Alkali-treated fiber-reinforced composite

Aydin et al. reported the influence of alkali treatment on the mechanical, thermal, and morphological properties of eco-composites made by short flax fiber reinforced PLA Scanning electron microscopy (SEM) revealed that the packed structure of the fibrils was deformed by the removal non-cellulosic materials. The mechanical tests indicated that the modulus of the untreated flax fiber/PLA composites was higher than that of PLA on the other hand, the modulus of alkali treated flax/PLA was lower than that of PLA. Thermal properties of the PLA in the treated flax fiber reinforced composites were also affected. Tg values of treated flax fiber reinforced composites were lowered by nearly 10°C for 10% NaOH treatment and 15°C for 30% NaOH treatment. A bimodal melting behavior was observed for treated fiber composites different than both of neat PLA and untreated fiber composites [60]. 

Mishra et al. [36, 37] tested the tensile and impact strength of maleic anhydride-treated sisal composite at different fiber volumes and found that tensile and impact strength decreased gradually from 40% fiber volume composite to 55% fiber volume polyester composite. It was concluded that maleic anhydride-treated composite at fiber volume 40% showed higher and better mechanical properties [36, 37]. Related to tensile properties evaluation, Mishra et al. [36, 37] concluded that a composite of alkali treated (5%) sisal fiber was fotmd to achieve better mechanical properties as compared to rmtreated, dewaxed, 10% alkali treated and bleached sisal fiber-reinforced composites. A 5% alkali-treated sisal fiber-reinforced composite... 

Figure 7.8 Tensile load-strain curves of neat PLA and ramie fiber-reinforced PLA composites (a) neat PLA, (b) untreated fiber-PLA, (c) alkali-treated fiber-PLA,...

Alkali treatment of jute fibers also improves the mechanical properties of thermoplastics. The vinyl ester resin reinforced with alkali-treated fibers shows improved mechanical properties. The maximum improvement was noted for the composites prepared with 4 h alkali-treated fibers at 35% fiber loading. The flexural strength improved by 20% and the modulus by 23%. The strength and modulus of the composites were found to be lower than the values estimated from the general rule of mixtures. For the jute/vinyl ester composites with 35% fiber content, the strength was decreased by 29% and 16% for the untreated and 4h alkali-treated fibers and the modulus was lower by 51% and 37% for the untreated and 4h alkali-treated fibers, respectively [154]. 

Ray D, Sarkar BK, Das S, Rana AK (2002) Dynamic mechanical and thermal analysis of vinylester resin matrix composites reinforced with untreated and alkali-treated jute fibers. Compos Sci Technol 62 911-917... 

In this chapter, both raw and alkali treated silk fibers are taken into consideration to characterize their properties first. The specific objective is to determine the modulus and strain to failure of the single silk fiber. Other aims of this work are to fabricate the unidirectional silk fiber reinforced polymer (MAPP and commercial grade PP) matrix composites by varying fiber volume fraction and to determine their mechanical properties such as tensile strength, flexure strength, impact strength, and hardness. 

Ray, D., Sarkar, B.K., Rana, A.K., and Bose, N.R. (2001) The mechanical properties of vinylester resin matrix composites reinforced with alkali-treated jute fibers. Composites Part A, 32, 119-127. 

Figure 6.12 Mechanical strength of untreated and alkali-treated continuous abaca fiber-reinforced furan resin composites [60].

Sipiao et al. [37] studied the mechanical properties of high-density polyethylene (HDPE) composites reinforced with palm fiber-treated alkali solution. 

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