Engineering plastics have a wide range of types and applications, and their excellent properties are often used to replace metal materials. Many friends in the plastic industry often worry about not distinguishing the characteristics of different types of plastics correctly when choosing the types of raw materials. Below, we will provide you with a detailed introduction to various types of engineering plastics from three aspects: basic performance, processing performance, and usage.
Polyphenylene ether PPO
1. Basic properties
(1) Specific gravity: 1.07g/cm
(2) Molding shrinkage rate: 0.3-0.8%
(3) Forming temperature: 260-290 ℃
(4) Drying conditions: 130 ℃, 4 hours
2. Material performance
(1) It is a white particle. Good overall performance, suitable for use in 120 degree steam, good electrical insulation, low water absorption, but prone to stress cracking. Modified polyphenylene ether can eliminate stress cracking;
(2) It has outstanding electrical insulation and water resistance, and good dimensional stability. Its dielectric properties rank first among plastics;
(3) MPPO is a modified material made by blending PPO and HIPS, and currently the materials on the market are all of this type;
(4) It has high heat resistance, with a glass transition temperature of 211 degrees Celsius and a melting point of 268 degrees Celsius. When heated to 330 degrees Celsius, it tends to decompose. The higher the content of PPO, the better its heat resistance, and the heat deformation temperature can reach 190 degrees Celsius;
(5) Good flame retardancy, self igniting, and moderate flammability when mixed with HIPS. Lightweight and non-toxic, it can be used in the food and drug industries. Poor light resistance and discoloration after prolonged use in sunlight;
(6) It can be blended and modified with ABS, HDPE, PPS, PA, HIPS, glass fiber, etc.
3. Forming characteristics
(1) Non crystalline material with low moisture absorption;
(2) Poor flowability, similar to Newtonian fluids, viscosity is relatively sensitive to temperature, and the thickness of the product is generally above 0.8mm. Extremely easy to decompose, producing corrosive gases during decomposition. It is advisable to strictly control the molding temperature, heat the mold, and reduce the resistance of the pouring system to the material flow;
(3) The water absorption rate of polyphenylene ether is very low by about 0.06%, but a small amount of water can cause the surface of the product to appear unsmooth phenomena such as silver threads. It is best to dry it, and the temperature should not be higher than 150 degrees, otherwise the color will change;
(4) The molding temperature of polyphenylene ether is 280-330 degrees, and the molding temperature of modified polyphenylene ether is 260-285 degrees.
4. Applicable scope
Produce heat-resistant parts, insulation parts, wear reducing and wear-resistant parts, transmission parts, medical and electronic parts; Can be used for gears, blades, valves and other parts at higher temperatures, and can replace stainless steel for use; Can produce screws, fasteners, and connectors; Electrical components of motors, rotors, casings, and transformers.
Thermoplastic polyester
PET (polyethylene terephthalate)
1. Basic properties
Previously mostly used as fibers, i.e. polyester fibers, now rapidly developing towards engineering plastics and packaging plastics. According to different uses, PET can be divided into fiber grade, film grade, blow bottle grade, and reinforced grade.
2. Material performance
(1) It is a colorless transparent or milky white semi transparent solid;
(2) It has high tensile strength, stiffness, and hardness, but has certain flexibility, good wear resistance, creep resistance, and can maintain these good mechanical properties over a wide temperature range;
(3) Has excellent electrical insulation;
(4) It has excellent weather resistance, and its mechanical properties can still maintain the initial 80% after six years of outdoor exposure;
(5) Resistant to weak acids, with good chemical stability to organic solvents and oils.
3. Applicable scope
(1) Produce thin films and photosensitive films, such as film substrates for cinematography and photographic films;
(2) As a packaging material for food, medicine, textiles, precision instruments, electrical components, etc., the hollow containers made of it have high strength, good transparency, non-toxic and odorless properties, and are widely used as plastic packaging materials for carbonated beverages, beer, edible oil, etc; Electrical materials;
(3) Used for making various electrical insulation materials, such as wires, switches, electrical enclosures, etc.
PBT (Polybutylene terephthalate)
1. Basic properties
There are two types of PBT used as engineering plastics: unmodified and modified. The unmodified grade has a high molding shrinkage rate and mechanical properties that are inferior to other engineering plastics, so it is rarely used alone. Nearly 80% of PBTs are modified.
2. Material performance
(1) It is a milky white crystalline solid, odorless, non-toxic, and has a glossy surface. The flexibility is better than PET, and the melting temperature and rigidity are relatively small;
(2) Has excellent electrical insulation. It can be maintained even in humid and harsh environments;
(3) Has good weather resistance;
(4) It can resist the corrosion of general chemicals, such as weak acids.
3. Applicable scope
(1) Produce various automotive parts, such as door handles, bumpers, rearview mirror shells, etc;
(2) Produce electronic and electrical components, such as connectors, sockets, plugs, fuse boxes, etc;
(3) Produce various electrical casings and components, such as telephone sets, indoor and outdoor lighting equipment casings, hair dryer components, etc.
Ultra high molecular weight polyethylene UHMWHPE
1. Basic properties
A special engineering plastic with a relative molecular weight exceeding 1.5 million and comprehensive properties that conventional molecular weight polyethylene does not possess. The molecular structure is identical to ordinary polyethylene, but the molecular weight is particularly high. Among UHMWPE with a relative molecular weight of over 1.5 million, there are also grades with relative molecular weights of 2 million, 3 million, or even over 5 million.
2. Material performance
(1) The average molecular weight is about 350000 to 8 million, and due to its high molecular weight, it has excellent impact resistance, wear resistance, self-lubrication, chemical corrosion resistance, and other properties that are unparalleled in other plastics;
(2) Excellent low-temperature resistance, still having high impact strength at -40 ℃, and can even be used at -269 ℃;
(3) Having electrical insulation, low water absorption, and physiological inertness;
(4) It has excellent resistance to stress cracking, creep, and fatigue.
3. Applicable scope
Used in fields such as machinery, transportation, textiles, papermaking, mining, agriculture, chemicals, and sports equipment, among which large packaging containers and pipelines are the most widely used; Due to its excellent physiological inertia, it has been used in clinical medicine as a heart valve, orthopedic surgical component, artificial joint, etc.
