Question

Describe the crystalline and amorphous states in thermoplastic and thermosetting polymers. How many transitions do take place in those polymers? Do you think that every polymer type has a melting point? why or why not?

Answer 1

Thermoplastic polymers are kind of resin at room temperature but when heated it melts and softens. Thermosets on heating form irreversible solid.

Crystalline are ordered solids such that same lattice of solid is obeyed in the entire range whereas amorphous solids do not have same lattice structure. When we compare, we can conclude that crystalline structure is in thermoplastic as it remains same even after heating whereas amorphous state is in thermoset plastic as doesn't have fix lattice once melted.

Number of transitions depend on the heating cycles. Thermoplastics regain the original texture even after heating whereas thermoset doesn't

Melting point is defined as temperature where solid changes to liquid. In polymer we cannt say it will change to liquid as there are bonds in between it which don't let it get converted directly into liquid. But bonds break, get deshaped and leads to this semi liquid type condition followed by pure liquid condition. Thus it differs from the nature of bond to bond present in the compound that will that have melting point or not as it leads to formation of semi liquid compound without further solidification.