Synthesis of sodium lignosulfonate from lignin extracted from oil palm empty fruit bunches by acid/alkaline treatment for reinforcement in natural rubber composites

Abstract This work studied a synthesis of sodium lignosulfonate (SLS) from the lignin which extracted from oil palm empty fruit bunches (OPEFB) by using batch method. The preparation of lignin from OPEFB was done by acid pretreatment using 1% (wt/wt) H2SO4 at 90 °C for 120 min in order to reduce hemicelluloses. Then lignin was extracted by 2.5% (wt/wt) NaOH at 90 °C for 180 min and precipitated by adjusting pH to 2 with 98% H2SO4. The obtained lignin was changed to SLS by using sodium bisulfite (NaHSO3). The study yields of prepared SLS conducted by varying concentration of NaHSO3. The obtained SLS was characterized by Fourier transform infrared spectroscopy and zeta potential compared to sodium lignosulfonate (commercial).</jats:p

Fabrication of Natural Rubber Latex Foam Composite Filled with Pineapple-leaf Cellulose Fibres

Abstract Pineapple leaf (PL) is a renewable agriculture residue which are abundance in Thailand. In this paper, cellulose powder was extracted from PL. Celluloses are typically used as fillers for rubber reinforced composites due to their properties such as high mechanical properties, low cost, low density, and biodegradability. The aim of this study was to optimize the method to prepare natural rubber latex foam (NRLF) with different cellulose loadings from 0 to 7 phr by using Dunlop method. The different steps for adding celluloses in this study were adding in pre-vulcanization process and in foaming process were studied. The tensile properties, density, compression, and microstructural characterization were studied. Morphological and microstructural performed by using scanning electron microscopy (SEM). It was found that adding cellulose in pre-vulcanization step showed well distribution of cellulose while adding cellulose in foaming process showed the settle of cellulose at the bottom of the foam sample. The tensile strength and elongation at break decreased with increasing of cellulose content whereas modulus increased with increasing of cellulose content.</jats:p

The modelling of the toughening of epoxy polymers via silica nanoparticles: The effects of volume fraction and particle size

AbstractSilica nanoparticles possessing three different diameters (23, 74 and 170 nm) were used to modify a piperidine-cured epoxy polymer. Fracture tests were performed and values of the toughness increased steadily as the concentration of silica nanoparticles was increased. However, no significant effects of particle size were found on the measured value of toughness. The toughening mechanisms were identified as (i) the formation of localised shear-band yielding in the epoxy matrix polymer which is initiated by the silica nanoparticles, and (ii) debonding of the silica nanoparticles followed by plastic void growth of the epoxy matrix polymer. These mechanisms, and hence the toughness of the epoxy polymers containing the silica nanoparticles, were modelled using the Hsieh et al. approach (Polymer 51, 2010, 6284–6294). However, it is noteworthy that previous modelling work has required the volume fraction of debonded silica particles to be measured from the fracture surfaces but in the present paper a new and more fundamental approach has been proposed. Here finite-element modelling has demonstrated that once one silica nanoparticle debonds then its nearest neighbours are shielded from the applied stress field, and hence may not debond. Statistical analysis showed that, for a good, i.e. random, dispersion of nanoparticles, each nanoparticle has six nearest neighbours, so only one in seven particles would be predicted to debond. This approach therefore predicts that only 14.3% of the nanoparticles present will debond, and this value is in excellent agreement with the value of 10–15% of those nanoparticles present debonding which was recorded via direct observations of the fracture surfaces. Further, this value of about 15% of silica nanoparticles particles present debonding has also been noted in other published studies, but has never been previously explained. The predictions from the modelling studies of the toughness of the various epoxy polymers containing the silica nanoparticles were compared with the measured fracture energies and the agreement was found to be good