Question

polymers
use the information below to answer the question.
polymers such as plastic come in many different forms and have many different
properties. the plastic industry is one of the largest areas of manufacturing, so there
are a lot of job opportunities for these types of 3d printers.
fused filament fabrication is a very common desktop model. two types of polymers
that we are focusing on are:

1. thermoplastic
2. thermoset plastic

thermoplastic
this material can be melted, solidified, and then re - melted. in this process, the
filament will be stored on a spool, which is loaded into the machine and run through.
as the machine is building the part, it melts the material and creates a layer. then as
the next layer is applied, it also slightly heats the layer below it, thereby binding the
two layers together. the finished product will harden as it cools.
thermoset plastic
this plastic is a resin that hardens after its been cured either by a laser or uv light.
once it has hardened, you will be unable to re - melt it. a common desktop printer is
called stereolithography (sla). in this type of system, it moves a build plate either up
or down depending on the model used.
in this particular model, the machine begins by spreading a layer of resin onto the
build plate and then moves the plate down. an ultraviolet (uv) light is then shone on
specific parts of the plate to harden the resin where the structure should be. the
machine then moves the plate down again to prepare for the next layer of resin to be
applied and the cycle continues.
differences in polymer properties
what is a thermoplastic?
a plastic that starts as a resin and solidifies once
a plastic that can be melted and solidified repeatedly
a plastic that needs to reach a certain temperature before it can solidify

Explanation:

As per the provided information, thermoplastic can be melted, solidified, and re - melted. The first option describes thermoset plastic (starts as resin and solidifies once). The third option is not in line with the given description. The second option "a plastic that can be melted and solidified repeatedly" matches the description of thermoplastic.

Answer:

a plastic that can be melted and solidified repeatedly