Plastics (Etech-251) Exam Questions with
Correctly Solved Answers
In standard polymer notation, what does the "n" represent?
Number of "repeat units" in the molecule
Which of these combinations are the tow critical components of the vulcanization process?
Sulfur and Heat
Which term describes an atom/molecule/compound that is used to speed up a chemical
reaction, such as polymerization?
Catalyst
What material was Dupont trying to replace when they developed their synthetic
polymers?
Silk
Which of the following people invented the first catalyst for cost effectively polymerizing
polypropylene?
Guillo Natta
Which scientist developed catalysts to produce polyethylene?
Karl Ziegler
Who developed the vulcanization process?
Charles Goodyear
,Who developed the first synthetic polyisoprene?
Fritz Hoffman
Who developed nitrocellulose?
Christian Friedrich Schonbein
Who developed the "condensation polymerization" process to make polyesters and nylons?
Wallace Carothers
Whos is widely credited as the "father of the modern plastics industry" and developed
phenolic resins that could be easily shaped and could be mass produced?
Leo Baekeland
Which scientist theorized that polymers are rigid and linear molecular chains and called
them "Macromolecules"?
Herman Staudinger
Which scientist was the first to understand liquid crystalline polymers and went on to
develop Kevlar?
Stephanie Kwolek
Who was the first to polymerize polyethylene from ethylene gas at high temperature and
pressure?
Eric Fawcett
,Which scientist theorized that polymer chains were flexible, not rigid and that some
polymers could crystallize?
Herman Mark
Polypropylene
(C3H6)
Nylon-6,6
(C12H22N2O2)
Polyethylene terephthalate (PET)
C10H8O4
Polyethylene
(C2H4)
Nylon 6
(C6H11NO)
Polystyrene
(C8H8)
Polycarbonate
(C15H16O2)
PVC
(C2H3Cl)
, What is the number average molecular weight (Mn) of the distribution shown below?
Provide your answer in units of g/mol.
(Sum molecular weight x number of chains)/Total Number of Chains
ΣMiNi/ΣNi=Mn
What is the weight average molecular weight (Mw) of the distribution shown below?
Provide your answer in units of g/mol.
((Molecular Weight^2)x number of chains)/Sum Molecular Weight (ΣMiNi)
Σ(Mi^2)Ni/ΣMiNi=Mw
What is the Dispersity of the distribution shown below?
Weight Average Molecular Weight/Number Average Molecular Weight (D)
Dispersity=Mw/Mn
(Σ(Mi^2)Ni/ΣMiNi)/(ΣMiNi/ΣNi)
Mathematically, viscosity is defined as Applied Force divided by Unit Area .
Shear Stress, Shear Rate
In a laminar pressure-driven flow, the fluid velocity is ________ in the center while the
shear stress is __________ in the center of the flow.
Highest, Zero
In a laminar pressure-driven flow, the fluid velocity is _________ along the wall while the
shear stress is __________ along the wall of the flow.
Zero, Highest
Correctly Solved Answers
In standard polymer notation, what does the "n" represent?
Number of "repeat units" in the molecule
Which of these combinations are the tow critical components of the vulcanization process?
Sulfur and Heat
Which term describes an atom/molecule/compound that is used to speed up a chemical
reaction, such as polymerization?
Catalyst
What material was Dupont trying to replace when they developed their synthetic
polymers?
Silk
Which of the following people invented the first catalyst for cost effectively polymerizing
polypropylene?
Guillo Natta
Which scientist developed catalysts to produce polyethylene?
Karl Ziegler
Who developed the vulcanization process?
Charles Goodyear
,Who developed the first synthetic polyisoprene?
Fritz Hoffman
Who developed nitrocellulose?
Christian Friedrich Schonbein
Who developed the "condensation polymerization" process to make polyesters and nylons?
Wallace Carothers
Whos is widely credited as the "father of the modern plastics industry" and developed
phenolic resins that could be easily shaped and could be mass produced?
Leo Baekeland
Which scientist theorized that polymers are rigid and linear molecular chains and called
them "Macromolecules"?
Herman Staudinger
Which scientist was the first to understand liquid crystalline polymers and went on to
develop Kevlar?
Stephanie Kwolek
Who was the first to polymerize polyethylene from ethylene gas at high temperature and
pressure?
Eric Fawcett
,Which scientist theorized that polymer chains were flexible, not rigid and that some
polymers could crystallize?
Herman Mark
Polypropylene
(C3H6)
Nylon-6,6
(C12H22N2O2)
Polyethylene terephthalate (PET)
C10H8O4
Polyethylene
(C2H4)
Nylon 6
(C6H11NO)
Polystyrene
(C8H8)
Polycarbonate
(C15H16O2)
PVC
(C2H3Cl)
, What is the number average molecular weight (Mn) of the distribution shown below?
Provide your answer in units of g/mol.
(Sum molecular weight x number of chains)/Total Number of Chains
ΣMiNi/ΣNi=Mn
What is the weight average molecular weight (Mw) of the distribution shown below?
Provide your answer in units of g/mol.
((Molecular Weight^2)x number of chains)/Sum Molecular Weight (ΣMiNi)
Σ(Mi^2)Ni/ΣMiNi=Mw
What is the Dispersity of the distribution shown below?
Weight Average Molecular Weight/Number Average Molecular Weight (D)
Dispersity=Mw/Mn
(Σ(Mi^2)Ni/ΣMiNi)/(ΣMiNi/ΣNi)
Mathematically, viscosity is defined as Applied Force divided by Unit Area .
Shear Stress, Shear Rate
In a laminar pressure-driven flow, the fluid velocity is ________ in the center while the
shear stress is __________ in the center of the flow.
Highest, Zero
In a laminar pressure-driven flow, the fluid velocity is _________ along the wall while the
shear stress is __________ along the wall of the flow.
Zero, Highest
