Category: Food Packaging Technology Objective Questions

Food Packaging Technology Multiple Choice Questions & Answers (MCQs) on “Thermoforming”.

1. In thermoforming, plastic sheets are heated to ________
a) Boiling point
b) Tg point
c) Sag point
d) Melting point
Answer: c
Clarification: In thermoforming, plastic sheets are heated to Sag point. It is the temperature at which the plastic softens and extends under its own weight, i.e., when the plastic begins to sag.

2. From which of the following processes, canopies for racing vehicles are made?
a) Drape forming
b) Mechanical forming
c) Pressure forming
d) Free blowing
Answer: a
Clarification: Canopies for racing vehicles are made from drape forming. Drape forming is the process by which the plastic sheet is heated, such that it can be bent and shaped into any form without using a vacuum.

3. SPPF in thermoforming stands for ____________
a) Soluble peer pressure forming
b) Soluble phase pressure forming
c) Solid peer pressure forming
d) Solid phase pressure forming
Answer: d
Clarification: SPPF in thermoforming stands for solid phase pressure forming. The SPPF process is primarily used to thermoform PP, a crystalline polymer that is difficult to thermoform uniformly in melt phase machines due to the sharp decrease in melt strength (viscosity) at its melting point.

4. APET is stable till 230°C.
a) True
b) False
Answer: b
Clarification: The given statement is false. CPET (Crystalline PET) is stable till 230°C. Whereas, APET (Amorphous PET) softens over 63°C. The CPET process is based on conventional reheat thermoforming where an extruded PET sheet containing nucleating agents to speed up and maximize crystallization is reheated to around 170°C where it softens. After this, it is transferred in a hot mold and held so the crystallinity develops. Then it is transferred to a second mould for cooling.

5. In drape forming technique _______ is used for forming.
a) Vacuum
b) High pressure
c) High Temperature
d) Low pressure
Answer: a
Clarification: In drape forming technique vacuum is used for forming. In vacuum forming, vacuum is heated below the preheated plastic sheet to draw sheet into cold mold cavity. The steps include heating the plastic sheet, placing the softened sheet is placed over a concave activity. Vacuum draws the sheet into cold cavity. The final product is then cooled.

6. Which of the following material is not thermoformed?
a) HIPS & ABS
b) POM & Nylon
c) PVC
d) PMMA
Answer: b
Clarification: Among the given options, POM & Nylon is not thermoformed. Whereas, HIPS- High Impact Polystyrene, ABS- Acrylonitrile Butadiene Styrene, PVC- Polyvinyl Chloride and PMMA- Poly(methyl methacrylate) are thermoformed.

7. Bath tubs are made by __________ technique.
a) Free forming
b) Pressure thermoforming
c) Match die thermoforming
d) Drape forming
Answer: d
Clarification: Bath tubs are made by drape forming technique. Drape forming is the process by which the plastic sheet is heated, such that it can be bent and shaped into any form without using a vacuum.

8. Thermoforming can be generally classified as ________ and _______ thermoforming.
a) pressure, temperature
b) vacuum, pressure
c) Thick gauge, thin gauge
d) Temperature, vacuum
Answer: c
Clarification: Thermoforming can be generally classified as Thick gauge and thin gauge thermoforming. Thick gauge thermoforming is a term used for making heavy duty parts, such as- plastic pallets, refrigerator liners, etc. Whereas, thin-gauge thermoforming is the term used to describe the manufacturing of lighter and smaller things, such as disposable cups, containers, trays, lids, and other products for the food, medical, and general retail industries.

9. Which of the following is not a mold used in thermoforming?
a) Aluminium mold
b) Steel mold
c) Wooden mold
d) Plastic mold
Answer: b
Clarification: Steel mold is not used in thermoforming. The mould used in thermoforming should be such that the plastic polymer to be thermoformed isn’t affected by it. The mold used in thermoforming are- aluminium mold, plaster of paris mold, plastic mold and wooden mold.

