Materials produced from plant biomass: part II: evaluation of crystallinity and degradation kinetics of cellulose

In this study Eucalyptus grandis (CEG) and Pinus taeda (CPT) cellulose fibers obtained from kraft and sulfite pulping process, respectively, were characterized using Fourier transform infrared (FTIR) spectroscopy and thermogravimetry (TGA). The degradation kinetic parameters were determined by TGA using Coats and Redfern method. FTIR results showed that CPT presented a more ordered structure with higher crystallinity than CEG. Thermogravimetric results showed that CPT had a higher thermal stability than CEG. The kinetic results revel that for CEG the degradation mechanism occurs mainly by random nucleation, although phase boundary controlled reactions also occurs while for CPT the degradation process is more related with phase boundary controlled reactions. Results demonstrated that differences between thermal stability and degradation mechanisms might be associated with differences in the cellulose crystalline structure probably caused by different pulping processes used for obtaining the cellulose fibers

Examining the Mechanical and Thermomechanical Properties of Polymethylmethacrylate Composites Reinforced with Nettle Fibres

Buyukkaya, Kenan/0000-0002-8263-0756WOS: 000519133700016The aim of this study was to determine the mechanical and thermomechanical properties of nettle fibre-reinforced polymethylmethacrylate composites. The polymethylmethacrylate composites reinforced with nettle fibres were manufactured using nettle fibres obtained using the natural methods. The nettle fibre contents were 0, 2.5, 5, 7.5, and 10 V-f %. The composites so formed were characterized in terms of their mechanical and thermomechanical properties. The mechanical properties of nettle-reinforced composites were characterized in terms of bending stress, bending modulus, impact strength, and fracture toughness tests, whilst their behaviour was determined by heat deviation temperature and Vicat softening temperature. The micro-mechanisms underlying the toughening and fracture processes were observed in the light of studies of the microstructure of fractures. From the mechanical properties of composites reinforced with 10% nettle fibres, an increase of 75% in bending stress, 40% in impact strength, and 106% in fracture toughness was recorded. The findings show that nettle fibres can be used as an important reinforcement material for environmentally friendly composite applications.Giresun University's Scientific Research Projects Office [FEN-BAP-A-250414-76]We would like to acknowledge the support of Giresun University's Scientific Research Projects Office (FEN-BAP-A-250414-76)