Category: Food Packaging Technology Objective Questions

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.

Food Packaging Technology MCQs on “Manufacture of Glass – 2”.

1. Lehr is a deadplate.
a) True
b) False
Answer: b
Clarification: The given statement is false. The containers, from the molder, are transferred from the deadplate to a large oven, known as a lehr, which is equipped with a belt conveyer.

2. The temperature during annealing is around ______
a) 250°C
b) 340°C
c) 540°C
d) 640°C
Answer: c
Clarification: This is achieved by raising the temperature of the container to approximately 540°C, holding it there for a few minutes and then cooling at a rate which is consistent with the removal of stress from a predetermined wall thickness.

3. The temperature at which annealing is done is known as _________
a) melting point
b) softening point
c) transition point
d) gradient point
Answer: b
Clarification: The temperature at which annealing is done is known as softening point of glass. It melts and reforms glass so that any cracks or deformity can be healed or removed.

4. The primary purpose of annealing is to improve transparency of glass.
a) True
b) False
Answer: b
Clarification: The given statement is false. The function of the annealing lehr is to produce a stable product by removing any residual stresses resulting from non-uniform cooling rates during forming and handling.

5. During cooling, the outside surface is hotter than the inside.
a) True
b) False
Answer: b
Clarification: The given statement is false. During cooling, the inside surface is hotter than the outside; this results in compression on the outer surface but tension at the inner surface. Sudden cooling results tensile stresses into the outer surfaces and compressional stresses in the interior surfaces. Poor annealing may result in breaking or cracking if interior is bruised or tension is high.

6. Lightweight bottles can handle temperature fluctuation better than regular bottles.
a) True
b) False
Answer: a
Clarification: The given statement is true. Due to the better thickness distribution of lightweight glass bottles, they withstand a maximum temperature difference (progressive thermal shock) of 5°C–10°C higher than the regular weight bottles.

7. Narrow-neck glass containers are formed by _______ process.
a) blow and press
b) press and press
c) press and blow
d) blow and blow
Answer: d
Clarification: Narrow-neck glass containers (bottles) are formed by blow and blow process. Bottles are made by a two step Blow & Blow process, in which a gob of glass is sent to a cast iron mold. The cast iron mold is externally air cooled and hence changes gob to a perform (also known as a parison or body blank).

8. Wide-mouth glass containers are formed by _______ process.
a) blow and press
b) press and blow
c) blow and blow
d) press and press
Answer: b
Clarification: Wide-mouth glass containers (jars) are formed by press and blow process. In the case of jars, a two-step WMP&B process is used. The body blank or parison is formed by pressing the gob of molten glass against the mold walls with a large plunger. When the cavity is filled, glass is then pushed down into the neck ring and the finish is formed.

9. Formation of glass jars takes place through blow moulding.
a) True
b) False
Answer: a
Clarification: The given statement is true. When the finish molding is complete, the plunger is retracted and air blown in from the bottom of the mold, enlarging the size of the bubble until the glass is pressed out against the blank mold to form a hollow, thick-walled preform or parison. The parison is then inverted and transferred to the blow mold. It elongates there as a result of its own weight and touches the base of the mold.

10. In the blow and blow process for glass container manufacture, the neck formation takes place before blank is blown.
a) True
b) False
Answer: a
Clarification: The given statement is true. The blow and blow process takes place in the following steps-
i. Gob dropped into blank mold
ii. Neck formed
iii. Blank blown
iv. Blank transferred to blow mold
v. Final shape blown
vi. Finished bottle.

11. Wide mouth press and blow process for glass container manufacture does not include which of the following steps?
a) Blank press
b) Neck formation
c) Final shape blown
d) Plunging
Answer: b
Clarification: Wide mouth “press and blow” process for glass container manufacture takes place in the following steps-
i. Gob dropped into blank mold
ii. Plunger presses blank shape
iii. Blank pressed Blank transferred to blow mold
iv. Final shape blown
v. Finished jar– give bullet points.

12. Impact strength of lightweight bottles is more than regular bottles.
a) True
b) False
Answer: a
Clarification: The given statement is true. The impact strength of lightweight bottles is more than regular bottles. It is because, lightweight glass bottles have a more homogenous thickness distribution. It also has a superior vertical load strength and better impact strength, especially in the heel.

13. In narrow neck press and blow (NNP&B) process, the plunger and gob together have the same volume as the blank mold cavity.
a) True
b) False
Answer: a
Clarification: The given statement is true. In narrow neck press and blow process, the plunger and gob together have the same volume as the blank mold cavity. In this, the gob is delivered into the blank mold. It is then pressed by a metal plunger to give it a shape.

14. What enables the glassmaker to decide exactly how the glass is distributed in the parison?
a) Density of gob and plunger
b) Mass of gob and plunger
c) Volume of gob and plunger
d) Temperature of gob and plunger
Answer: c
Clarification: The volume of gob and plunger enables the glassmaker to decide exactly how the glass is distributed in the parison and, hence, to be able to more accurately control the uniformity of glass distribution in the finished container. Indeed, weight savings of up to 30% can be made. The second stage is similar to the B&B process.

15. What accounts for greater impact strength of lightweight bottles?
a) Uniform distribution of weight
b) Uniform distribution of pressure
c) Uniform distribution of volume
d) Uniform distribution of density
Answer: a
Clarification: The uniform distribution of weight accounts for greater impact strength of lightweight bottles. The parison is blown to a finished container having a more uniform wall thickness and, as a result, higher strength.

MCQs on all areas of Food Packaging Technology,