Enhancement of Thermo-mechanical Properties of Okra Fiber by Photografting Technique

Abstract

In this study, okra fibers were chemically modified with three different monomers such as ethylene glycol dimethacrylate (EGDMA), 2-hydroxyethyl methacrylate (HEMA) and methyl methacrylate (MMA) solutions in the presence of methanol (MeOH) and photoinitiator (Irgacure-500) under ultraviolet (UV) radiation with a view to improve thermo-mechanical characteristics. Based on grafting efficiency and mechanical attributes the intensity of UV radiation and monomer concentration were maximized. A series of solutions by varying the concentrations (10–70%) of monomers in MeOH along with 2% photoinitiator were prepared. Experimental results revealed that fibers grafted with 30% EGDMA at 30th pass, 30% HEMA at 20th pass and 40% MMA at 30th pass of UV radiation achieved optimum mechanical properties over untreated fiber. The optimized solutions were further enhanced by adding various concentrations (1–2%) of urea, and the best properties were obtained with 1.5% urea-treated fiber. The chemical bonds formed due to photografting were inspected by Fourier transform infrared spectroscopy (FTIR). Degradation behavior under heat was performed through thermogravimetric analysis (TGA/DTG) and found that photografted fiber showed well-improved thermal stability than the untreated sample. Water uptake test exhibited that grafting reduced water retention capacity of treated fiber significantly. Furthermore, simulating weathering test also executed.