250+ TOP MCQs on Blending and Vapor Deposition in Thermoplastics and Answers

Food Packaging Technology Interview Questions and Answers for freshers on “Blending and Vapor Deposition in Thermoplastics”.

1. Smart blending works on the principle of ________
a) Chaotic addition
b) Chaotic advection
c) Chaotic adversion
d) Chaotic abstraction
Answer: b
Clarification: Smart blending works on the principle of chaotic advection. It refers to the chaotic (non-periodic) motion of a particle in a fluid that can occur even where the flow field is simple and periodic, which causes successive shear deformations and reorientations.

2. A __________ is a highly concentrated blend of an additive and a carrier resin.
a) Masterpolymer
b) Mastermixture
c) Masterbatch
d) Masterblend
Answer: c
Clarification: A masterbatch is a highly concentrated blend of an additive and a carrier resin. A masterbatch is a highly concentrated blend of an additive with a a carrier resin that should be compatible and miscible in the resin into which it is being blended. Film manufacturers commonly blend a masterbatch into the resin at the extruder feed hopper when making film or sheet.

3. Which of the following metal is not used in vacuum metallization?
a) Aluminium
b) Nickel
c) Chromium
d) Sodium
Answer: d
Clarification: Sodium is not used in metallization. Vacuum metallization is a method in physical vapour deposition process and produces coatings by thermal evaporation of metals in a vacuum. Physical method includes vaporization of the metal, which is later deposited on the surface by condensation.

4. Which of the following is not a heating source in metallization?
a) Convection heating
b) Resistance heating
c) Induction heating
d) Electron beam heating
Answer: a
Clarification: Convection heating is not a heating source in metallization. In resistance heating, aluminium wire is fed onto a block of metal that is heated by holding it in a carbon crucible or boat across which a high current is arched. A pool of melted metal forms in the boat cavity and evaporates into a cloud above the source. In induction heating, heating is done by passing a high current through heating coils, causing an induced magnetic field inside the coils. In electron beam heating, the source is heated by electron beam.

5. Energy of an electron is upto ______ in electron beam heating.
a) 15eV
b) 15keV
c) 30eV
d) 30keV
Answer: b
Clarification: Energy of an electron is upto 15keV in electron beam heating. Electron beam heating allows tight control of the evaporation rate and although more expensive, it is notably simpler and much more versatile as it can be used to evaporate many different materials. It must be ensured that no secondary electrons impinge on the polymeric web.

6. Adding more metal during the metallization process increases barrier properties.
a) True
b) False
Answer: a
Clarification: The given statement is true. Metallization process has a strong and complex effect on the development of adhesive and barrier properties of metallized films. Thicker films leads to adhesion problems and even flaking, if the metallized layer becomes too thick. The thinner coatings tend to be full of pinholes and may even be transmitted lights to some degree.

7. __________ is a PVD technique in which the bulk material is released into the vacuum by bombardment from an ion source.
a) Splattering
b) Sputtering
c) Splashing
d) Spreading
Answer: b
Clarification: Sputtering is a PVD technique in which the bulk material is released into the vacuum by bombardment from an ion source. The material coalesces onto the substrate surface, thus forming a thin film.

8. _____________ involves depositing successive layers of different substances to produce layered, crystalline films.
a) Atomic layer chemical vapor deposition
b) Combustion chemical vapor deposition
c) Low pressure chemical vapor deposition
d) Plasma enhanced chemical vapor deposition
Answer: a
Clarification: Atomic layer chemical vapor deposition (ALCVD) involves depositing successive layers of different substances to produce layered, crystalline films. In short, ALCVD is a method in chemical vapor deposition in which deposition occurs through chemisorption of pulsed chemical reactant.

9. In Plasma Enhanced Chemical Vapor Deposition, deposition occurs at a _______ temperature.
a) Higher
b) Constant
c) Increasing
d) Lower
Answer: d
Clarification: In Plasma Enhanced Chemical Vapor Deposition, deposition occurs at a low temperature. The use of plasma helps to deposit thin films from a gaseous state to a solid state on the substrate; hence it enhances chemical reaction rates. The plasma is created by alternating or direct current discharge between two electrodes. The space between electrodes is filled with reacting gases which contains reactive ions and radicals.

10. Which film is used for improving barrier properties of PET bottles?
a) PVC
b) PED
c) DLC
d) GLC
Answer: c
Clarification: DLC (Diamond like Carbon) film is used for improving barrier properties of PET bottles. There is deposition of a very thin DLC film on the inner surface of PET bottle by PECVD mechanism. DLC film provides gas barrier properties, flavour barrier, UV barrier, chemical inertness, recyclability, etc.

11. Which of the following CVD technique is a flame based technique?
a) CCVD
b) PECVD
c) LPCVD
d) ALCVD
Answer: a
Clarification: CCVD (Combustion Chemical Vapor Deposition) is a flame based technique. In this, the metal-bearing chemicals are first dissolved in a solution that typically is a combustible fuel. The solution is then atomized to form microscopic droplets that are carried by an O₂ stream to the flame where they are combusted. The heat from the flame provides the energy required to vaporize the droplets and for the precursors to react and deposit on the substrate.