CLO2.4 Determine the structure and morphology of the polymer /polymer matrix com
ID: 1867628 • Letter: C
Question
CLO2.4 Determine the structure and morphology of the polymer /polymer matrix composites and site the effect of additives on polymer properties Question a) Shortly explain the difference between the type of the additives (fibers, fillers and coupling agents) used in polymer matrix composites b) Briefly explain the effect of fiber length, content (% volume) and orientation on mechanical properties of polymer matrix composites based on the given graphs below. -30"? composite, V0.26 6 400 23"? ? 150 . 50 50 00,05 0,10 0,5 020 02 25 75 100 125Explanation / Answer
Additive / Filler /
Reinforcement
Common materials
Effects on polymer properties
Reinforcing fibers
Baron, carbon, fibrous minerals, glass, Kevlar
Increases tensile strength.
Increases flexural modulus.
Increases heat-deflection temperature (HDT).
Resists shrinkage and warpage.
Conductive fillers
Aluminum powders, carbon fiber, graphite
Improves electrical and thermal conductivity.
Coupling agents
Silanes, titanates
Improves interface bonding between polymer matrix and the fibers.
Flame retardants
Chlorine, bromine, phosphorous, metallic salts
Reduces the occurrence and spread of combustion.
Extender fillers
Calcium carbonate, silica, clay
Reduces material cost.
Plasticizers
Monomeric liquids, low-molecular-weight materials
Improves melt flow properties.
Enhances flexibility.
Colorants (pigments and dyes)
Metal oxides, chromates, carbon blacks
Provides colorfastness.
Protects from thermal and UV degradation (with carbon blacks).
Blowing agents
Gas, azo compounds, hydrazine derivatives
Generates a cellular form to obtain a low-density material.
The effects of the fiber length on mechanical properties of high dosage short fiber carbon composites
1. High dosage composites exhibits very low efficiency parameters both in stiffness and particularly in tensile strength. Stiffness increases in order of 25% when fiber length increases from 2mm to 4mm, but afterwards tends to decrease for 6mm fiber length composites. The same tendency was observed for the tensile strength.
2.- For high fiber dosage composites poor fiber dispersion and disorder was achieved, particularly for 6mm fiber length.It is reported that even small amounts of fibers drastically increased composite strength. However, for high fiber dosage the dispersion and interface adhesion is quite poor reaching to lower stiffness and strength efficiency. The effects of fiber length on mechanical properties of low content of short fiber reinforced composites is usually associated with a gain with the increasing of fiber length,
3. If the fiber is orientated in the direction of loading the stiffness of the polymer composites is increases while if the fiber is orientated in transverse direction of loading its stiffness decreases.
Additive / Filler /
Reinforcement
Common materials
Effects on polymer properties
Reinforcing fibers
Baron, carbon, fibrous minerals, glass, Kevlar
Increases tensile strength.
Increases flexural modulus.
Increases heat-deflection temperature (HDT).
Resists shrinkage and warpage.
Conductive fillers
Aluminum powders, carbon fiber, graphite
Improves electrical and thermal conductivity.
Coupling agents
Silanes, titanates
Improves interface bonding between polymer matrix and the fibers.
Flame retardants
Chlorine, bromine, phosphorous, metallic salts
Reduces the occurrence and spread of combustion.
Extender fillers
Calcium carbonate, silica, clay
Reduces material cost.
Plasticizers
Monomeric liquids, low-molecular-weight materials
Improves melt flow properties.
Enhances flexibility.
Colorants (pigments and dyes)
Metal oxides, chromates, carbon blacks
Provides colorfastness.
Protects from thermal and UV degradation (with carbon blacks).
Blowing agents
Gas, azo compounds, hydrazine derivatives
Generates a cellular form to obtain a low-density material.