Bio-Based Rigid Polyurethane Foam Composites Reinforced with Bleached Curauá Fiber

Abstract

This study aims to evaluate the influence of using a bleached Curauá fiber (CF) as filler in a novel rigid polyurethane foam (RPUF) composite. The influence of 0.1, 0.5 and 1 wt.% of the reinforcements on the processing characteristics, cellular structure, mechanical, dynamic-mechanical, thermal, and flame behaviors were assessed and discussed for RPUF freely expanded. The results showed that the use of 0.5 wt.% of CF resulted in RPUF with smoother cell structure with low differences on the processing times and viscosity for the filled pre-polyol. These morphological features were responsible for the gains in mechanical properties, in both parallel and perpendicular rise directions, and better viscoelastic characteristics. Despite the gains, higher thermal conductivity and lower flammability were reported for the developed RPUF composites, related to the high content of cellulose and hemicellulose on the bleached CF chemical composition. This work shows the possibility of using a Brazilian vegetable fiber, with low exploration for the manufacturing of composite materials with improved properties. The developed RPUF presents high applicability as enhanced cores for the manufacturing of structural sandwich panels, mainly used in civil, aircraft, and marine industries.

The Influence of Density on the Mechanical Response of Reinforced High-Density Polyurethane Foams: A Statistical Approach

“…That is, the modulus will increase much more significantly with not-so-relevant increments in bulk density. This effect may be related to the greater uniformity of the cells from that point onwards, which promotes less dispersion in size and elongation, as previous reported on the micrographs [8].…”

“…Despite the gains reported in previous reports, no relations on cell size/distribution were made as well as relations regarding the gains in density and its influence in gains in compressive or tensile response of such foams. Indeed, there is some analytical models that correlates the differences in morphological aspects with mechanical response [8], however, for the best of our knowledge, there is no reports using statistical models, such as linear regression for the prediction of properties over a specific range of density or cell size. Then, this paper aims to present a statistical method to predict the properties of foams, depending on the density.…”

Impact of Sunflower Press Cake and Its Modification with Liquid Glass on Polyurethane Foam Composites: Thermal Stability, Ignitability, and Fire Resistance

“…These polysaccharides expedite the conversion of volatile gases from PUR. Slightly lower values for T max1 were suspected for the PUR foam composites with SFP and SFP/LG fillers and were related to the insufficient dispersion and formation of clusters into the PUR system, which can alter the cross-link density of the products [ 47 ]. However, the addition of the non-flame retardant SFP or SFP/LG filler did not change the temperature in the first stage, indicating a sufficient filler dispersion and cross-link density of the resultant PUR foam composites, while the incorporation of flame retardant fillers gave rather lower results.…”

Cost-Effective Fabrication of Modified Palygorskite-Reinforced Rigid Polyurethane Foam Nanocomposites

“…Additional regulators containing catalysts and surfactants are also added to adjust the physical and chemical properties of RPUFs [6]. With the increase in people's interest in RPUFs and their wide range of applications, improving the comprehensive performance of RPUFs, particularly mechanical property and thermal stability, has become an important topic [7]. The addition of fillers has been regarded as an effective route to the reinforcement of RPUFs.…”