Compatibilization of polypropylene/poly(3-hydroxybutyrate) blends

Blending polypropylene (PP) with biodegradable poly(3-hydroxybutyrate) (PHB) can be a nice alternative to minimize the disposal problem of PP and the intrinsic brittleness that restricts PHB applications. However, to achieve acceptable engineering properties, the blend needs to be compatibilized because of the immiscibility between PP and PHB. In this work, PP/PHB blends were prepared with different types of copolymers as possible compatibilizers: poly(propylene-g-maleic anhydride) (PPMAH), poly (ethylene-co-methyl acrylate) [P(EMA)], poly(ethylene-co-glycidyl methacrylate) [P(EGMA)], and poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) [P(EMAGMA)]. The effect of each copolymer on the morphology and mechanical properties of the blends was investigated. The results show that the compatibilizers efficiency decreased in this order: P(EMAGMA) > P(EMA) > P(EGMA) > PP-MAH; we explained this by taking into consideration the affinity degree of the compatibilizers with the PP matrix, the compatibilizers properties, and their ability to provide physical and/or reactive compatibilization with PHB. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 3511-3519, 2012Fundacao de Amparo a Pesquisa do Estado de Sao PauloCoordenacao de Aperfeicoamento de Pessoal de Nivel SuperiorConselho Nacional de Desenvolvimento Cientifico e Tecnologico (Brazil

Thermal Transport and Rheological Properties of Hybrid Nanofluids Based on Vegetable Lubricants

Nanofluids based on vegetal oil with different wt.% of carbon nanotubes (CNT), hexagonal boron nitride (h-BN), and its hybrid (h-BN@CNT) were produced to investigate the effects of these nano-additives on the thermal conductivity and rheological properties of nanofluids. Stable suspensions of these oil/nanostructures were produced without the use of stabilizing agents. The dispersed nanostructures were investigated by SEM, EDS, XRD, and XPS, while the thermal conductivity and rheological characteristics were studied by a transient hot-wire method and steady-state flow tests, respectively. Increases in thermal conductivity of up to 39% were observed for fluids produced with 0.5 wt.% of the hybrid nanomaterials. As for the rheological properties, it was verified that both the base fluid and the h-BN suspensions exhibited Newtonian behavior, while the presence of CNT modified this tendency. This change in behavior is attributed to the hydrophobic character of both CNT and the base oil, while h-BN nanostructures have lip-lip “bonds”, giving it a partial ionic character. However, the combination of these nanostructures was fundamental for the synergistic effect on the increase of thermal conductivity with respect to their counterparts

Photodegradation of composite obtained by the addition of colloidal silicon dioxide in the blend PBA/PLA

Este trabalho tem por objetivo avaliar o efeito da silica coloidal no processo de fodegradação da blenda de poli (adipta de butileno-co-tereflato de butileno)/poli (ácido láctico) - PBAT/PLA . Os compósitos de PBA/PLA com adição de sílica coloidal com composições de 5% e 10% em massa de silica foram obtidos pelo método de intercalação no polímero fundido em uma extrusora de dupla rosca. as amostras foram expostas à radiação UV por tempos de até 40 dias e caracterização por análises de espectroscopia vibracional de absorção no infravermelho (FTIR)

Photodegradation of poly(3-hydroxybutyrate)

The effect of ultraviolet radiation on the properties of poly(3-hydroxybutyrate) (PHB) was studied. The PHB investigated is produced from microbial fermentation using saccharose from sugarcane as the carbon source to the bacteria. The material was exposed to artificial UV-A radiation for 3, 6, 9 and 12 weeks. The photodegradation effect was followed by changes of molecular weight, of chemical and crystalline structures, of thermal, morphological, optical and mechanical properties, as well as of biodegradability. The experimental results showed that PHB undergoes both chain scission and cross-linking reactions, but the continuous decrease in its mechanical properties and the low amount of gel content upon UV exposure indicated that the scission reactions were predominant. Molar mass, melting temperature and crystallinity measurements for two layers of PHB samples with different depth suggested that the material has a strong degradation profile, which was attributed to its dark colour that restricted the transmission of light. Previous photodegradation initially delayed PHB biodegradability, due to the superficial increase in crystallinity seen with UV exposure. The possible reactions taking place during PHB photodegradation were presented and discussed in terms of the infrared and nuclear magnetic resonance spectra. A reference peak (internal standard) in the infrared spectra was proposed for PHB photodegradation. (C) 2010 Elsevier Ltd. All rights reserved.FAPESPCAPESCNP

Evaluation of thermostabilization of PLA/PBAT blend by using torque rheometer

Este trabalho teve como objetivo avaliar antioxidantes (primários e secundários) no processo de estabilização térmica da blenda PLA/PBAT usando um reômetro de torque como ferramenta prévia de avaliação do processo de estabilização. Os processamentos em um misturador interno acoplado com um reômetro de torque mostraram-se ser uma boa ferramenta para avaliar o poder estabilização dos aditivos aqui usados

