Structure Property Relationship of PolymerCourse Title: Advanced Polymer Engineering

Course No: ACCE 503

RASHIDUL ISLAMID: 20121107007

Applied Chemistry and Chemical Engineering.BSMRSTU, Gopalganj.

1. Solubility

• Solubility is the ability of a polymer to dissolve in a solvent.

• Solubility change with change in polymer structure.– Increases with short branch

– Decreases with long branch

– Decreases with crosslinking

Crosslinked polymer

2. Glass Transition Temperature (Tg)

• The temperature at which a polymer transitions from a hard, glassy material to a soft, rubbery material.

Tg decreases with Chain Flexibility

• Tg depends on the ability of a chain to undergo internal rotations.

• Higher the freedom of rotation, the more flexible are thechains.

• Linear polymers with single bonds have high degree ofrotation.

• The presence of aromatics, cyclic structures in backbonehinder this rotation.

Tg decreases with big bulky side groups

• Big bulky side groups can lower the Tg

• The big side groups limit how closely the polymer chains can pack together. The further they are from each other, the more easily they can move around.

• We can see this with a series of methacrylate polymers

Tg increase with Cross-linking

• cross-linking increases Tg since

• The presence of covalent bonding between chains reducesmolecular freedom

Tg = -93 °C

Tg= 50 °C

Tg decreases with Plasticizer

• Plasticizers are small molecules which occupy position between polymer chains

• To increase flexibility, elongation and to reduce hardness

3. Thermal stability

• Thermal stability is the stability of a polymer at high temperatures.

• Aromatic cyclic chains are more stable than aliphatic carbon chains at elevated temperatures.

• Polyvinyl fluoride and PVDF are more stable to elevated temperatures than the corresponding chloride polymers. polytetrafluoroethylene (PTFE) is highly stable.

• < < <

• Presence of an oxygen or a sulfur atom in the backbones such as polyphenylene oxide (PPO), polyphenylene sulfide (PPS), and polyphenylene sulfone are highly stable at elevated temperatures.

4. Tensile strength

• The tensile strength of a polymer quantifies how much stress the polymer will endure before failing.

• Tensile strength changes with change in polymer structure.

• Branched< Linear< Crosslinked

References

• Raymond B. Seymour & Charles E. Carraher, Jr; Structure-Property Relationships in Polymers

• http://www.socoolglasses.com/definition-of-glass-transition-temperature/

• http://pslc.ws/macrog/tg.htm

• http://chemistry.tutorvista.com/analyticalchemistry/homopolymer.html