RTICLE Applied Polymer (a) (d) matrix Figure 1. SEM micrographs of the longitudinal fibers aspects for the composites: (a)100 am of NFRUP, (b)20 um of NFRUR, ()100 km of(d) EGMRUR, and(d)20 um of EGMRUP. the polished cross sections of the NFRUP and EGMRUP com posites. Figure 2(a)shows the cross section of a natural fiber, and Figure 2(c) shows the double aspects of the glass fibers, which were randomly dispersed in the matrix, that is, longitudi nal fibers aspects and fibers cross-sectional aspects. In Figure 2(b), a closer observation of the interface in the micrographs of he NFRUP composite proved better close contact between the the matrix than that in the case of the up film filled with palm tree fibers studied by Adami et al. In addition, Figure 2(b)reveals a tiny and narrow gap around the fiber that may have eventually led to cracking in the NFRUP composite Figure 2 SEM micrographs of the polished cross sections for the compo- because fatigue crack propagation resistance depends on the sites: (a m of NFRUR, (b) 10 um of NFRUP, (c) 100 um of of egmrup 490 J. APPL. POLYM.Sc.2013,D0:10.1002PP38499 WILEYONLINELIBRARY. COM/APP EWILEY NONLINE LIBRARYthe polished cross sections of the NFRUP and EGMRUP com￾posites. Figure 2(a) shows the cross section of a natural fiber, and Figure 2(c) shows the double aspects of the glass fibers, which were randomly dispersed in the matrix, that is, longitudi￾nal fibers aspects and fibers cross-sectional aspects. In Figure 2(b), a closer observation of the interface in the micrographs of the NFRUP composite proved better close contact between the fibers and the matrix than that in the case of the UP film filled with palm tree fibers studied by Kadami et al.24 In addition, Figure 2(b) reveals a tiny and narrow gap around the fiber that may have eventually led to cracking in the NFRUP composite because fatigue crack propagation resistance depends on the matrix–fiber adhesion.25–27 However, Azimi et al.25 reported Figure 1. SEM micrographs of the longitudinal fibers aspects for the composites: (a) 100 lm of NFRUP, (b) 20 lm of NFRUP, (c) 100 lm of EGMRUP, and (d) 20 lm of EGMRUP. Figure 2. SEM micrographs of the polished cross sections for the compo￾sites: (a) 100 lm of NFRUP, (b) 10 lm of NFRUP, (c) 100 lm of EGMRUP, and (d) 10 lm of EGMRUP. 490 J. APPL. POLYM. SCI. 2013, DOI: 10.1002/APP.38499 WILEYONLINELIBRARY.COM/APP ARTICLE