Fotodegradação de compósitos de poliestireno/argila montmorilonita: efeito do tipo de argila e presença de sal Photodegradation of polystyrene/montmorillonite clay: the effect of the type of clay and presence of salt

Compósitos de poliestireno/montmorilonita (PS/MMT) contendo 2,5% em peso de argila foram preparados com dois tipos de argila modificada com sais quaternários de amônio. Também foram preparadas amostras do PS + sal quaternário de amônio, utilizando-se proporção de sal semelhante à usada na modificação da argila. Todas as amostras foram expostas à radiação UV por períodos de até 12 semanas, e em seguida foram realizados testes para avaliar as modificações em massa molar, propriedades mecânicas (tração e impacto), estrutura química (FTIR) e superfície de fratura (MEV) dessas amostras. Os resultados mostraram que compostos metálicos existentes na argila catalisam o processo fotodegradativo do PS e a presença isolada do sal não altera significativamente o comportamento do PS frente à radiação UV.<br>Composites of polystyrene/montmorillonite (PS/MMT) containing 2.5 wt. (%) clay were prepared with two types of clays modified with quaternary ammonium salts. Were also prepared samples of PS + quaternary ammonium salt, using the same amount employed in modifying the clay. All samples were exposed to UV radiation for up to 12 weeks, and then tests were conducted to evaluate the changes in molecular weight, mechanical properties (tensile and impact), chemical structure (FTIR) and fracture surface (SEM) of these samples. The results showed that metal compounds existing in clay catalyzes the photodegradation process of PS and the presence of salt alone does not significantly alter the behavior of PS under UV

Estudo do efeito do tipo de polipropileno na fotodegradação da blenda polipropileno/poliestireno de alto impacto Influence of the type of polypropylene on the photodegradation of blends of polypropylene/high impact polystyrene

Este trabalho visa avaliar a influência do tipo de polipropileno no comportamento da blenda polipropileno/poliestireno de alto impacto (PP/HIPS) quando exposta à radiação UV. Foram usados uma resina virgem de PP (PPv) e outra reprocessada (PPrep). Inicialmente, avaliou-se o comportamento individual dos componentes da blenda, HIPS, PPv e PPrep, quando submetidos à radiação UV por até 15 semanas de exposição. As técnicas de caracterização utilizadas para monitorar o desempenho tanto das resinas individualmente quanto das blendas submetidas à radiação UV foram: propriedades mecânicas (tração e impacto), medidas de índice de fluidez (MFI), análise térmica (DSC), espectroscopia no infravermelho (FTIR) e microscopia eletrônica de varredura (MEV). A partir dos resultados com essas técnicas verificou-se que o PPv foi a resina mais afetada pela radiação e consequentemente as blendas preparadas com esse PP também foram mais sensíveis à fotodegradação do que as demais. Em termos de fotoestabilização este resultado mostra-se interessante, já que as blendas PP/HIPS preparadas com uma resina previamente degradada necessitariam de menores teores de aditivos do que esse mesmo tipo de blenda preparada com resina virgem.The influence from the type of polypropylene on the photodegradation resistance of blends of polypropylene/high impact polystyrene (PP/HIPS) was studied. A virgin polypropylene (PPv) and another sample that suffered prior thermo-mechanical degradation (PPrep) were used. All materials, components of the blends and blends were exposed to UV radiation for up to 15 weeks. They were characterized as a function of time of UV exposure using differential scanning calorimetry (DSC), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The mechanical (tensile and impact) properties and melt flow indexes of the materials were also evaluated. The experimental results revealed that PPv resin and its blends were more sensitive to UV radiation than PPrep and its blends. In terms of photostabilization this finding is very interesting, since PP/HIPS blends prepared with a previously degraded polyolefin would require smaller amounts of additives than the same kind of blends prepared with virgin resin

The role of shear and stabilizer on PLA degradation

The role of temperature, shear and oxygen on PLA degradation was investigated. Thermo-mechanical degradation induces a larger decrease in PLA molecular weight than thermo-oxidative degradation. This was associated with different degradation processes (mainly chain scission) that took place under the two conditions. Given the PLA robustness to endure reprocessing, it was possible to conclude that the primary and secondary antioxidant (B900) had a synergetic effect on PLA stability.The authors acknowledge the n-STeP - Nanostructured systems for Tailored Performance, with reference NORTE-07-0124-FEDER-000039, supported by the Programa Operacional Regional do Norte (ON.2), PEst-C/CTM/LA0025/2013 (Strategic Project - LA 25 - 2013-2014) and PEST-C/QUI/UIO686/2013. Acknowledges are also due to the NMR Portuguese network (PTNMR, Brucker Avance III 400-Univ. Minho). GIMP is grateful to FAPESP (Process 2010/07651-9) and CNPq (Process 304902/2012-8) Brazilian funding agencies for the financial support.info:eu-repo/semantics/publishedVersio