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The morphological, thermal and non-isothermal crystallization behavior of poly(vinylidene fluoride) (PVDF) and its blends with poly(methyl methacrylate) (PMMA) processed in low (LSM) and high (HSM) shear mixers were studied by differential scanning calorimetry (DSC). The processing effect on the PVDF melt and crystallization kinetics was described and the effect of PMMA on the PVDF crystallization was also investigated. The addition of PMMA into PVDF increases of relative B phase content independent of the processing conditions. The validity of the modified Avrami and Kolmogorov-Johnson-Mehl-Avrami (KJMA) models for the non-isothermal crystallization of PVDF/PMMA blends are discussed. The KJMA method described accurately the non-isothermal crystallization behavior. The results showed a shift in the PVDF crystallization/fusion peak to lower temperatures. The activation energies for crystallization of PVDF and its blends evaluated through the isoconversional method using Friedman's approximation were higher for samples processed in the LSM. Differences in the activation energies were related to the ability of the molecular segments to crystallize when reaching the growing crystallization front, confirming that the mixing process has some effect on the interaction between the polymers. On the other hand, the isoconversional methods in combination with the KJMA equation provide better understanding of the kinetics of the crystallization process demonstrated by a strongly dependence of activation energy (Ea), relative crystalline fraction (XT), and global and local Avrami exponents (n and n (XT)).

The sisal rope was cut into 3 cm long fibers and the fibers were washed (100 mL of water per gram of fiber) in distilled water for 30 minutes. The fibers were dried in an oven with ventilation for 180 minutes at 60 °C.

This chapter provides a brief overview of the agricultural context of cotton in Brazil, providing a broad perspective of the different geographical, social, ecological and economic circumstances under which cotton is cultivated. It covers the genetic diversity, geographical distribution, morphology, physiology and development of cotton and describes the species diversity associated with cotton in Brazil.It also describes the three main production areas in Brazil (which differ significantly in their topographical, climatic, ecological and socioeconomic characteristics), and the corresponding productivity, farming systems and economic status of the farmers in these areas. It identifies the main biological and socioeconomic constraints to cotton production and summarizes the main pest problems, contextualizing the target Lepidoptera within the broader pest complex. It introduces integrated pest management as a possible solution to pest problems.

Neste trabalho são apresentados e discutidos os resultados das propriedades mecânicas de novos materiais compósitos preparados com resíduos de fibras têxteis poliméricas e de polímeros commodities. As fibras naturais oferecem vantagens sobre as sintéticas, em termos de propriedades mecânicas e térmicas. Os compósitos foram preparados a partir da mistura de polietileno de alta densidade (HDPE) e resíduos de fibras têxteis (50% algodão /50% acrílico) em teores crescentes de 10 a 40%, em um misturador de alta velocidade, utilizando Surlyn 2601, Polybond 3009 e Polybond 1009 como agentes compatibilizantes. Corpos-de-prova para ensaios de tração, flexão e impacto foram produzidos a partir de chapas obtidas em uma prensa hidráulica. Os compósitos que utilizaram agentes compatibilizantes apresentaram os melhores resultados de resistência à tração e à flexão, principalmente com 5% do agente Polybond 3009 e 20 a 40% de resíduos de fibras têxteis.

In this study, composites were made with wood sawdust residues and a polyolefi n. Experiments were carried out in order to analyze different parameters for processing the composites. The parameters analyzed were the sawdust/polymer ratio and the type of coupling agent. The sawdust and the polymer were mixed in a single extruder in order to produce profi les. The results showed that the composites made of HDPE and sawdust had good mechanical properties, suitable for industrial applications. These results, together with the availability of the residues in the northeast of Rio Grande do Sul state, (Brazil), makes these composites a good alternative for the use of residues.

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