Question

Complete the following statements about the crystallinity in polymers by choosing the right answers in the [box].

Most thermoset polymers are [amorphous/crystalline] .

Some thermoplastic polymers are semi-crystalline, meaning they have both higher density  [amorphous/crystalline] regions and lower density  [amorphous/crystalline] regions.

In many semi-crystalline polymers, the polymer chains fold into [lamellae/spherulite] structures which can be part of a larger  [lamellae/spherulite] structure which is formed around a nucleation site.

In semi-crystalline polymers, the glass transition temperature is where there is an increase in the ability of the polymer chains to move in the  [amorphous/crystalline] regions. The melting point is where the  [amorphous/crystalline] regions turn into a liquid.

Answer 1

Answer 1. Amorphous

The normal state of most thermoset polymers is to be an amorphous solid at room temperature. The arrangement of the polymer molecules is a random arrangement, meaning the polymer structure does not have a repeating arrangement of polymer chains.

Answer 2. Crystalline region higher density

Answer 3. Amorphous region lesser density

Explanation

Crystalline areas are generally more densely packed than amorphous areas.This results in a higher density, up to 15% depending on the material. For example, polyamide 6 (nylon) has crystalline density ρc= 1.24 g/cm3 and amorphous density ρa= 1.08 g/cm3).

Answer 4. Lammlle

Answer 5. Spherulites

Explanation

Crystallization of polymers is a process associated with partial alignment of their
molecular chains. These chains fold
together and form ordered regions called
lamellae, which compose larger spheroidal
structures named spherulites.

Answer 6. Amorphous

Answer 7. Crystalline

The glass–liquid transition, or glass
transition, is the gradual and reversible
transition in amorphous materials (or in
amorphous regions within semicrystalline
materials) from a hard and relatively brittle
"glassy" state into a viscous or rubbery
state as the temperature is increased.