Question 1

A large number of polymers are synthesized from monomers that are derived from ethylene.Replacing one or more of the hydrogen atoms on the ethylene monomer does not change the properties of the polymer.

Accepted Answer

Replacing hydrogen atoms on the ethylene monomer can significantly alter the properties of the resulting polymer, affecting characteristics like flexibility, strength, and chemical resistance.

Question 2

All polymers made from polyethylene will have the same density.

Accepted Answer

Polyethylene can have different densities depending on its molecular structure, such as low-density polyethylene (LDPE) and high-density polyethylene (HDPE).

Question 3

Plasticizers,such as biphenyls,are very soluble in water.

Accepted Answer

Plasticizers, including biphenyls, are not very soluble in water. They are typically added to materials like plastics to improve flexibility and durability, and are often used in oil-based solutions or emulsions.

Question 4

Polyester is an example of a condensation polymer.

Accepted Answer

Polyester is formed through a condensation reaction between a dicarboxylic acid and a diol. This process involves the elimination of a small molecule, typically water, and the formation of covalent bonds between the monomers. Therefore, polyester is a condensation polymer.

Question 5

Chewing gum is easier to remove from clothing if ice is applied to the gum.This works because applying ice lowers the temperature of the gum to below its glass transition temperature (Tg),so the gum becomes brittle and can be removed more easily.

Accepted Answer

When ice is applied to the gum, its temperature is lowered below the Tg, making it more brittle and easier to remove from clothing.

Question 6

Amorphous polymers tend to have great strength and rigidity while crystalline polymers tend to have greater elasticity.

Accepted Answer

Amorphous polymers do not have a specific ordered structure like crystalline polymers, which allows them to be more flexible and less rigid. Crystalline polymers, on the other hand, have a more ordered structure which makes them more rigid but less elastic.

Question 7

Approximately 50% of the plastic currently used in the United States is recycled each year.

Accepted Answer

According to the EPA, in 2018 only 8.5% of plastic waste generated in the US was recycled, while the rest ended up in landfills or as litter.

Question 8

A silicone polymer has a series of alternating silicon and oxygen atoms in the polymer chain.

Accepted Answer

A silicone polymer, also known as a polysiloxane, consists of a chain of silicon atoms (Si) alternated with oxygen atoms (O) and other organic groups (such as methyl or phenyl groups) attached to the silicon atoms.

Question 9

Polyethylene has double bonds,but ethylene does not.

Accepted Answer

Polyethylene is a polymer made from ethylene monomers, which contain double bonds. However, in polyethylene, these double bonds are broken during polymerization, resulting in a saturated polymer chain without double bonds.

Question 10

Neoprene is an elastomer that shows better resistance to oil and gasoline than other elastomers.

Accepted Answer

Neoprene has good resistance to oil and gasoline, making it a popular choice for automotive and industrial applications.

Question 11

A plasticizer makes a material more flexible and less brittle by raising its glass transition temperature (Tg).

Accepted Answer

Plasticizers lower the glass transition temperature (Tg), making the material more flexible and less brittle.

Question 12

Polychlorinated biphenyls (PCBs)are no longer used as plasticizers because they are considered to be an environmental hazard.

Accepted Answer

PCBs are considered to be persistent organic pollutants (POPs), which accumulate in the environment and can have negative effects on human and animal health, including being potentially carcinogenic and disrupting endocrine systems. Therefore, their production and use have been banned or severely restricted in many countries.

Question 13

Fire-retardant fabrics often have nitrogen or zinc atoms incorporated into the fibers of the polymers from which the cloth is made.

Accepted Answer

The answer of Fire-retardant fabrics often have nitrogen or zinc...

Question 14

Thermosetting resins will decompose rather than melt when they are heated to a high temperature.

Accepted Answer

Thermosetting resins are cross-linked polymers that undergo irreversible chemical changes when they are cured. This makes them resistant to heat and they tend to decompose when heated to a high temperature rather than melt like thermoplastics.

Question 15

Plasticizers are liquids of low volatility which can be lost by diffusion or evaporation as a plastic material ages.

Accepted Answer

Plasticizers are added to plastics to increase their flexibility and durability. However, as the plastic ages, the plasticizer molecules can diffuse out of the material or evaporate, leading to a loss of flexibility and an increase in brittleness.

Question 16

Crystalline polymers tend to have great strength while amorphous polymers tend to have greater elasticity.

Accepted Answer

Crystalline polymers have ordered structures that provide strength, while amorphous polymers have disordered structures that allow for more flexibility and elasticity.

Question 17

Thermosetting polymers can be melted and reformed into different shapes.

Accepted Answer

Thermosetting polymers cannot be melted and reformed into different shapes like thermoplastic polymers can. Once they are set or cured, they retain their shape and cannot be reshaped by heating.

Question 18

The glass transition temperature,Tg,is the temperature above which the polymer becomes brittle.

Accepted Answer

The glass transition temperature, Tg, is the temperature below which the polymer is in a glassy or rigid state and above which it becomes rubbery or flexible. Therefore, the statement is false; the polymer becomes brittle below the Tg, not above it.

Question 19

The wings of some airplanes are made from composite materials.

Accepted Answer

Composite materials, which typically include carbon fiber, are often used in the construction of airplane wings due to their high strength-to-weight ratio.

Question 20

All polymers are made from synthetic sources.

Accepted Answer

Polymers can be made from both natural and synthetic sources. Natural polymers include proteins, cellulose, and DNA, while synthetic polymers include plastics, nylon, and silicone.

Quiz 10: Polymers