0.25 °F or even lower at 175 °F. The drying time depends on the amount of water absorbed, usually in the range of 4-16 hours.
The melting temperature during injection molding is in the range of 615-650 °F, and the residence time of the material in the barrel is not more than 10 minutes, so that the mechanical properties of the injection molded product are the best. The mold temperature is required to be at least 275 °F in order to obtain a product with the best crystallization and dimensional stability. Partially thick-walled parts can be injection molded at lower mold temperatures due to slower cooling rates. The mold temperature is critical to optimize the surface feel of the finished part. The mineral filler grade PPA resin used for vacuum metallization into electroplated metal requires a mold surface temperature of 350 °F.
Due to its outstanding physical, thermal and electrical properties, especially the moderate cost, PPA resins offer a wide range of applications. Together with these excellent chemical resistance, PPA has become a candidate for many uses in the automotive industry. A better aerodynamic body design, along with a higher performance motor, will increase the temperature of the engine compartment, making traditional thermoplastics seem inadequate. These new requirements make PPA one of the candidates for the following components: automotive headlamp reflectors, housings, pulleys, sensor housings, fuel line components and electrical components.
The development direction of electrical components is miniaturization and high temperature unity, such as infrared consolidation and vapor phase solidarity, which requires the superior performance of PPA. Flame-retardant PPA has excellent electrical properties, high HDT value, high high-temperature flexural modulus, and thin-walled parts that can be grown with minimal flash processing, making it suitable for switchgear. Connector, brush holder and motor bracket.
Mineral filler grade PPA is used for reflective surfaces and metallization applications, including automotive headlights, decorative fittings and hardware. The unreinforced impact modified grade PPA has excellent balance mechanical and high temperature properties. Extraordinary toughness and these properties are minimally affected by humidity, including oilfield components, military supplies, sporting goods, fan impellers and gears, and personal safety products.
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