What are plastics developped from?
petroleum and fossil fuels
what are the building blocks of plastics
monomers which form polymers
name the two types of plastics
- thermoplastics
- thermosetting
what is a thermoplastic?
a plastic that becomes soft when heated to be molded and that hardens (3/4 plastics in the category)
what is thermosetting
a plastic the remains permanently shaped, even when heated. Made by adding monomers to a mold, once hardened cannot be chnaged. (melamine and polyesters) can’t be recycled
list the 2 signs of degradation for ceramics
- cracking
- change in colour
list some types of degredation and how to combat them
- Penetration of liquid—-add water proof coating
- Oxidation —- add antioxidants (carbon black)
- Ultraviolet rays —- add dark pigments to absorb UV rays
how do ceramics form
when certain inorganic compounds (metal & non-metal) is extremely heaed, the water in it evaporates and the bonds between the compounds are created to form ceramics
list some examples of ceramics
bricks, clay, pots, glass
list some forms of degradation for ceramics and how to fix them
- exporsure to H2SO4 or Ca(OH)2——-avoid exposure
- Thermal shock—– avoid exposure to extreme temperature fluctuations
what are composites composed of
matrix and reinforcement
describe a plastic matrix and its properties
thermoseting plastics are most often used as matrices and are often referred to as resins.
* Durable
* Lightness
* Resilience
* Low cost
describe a metallic matrix and its properties
made of metals or alloys
* ductile
* conductive
* stiff
describe a ceramic matrix and its properties
made of ceramics, often glass
* durable
* heat resistant
describe fiberglass reinforcement and its properties
made of fiberglass (ceramic) in the form of fibers
* stiffness
* corrosion resistance
describe aramind fibers reinforcement and its properties
known as kevlar and one of the few plastics used as reinforcement
* low density
* resilience
describe carbon fibers reinforcement and its properties
obtained by carbonizing polymers
* stiffness
* low density
* electrical conductivity
list some forms of degradation for composites and how to fix them
- deformation or breaking of the matrix or reinforcements—–avoid misuse
- a lost of adherence between the matrix and reinforcement —- adhere well
what are alloys
a mix of metal & metal or metal & nonmetal
how can metals and alloys degrade
they can oxidize or chemically alter if exposed to the elements (acid rain, rain, salt, oxygen)
how do you protect metals and alloys?
coating with other metals OR
coating with paint, enamel, grease, resin and antioxidants can be applied if the alloy contains metal to avoid rust.
describe modified wood
it’s altered wood as it is mixed with other substances like glue. this is less costly and often harder than wood
describe the degradation of wood and how to fix it
fungi, microorganisms and insects can infest and feed off wood——coat it with varnish, high heat treatment which removes water
