1. What is the unit of coefficient of Solubility coefficient?
a) m2s
b) m2/s
c) m/s
d) ms
Discussion
Explanation: The unit of coefficient of Solubility coefficient is m2/s. Solubility coefficient is a measure of how much permeate solubilises through the plastic polymer. It depends on degree of interaction between polar water molecule and polymer molecular structure.
2. What is the unit of coefficient of Permeability?
a) s/m2
b) m2/s
c) m/s
d) m2
Discussion
Explanation: The unit of coefficient of Permeability is m2. Permeability can be calculate by the formula- P=Qk/(AtΔP), where, P:Permeability, Q:Quantity of permeant, k:thickness, A:area, t:time, ΔP:pressure drop across polymer.
3. If a plastic film has high OTR, it will have a high WVTR too.
a) True
b) False
Discussion
Explanation: The given statement is false. There are many plastics which act as a good water vapour barrier and a poor gas barrier. It is because of different Water Vapour Transmission and Oxygen Transmission rates. For example, EVOH has low Oxygen Transmission Rate but higher Water Vapour Transmission Rate.
4. Permeability can also be calculated by the formula _____________
a) P=Qk/(AtΔP)
b) P=Qt/(AkΔP)
c) P=Q/(AktΔP)
d) P=QA/(ktΔP)
Discussion
Explanation: Permeability can also be calculated by the formula- P=Qk/(AtΔP). Where, P:Permeability, Q:Quantity of permeant, k:thickness, A:area, t:time, ΔP: pressure drop across polymer. Permeability is directly proportional to Quantity of permeant and thickness and inversely proportional to area, time and pressure difference.
5. The uptake of food components such as aroma and flavour by plastic films is known as ________
a) Scavenging
b) Broiling
c) Scalding
d) Scaling
Discussion
Explanation: The uptake of food components such as aroma and flavour by plastic films is known as Scaling. Such plastics have a greater permeability and hence are not suitable for primary packing. Such packaging materials are either used for tertiary or pellet packing.
6. Which of the following is the best Oxygen barrier?
a) EVOH
b) PS
c) PE
d) PP
Discussion
Explanation: Amongst the following, EVOH is the best Oxygen barrier as it has low Oxygen transmission rate. Plastic films with low oxygen transmission rate are good barriers and plastic films with higher oxygen transmission rates are poor barriers.
7. Permeability can be related to which law of Food Engineering?
a) Fourier Law
b) Kohlrausch’s Law
c) Fick’s Law
d) Newton’s Law
Discussion
Explanation: Permeability can be related to Fick’s law of diffusivity. It relates the diffusion flux (J) to the steepness of concentration gradient, where D is diffusion coefficient, C is concentration and x is the distance. It is given by the formula: J = -δC/δx.
8. Which of the following is not a type of calender?
a) I type
b) L type
c) Z type
d) M type
Discussion
Explanation: M type is not a type of calender. In I type of roller setup, the rollers are placed horizontally. In L type arrangement of roller setup, is I type setup mirrored vertically. In Z type arrangement of rollers, each pair of rollers is placed at right angles to the next pair in chain.
9. Calendering and extrusion are similar processes.
a) True
b) False
Discussion
Explanation: This is a false statement. Calendering and extrusion are different processes. Extrusion is a process of passing the molten plastic through a shaping device, to give it any form. Whereas, calendering is a complementary process to film and sheet extrusion, which involves the formation of continuous sheets of controlled thickness by passing plastic materials through rollers.
10. As defined by ASTM, the thickness of a plastic film (after single extrusion) should be not more than ________
a) 0.25mm
b) 0.50mm
c) 0.01cm
d) 1mm
Discussion
Explanation: As defined by ASTM, the thickness of a plastic film (after single extrusion) should be not more than 0.25mm. ASTM, American Society for testing materials is an international standards organisation which functions to set standards for miscellaneous materials.