20. Polymerisation
A section of Chemistry, 9701
Listing 10 of 116 questions
In today’s world we make use of a wide range of different polymers. These polymers are often substitutes for traditional materials, but may have more useful properties. Complete the table identifying one traditional material that has been replaced by each polymer. traditional material modern polymer and its use PVC in packaging Terylene in fabrics polycarbonate bottle Throwing away articles made from polymers after use is a major environmental concern for two main reasons. Identify each of these reasons and suggest a strategy that has been adopted to try to overcome each of these. reasons : strategy 1 : strategy 2 : One suggestion for the disposal of polymers is to use them as a fuel to provide energy for small-scale power stations or district heating schemes. Identify one polymer which would be unsuitable for this use, explaining the reason behind this. polymer reason Polymers can be either thermoplastic or thermosetting. Name a thermoplastic polymer. State which type of polymerisation produces thermoplastic polymers, explaining your answer in terms of the structure of the polymer.
9701_w11_qp_41
THEORY
2011
Paper 4, Variant 1
View
In today’s world we make use of a wide range of different polymers. These polymers are often substitutes for traditional materials, but may have more useful properties. Complete the table identifying one traditional material that has been replaced by each polymer. traditional material modern polymer and its use PVC in packaging Terylene in fabrics polycarbonate bottle Throwing away articles made from polymers after use is a major environmental concern for two main reasons. Identify each of these reasons and suggest a strategy that has been adopted to try to overcome each of these. reasons : strategy 1 : strategy 2 : One suggestion for the disposal of polymers is to use them as a fuel to provide energy for small-scale power stations or district heating schemes. Identify one polymer which would be unsuitable for this use, explaining the reason behind this. polymer reason Polymers can be either thermoplastic or thermosetting. Name a thermoplastic polymer. State which type of polymerisation produces thermoplastic polymers, explaining your answer in terms of the structure of the polymer.
9701_w11_qp_42
THEORY
2011
Paper 4, Variant 2
View
The increasing awareness of the diminishing supply of crude oil has resulted in a number of initiatives to replace oil-based polymers with those derived from natural products. One such polymer, ‘polylactide’ or PLA, is produced from corn starch and has a range of applications. The raw material for the polymer, lactic acid (2-hydroxypropanoic acid), is formed by the fermentation of corn starch using enzymes from bacteria. Calcium hydroxide is added to the fermentation tanks to prevent the production of lactic acid from slowing down. Why might high acidity reduce the effectiveness of the enzymes? The structure of lactic acid is shown. H C CO2H CH3 HO What type of reaction takes place in this polymerisation? Lactic acid exists in two stereoisomeric forms. Draw the other form in the box. One of the reasons PLA has attracted so much attention is that it is biodegradeable. This does, however, restrict some potential uses. The simple polymer has a melting point of around 175 °C, but softens between 60-80 °C. However, its thermoplastic properties enable it to have a range of uses in fi bres and in food packaging. Explain why PLA would not be a suitable packaging material for foods pickled in vinegar. PLA containers are not used for hot drinks. Suggest why. Lactic acid can also be co-polymerised with glycolic acid. HO C H H C O OH glycolic acid Draw a section of the co-polymer showing one repeat unit. Suggest what typeof bonding will occur between chains of this co-polymer, indicating the groups involved. Suggest one property in which the co-polymer differs from PLA.
9701_w12_qp_41
THEORY
2012
Paper 4, Variant 1
View
The increasing awareness of the diminishing supply of crude oil has resulted in a number of initiatives to replace oil-based polymers with those derived from natural products. One such polymer, ‘polylactide’ or PLA, is produced from corn starch and has a range of applications. The raw material for the polymer, lactic acid (2-hydroxypropanoic acid), is formed by the fermentation of corn starch using enzymes from bacteria. Calcium hydroxide is added to the fermentation tanks to prevent the production of lactic acid from slowing down. Why might high acidity reduce the effectiveness of the enzymes? The structure of lactic acid is shown. H C CO2H CH3 HO What type of reaction takes place in this polymerisation? Lactic acid exists in two stereoisomeric forms. Draw the other form in the box. One of the reasons PLA has attracted so much attention is that it is biodegradeable. This does, however, restrict some potential uses. The simple polymer has a melting point of around 175 °C, but softens between 60-80 °C. However, its thermoplastic properties enable it to have a range of uses in fi bres and in food packaging. Explain why PLA would not be a suitable packaging material for foods pickled in vinegar. PLA containers are not used for hot drinks. Suggest why. Lactic acid can also be co-polymerised with glycolic acid. HO C H H C O OH glycolic acid Draw a section of the co-polymer showing one repeat unit. Suggest what typeof bonding will occur between chains of this co-polymer, indicating the groups involved. Suggest one property in which the co-polymer differs from PLA.
9701_w12_qp_42
THEORY
2012
Paper 4, Variant 2
View
Questions Discovered
116