What do the initials WVTR stand for and how is WVTR expressed?
Answer
WVTR - water vapor transmission rate; WVTR is expressed as grams of water vapor transfer per 100 sq in of film of 1 mil thickness per 24 hours under defined conditions of temperature, humidity and pressure
Card 302
Question
High density polyethylene are made up of carbon chains that are highly branched.
Answer
FALSE (HDPE - linear LDPE - highly branched)
Card 303
Question
If temperature increases, a PP film will melt and vaporize into PP molecules.
Answer
FALSE.
Card 304
Question
Molecular weight of food packaging material is typically between 5,000 and 50,000.
Answer
FALSE.
Card 305
Question
PVDC is considered more environmentally friendly than EVOH.
Answer
FALSE.
Card 306
Question
In packaging materials, covalent bonds are more commonly found than ionic bonds.
Answer
TRUE.
Card 307
Question
As molecular weight increases, both tensile strength and viscosity of a packaging polymer increase.
Answer
TRUE.
Card 308
Question
Low density polyethylene is a good oxygen barrier compared to nylon.
Answer
False
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