Biomedical Engineering Reference
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result in premature composite failure because the reinforcing cellulose
simply pulled out of the matrix without contributing to the strength or
stiffness of the material. It was observed that, there is a sudden increase of
tensile strength at 50:50 compositions, which indicates that good compat-
ibility of the matrix and the fiber at that composition.
9.3.1.4
OXYGEN PERMEABILITY TEST
Oxygen permeability depends on chain flexibility, phase and physical state
of the polymer and packing of its molecules. The most permeable poly-
mers are amorphous, with very flexible chains, in a high elastic state. The
gas permeability of crystalline polymer is much lower. The high molecular
weight glassy polymers with rigid chains have very low gas permeability.
With decreasing chain flexibility gas permeability decreases. Closer pack-
ing of the molecules supports permeability resistance.
TABLE 9.4
OTR Values of Ten (Modified Cellulose/(PLA or PVA or PP)) Film
Composites
Modified cel-
lulose+ PLA
OTR values;
Cc/sqm/day/atm
Graph for Oxygen permeation versus Parts
per hundred Modified Cellulose in a (modi-
fied cellulose/(PLA or PVA or PP) blend
10+90
1876
20+80
1704
30+70
1543
40+60
1443
50+50
1342
60+40
1231
70+30
1123
80+20
1086
90+10
989
95+05
843
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