3.3. Creep property
The scatter plots in Fig. 2 show the evolution of creep strain against time at various stress levels for PE and PE/SF composites of various fiber contents. Creep strain and creep strain rate increased as the stress level increased. In addition, creep strain
and creep strain rate decreased as the fiber content increased.This was consistent with the findings reported in the literature [19–21]. Fig. 3 demonstrates the comparison of creep property between three composites with the same fiber content 20%), one of which did not undergo interfacial compatibilization
with MAPE, whereas the other two were interfacially compatibilized with MAPE through simultaneous blending and preimpregnation, respectively. It was found that there was a reduction of creep strain after interfacial modification, and the preimpregnation process provided more significant improvement in creep resistance. The former can be attributed to the mechanism that the compatibilizer enhances the compatibility between
the sisal fiber and the PE matrix to form stronger interfacial adhesion, and hence stress could be transmitted to the sisal fibers from the matrix more effectively, while the latter can be explained by the more effective interfacial compatibilization by
the pre-impregnation process.