Elastomers Flashcards
what are elastomers?
highly elastic polymers that return to their original shape after being stretched
elastomers structure?
- thermosets
- cross- linked
- irregularly coiled
- molecules straighten out in the direction of pull
what are thermoplastic elastomers? [TPEs]
polymer blends that can be heated and moulded without forming cross links
give 2 named examples of a TPE
Elastron and Riteflex
what are 2 properties of TPEs?
- similar properties to cross linked elastomers like rubber
- lightweight, chemical resistant, cheap
- faster processing times than cross linked elastomers
what is stretching?
when the material is stretched and returns to its original shape
what is stretching allow in elastomers? [2] and uses
- expand and contract due to temperature changes
- inflated or pressurised
- can be worn to compress and injury or to keep water out
what do elastomers flexibility and impact absorption allow?
enhancement of a products ergonomics
what can elastomers be used for and the process required to make them?
- over moulding makes spongy grips or textures
- toothbrushes
- sleeves and handles
- pens
- sports bottles
what is an elastomers texture and what does it depend on?
self- finishing and depends on the way it is processed
how are elastomers textured?
- texture pressed or rolled into them
- textured moulds
- natural rubber is smooth
what are the textures of:
- natural/synthetic rubber
- neoprene
- silicone
- smooth
- spongy [open celled]
- silky
what is the 1st elastomer [Indian rubber]and how it is obtained?
natural tree rubber got by tapping milky sap [called latex] of a rubber tree
what are the uses of Indian rubber?
- flexible tubing
- tires
- waterproof clothing
- rubber balls
- balloons
what is the process of curing rubber?
vulcanisation
what is the process of vulcanisation and its product?
- curing agent added to the latex
- heated and pressurised
- makes a tough rubber that can easily retain its shape
what is natural rubber and its properties?
Indian rubber [from trees]
- mouldable
- self finishing
- good tensile strength
- elastic
- hard
- good insulator
uses of natural rubber? [cars]
- gaskets
- hoses
- belts
why can natural rubber be used for baby bottles?
non-toxic so safe for use in products that contact skin
what other uses does natural rubber have?
- washing up gloves
- swimming hats
- socks
- latex free gloves
what is BR and its properties?
Polybutadiene or butadiene rubber [synthetic rubber]
- strong
- resistant to wear
- thermal resistant against friction
- like natural rubber
Uses of polybutadiene rubber
- racing car tires
- hiking shoes
what is a difference and similarity between open and closed cell neoprene?
- open cell is more spongy and less dense
- closed cell is dense, smooth and heat resistant
- both resistant to degradation
what is neoprene and its uses?
Polychloroprene rubber [PC rubber]
- hoses
- gaskets
- door seals
what textiles use neoprene?
wetsuits
laptop cases
sports braces
pencil cases
what properties make neoprene good for textiles?
- stretchy
- breathable
- waterproof
- cut/stitched or glued
what is silicone rubber and its properties?
stable and non-reactive material
- extreme temperature resistant
- self lubricating
- smooth
- NOT abrasion resistant
what are the uses or silicone rubber?
- watch straps
- ice trays
- oven gloves
- bracelets
- hairbands
name 5 uses of silicone in industry
- seals/ sealants
- mould making
- lubricant
- medical implants
- prosthetics