10. Thermoforming is the same as blow moulding.
a) True
b) False
Answer: b
Clarification: The given statemet is false. Thermoforming and blow moulding are totally different processes. Thermoforming is the process in which an article is heated stretched and cooled to give it a desirable shape. Whereas, in blow moulding, the thermoplastic is heated and put into the desired container and then shaped by blowing air through it.

11. The CPET containers, made by thermoforming are stable upto what temperature?
a) 230°C
b) 150°C
c) 300°C
d) 500°C
Answer: a
Clarification: CPET (Crystallized Polyethylene terephthalate)containers, made by thermoforming are stable upto 230°C. The optimum amount of crystallinity is 28%–32%. CPET containers must be crystalline enough to be heat resistant but not so crystalline as to be too brittle for the application, for example, impact resistance at freezer temperatures.

12. The two dominant means of thermoforming sheet for food packaging containers are _____ & _____
a) Solid phase pressure forming, liquid phase pressure forming
b) Liquid phase process, vapour phase pressure forming
c) Melt phase process, liquid phase pressure forming
d) Melt phase process , solid phase pressure forming
Answer: d
Clarification: The two dominant means of thermoforming sheet for food packaging containers are melt phase process and solid phase pressure forming. The melt phase process is most applicable to monolayer structures that have relatively high melt strength at thermoforming temperatures, for example, HIPS, PVC and PC. The SPPF process is primarily used to thermoform PP, a crystalline polymer that is difficult to thermoform uniformly in melt phase machines due to the sharp decrease in melt strength (viscosity) at its melting point.

13. _______ are defined as plastics whose apparent density is decreased.
a) Cellular plastics
b) Polyplastics
c) Thermoplastics
d) Artificial plastics
Answer: a
Clarification: Cellular plastics are defined as plastics whose apparent density is decreased substantially by the presence of numerous cells dispersed throughout their mass. The terms foamed plastic, expanded plastic and plastic foam are also used for cellular plastics. They have desirable properties such as, high strength-to- weight ratio and good insulating and cushioning properties.

14. In general, temperatures for melt phase thermoformed Polypropylene is greater than SPPF Polypropylene.
a) True
b) False
Answer: a
Clarification: The above statement is true. In general, temperatures for melt phase thermoformed Polypropylene is greater than SPPF(Solid phase pressure formed) Polypropylene. It is melt phase thermoformed at 154°C–157°C and SPPF at 141°C–146°C, where it is still virtually a solid with high viscosity, requiring the application of strong forces.

Food Packaging Technology Multiple Choice Questions & Answers (MCQs) on “Surface Treatment of Glass”.

1. Temperature of hot-end treatment is glass is around ______
a) 300°C
b) 450°C
c) 250°C
d) 550°C
Answer: d
Clarification: In hot-end treatment (typically carried out while the glass container is at 550°C), vapor containing tin or titanium (generally in the form of a tetrachloride) is brought into contact with the outside of the container, forming a thin unimolecular film of metal oxide.

2. Why is hot-end treatment is done in glass?
a) To prevent surface damage
b) To ensure better adhesion and
c) To strenghthen the surface
d) To prevent surface damage, ensure better adhesion and strenghthen the surface
Answer: a
Clarification: Hot-end treatment is done in glass to prevent surface damage. This treatment is done while the container is still hot, strengthens the surface and improves the adhesion of the subsequent cold-end coating.

3. Temperature of cold-end treatment is glass is around ______
a) 200°C
b) 150°C
c) 100°C
d) 80°C
Answer: c
Clarification: Cold-end treatment (typically carried out while the glass container is at less than 100°C) is designed to protect the container surface and assist its flow through the filling line.

4. Cold-heat treatment is primarily done to increase the lubricity.
a) True
b) False
Answer: a
Clarification: The given statement is true. Typically, it involves spraying an organic material in an aqueous base containing either waxes, stearates, silicones, oleic acid or polyethylene onto the outside of the container to increase its lubricity by providing a surface with a low coefficient of friction. It is important to check the compatibility of the cold-end treatment with any adhesives used to attach labels.

5. The function of hot-end treatment and cold-heat treatment in glass is the same.
a) True
b) False
Answer: b
Clarification: The given statement is false. The function of hot-end treatment and cold-heat treatment in glass is the different. Hot-end treatment is done primarily to prevent surface damage like blurring, whereas, cold-heat treatment is done to increase the lubricity of the surface for better adesion.

