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,