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7 Cards in this Set
- Front
- Back
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Explain how polymers are made. |
Multiple monomers (double bond) are joined in a reaction (polymerisation) to create polymers (single bonds). |
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Give an example of a polymer that has different properties in different conditions. |
High density polyethene (HDPE): Strong, softens at 120°C. Low density polyethene (LDPE): Softens at 85°C, more flexible and weaker than HDPE. |
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Explain why Polyvinyl chloride is fit for it's purpose. |
Used for wall coverings, electric cables and packaging. Is stiff and hard wearing so is reliable and strong enough for the job. |
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Define thermosetting and give an example. |
Do not soften when heated and cannot be reshaped. Example: Vulcanised rubber. |
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Define thermosoftening and give an example. |
Can be reheated while hot. Example: Polyethene. |
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Explain cross linking in thermosetting. |
The links created between polymer chains create stronger bonds and prevent movement between the chains. If the chains can't be broken the molecule can't be melted. |
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Explain how intermolecular forces between the polymer molecules in thermosoftening affects their properties. |
Polymers melt when their intermolecular forces are over come. Weak intermolecular forces pull the polymer molecules towards each other. |
