Navegando por Palavras-chave "Síntese De Polímeros"

Agora exibindo 1 - 1 de 1
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Desenvolvimento De Látexes Híbridos De Estireno/Acrilato De N-Butila/Lignina Via Polimerização Em Emulsão E Miniemulsão
    (Universidade Federal de São Paulo (UNIFESP), 2017-03-03) Messmer, Nigel Roderick [UNIFESP]; Oliveira, Mauricio Pinheiro De [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The use of Kraft Lignin (KL) to produce hybrid latexes has received much attention in recent years because it is derived from renewable resources, is available in large quantities from the pulp and paper industry and also contributes to reducing the final cost of the product. This study’s objective is to develop organic/organic hybrid latex by emulsion and miniemulsion polymerization techniques to synthesize copolymers of styrene (St), n-butyl acrylate (ABu), and methacrylic acid (AMA) with different concentrations of KL. The study intends to understand the effect of the KL on the properties not only of the latexes, but also on the copolymers themselves. The emulsion polymerizations were conducted varying 2 parameters: different concentrations of KL (0; 0,5; 1,0; and 2,0%), and different intervals of time between shots. The resulting latexes were characterized in relation to global conversion, average particle size and particle size distribution, zeta potential, residual monomer concentration and coagulum concentration, latex stability and particle morphology. The polymers were evaluated through thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy FTIR), nuclear magnetic resonance (1H-NMR), gel permeation chromatography (GPC) and waterabsorption as well relative hardness. Latexes with different concentrations of KL were produced via emulsion and miniemulsion polymerization. Independent of the polymerization technique, increases in KL concentration cause reduction of: overall conversion, reaction velocity, particle diameter and surface tension. Further, we observed that increasing the reaction time had a small effect on the final overall conversion though insufficient to achieve conversion levels exhibited in reactions without the presence of KL. Among the concentrations tested, the greatest concentration of KL, 2%, exhibited the greatest effect on the properties of the latexes and the copolymers (morphology, water-resistance, and molar mass). The presence of KL also altered the color of the latexes and of the copolymers limiting its use in certain industrial applications.