Obtenção e caracterização de microfibras de borracha natural incorporadas com negro de fumo
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Data
2020-08-07
Autores
Sousa, Eliraldrin Amorin de
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Universidade Estadual Paulista (Unesp)
Resumo
Atualmente, os materiais com dimensões micrométrica e nanométrica vem sendo bastante explorados por pesquisadores da área de materiais, principalmente pela possibilidade de desenvolvimento de materiais funcionais. A incorporação de nano/micropartículas nas fibras possibilita um gama de aplicações em diversas áreas. Nesse cenário, as nano/microfibras poliméricas têm ganhado bastante destaque para aplicações como sensores, filtros, carreadores de drogas, materiais piezo-resistivos, entre outras. Essas estruturas têm sido produzidas principalmente pela técnica de electrospinnig e desde de 2009 também pela técnica de fiação por sopro em solução (FSS). A produção de membranas porosas obtidas a partir de micro/nanofibras de borracha natural (BN), tem sido um desafio devido sua alta retração após o estiramento. Nesse sentido, o presente trabalho teve como principal objetivo desenvolver uma metodologia para produzir, por meio da técnica de FSS, membranas porosas constituídas de microfibras de BN, microfibras de BN incorporadas com agentes vulcanizantes (BN4V), microfibras de BN incorporadas com negro de fumo (NF) e microfibras de BN incorporadas com agentes vulcanizantes e partículas de NF. As microfibras apresentaram uma morfologia achatada com larguras médias variando de (15 ± 6) μm a (101 ± 9) µm, dependendo das condições de processamento. As membranas microfibrosas BN4V, submetida ao tratamento térmico em 90°C por 3 h, apresentaram os maiores valores de resistência à ruptura e de deformação à ruptura, (4,9 ± 0,8) MPa e 867%, respectivamente. As membranas com incorporação de NF apresentaram uma redução na resistência à ruptura, na deformação à ruptura e na hidrofilicidade, quando comparadas à amostra BN4V (90°C por 3 h). Por outro lado, houve um aumento de 9 ordens de grandeza na condutividade elétrica. O limiar de percolação foi encontrado por volta de 7,4 %m de NF. As análises de DSC das membranas fibrosas, incorporadas ou não com NF, vulcanizadas ou não, apresentou temperatura de transição vítrea no intervalo de –65°C à –61°C. As análises termogravimétricas indicaram que as amostras são termicamente estáveis abaixo de 150°C. Nas análises piezo-resistivas, o sensor de deformação sob vários ciclos de carga-descarga, exibe estabilidade e repetibilidade nas respostas de resistência elétrica com fator gauge em torno de 3 para a amostra com 10 %m de NF.
Currently, materials with micrometric and nanometric dimensions have been extensively studied due to the possibility of developing functional materials. The incorporation of nano/microparticles in the fibers allows a range of applications in several areas. In this scenario, polymeric nano/microfibers have gained a lot of prominence for applications such as sensors, filters, drug carriers, piezo-resistive materials, among others. These structures have been produced mainly by the electrospinnig technique and since 2009 also by the solution blowing spinning (SBS) technique. The production of porous membranes obtained from micro/nanofibers of natural rubber (NR), has been a challenge due to its high retraction after stretching. In this sense, the present work had as main objective to develop a methodology to produce, using SBS technique, porous membranes made up of NR microfibers, NR microfibers incorporated with vulcanizing agents (BN4V), NR microfibers incorporated with carbon black (CB) and NR microfibers incorporated with vulcanizing agents and CB particles. The microfibers showed a flattened morphology with average widths ranging from (15 ± 6) μm to (101 ± 9) µm, depending on the processing conditions. The BN4V microfiber membranes, subjected to heat treatment at 90°C for 3 h, presented the highest values of resistance to rupture and deformation to rupture, (4.9 ± 0.8) MPa and 867%, respectively. Membranes with CB incorporated showed a reduction in rupture resistance, deformation to rupture and hydrophilicity, when compared to the sample BN4V (90°C for 3 h). On the other hand, an increase of up to 9 orders of magnitude in electrical conductivity was achieved. The percolation threshold was found to be around 7.4 wt% of CB. DSC analyzes of NR fibrous membranes, incorporated or not with CB, vulcanized or not, showed a glass transition temperature in the range of –65°C to –61°C. Thermogravimetric analyzes indicated that the samples are thermally stable below 150°C. In piezo-resistive analyzes, the deformation sensor under several charge-discharge cycles, exhibits stability and repeatability in electrical resistance responses with a gauge factor around 3 for the sample with 10 wt% of CB.
Currently, materials with micrometric and nanometric dimensions have been extensively studied due to the possibility of developing functional materials. The incorporation of nano/microparticles in the fibers allows a range of applications in several areas. In this scenario, polymeric nano/microfibers have gained a lot of prominence for applications such as sensors, filters, drug carriers, piezo-resistive materials, among others. These structures have been produced mainly by the electrospinnig technique and since 2009 also by the solution blowing spinning (SBS) technique. The production of porous membranes obtained from micro/nanofibers of natural rubber (NR), has been a challenge due to its high retraction after stretching. In this sense, the present work had as main objective to develop a methodology to produce, using SBS technique, porous membranes made up of NR microfibers, NR microfibers incorporated with vulcanizing agents (BN4V), NR microfibers incorporated with carbon black (CB) and NR microfibers incorporated with vulcanizing agents and CB particles. The microfibers showed a flattened morphology with average widths ranging from (15 ± 6) μm to (101 ± 9) µm, depending on the processing conditions. The BN4V microfiber membranes, subjected to heat treatment at 90°C for 3 h, presented the highest values of resistance to rupture and deformation to rupture, (4.9 ± 0.8) MPa and 867%, respectively. Membranes with CB incorporated showed a reduction in rupture resistance, deformation to rupture and hydrophilicity, when compared to the sample BN4V (90°C for 3 h). On the other hand, an increase of up to 9 orders of magnitude in electrical conductivity was achieved. The percolation threshold was found to be around 7.4 wt% of CB. DSC analyzes of NR fibrous membranes, incorporated or not with CB, vulcanized or not, showed a glass transition temperature in the range of –65°C to –61°C. Thermogravimetric analyzes indicated that the samples are thermally stable below 150°C. In piezo-resistive analyzes, the deformation sensor under several charge-discharge cycles, exhibits stability and repeatability in electrical resistance responses with a gauge factor around 3 for the sample with 10 wt% of CB.
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Palavras-chave
borracha natural, membrana porosa elastomérica, fiação por sopro, natural rubber, porous elastomeric membrane, solution blow spinning