Influência das razões de pré-polímero na matriz poliuretânica de óleo de mamona em compósito com alto teor fibras de fibras de piaçava da Amazônia

Abstract

The massive growth of waste generation has stimulated the demand for the production of environmentally friendly materials, focusing on the use of waste and renewable materials. Meeting these needs, the production of composite materials reinforced with vegetable fibers has been widely studied and applied in recent decades. In this context, this work proposes the production and characterization of composites with residue of piassava fibers from the Amazon, originating from a brooms company and treated with alkaline and polyurethane solution derived from castor oil with variations in the proportion of Prepolymer. High fiber content (85 wt%) were used with the variation in the proportions of polyurethane prepolymer. Untreated and treated piassava fibers were chemically characterized by FTIR, TGA / DTG and DSC. The percentage of prepolymer isocyanates and the hydroxyl number of the polyol were characterized and TGA / DTG-DSC and FTIR were performed along with the prepolymer-modified resins. The composites were characterized for their density, thickness swelling, FTIR, TGA / DTG, DSC, flexural strength, water absorption and SEM (surface and fracture region). The treatment of the fibers of piassava provided a reduction in the percentage of hemicellulose, as already expected, in order to improve the surface for adhesion with the matrix. Results from the prepolymer variation study showed that the increase in the prepolymer ratio caused displacement at the degradation temperature peaks, decreasing the thermal stability according to the isocyanate increase (NCO). FTIR analysis showed that the excess amount of prepolymer (PP) in the mixture generated an unreacted isocyanate residue after formation of the polyurethane. Regarding the characterization of the composites by flexural strength, higher resistance was observed with increasing PP ratio. The results of swelling, moisture and flexion showed expected values, which are within the standard. In general, the CP2 and CP3 composites presented promising results for applications in dry conditions, considering the large amount of material from a renewable source, which tends to favor water absorption.