Sisal Fiber-Reinforced Green Composites: Effect of Ecofriendly Fiber Treatment Saurabh Chaitanya , Inderdeep Singh Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India This research endeavor explores the effect of economi- cal and environment-friendly treatment of sisal fibers, prior to their incorporation into poly-lactic acid (PLA). Biocomposites incorporating sisal fibers (30% [w:w]) treated with sodium bicarbonate (10% [w:v]) aqueous solution for varying time periods (24, 72, 120, and 168 h) were developed using extrusion-injection molding pro- cess. Thermogravimetric analysis, morphological exam- ination, Fourier-transform infrared spectroscopy, and lignocellulosic composition analysis of raw and treated sisal fibers established a gradual removal of hemicellu- losic content from fiber surface with increasing treat- ment time. Biocomposites incorporating sisal fibers treated for 72 h exhibited optimum tensile, flexural, and compressive properties. While in case of impact testing, biocomposites incorporating sisal fibers treated for 24 h exhibited maximum impact strength. The optimum results were found comparable to sodium hydroxide treated sisal fiber-reinforced biocomposites. Hence, considering commercialization of biocomposites, sodium bicarbonate treatment offers huge potential to substitute ecologically hazardous sodium hydroxide treatment ensuring good mechanical properties. POLYM. COMPOS., 00:000–000, 2017. V C 2017 Society of Plastics Engineers INTRODUCTION Biocomposites have emerged as a new class of sustain- able materials to counter the environmental concerns raised by the squandered use of conventional polymer products over the last few decades. Biocomposites possess several advantages such as high specific strength, biode- gradability, renewability, and recyclability over conven- tionally used polymers and polymer matrix composites. Biocomposites usually consists of a biopolymer matrix reinforced with lignocellulosic fibers. Biopolymer matri- ces such as PLA [1], poly(3-hydroxybutyrate-co-3- hydroxyvalerate) (PHBV) [2], poly(butylene succinate) (PBS) [3], polycaprolactone (PCL) [4], and so on have been developed and their applicability is being explored. PLA is the most widely used, commercially available bio- polymer derived from renewable resources, and has the potential to substitute several conventional polymers used in engineering applications [5]. However, its high produc- tion cost and brittle nature is hampering its wide spread application. To overcome these shortcomings, the incor- poration of lignocellulosic fibers is being explored as reinforcement into PLA matrix to form fully degradable, renewable resource derived biocomposites [6, 7]. Lignocellulosic fibers used as reinforcement into bio- composites offer several distinct advantages of being less dense, readily available at low cost and comparable spe- cific strength, over traditionally used glass fibers. Sisal fibers are widely cultivated throughout the world and are generally used for making ropes, handicrafts, papers, and textile fibers. Apart from these applications, sisal fibers also exhibit the potential to be used as reinforcement into commercial polymer composites due their high strength and abundant availability [8]. Lignocellulosic fibers com- prise of cellulosic fibrils, bonded together by the noncel- lulosic content such as lignin, hemicellulose, pectin, and waxes. The behavior of lignocellulosic fibers is signifi- cantly influenced by the composition of these binding constituents [9]. However, excessive presence of these on the fiber surface restricts the formation of a good interfa- cial bond at the fiber–polymer interface. To overcome this hindrance, fiber surface modification of lignocellu- losic fibers using physical or chemical treatments has been suggested by several researchers. Fiber surface mod- ifications using chemical treatment have been found to be more effective compared to physical treatments. Merceri- zation of lignocellulosic fibers using sodium hydroxide (NaOH) treatment is the most widely used chemical treat- ment for fiber surface modification. In the previous study, authors explored the effect of sodium hydroxide treatment and fiber concentration on sisal fiber reinforced PLA bio- composites [10]. It was recorded that mercerization of sisal fibers using NaOH (5% w:w) solution, enabled 30 wt% sisal fibers-reinforced PLA biocomposites to exhibit maximum improvement in the tensile, flexural, and Correspondence to: S. Chaitanya; e-mail: saurabh9602@gmail.com or I. Singh; e-mail: scmeddme@iitr.ac.in DOI 10.1002/pc.24511 Published online in Wiley Online Library (wileyonlinelibrary.com). V C 2017 Society of Plastics Engineers POLYMER COMPOSITES—2017