Biomedical Engineering Reference
In-Depth Information
(w/w) of compatibilizer. The strength was increased for
----in situ
grafted composites
with grafting content but the lower strength was observed in case of i-grafted GMA at
similar compositional level. The modified law of mixtures equation for discontinuous
short fiber composites is given below (Chen et al., 1998):
L
*
(1)
s
=
KV
s
1
− +−
c
(1
V
)
s
c
f
f
f
m
2
L
D
s
τ
(2)
f
L
=
c
2
i
where s is the tensile strength of the composite, which is the empirical fiber effi-
ciency parameter,
V
is the volume fraction of fiber,
is is the tensile strength of fiber,
is is the tensile strength of the matrix at the breaking strain of the fiber,
L
is the fiber
length,
L
is the critical fiber length,
D
is the diameter of the fiber, and
τ
is the inter-
facial shear strength. From equations (1) and (2), it is seemed that the s value rise up
with increasing of
τ
value which in turn depends on the improvement of interfacial
adhesion between the fiber and matrix, when K, L, and D are assumed constant in all
composite systems. The fiber fraction (
V
) was also constant in all composites com-
position. It indicates that better adhesion gives higher
*
τ
value resulting in the increase
in the tensile strength of the composites.
Figure 7.
Effect of monomer content (MA/GMA) in compatibilized composites on normalised tensile
properties.
The tensile modulus increased almost linearly but at higher compatibilizer content
got decreased. The mixing time was higher in i-GMA grafted LLDPE composites
and thus, the chances of the breakage of fibers increased which in turn reduced the
efficiency of fibers. This may be the possible cause for the reduction of the modulus
of these composites.
effect of
----in situ
and Pre-grafted Polymer on interfacial adhesion of
Composites
The fracture morphology of composites modified with
----in situ
and pre-grafted
polymer as a compatibilizer was shown in the
Figure 8.
The morphology of 30 wt%
Search WWH ::
Custom Search