25 Fill the Blank Those which soften on heating and then harden again on cooling

Question

25 Fill the Blank Those which soften on heating and then harden again on cooling These are called.................... polymers because they keep their plastic properties bonds between the chains when the plastic is heated These polymer molecules consist of long chains which have only weak The bonds between the chains are so weak that they can be broken The chains can then move around to form a different shape The weak bonds reform when it is cooled and the thermoplastic material keeps its new shape thermoplastic 26 Fill the Blank Those which never soften once thev have been moulded shape, that shape cannot be altered chemical bonds between them when the plastic is heated thermosetting These are called..................... polymers because once set into a These polymer molecules consist of long chains which have many strong The bonds between the chains are so strong that they cannot be broken This means that the thermosetting material always keeps its shape 27. How Do you call these chemical names (abbreviation) Polyvinyl chloride...(PVC): electrical cables cover, credit cards, car instrument panels Polystyrene: disposable spoons, forks, StyrofoamM plexiglass Polyamide (nylon): textiles and fabrics, gears, bushing and washers, bearings PET..........(polyethylene terephthalate): bottles for acidic foods like juices, food trays TexTM (raincoats), dental floss

Explanation / Answer

25)

Thermoplastics - they retain their properties when they are cooled after heating. Due to this property recycling is easy for these plastics.

26)

Thermosets- they do not retain their original property once they are formed and shaped. Due to this property they are very difficult to recycle.

27)

Polyvinyl chloride (PVC) - chemical formula- CH2=CHCL

Polystyrene- chemical formula - (C8H8)n , Poly(1-phenylethene)

Acrylics- PMMA- chemical formula- (C5O2H8)n

POLYAMIDE- chemical formula- -CO-NH- repeating amide.

PET- (C10H8O4)n

IUPAC name- Poly(ethyl benzene-1,4-dicarboxylate)

PTFE- chemical formula- (C2F4)n

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