6. What are shrink sleeves in glass?
a) Adhesives
b) Temperature control
c) Protective labels
d) Lubricants
Answer: c
Clarification: Shrink sleeves are protective sheets used on glass. Most shrink sleeves are made of oriented plastic films that shrink around a glass container when heat is applied. Two types of protective labels are used on glass bottles in the form of a body sleeve: one constructed from thin, foamed PS; the other is made from uniaxially oriented PVC or PS. PVC offers some thermal insulation. Whereas PS contains the glass fragments and prevents shattering of glass, if droppped.

7. Hot-end coatings are applied before the container enters the annealing oven.
a) True
b) False
Answer: a
Clarification: The given statement is true. Hot-end coatings are applied before the container enters the annealing oven (when the glass is still hot due to the previous forming process).

8. Cold-end coatings are applied before the container enters the annealing oven.
a) True
b) False
Answer: b
Clarification: The given statement is false. Cold-end coatings are applied after the container comes out of the annealing oven and cools. It is mainly applied to increase the lubricity and minimize the scratching of surfaces.

9. Which of the following is not a cold-end coating?
a) Waxes
b) Polyvinyl alcohol
c) Silicon
d) Nylon
Answer: d
Clarification: Nylon is not a cold-end coating. Cold-end coatings typically consist of lubricants such as waxes, polyethylene, polyvinyl alcohol, and silicone.

10. Which of the following is a hot-end coating?
a) Tin chloride
b) Sodium hydroxide
c) Lithium aluminium hydride
d) Boron
Answer: a
Clarification: Hot end coatings consist of tin chloride (which reacts to form tin oxide) or organo-tin. These compounds are applied in vapor form and leave a rough high-friction surface on the glass container, which provides a good adhesive surface for the cold-end coatings. They also supply hardness, fill in minor cracks, and compress the glass surface.

11. The term “birdswings” and “spikes” used in glass refers to _______
a) cold-treatment
b) heating oven
c) heat treatment
d) defects.
Answer: d
Clarification: Some 60 defects can occur in finished glass containers, ranging from critical defects such as “birdswings” and “spikes” (long, thin strands inside the container that would probably break off when the container was filled) to minor defects such as “wavy appearance” (an irregular surface on the inside).

Food Packaging Technology Questions and Answers for Experienced people on “Blow Molding in Thermoplastics”.

1. Molten tube of thermoplastic is called _______
a) Parison
b) Thermotube
c) Parrison
d) Tubling
Answer: a
Clarification: Molten tube of thermoplastic is called parison. It is a long plastic tube, with a hole, to let compressed air pass through it. Making parison is the first step of blow moulding. Parison is also known as Preform.

2. Small pharmaceutical bottles with accurate neck finish is formed by _______ process.
a) Calendering
b) Injection Blow Moulding
c) Extrusion Blow Moulding
d) Rotational Moulding
Answer: b
Clarification: Small pharmaceutical bottles with accurate neck finish are formed by Injection blow moulding process. In injection moulding process, the parison is formed in one mold and then, while still molten, is transferred to a second mold where blowing with compressed air forms the final shape. After cooling, the mold is opened and the bottle is ejected.

3. Which of the following is not a type of Blow moulding?
a) Injection stretch blow molding
b) Injection blow molding
c) Thermoforming
d) Extrusion blow molding
Answer: c
Clarification: Thermoforming is not a type of Blow moulding. There are three main types of blow molding- extrusion blow molding, injection blow molding, and injection stretch blow molding. Thermoforming is a different process in which thermoplastics are converted into desirable shape by heating and stretching.

4. Which of the plastics cannot be extrusion blown?
a) HDPE
b) PP
c) PVC
d) PET
Answer: d
Clarification: The common grades of PET(Polyethylene Terephthalate) cannot be extrusion blown. Extrusion blow moulding is widely used with the following resins: HDPE- High Density Polyethylene, PP- Polypropylene, PVC- Polyvinyl Chloride. The most common blow molding resin is HDPE used to produce containers ranging in size from 30 mL to 200L.

