MMET 281 EXAM I QUESTIONS
WITH 100% CORRECT
ANSWERS
What are the characteristics of amorphous material? - Answer- -soften over a range of
temperatures
-characterized by glass transition temperature
-PC and PMMA
What are the characteristics of crystalline plastics? - Answer- -fairly distinct melting
temperature
-usually translucent or opaque
-higher shrinkage and warpage factors
Define molecular orientation - Answer- the stretching and straightening of molecules,
especially in crystalline plastics
Define Residual stress - Answer- physical effect of tendency of molecules to return to
their un-oriented state
Define annealing - Answer- the controlled heating of a part to relieve stresses
introduced in the manufacturing process
What are the two types of molecular orientation? - Answer- uniaxial oriented and biaxial
oriented
What are the characteristics of uniaxial oriented plastics? - Answer- -crack easily in one
direction
-curl when heated
-shrink in only one direction when heated
What are the characteristics of biaxial oriented plastics? - Answer- -molecules are
stretched in two directions
-shrink in two directions when heated
What are the types of degradable plastics? - Answer- photo, bio, and water degradable
, What kind of plastics are non-recyclable? - Answer- thermosets
What are the alternatives to recycling? - Answer- incineration and degradable plastics
What are the primary types of chemical bonds? - Answer- metallic, ionic, covalent
What are hydrocarbons? - Answer- molecules consisting of hydrogen and carbon
What are saturated hydrocarbons? - Answer- those that only contain single bonds
Intermolecular forces affect ____ - Answer- melting point and tensile strength
What are the types of intermolecular forces? - Answer- Van der Waal's, dipole, and
hydrogen bonds
Define monomer - Answer- a molecule that may bind to other molecules to form a
polymer
What were the problems in using natural polymers? - Answer- supply, preparation,
properties
What are some examples of natural polymers? - Answer- horn, shell, hooves, shellac,
gutta percha
What is shellac/what is it made from? - Answer- a natural polymer made from the lac
insect
What is the name of the natural polymer made from tree products? - Answer- Gutta
Percha
What is casein? - Answer- a milk curd product that is modified by formaldehyde
What was casein used for? - Answer- buttons, umbrella handles
What is rubber made from? - Answer- natural latex
How is vulcanized rubber made? - Answer- sulfur and heat are added
-more sulfur=harder rubber
What is celluloid? - Answer- plant product, modified natural polymers
What is bakelite? - Answer- an early, completely synthetic material
What is bakelite used for? - Answer- billiard balls, telephones, early automotive parts
WITH 100% CORRECT
ANSWERS
What are the characteristics of amorphous material? - Answer- -soften over a range of
temperatures
-characterized by glass transition temperature
-PC and PMMA
What are the characteristics of crystalline plastics? - Answer- -fairly distinct melting
temperature
-usually translucent or opaque
-higher shrinkage and warpage factors
Define molecular orientation - Answer- the stretching and straightening of molecules,
especially in crystalline plastics
Define Residual stress - Answer- physical effect of tendency of molecules to return to
their un-oriented state
Define annealing - Answer- the controlled heating of a part to relieve stresses
introduced in the manufacturing process
What are the two types of molecular orientation? - Answer- uniaxial oriented and biaxial
oriented
What are the characteristics of uniaxial oriented plastics? - Answer- -crack easily in one
direction
-curl when heated
-shrink in only one direction when heated
What are the characteristics of biaxial oriented plastics? - Answer- -molecules are
stretched in two directions
-shrink in two directions when heated
What are the types of degradable plastics? - Answer- photo, bio, and water degradable
, What kind of plastics are non-recyclable? - Answer- thermosets
What are the alternatives to recycling? - Answer- incineration and degradable plastics
What are the primary types of chemical bonds? - Answer- metallic, ionic, covalent
What are hydrocarbons? - Answer- molecules consisting of hydrogen and carbon
What are saturated hydrocarbons? - Answer- those that only contain single bonds
Intermolecular forces affect ____ - Answer- melting point and tensile strength
What are the types of intermolecular forces? - Answer- Van der Waal's, dipole, and
hydrogen bonds
Define monomer - Answer- a molecule that may bind to other molecules to form a
polymer
What were the problems in using natural polymers? - Answer- supply, preparation,
properties
What are some examples of natural polymers? - Answer- horn, shell, hooves, shellac,
gutta percha
What is shellac/what is it made from? - Answer- a natural polymer made from the lac
insect
What is the name of the natural polymer made from tree products? - Answer- Gutta
Percha
What is casein? - Answer- a milk curd product that is modified by formaldehyde
What was casein used for? - Answer- buttons, umbrella handles
What is rubber made from? - Answer- natural latex
How is vulcanized rubber made? - Answer- sulfur and heat are added
-more sulfur=harder rubber
What is celluloid? - Answer- plant product, modified natural polymers
What is bakelite? - Answer- an early, completely synthetic material
What is bakelite used for? - Answer- billiard balls, telephones, early automotive parts
