Question

1. Explain why polymers are stronger when they contain crosslinking.

2. Explain how your polymer degradation observations relate to the properties of your polymer.

Answer 1

1) Crossed linked polymers contain additional bonds between the molecules that provide resistance to flow. All of the extra links or bonds must be broken before the molecules can move relative to each other.

2)

Polymer degradation is a change in the properties of the polymer – such as tensile strength, color, shape, molecular weight – or of a polymer-based product under the influence of one or more environmental factors, such as heat, light, chemicals, or any other applied force. Degradation is often due to a change in the chemical and/or physical structure of the polymer chain, which in turn leads to a decrease in the molecular weight of the polymer. These changes may be undesirable, such as changes during use, or desirable, as in biodegradation or deliberately lowering the molecular weight of a polymer. Such changes occur primarily because of the effect of these factors on the chemical composition of the polymer.

The susceptibility of a polymer to degradation depends on its structure. Epoxies and chains containing aromatic functionality are especially susceptible to ultraviolet degradation while hydrocarbon-based polymers are susceptible to thermal degradation and are often not ideal for high-temperature applications.

The degradation of polymers to form smaller molecules may proceed by random scission or specific scission.