The properties of polymer material are affected by its average
molecular weight (MW ) and its statistical distribution. Increasing the
average MW results in increasing:
- Tensile strength
- Elongation
- Impact strength
- Stress crack resistance
- Heat resistance
- Increased impact strength
- Decreased stress crack resistance
- Decreased processability
- Increasing crystallinity results in:
- Increasing stiffness or hardness
- Increasing heat resistance
- Increasing tensile strength
- Increasing modulus
- Increasing chemical resistance
- Decreasing diffusive permeability
- Decreasing elongation or strain at failure
- Decreasing flexibility
- Decreasing impact strength
- Decreasing stress crack resistance