In this work, we undertook a comparative study of the dynamic dielectric analysis of two composites: natural-fiber-reinforced unsaturated polyester (NFRUP) and E-glass-mat-reinforced unsaturated polyester (EGMRUP). In both composites, two common relaxation processes were identified, the first of which was the a-mode relaxation associated with the glass transition of the matrix. The second one was associated with conductivity that occurred because of the carriers' charge diffusion and was observed at temperatures above the glass transition and at low frequencies. However, the interfacial or Maxwell-Wagner-Sillars polarization was noticed only in the NFRUP composite. This dielectric study also revealed that compared to E-glass fibers, natural fibers enhanced the thermal insulation in the composite. Also, the study of the fiber adhesion in the matrix with scanning electron microscopy, differential scanning calorimetry, and tensile testing revealed a great compatibility of the fibers with the matrix in both composites.
Dielectric study was investigated in order to probe the interfacial region fibers/matrix of the polyester composite reinforced with alfa/wool/thermo-binder fibers. Dielectric spectra were measured in the frequency range from 10−1 Hz to 106 Hz, and temperature interval from 40 °C to 150 °C. This study revealed the presence of two dielectric relaxations in the composite. While the first one was attributed to the α mode relaxation associated with the glass transition of the matrix, the second was associated with the conductivity resulting from the carriers' charges diffusion noted for high temperature above glass transition and low frequencies. As this study did not show the presence of the interfacial polarization effect in the composite, it was accomplished with the vibrational study using the FT-IR and Raman techniques. A great compatibility between fibers and matrix was proven by a less hydrophilic character of the reinforcement giving rise to additional valence vibrations from wool fibers and hydrogen bonds.
The presence of wool fibres in non-woven Alfa fibres sheet was investigated as a mean of improving adhesion of Alfa fibre-reinforced unsaturated polyester composite. FT-IR and Raman spectroscopy results revealed that such improvement could occur by a decrease in the hydrophilic character of the Alfa fibres owing to the presence of wool fibres. Hence, physical and chemical interactions could happen between the reinforcement and the matrix as demonstrated by FT-IR and Raman spectroscopy results. Tensile testing performed on this composite confirmed that such adhesion could occur according to its excellent specific parameters despite of its low tensile strength attributed to a higher fibre to fibre contact of wool fibres.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.