Properties of Differently Compatibilized Bamboo Fiber Reinforced PE Composites - Natural Polymers, Biopolymers, Biomaterials, and Their Composites, Blends, and IPNs - page 112

The cross-head speed of 5 mm/min was used for tensile specimens. Tensile proper-
ties were measured from the stress-strain curve. The tensile strength and modulus of
composites was normalized with the neat LLDPE tensile strength and modulus. The
interfacial morphology of the varying compatibilized composites was investigated by
doing cryogenic fracture of tensile specimen in liquid nitrogen. Before fracture, all
specimens were dried at a temperature of 80°C in a vacuum oven. The fractured sur-
face was analyzed using scanning electron microscopy (SEM) (Cambridge stereoscan
360) after coating with gold to avoid the electrostatic charging and poor image resolu-
tion. The extent of interfacial adhesion between bamboo-fiber and the matrix can be
investigated by examining the SEM microphotographs.

results aNd disCussioNs
degradation Behavior of Compatibilized Composites
Figure 2 and 3 shows the degradation behavior of i-grafted and p-grafted polymer
composites. All the composites showed two steps mass loss. First step mass loss was
related to the degradation of cellulose and degradation of remaining lignin (at ap-
proximately 400°C) and second step mass loss was related to matrix (at approximately
500°C). It has been reported that LLDPE showed a single step decomposition in the
temperature range of 400-500°C with almost no char yield. It was found that in un-
compatibilized composites, the first weight loss was increased from 11.4 to 23.9%
and matrix loss was decreased from 87.5 to 71.6% as a function of fiber content (from
20 to 50 weight percent). The first weight loss for 30 wt% fiber in uncompatibilized
composite, as TGA traces reported in literature (Kumar et al., 2010), was 13.5 while
the matrix loss was 85.0%. From the Figure 2 and 3, it is evident that the initial decom-
position temperature (IDT) of p-grafted /----in situ grafted compatibilized composites
decrease with increase of the grafted content/compatibilizer.

Figure 2. TGA traces of short delignified bamboo fiber reinforced composites in presence of pre-
grafted polymer as a compatibilizer ( W=
L

f irst weight loss,

W=
L

second weight loss).