Obtenção de espumas flexíveis de poliuretano com celulose de Pinus elliottii

Abstract

ResumoNeste trabalho foram desenvolvidas espumas flexíveis de poliuretano com a adição de celulose de Pinus nas concentrações de 0,5; 1 e 2% (m/m). A celulose foi submetida ao processo de fibrilação mecânica e posterior secagem por aspersão (spray dry) sendo caracterizada quanto a sua morfologia por MEV e MET. As espumas foram produzidas pelo método de batelada (one-shot) com a adição e mistura da fibra junto ao poliol. As espumas foram caracterizadas por MEV, densidade aparente e resistência à compressão. Os principais resultados indicam que a fibrilação mecânica promove a obtenção de fibras em escala nanométrica, porém durante a secagem, ocorre aglomeração ocasionando aumento para escala micrométrica. As propriedades mecânicas da espuma obtiveram acréscimos de 40 e 50% na resistência à compressão com a adição de 0,5 e 1% de celulose, respectivamente, evidenciando seu potencial como aditivo alternativo para o desenvolvimento de espumas de poliuretano. Palavras-chave: celulose, espuma, fibrilação, poliuretano, spray dry. AbstractIn this work, flexible polyurethane foams were developed with the addition of Pinus cellulose at concentrations of 0.5; 1 and 2 wt%. The cellulose was subjected to mechanical fibrillation process and subsequent dried by spray dry process. It was characterized morphologically by SEM and TEM. The foams were produced by one-shot method by adding and mixing the fiber with the polyol. The foams were characterized by SEM, apparent density and compression strength. The main results indicate that the mechanical fibrillation promotes the obtainment of nanoscale fibers, but during the drying process, agglomeration occurs causing an increase reaching the micrometer scale. The mechanical properties of the foam increased by 40 and 50% in compressive strength with the addition of 0.5% and 1% of cellulose, respectively, showing its potential as an alternative additive for the development of polyurethane foams.

Removal of Cr(III) From Water By Polyurethane Foam Incorporated With Green Liquor Dregs Waste

“…The use of rice husk as filler in PU foams yielded distorted cells and less uniformity when compared to neat ones (Silva et al, 2013). In other previous study, the addition of cellulose fillers also promoted a more irregular PU structure, which was worse for high filler contents (Macedo et al, 2017). A similar behavior was reported for PU foams filled with lignin particles, which presented a more heterogeneous cellular structure ascribed to the lignin insertion, although the particle size distribution did not influence in this case (Dražić et al, 2016;Santos et al, 2017).…”

“…The morphology of polyurethane foams is a honey comb-like structure, in which the gas bubbles are surrounded by polymeric cells and the addition of a solid filler may change overall the cell wall structure (Gu et al, 2013;Macedo et al, 2017). The high number of elliptical closed cells elongated in the expansion direction indicates a proper polymerization process of the neat PU (Delucis et al, 2018).…”

Magnetic foams from polyurethane and magnetite applied as attenuators of electromagnetic radiation in X band

“…The apparent density is a function of the content of the blowing agents added to the material formulation, but may be altered when fillers added to the formulation have residual moisture. [ 41,48 ] To F1, F5, and F30 samples, its apparent density did not show a significant variation in relation to F0 sample, Table 2, which suggests that the moisture of the Fe 3 O 4 sample, identified from its FTIR spectrum, was not released during the reaction of Polyurethane polymerization. On the other hand, the pycnometer density of these samples increased significantly with increasing Fe 3 O 4 content, which can be associated with the higher density of the magnetite in relation to the polymer.…”

Tobacco stalk lignocellulosic nanofibers characterization for pharmaceutical applications

“…For SD samples, lignocellulosic suspensions were dried in a Büchi mini spray dryer B-290 (Switzerland) in open mode using compressed air and rate of 4 mL.min -1 . The inlet and outlet temperatures were 150˚C and 89˚C, respectively (Macedo et al, 2017).…”