The biobased chain extended polyurethane (PU) was synthesized by reacting castor oil based polyol with different diisocyanates [toluene-2,4-diisocyanate (TDI) and hexamethylene diisocyanate (HMDI)] and chain extender such as glutaric acid. Biocomposites have been fabricated by incorporating the silk fiber into both TDIand HMDI-based PUs. The effect of incorporation of silk fiber into TDI-and HMDI-based neat PU on the physicomechanical properties such as density, surface hardness, tensile strength, and percentage elongation have been investigated. The dynamic mechanical properties and the thermal stability of neat PUs and the silk fiber incorporated PU composites have been evaluated. The TDI-based neat PU has showed higher mechanical properties compared to HMDI-based PU. The incorporation of 10% silk fiber into TDI-and HMDIbased PU resulted in an enhancement of tensile strength by 1.8 and 2.2 folds, respectively. The incorporation of silk fiber into biobased chain extended PU increased the glass transition temperature (T g ) of the resultant biocomposites. The morphology of tensile fractured neat PUs and their biocomposites with silk fiber was studied using scanning electron microscope (SEM). POLYM. ENG. SCI., 50:851-856,
The effect of varying the content of the ionic liquid based on phosphonium, tributyl (ethyl)-phosphonium diethylphosphate, was studied acting with a dual role as a curing and dispersing agent to obtain multiwalled carbon nanotube nanocomposites (MWCNT) dispersed in epoxy resin (ER). The effect of this ionic liquid in the mixtures was evaluated to obtain a better dispersion of the charge in the epoxy matrix, and consequently the impact on the curing of the nanocomposites. The effectiveness of the dispersion was evaluated morphologically by scanning electron microscopy (SEM). The non-covalent functionalization of nanotube nanocomposites (CNT) with IL resulted in better reinforcing effect and higher conductivity, as well as the use of high-speed speed mixer combined with acetone, culminated in better mixing and processing conditions. Under these conditions, the composite showed high electrical conductivity and good dynamic-mechanical properties. The systems with 10phr of the ionic liquid showed the highest of ΔH (heat of reaction), and these values can be attributed to the better adjustment of the stoichiometry, favoring the crosslinking of the resin. the systems with 10phr of the ionic liquid showed the highest of ΔH (heat of reaction), and these values can be attributed to the better adjustment of the stoichiometry, favoring the crosslinking of the resin. However, the systems prepared with 30phr of ionic liquid showed lower values of ΔH, possibly due to its excess in the mixture, culminating in the imbalance of resin/hardener stoichiometry. This can be seen in the scanning electron microscopy (SEM), whose sample cured with 30phr showed cracks, due to the excess of the crosslinking agent causing incomplete curing, making the material more fragile.
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