Additives and Compounding Questions and Answers

Answer: A

The match is P-3, Q-1, R-4, S-2.

• Tricresyl phosphate is a plasticiser, used especially in PVC, where it also adds flame retardance.
• Calcium carbonate is the most common inexpensive filler.
• Azodicarbonamide decomposes on heating to release nitrogen and other gases, so it is a chemical blowing agent for foams.
• o-Hydroxybenzophenones absorb ultraviolet light and release it harmlessly as heat, so they are UV stabilisers.

The other options mismatch these well-known roles, for example making azodicarbonamide a plasticiser or calcium carbonate a blowing agent.

Answer: B

The match is P-4; Q-3; R-2; S-1.

• Aluminium trihydrate is a flame retardant: on heating it decomposes endothermically and releases water vapour, cooling the polymer and diluting flammable gases.
• Phenyl salicylate (salol) absorbs ultraviolet light and is used as a UV absorber.
• Azodicarbonamide decomposes on heating to nitrogen and other gases, so it is a chemical blowing agent for foams.
• 4-Methyl-2,6-di-t-butyl phenol is butylated hydroxytoluene (BHT), a hindered phenol antioxidant.

The other options assign BHT or azodicarbonamide to roles they do not play.

Answer: D

The match is P-4; Q-1; R-2; S-3.

• p-Phenylenediamine derivatives are the standard antiozonants for rubber.
• Trixylyl phosphate is a phosphate ester plasticiser that also acts as a flame retardant.
• Polybutadiene rubber dispersed in a brittle matrix such as polystyrene is an impact modifier.
• Talc particles provide sites for crystallization in polypropylene: a nucleating agent.

The other options swap these roles, for example calling talc a flame retardant or polybutadiene a nucleating agent.

Answer: C

The most suitable compatibilizer is Polymethyl methacrylate (PMMA).

A compatibilizer must be miscible with, or strongly interact with, both phases. PMMA is one of the few polymers that is miscible with PVDF, through interactions between its ester carbonyl groups and the slightly acidic \(CH_{2}\) hydrogens of PVDF. PMMA is also miscible with the styrene-acrylonitrile (SAN) matrix of ABS over a useful composition range. Placed at the interface, it bridges the two phases and improves adhesion.

SAN mixes with the ABS matrix but not with PVDF. Polybutadiene is the rubber phase of ABS and is incompatible with PVDF. Nylon 6 interacts with neither in a way that would bridge them.

Answer: C

A suitable compatibilizer is poly(ethylene-block-propylene).

Polyethylene and polypropylene are immiscible, so their blend separates into coarse phases with weak interfaces. A block copolymer with one block like each component locates at the interface, each block entangling with its own phase. This lowers the interfacial tension, refines the morphology and improves adhesion between phases, which is what a physical compatibilizer does.

Polycaprolactam (nylon 6), poly(lactic acid) and polycarbonate share no segments with either polyolefin and would not bridge the interface.

Answer: B

The correct matching is P-III ; Q-IV ; R-II ; S-I.

• Azodicarbonamide decomposes on heating to release nitrogen and other gases, so it is a chemical blowing agent for foams (III).
• 2-(2-Hydroxyphenyl)benzotriazoles absorb UV light and dissipate it as heat, protecting the polymer: a UV absorber (IV).
• (3-Aminopropyl)triethoxysilane bonds to glass or mineral surfaces through its silanol groups and to the polymer through its amine: a coupling agent (II).
• Ammonium polyphosphate is an intumescent flame retardant (I).

Option A swaps the blowing agent and the UV absorber, and the others misplace the silane or the phosphate.