Common types of plastics, advantages and disadvantages, the main flaw

Plastic is a resin as a main component, at a certain temperature and pressure molded into a certain shape, and at room temperature can be maintained given the shape of the high molecular weight organic material. Plastic light weight, high strength. Usually density 0.9-2.3g / mm³ is 1 / 8-1 / 4, 1/2 of aluminum, iron and steel excellent electrical insulation properties, good chemical stability, anti-friction wear resistance, light transmittance and protective properties Good, good damping silencer performance. After heating the surface of the plastic according to the performance into thermosetting plastics and thermoplastics. Occur at a certain temperature over a period of time of heat, pressure or added hardener chemical reaction and hardened, hardened plastic chemical structure changes, hard, insoluble in solvents, no longer softened after heating, such as temperature: thermosetting plastic Features too high to decompose. Such as Bakelite (commonly known as bakelite), epoxy plastic (EP) and the like. Thermoplastic Features: biological state change hair after being heated to soften or melt into a sticky fluid state from a solid, but can harden after cooling from solid, and the process can be repeated many times. The molecular structure of the plastic itself is not changed. Plastics such as polyethylene (PE), polyvinyl chloride (PVC).

PC material (polycarbonate)

Advantages: 1 has high strength and elastic modulus, high impact strength, wide temperature range.

2. High transparency and freedom of dyeing

3. good fatigue resistance

The excellent electrical characteristics

5. low mold shrinkage, good dimensional stability.

Disadvantages: 1. hydrolysis resistance

2. chemical resistance, notch effect

3. The problem is easy to produce finished poorly designed internal stress.

Chemical and physical properties: PC is a non-crystalline engineering materials, with a particularly good impact strength, heat stability, gloss, inhibit bacterial properties, flame retardant properties and fouling resistance. PC de gap estimated impact strength in Iraq (otched Izod impact stregth) is very high and very low shrinkage rate, usually 0.1% to 0.2%. PC has good mechanical properties, but poor flow characteristics, so the injection molding process more difficult this material. PC quality in the selection of the material, we should expect the final product as a benchmark. If the plastic parts require high impact resistance, then use a low turnover rate of PC material; the other hand, you can use the high turnover rate of PC material, which can optimize the injection molding process.

Material ABS (acrylonitrile - butadiene - styrene copolymer, commonly known as: super glue is not broken)

Advantages: 1. hard, easy extrusion

2. Flame

3. easy to dye

4. Impact

5. The surface resistance

Disadvantages: 1. poor solvent resistance

2. Low Dielectric strength

3. Low stretch rate

Forming characteristics: 1. amorphous material, liquid medium, moisture large, must be fully dry, glossy plastic surface should take time to preheat the drying 80-90 degrees, 3 hours

2. should take high melt temperature high mold temperature, high precision mold, mold temperature should take 50-60 degrees, high-gloss heat-resistant plastic parts, mold temperature should take 60-80 degrees.

Chemical and physical properties: ABS is, butadiene and styrene of three monomers synthesized from acrylonitrile. Each of the monomers having different characteristics: acrylonitrile high strength, thermal stability and chemical stability; butadiene have toughness and impact resistance properties; styrene easy processing, high-quality finish and high strength. Morphologically, ABS is an amorphous material. Polymerization of three monomers produces a terpolymer having two phases, a styrene - acrylonitrile continuous phase, and the other is a polybutadiene rubber dispersed phase. The properties of ABS depends on the ratio of the monomers and the molecular structure of the two phases. This allows great flexibility in product design, and the resulting market hundreds of different quality ABS material. These different quality materials offer different characteristics, such as moderate to high impact resistance, from low to high finish and high heat distortion characteristics. ABS material with superior ease of processing, appearance, low creep and excellent dimensional stability and high impact strength.

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