polymer intro 1 and 2

Question 1

difference between crystalline and amorphous polymers

Answer 1

crystalline- highly ordered, close packing, regular pattern of interactions, more dense, less space, rigid, motion limited by extensive intermolecular interactions

amorphous- disordered, random molecular arrangement, loosely packed, random intermolecular interactions at points of entanglement, lots of space, easy motion, only limited by points of entanglement

Question 2

factors that influence crystallinity

Answer 2

speed and temp of solidification- when a melted polymer cools/dries rapidly it is an amorphous, if slowly then its crystalline

molecular structure must be regular, irregular polymers cant form regular arrangements

crystalline state is lowest energy and favoured

Question 3

how do crystalline polymers form

Answer 3

1. nucleation- polymer dries/cools and tiny crystals form at points of molecular contact
2. if enough molecular space/time/thermal motion the molecules rearrange and there is crystal growth from nucleation sites, crystalline regions grow outwards
3. if moth polymer is involved, material becomes polycrystalline, microstructure turns milk opaque and dense

Question 4

what is semi crystalline

Answer 4

polymers that possess both ordered and disorganised amorphous domains