What are some limiting properties of plastics and in what ge

What are some limiting properties of plastics, and in what general area do they fall.

Solution

Some of the limiting properties of plastic :-

1. Dimensional stability of plastic:

a. Thermoplastic are quite sensitive to heat, their strength often drops rapidly as temperature increses above normal environmental condtition.

b. Thermosetting plastic often offer good strength but upper limit is about 250^oc.

2. Corrosion resistance of plastic are generally good but they often absorb moisture and this in turn decreses the strength.

3. Both ultravoilet radition and particulate can markedly alter the properties so a limit the environmental use of plastic.

4. Plastic are difficult to repair, if broken.

5. Plastic can be flexible or rigid but none of plastic posses strength properties that approach those of engineering material unless they are reinforced in form of composite.

6. Good specific strength( strength to weight ratio) but low impact strength(exception- ABS, high-density polyethylene, and polycarbonate).

7. Plastic can be reused repeadlty but the repeative heating and cooling cycle affcts mold life and the time required for thermal cylce influences productivity.

General area of limiting properties are :-

1. Dimensional accuracy

2. Strength and durabilty

3. Corrosion and humidity resistance

4. Reuseability