Chapter 1 : Introduction of Polymer_2

What is the behavior of thermoplastics when exposed to heat?

• Retain their form and stay solid

• Melt under heat after curing

• Become liquid at room temperature

• Degrade without entering a fluid phase

What is a characteristic of thermoset plastics?

• Overheating can cause degradation without entering a fluid phase

• Solid at room temperature but become soft when heated

• Can be reshaped or remoulded

• Can be recycled

What is the molecular weight of a linear polymer represented by?

• Polydispersity index

• Number average molecular weight

• Degree of polymerization

• Weight average molecular weight

What is the degree of polymerization a measure of?

• Molecular weight

• Repeat units in the chain

• Chain length

• Polydispersity

What is the ratio used to express the 'width' of the molecular weight distribution?

• Number average molecular weight

• Degree of polymerization

• Weight average molecular weight

• Polydispersity index

What is the main difference between natural polymers and synthetic polymers in terms of molecular weight distribution?

• Natural polymers have a narrow distribution

• Synthetic polymers have a narrow distribution

• Natural polymers have a broad distribution

• Synthetic polymers have a broad distribution

What is the purpose of determining the polydispersity index in polymer chemistry?

• To express the width of the molecular weight distribution

• To determine the chain length

• To measure the degree of polymerization

• To calculate the molecular weight

Which method is used to determine the molecular weight of polymers?

• Gel permeation chromatography

• Viscometry

• Light scattering

• Small angle neutron scattering

What is the average molecular weight of polypropylene with a degree of polymerization of 3 x 10^4?

• 75,000 g/mol

• 50,000 g/mol

• 100,000 g/mol

• 25,000 g/mol

What is the main drawback of thermoset plastics?

• Cannot be recycled

• Can be reshaped easily

• Have superb electrical insulation properties

• Can withstand high temperatures without losing shape