Unsaturated polyester-toughened epoxy composites: Effect of sisal fiber on thermal and dynamic mechanical properties

Abstract

In the present study, the mechanical and thermal properties of sisal fiber-reinforced unsaturated polyester (UP)-toughened epoxy composites were investigated. The sisal fibers were chemically treated with alkali (NaOH) and silane solutions in order to improve the interfacial interaction between fibers and matrix. The chemical composition of resins and fibers was identified by using Fourier-transform infrared spectroscopy. The UP-toughened epoxy blends were obtained by mixing UP (5, 10, and 15 wt%) into the epoxy resin. The fiber-reinforced composites were prepared by incorporating sisal fibers (10, 20, and 30 wt%) within the optimized UP-toughened epoxy blend. Scanning electron microscopy was used to analyze the morphological changes of the fibers and the adhesion between the fibers and the UP-toughened epoxy system. The results showed that the tensile and flexural strength of (alkalisilane)-treated fiber (30 wt%) -reinforced composites increased by 83% and 55%, respectively, as compared with that of UP-toughened epoxy blend. Moreover, thermogravimetric analysis revealed that the (alkali-silane)-treated fiber and its composite exhibited higher thermal stability than the untreated and alkali-treated fiber systems. An increase in storage modulus and glass transition temperature was observed for the UP-toughened epoxy matrix on reinforcement with treated fibers. The water uptake behavior of both alkali and alkali-silanetreated fiber-reinforced composites is found to be less as compared with the untreated fiber-reinforced composite. J. VINYL ADDIT. TECHNOL., 00:000-000, 2015.

Effect of chemical treatment on the thermal properties of hybrid natural fiber‐reinforced composites

“…40 Finally, all the composites presented lower damping values than the one found for the polymer matrix as was reported in the literature 31,36,41 (Table VII). 40 Finally, all the composites presented lower damping values than the one found for the polymer matrix as was reported in the literature 31,36,41 (Table VII).…”

“…As expected, the composites treated with mixed treatment presented the highest tan δ value, due to the increase of surface roughness and the addition of the coupling agent. 40 Finally, all the composites presented lower damping values than the one found for the polymer matrix as was reported in the literature 31,36,41 (Table VII).…”

Fabrication and evaluation of acrylated epoxidized castor oil‐toughened diglycidyl ether of bisphenol A nanocomposites

“…Finally, the rigid DGEBA system becomes flexible due to the plasticization effect. [63][64][65][66] However, the char yield for the AC1-AC4 systems is higher than the A1-A4 systems; char residues at 700 8C are given in Table 3. In addition, the thermal stability of DGEBA/0.01 g/g OMMT was higher than the other systems, seen in Figure 7.…”

“…This is attributed to the physical barrier effect of clay, which increases the effective cross-linking density with the presence of alkylammonium ions and the interaction between the DGEBA/AECO and clay, and further acts as a catalyst for the amine-cured DGEBA/AECO system. [63][64][65][66] However, the char yield for the AC1-AC4 systems is higher than the A1-A4 systems; char residues at 700 8C are given in Table 3. This is due to the volatile products formed during the decomposition of the matrix reducing the thermal conductivity of materials during combustion, thus the thermal stability of the system is improved.…”

“…Hence, it provides more stiffness to the blends. [65] These changes in T g values are due to the cross-linking density increasing with the strong covalent bonds formed between primary NH 3 ions and blends, and can be ascribed to the enhancement of interfacial interaction between the DGEBA/ AECO and clay. Figures 12-13 present the tan delta as a function of temperature for the A1-A4 and AC1-AC4 samples.…”