RESUMEN
Isocyanates are critical components that affect the crosslinking density and structure of polyurethane (PU) foams. However, due to the cost and hazardous nature of the precursor for isocyanate synthesis, there is growing interest in reducing their usage in polyurethane foam production-especially in rigid PU foams (RPUF) where isocyanate is used in excess of the stoichiometric ratio. In this study, lignin-containing nanocellulose fibrils (LCNF) were explored as mechanical reinforcements for RPUF with the goal of maintaining the mechanical performance of the foam while using less isocyanate. Different amounts of LCNF (0-0.2 wt.%) were added to the RPUF made using isocyanate indices of 1.1, 1.05, 1.0, and 0.95. Results showed that LCNF served as a nucleating agent, significantly reducing cell size and thermal conductivity. LCNF addition increased the crosslinking density of RPUF, leading to enhanced compressive properties at an optimal loading of 0.1 wt.% compared to unreinforced foams at the same isocyanate index. Furthermore, at the optimal loading, LCNF-reinforced foams made at lower isocyanate indices showed comparable stiffness and strength to unreinforced foams made at higher isocyanate indices. These results highlight the reinforcing potential of LCNF in rigid polyurethane foams to improve insulation and mechanical performance with lower isocyanate usage.
RESUMEN
This article presents statistical data on the reinforcing effect of three different fibres (sisal, eucalyptus pulp and polypropylene) on the physical and mechanical properties of an alkali activated natural soil produced using extrusion technique for the development of earth-based building materials. The experimental testing program involved characterisation of composite mixtures including a plain unreinforced stabilised matrix (which was plain soil mixed with alkali activator solution) as well as composite mixtures incorporating 3 volume fractions of fibres (0.5, 1.0 & 2.0 vol.%) of each fibre type. Composites were tested to evaluate physical properties (density and water absorption) and flexural response under 4-point loading in both dry and saturated conditions. The obtained values were statistically analyzed using one-way analysis of variance (ANOVA), followed by Tukey multiple comparison tests to ascertain the effect of the reinforcing fibres on the physical and mechanical properties of the composites. Results obtained show unique reinforcing effects of the different fibre types in the alkali activated matrices and the sensitivity of the earth based matrix to variations in fibre volume fraction. This data article is related to "Effects of Fibre Reinforcements on Properties of Extruded Alkali Activated Earthen Building Materials" [1].