So many plastic materials, do you choose ABS or PP?

ABS plastic:

Mechanical properties

Plastic ABS has excellent mechanical properties, excellent impact strength and can be used at extremely low temperatures. Plastic ABS has excellent wear resistance, good dimensional stability and oil resistance. It can be used for medium and low speeds. Bearing. ABS has greater creep resistance than PSF and PC, but smaller than PA and POM.

Thermal performance

The heat distortion temperature of plastic AB S is 93~118 °C, and the product can be improved by about 10 °C after annealing. ABS can still show certain toughness at -40 °C, and can be in the temperature range of -40~100 °C. use.

Electrical performance

Plastic ABS has good electrical insulation and is almost independent of temperature, humidity and frequency, and can be used in most environments.

Environmental performance

Plastic ABS is not affected by water, inorganic salts, alkalis and various acids, but it is soluble in ketones, aldehydes and chlorinated hydrocarbons. It can be stress cracked by glacial acetic acid, vegetable oil, etc. ABS has poor weatherability. Under the action of ultraviolet light, it is easy to produce degradation; after half an year outdoors, the impact strength is reduced by half.

Edit this paragraph processing performance

Molding

Plastic ABS can also be said to be modified by polystyrene. It has higher impact strength and better mechanical strength than HIPS. It has good processing properties and can be injection molded using plastic molding equipment such as injection molding machines and extruders. Extrusion, blow molding, calendering, lamination, foaming, thermoforming, welding, coating, electroplating and machining. ABS has high water absorption and needs to be dried before processing. The drying temperature is 70~85°C. The drying time is 2~6h; ABS products are prone to internal stress during processing. If the stress is too large, the product will be cracked. Annealing should be carried out. The parts are placed in a hot air circulating drying oven at 70~80 °C for 2~4h. , then cool to room temperature.

Extrusion process

Extrusion. Plastic ABS produces pipes, plates, sheets, profiles and other products. Pipes can be used for pipes of various water pipes, gas pipes, lubricating oils and fuel oils; plates and sheets can be used for flooring, furniture, tanks, filtration , wall partition and thermoforming or vacuum forming. The screw length to diameter ratio of the extruder is usually higher, L/D is between 18~22, the compression ratio is (2.5~3.0):1, and the gradient type should be used. The torpedo head screw and barrel temperature are: hopper part 150~160°C, barrel front 180~190°C, die temperature 185~195°C, mold temperature 180~200°C, second blow molding temperature can be controlled at 140 Between ~180 °C.

And PP (polypropylene):

Mechanical properties

Polypropylene has high crystallinity and regular structure, so it has excellent mechanical properties. The absolute value of polypropylene mechanical properties is higher than that of polyethylene, but it is still a low grade in plastic materials, and its tensile strength can only reach 30 MPa. Or a slightly higher level. Polypropylene with a higher isotactic index has higher tensile strength, but with the increase of the isotactic index, the impact strength of the material decreases, but does not change after falling to a certain value.

Temperature and loading rate have great influence on the toughness of polypropylene. When the temperature is higher than the glass transition temperature, the impact damage is ductile fracture, brittle fracture is lower than the glass transition temperature, and the impact strength value is greatly reduced. The loading rate can be increased. The temperature at which the ductile fracture transitions to the brittle fracture is increased. The polypropylene has excellent bending fatigue resistance, and the product can be bent 106 times at normal temperature without damage. However, at room temperature and low temperature, the molecular structure is high due to its own structure. Therefore, the impact strength is poor. The most outstanding performance of polypropylene is the resistance to bending fatigue, commonly known as the hundred fold adhesive.

Thermal performance

Polypropylene has good heat resistance, and the product can be sterilized at temperatures above 100 °C. Under the condition of no external force, it is not deformed at 150 °C. The embrittlement temperature is -35 °C, and it will be lower than -35 °C. Brittleness occurs, and cold resistance is inferior to that of polyethylene. The reported values ​​for the glass transition temperature of polypropylene are 18qC, 0qC, 5°C, etc., which is also because people use different samples, in which the ratio of crystal phase to amorphous phase is different. The melting length of the amorphous part of the molecular chain is different. The melting temperature of polypropylene is about 40-50% higher than that of polyethylene, about 164-170 ° C, and the melting point of 100% isotactic polypropylene is 176 ° C.

Chemical stability

PP has good chemical stability. Besides being attacked by concentrated sulfuric acid and concentrated nitric acid, it is stable to various other chemical agents, but low molecular weight aliphatic hydrocarbons, aromatic hydrocarbons and chlorinated hydrocarbons can soften and swell polypropylene. At the same time, its chemical stability increases with the increase of crystallinity, so polypropylene is suitable for making various chemical pipes and fittings with good anti-corrosion effect.

Electrical performance

It has a high dielectric constant and can be used to make heated electrical insulation products with increasing temperature. Its breakdown voltage is also high, suitable for use as electrical accessories, etc. It is resistant to voltage and arc resistance, but High static electricity, easy to age with copper contact

There are a lot of plastic raw materials. In selecting plastic materials, it is necessary to compare the properties of different materials according to the purchased products.