chapter 2 matrix material
advantages of poly mer
low density
heat insulating
electrically insulating
cost efficient
easy automated process
recycable
longtime stable
energy recovery
disadvantages of polymers
low strength
mostly based on fossile oil
low heat stability
for recycling need seperation
low stiffness
risks by additives
emission by additive
application
aqriculture: foils foam
constructiion: isolation ,pipes
medical: implant
aerospace: structural material
entertaiment: CD films
clectronics: chip print
additive to polymers
antiaging agent
antioxidant
emulgators
colorant
solvant
hardener
softner
flame retardant
difference polymer and plastic
polymers are large molecules composed of repeating structural units called monomers.
plastics are type of polymers, plastics are sythetic polymers
structure of polymers
•significantly different from metal(no crystal lattic structure)
•material cohesion by long molecular chains
•these are intertwine
•depending the type of polymer it is pissible to have semi crystalline area
type of polymers
@organic base
@manufacture by synthesis
organic: composed of hydrocarbons(methan,ethan,ethylen,acetylen,polyethylen)
synthetic:
**new substant is made from different reactant
**base polymers is always Ethan
**the structure of molecules is called constitution
bond type
metallic bond
ionic bond
covalent bond
intermolecular forces
influence of matrix on polymers
**crucial for thermal,mechanical behavior and physical and chemical properties
** fille lead to manipulation. of the property profile
material type in polymers
mostly thermosetting resins and thermoplastic in use
**thermoplastics are increasingly gaining importance.
task of matrix in coposite material
**keeping the part in shape
**compensating overloads
**protecting the fibers from **enviromental influence
**keeping the finers stick together
**initiating external forces to the fibers and transmitting from fiber to fiber
criteria for selection material
material. process
process:
curing behavior
processing time
viscosity
material:
resistance,reaction to fire, fracture,electrical & mechanical properties,temprature limit
polyaddition
connection of the chains produce via c-c bonda
one reaction step triggers next
no formation of eliminate product
Radical polymerization
same or similar monomers as base material
with double bond
start chain reaction-chain growth-chain termination
polycondensation
same or different monomers
individual reaction steps occur indepently from eachother
linking of monomers connected with elimination of reaction product
chemical and physical shrinkage
chemical
reduction of the volume of material without physical impact=increase density
chemocal change of structure,anisotropic,volume contraction,internal stress,
physical shrimkage
thermal expansion or contraction
volume stay constant
plastic (polymers)
thermoplastics
elastomers
thermosets
thermoplastin group
{amorphous
semi-crystalline}
[amorphous]. multiphase , single phase
[semi crystalline]. multi phase
chemically not cross-linked
elastomers group
saturated
unsaturated
widely meshed
thermosets group
high pressure
low pressure
closely meshed
cross-linking
**strong covalent bonds between the molecules
**elastomers or widely cross linked
**thermosets are closely cross linked
in thermosets distortion are hardly possible
in elastomer good deformable by net distortion,return to initial position