Civil Engineering Reference
In-Depth Information
300
PP matrix
PP/KE (1 mm) 40wt%
PP/KE (10 mm) 40wt%
230.7
185.2
200
181.4
151.5
151.0
137.6
139.1
120.0
114.7
100
0
clay 0 wt%
clay 5 wt%
clay 10 wt%
Figure 7.3
h e coei cient of thermal expansion of nanobiocomposites. I. Na. Sim
et al.
KE(10 mm)/nanoclay nanobiocomposites are 0.3, 13.7 and 16.6% lower than those of
PP/KE(1 mm)/nanoclay nanobiocomposites with 0, 5 and 10 wt% nanoclay loadings,
respectively. h is seems to be due to the characteristic of long i ber of KE (10 mm) and
good adhesion between KE, nanoclay and PP matrix compare to KE (1 mm).
7.3.3
Dynamic Mechanical Analysis (DMA)
Dynamic Mechanical Analysis (DMA) measurement performed over a wide range of
temperature provides valuable information about the interfacial characteristics and the
storage, loss modulus and tan delta of polymer composites. Figures 7.4 and 7.5 show
the ef ect of KE i ber length on storage modulus and tan delta of PP matrix, PP/KE bio-
composites and PP/KE/clay nanobiocomposites. h e storage modulus of PP/KE bio-
composites with 40 wt% KE loading at −30°C increased by 30.3% and 72.7% with i ber
length of 1 mm and 10 mm, respectively, compared to those of the PP matrix. h is is
attributed to the reinforcement ef ect imparted by the KE that stress can be transferred
from the PP matrix to the KE [12]. h e tan delta peaks of PP nanocomposites and PP
nanobiocomposites were decreased with increasing KE i ber length and nanoclay load-
ings because damping in the transition region was from the imperfection in elasticity
and energy used to deform the material and was dissipated into heat. h erefore, it can
be expected that intermolecular chain with reinforcement led to the reduction in fric-
tion [21]. As shown in Figure 7.5, the storage modulus of PP/KE(10 mm) nanobiocom-
posites with 0, 5 and 10 wt% nanoclay was 32.6, 31.1 and 21.4% higher, respectively,
than that of PP/KE (1 mm) nanobiocomposites. h is showed that longer i ber has a
greater interfacial adhesion and strong bonding with polymer matrix [17].
h e storage modulus of PP matrix, PP/KE (10 mm) biocomposites and PP/KE (1
mm) biocomposites at −30°C increased by 15, 3.5 and 4.7% with the addition of 5
wt% nanoclay, respectively, compared to those of the PP biocomposites without nano-
clay. h is results from a uniform distribution of nanoclay and the incorporation of the
reinforcing KE restricting the mobility of the polymer molecules by good interactions
among KE, PP matrix and nanoclay. On the contrary, storage modulus of nanobiocom-
posites with 10 wt% nanoclay decreased due to agglomeration of nanoclay in the PP
matrix.
