Potential aspect of rice husk biomass in Australia for nanocrystalline cellulose production

Nanocrystalline cellulose(NCC) was produced from rice husk biomass(Oryza sativa) by a chemical extraction process to explore the potential aspect of agro-waste biomass in Australia. In this work, the delignified rice husk pulp(D-RHP) was produced by alkaline delignification of raw rice husk biomass(R-RHB) using 4 mol·L^(-1) alkali solutions(Na OH) in a jacketed glass reactor under specific experimental conditions. D-RHP was bleached using 15% sodium hypochlorite, and the bleached rice husk pulp was coded as B-RHP. Finally,raw suspension of NCC was produced by the acid hydrolysis of B-RHP using 4 mol·L^(-1) sulphuric acid. The raw suspension of NCC was neutralized by a buffer solution and analyzed by TAPPI, FT-IR, XRD, SEM, AFM, and TEM. FT-IR spectra of NCC are different to R-RHB but similar with B-RHP and D-RHP. From XRD results, the crystallinity of NCC was found to be approximately 65%. In AFM analysis particle thicknesses have been confirmed to be in the range of(25 ± 15.14) nm or(27 ± 15.14) nm which is almost the same. From TEM analysis particle dimensions have been confirmed to be in the range of(50 ± 29.38) nm width and(550 ± 302.75) nm length with the aspect ratio ~ 11:1(length/diameter) at a 500 nm scale bar. On the other hand, at a 200 nm scale bar the particle dimensions have been confirmed to be in the range of(35 ± 17) nm width and(275 ± 151.38)nm length with the aspect ratio ~ 8:1. The aspect ratio of individual crystalline domain was determined in TEM analysis which is 10:1(100/10). Therefore the aspect ratios and dimensions of nanoparticles in NCC suspension are almost the same and in nano-meter scale, as confirmed from both AFM and TEM results. The yield of NCC from B-RHP was found to be approximately 95%, and the recovery of cellulose from R-RHB is about 90%.

Influence of graphene nanoplatelet incorporation and dispersion state on thermal, mechanical and electrical properties of biodegradable matrices

Graphene nanoplatelets （GNPs） were used as multifunctional nanofiller to enhance thermal and mechanical properties as well as electrical conductivity of two different biodegradable thermoplastics： poly lactide （PLA） and poly （butylene adipate-co-terephthalate） （PBAT）. Morphological investigations showed different levels of GNP dispersion in the two matrices, and consequently physical properties of the two systems exhibited dissimilar behaviours with GNP incorporation. Crystallinity of PLA, determined from differential scanning calorimetry, was observed to increase markedly with addition of GNPs in contrast to the decrease in crystallinity of PBAT. Isothermal and non-isothermal thermogravimetric analyses also revealed a more significant delay in thermal decomposition of PLA upon addition of GNPs compared to that of PBAT. Furthermore, results showed that increasing GNP content of PLA and PBAT nanocomposites influenced their Young＇s modulus and electrical conductivity in different ways. Modulus of PBAT increased continuously with increasing GNP loading while that of PLA reached a maximum at 9wt% GNPs and then decreased. Moreover, despite the higher conductivity of pure PBAT compared to pure PLA, conductivity of PLA/GNP nanocomposites overtook that of PBATIGNP nanocomposites above a certain GNP concentration. This demonstrated the determining effect of nanoplatelets dispersion state on the matrices properties.