5. Two stage stretch blow moulding is also known as _________ method.
a) Extrusion
b) Reheat and blow method
c) Thermoforming
d) Injection
Answer: b
Clarification: Two stage stretch blow moulding is also known as reheat and blow method method. In this, the parisons are first injection molded in a completely separate stage and stored at ambient temperature until required. Then, they are are then reheated to between 90°C and 110°C and blown to their final shape.

6. The most widely used polymer in Stretch Blow Moulding is _______
a) PE
b) PVC
c) PP
d) PET
Answer: d
Clarification: The most widely used polymer in Stretch Blow Moulding is PET- Polyethylene Terephthalate. PET is used in the manufacture of carbonated beverages packing bottles.

7. EBM produces smoother finished parts which are scrap free, when compared to IBM.
a) True
b) False
Answer: b
Clarification: The above statement is false. The IBM produces smoother finished parts which are scrap free, when compared to EBM. In addition to that, the dimensions of the bottle (including the neck finish) show very little variation from bottle to bottle, and with some materials, improved strength and clarity are obtained due to the effect of a limited degree of biaxial orientation.

8. _________ improves strength and barrier properties of plastic.
a) Stretching
b) Blowing
c) Heating
d) Cooling
Answer: a
Clarification: Stretching improves strength and barrier properties of plastic. It happens because the orientation and arrangement of monomers changes, hence changing the strength and barrier properties.

9. Pressure used in IBM ranges from _______
a) 2,000 – 3,000 psi
b) 100 – 500 psi
c) 500 – 800 psi
d) 25 – 150 psi
Answer: a
Clarification: Pressure used in IBM ranges from 2,000 – 3,000 psi. Because of this, there is a development of high internal stresses in this process.

10. Pressure used in Blow moulding in general ranges from ________
a) 1000 – 2000 psi
b) 200 – 500 psi
c) 500 – 800 psi
d) 25 – 150 psi
Answer: d
Clarification: Pressure used in Blow moulding in general ranges from 25-150 psi. Blow moulding, in general is a low pressure process, to make hollow and seemless parts.

11. ________ is used to obtain bioriented products.
a) Extrusion blow molding
b) Stretch blow moulding
c) Injection blow molding
d) Thermoforming
Answer: b
Clarification: Stretch blow moulding is used to obtain bioriented products. In injection stretch blow moulding, the process begins with an injection moulded parison. The parison is pre-heated, stretched in the axial direction and blown into its final shape by a stretch blow moulding machine, which results in changing its orientation.

12. PTFE can be processed using conventional moulding machinery.
a) True
b) False
Answer: b
Clarification: The given statement is false. PTFE-Polytetrafluoroethylene can only be processed through compression moulding. In this process, the plastic is heated and simply moulded, where the plastic takes the shape of the mould.

13. The reheating temperature in reheat and blow method ranges from ________
a) 180° – 250°C
b) 90° – 110°C
c) 150° – 200°C
d) 200° – 250°C
Answer: b
Clarification: The reheating temperature in reheat and blow method ranges from 90° – 110°C. After reheating the plastics, they are blown into their final shape.

14. Cull is associated with _______
a) Rotational moulding
b) Injection moulding
c) Auxiliary ram type transfer moulding
d) Pot type transfer moulding
Answer: d
Clarification: Cull is associated with auxiliary ram type transfer moulding. Cull is the term to define the part which leaves the waste material in the moulding process. Auxiliary ram type transfer moulding is the method used to exert pressure on the material in the pot.

15. PS foams are produced by ________
a) injection moulding and extrusion moulding
b) extrusion moulding only
c) injection moulding only
d) stretch blow moulding only
Answer: a
Clarification: Polystyrene foams are produced by Injection moulding and extrusion moulding. With injection molded foam, machines similar to normal injection molding machines are used, except that steam is injected to heat the beads that contain a foaming agent. Extruded PS foam is produced by free expansion of hot PS, blowing agents and additives through the slit orifice of a high L/D ratio extruder to about 40 times the pre-extrusion volume.

Food Packaging Technology for Experienced people,