Food Packaging Technology Multiple Choice Questions & Answers (MCQs) on “Thermoplastic Polymers – Shrink and Stretch Films”.
1. Which of the following is not used as a stretch film?
a) Polyolefins
b) PVC
c) PVdC
d) PET
Answer: d
Clarification: PET is not used as a stretch film. PET has its greatest use in bottles for juices and soft drink due to its barrier and mechanical properties. Shrink films are composed of three basic categories: polyolefins, PVC and PVdC copolymer.
2. LLDPE is produced by copolymerisation of ethylene with ______
a) Di-olefins
b) Gamma olefins
c) Beta olefins
d) Alpha olefins
Answer: d
Clarification: LLDPE is produced by copolymerisation of ethylene with alpha olefins. LLDPE- Linear Low Density Polyethylene has better stretch properties when compared to LDPE- Low Density Polyethylene.
3. PVDC stands for ________
a) Polyvinylidene Chloride
b) Polyvinyl Dichloride
c) Polyvinyldeca Chloride
d) Polyvinyldiene Chloride
Answer: a
Clarification: PVDC stands for Polyvinylidene Chloride. PVdC is a polymer of Vinylidene chloride. PVDC is also known as coated PVC. PVDC has lower OTR and WVTR when compared to PVC, by a factor of 5-10.
4. A plastic wrap is the same as stretch wrap.
a) True
b) False
Answer: b
Clarification: The above statement is false. A plastic wrap is same as shrink wrap. It is the shrink wrap used in foods. It is used to wrap food items, so as to preserve them for a longer period of time. The most commonly used plastic wrap is PVC.
5. BOPP stands for __________
a) Biaxially operated polypropylene
b) Biaxiallyoriented propylene
c) Biaxiallyoriented packaged propylene
d) Biaxially oriented polypropylene
Answer: d
Clarification: BOPP stands for biaxially oriented polypropylene. BOPP is mostly used in packaging labels. It is a product of heat-setting, the process in which a film is reheated in a constrained strain. It is produced by the tenderframe technology for orientation of plastic films.
6. Find the odd one.
a) Cling film
b) Plastic wrap
c) Saran wrap
d) Stretch film
Answer: d
Clarification: Stretch film is the odd one. Cling film, plastic wrap and saran wrap are the terms which denote a thin plastic film used for packaging of food. It is also known as shrink wrap and food wrap. Stretch film is used for wrapping secondary or higher forms of packaging. It can never be used as a primary packaging material.
7. In __________ no sealing is required.
a) Plating
b) Laminating
c) Stretch wrapping
d) Shrink wrapping
Answer: c
Clarification: In stretch wrapping, no sealing is required. Its main function is pallet unitizing. During stretch wrapping, the material is covered in such a way that the film’s elasticity holds the load tightly together and hence, no sealing is required.
8. Which of the following polymer is used as a shrink film for foods and snacks?
a) PE
b) PP
c) PVC
d) Polyolefin
Answer: d
Clarification: Polyolefin films are used for shrink wrapping of foods, snacks and retail items. It is a clear film that shrinks evenly in all directions. This film allows scents to permeate it. Since it requires high temperatures to shrink the film, it’s often applied with a shrink wrap machine which increases productivity and allows items to be bundled together.
9. Which of the following polymer is used as a shrink film for CDs and DVDs?
a) PE
b) PP
c) PVC
d) Polyolefin
Answer: c
Clarification: PVC- Polyvinyl Chloride is used as a shrink film for CDs and DVDs (and also Blu-ray discs). PVC shrink films have high strength with good clarity and gloss. Its major use is in shrink wrapping CDs, DVDs and discs, but is also used for shrink wrapping of books, toys and food items.
10. Thermosetting polymers can be used for shrink or stretch wrapping.
a) True
b) False
Answer: b
Clarification: The above statement is false. Thermosetting plastics cannot be used as shrink or stretch films. There are only four types of thermoplastics used for shrink wrapping currently, which include – Polyethylene, Polypropylene, Polyolefin and Polyvinyl Chloride.
11. Which of the following polymer is used for wrapping large and bulky items?
a) PE
b) PP
c) PVC
d) Polyolefin
Answer: a
Clarification: PE- Polyethylene is used for wrapping large and bulky items. PE shrink films are thicker, stronger and more durable than other shrink films. PE shrink films are often used to wrap bottled water, canned goods and other heavy objects. It is deal for wrapping large and bulky items during transit. These films are so strong that they can replace corrugated boxes.
12. Which of the following polymer is also called general purpose shrink film?
a) PE
b) PP
c) PVC
d) Polyolefin
Answer: b
Clarification: Polypropylene film is also known as general purpose shrink film. It is because this is the most used plastic for wrapping retail items. It has the property of shrinking at low temperatures while providing durable seals.
13. Which of the following is not a type of overwrap?
a) Decorative wrap
b) Paper wrap
c) Stretch wrap
d) Shrink wrap
Answer: c
Clarification: Stretch wrap is not a type of overwrap. An overwrap is also known as a polywrap. Shrink wrap is a polymer plastic film, which shrinks on the application of heat. Paper wrap, like Kraft paper is used to overwrap items in a package or to overwrap a package. Decorative packaging is the quaternary packaging, which aims to enhance the looks of the good.