Question 1

Huge macromolecules are formed by the ____ of small mers .&#10;A) pyrolysis&#10;B) polymerization&#10;C) hydrolysis&#10;D) oxidation

Accepted Answer

Polymerization is the process by which small molecules, called monomers, combine chemically to produce a large chain or network molecule, known as a polymer. This process is fundamental in creating various synthetic and natural polymers, including plastics, resins, and proteins.

Question 2

Commercial polymers range from a PI of about 2 to____.&#10;A) 10&#10;B) 20&#10;C) 30&#10;D) 40

Accepted Answer

D

Question 3

When monomers combine to form blocks two units long and then, in turn, combine to form blocks four units long, in sequence, it is known as ____ polymerization.&#160;&#10;A) stepwise&#10;B) emulsion&#10;C) chain growth&#10;D) catalytic

Accepted Answer

This process is known as stepwise polymerization, where monomers combine in a step-by-step fashion, first into dimers, then into larger chains, unlike chain growth polymerization where monomers add to the chain one at a time.

Question 4

Chain polymerization and stepwise polymerization produce molecules of varying molecular lengths, resulting in the need to ascertain the number and weight ____ of the distribution. &#160;&#10;A) polydispersity index&#10;B) standard deviation&#10;C) average molecular weight&#10;D) physical properties

Accepted Answer

The answer of Chain polymerization and stepwise polymerization produce molecules...

Question 5

Because determining average molecular lengths of a sample is difficult, manufacturing companies use ____ for a &#34;quick and dirty&#34; estimation of the average molecular lengths in a sample. &#160;&#10;A) polydispersity index&#10;B) melt index values&#10;C) mode values&#10;D) the median value

Accepted Answer

Melt index values are used by manufacturing companies as a quick and dirty estimation of the average molecular lengths in a sample because they provide an indirect measure of molecular weight, which correlates with molecular length. The melt index measures the flow of a polymer melt under specific conditions, and higher values typically indicate lower molecular weight (and thus shorter molecular lengths).

Question 6

Changes in the MFI are ____ average chain lengths (the average molecular weight). &#160;&#160;&#160;&#160;&#10;A) independent of&#10;B) inconsistently related to&#10;C) positively correlated with&#10;D) inversely correlated with

Accepted Answer

Melt Flow Index (MFI) is inversely correlated with average chain lengths; as the molecular weight increases, the MFI decreases because longer chains flow less easily.

Question 7

In bulk polymerization, ____ guarantee a high ratio between surface area and volume.&#10;A) narrow, tubular reactors&#10;B) catalysts&#10;C) small drops of monomer&#10;D) heat stabilizers

Accepted Answer

Narrow, tubular reactors guarantee a high ratio between surface area and volume in bulk polymerization, enhancing heat transfer and reducing the risk of runaway reactions.

Question 8

The polydispersity index (PI) is similar to a ____ for normal distribution&#10;A) mean&#10;B) standard deviation&#10;C) mode&#10;D) median

Accepted Answer

The polydispersity index (PI) is a measure of the distribution of molecular mass in a given polymer sample. It is similar to the standard deviation in a normal distribution, as both provide information about the spread or dispersion of values around the mean.

Question 9

To avoid using solvents, emulsion and suspension polymerization processes utilize ____to surround the tiny droplet of monomer. &#160;&#160;&#10;A) melting agents&#10;B) condensers&#10;C) catalysts&#10;D) water

Accepted Answer

Emulsion and suspension polymerization processes use water to surround the tiny droplets of monomer, thereby avoiding the use of solvents. This method allows the polymerization to occur within these water-encased droplets.

Question 10

When a melt flow index (MFI) increases, the flow length ____.&#10;A) drops to zero&#10;B) decreases&#10;C) increases&#10;D) is unaffected

Accepted Answer

When the melt flow index (MFI) of a material increases, it indicates that the material has become less viscous and flows more easily. Therefore, the flow length, or the distance the material can flow or be injected in a mold, increases.

Question 11

In polymerizing polystyrene from styrene monomers, the monomer is dissolved in about 80 percent ____.&#10;A) water&#10;B) formaldehyde&#10;C) benzene&#10;D) acetaldehyde

Accepted Answer

The answer of In polymerizing polystyrene from styrene monomers, the...

Question 12

In selecting material grade plastics, high-flow grades often include internal ____ to promote flow. &#160;&#10;A) lubricants&#10;B) metals&#10;C) carbonaceous materials&#10;D) glass additives

Accepted Answer

The answer of In selecting material grade plastics, high-flow grades...

Question 13

A common byproduct of stepwise polymerization is ____and hydrogen chloride.&#10;A) f ormaldehyde&#10;B) acetaldehyde&#10;C) benzene&#10;D) acetic acid

Accepted Answer

The answer of A common byproduct of stepwise polymerization is...

Question 14

The type of polymerization that begins at one location by the action of a chemical initiator and almost instantaneously completes the chain without yielding chemical byproducts is called ____ polymerization.

A) condensation
B) catalytic
C) emulsion
D) chain growth

Accepted Answer

The answer of The type of polymerization that begins at...

Question 15

The selection of a grade of material is complicated so petrochemical companies provide ____values on material data sheets (MSDS).&#160;&#10;A) average molecular weight&#10;B) polydispersity index&#10;C) MFI&#10;D) standard deviation

Accepted Answer

The answer of The selection of a grade of material...

Deck 8: Characterization and Selection of Commercial Plastics