Derval dos Santos Rosa | UFABC - Federal University of ABC (original) (raw)
Papers by Derval dos Santos Rosa
Polymer Testing, 2000
Sample preparation and test conditions are parameters recognised to influence Oxidative Induction... more Sample preparation and test conditions are parameters recognised to influence Oxidative Induction Time (OIT) results obtained by Differential Scanning Calorimetry (DSC). Therefore, many laboratory practices have been written to prevent this interference. However, quantitative results on the variability of OIT as a function of these parameters have not been presented systematically in the literature. The following parameters were investigated using a two level factorial design and High Density Polyethylene samples: (1) sample shape-pulverising and cutting pieces of sample; (2) amount of sample-2 and 8 mg; (3) heating rates to reach the isotherm-fast and 10°C/min; (4) oxygen flow-20 and 60 ml/min. Sample shape, amount of sample and heating rate were the parameters that showed significant variability. Higher order interactions were considered negligible. Finally, the variation of the parameters under assessment was described by a linear model obtained with the aide of the chemometric method of Yates' Algorithm.
Effects of the compatibilizer PE‐g‐GMA on the mechanical, thermal and morphological properties of... more Effects of the compatibilizer PE‐g‐GMA on the mechanical, thermal and morphological properties of virgin and reprocessed LDPE/corn starch blends
The inappropriate storage of solid wastes, particularly those containing polymeric materials, is ... more The inappropriate storage of solid wastes, particularly those containing polymeric materials, is a serious cause of environmental pollution and has led to much investigation on the use of biodegradable polymers. In this work, we examined the biodegradation properties of different blends of the binary system poly(?-caprolactone) (PCL) and cellulose acetate (CA). The parameters assessed included the change in mass during aging in simulated soil, the occurrence of morphological alterations and the tensile strength at break. The incorporation of PCL improved the biodegradation rates of the blends, with those that had the highest phase separations also showing the greatest morphological alterations, probably because of polymer chain hydrolysis.
Progress in Rubber, Plastics and Recycling Technology
The storage of post-consumer unsaturated polyester/glass fibre composites impacts negatively on t... more The storage of post-consumer unsaturated polyester/glass fibre composites impacts negatively on the environment due to its persistence (long lifetime of both the glass fibre and the resin) as well as the high volume/weight ratio of the residues. In this work we introduce a new approach for the recycling process of artefacts made of these polyester/glass fibre composites that involves the dispersion of the ground, not powdered, composite in raw polyester resin. Room temperature resin curing was employed. Flexural and impact tests were performed to optimize the processing conditions and the manufacturing process. Significant improvement in texture, flexural strength and impact resistance of sheets were achieved by pressing and heating the sheets at 40∞C and 50∞C during curing. The artefacts utilized in our work were post-consumer public telephone weather protector caps, which, in Brazil, are manufactured with a composite of unsaturated polyester/glass fibre. Although we used this spec...
The polymer polyethylene (PE) is a flexible, light, transparent and impermeable material, which i... more The polymer polyethylene (PE) is a flexible, light, transparent and impermeable material, which it takes it more than a hundred years to be degraded. One of the possible solutions for this low rate of degradability is applying the biodegradable polymer, that is, polymers that present their chemical structure modified by the action of the microorganisms. The main of this work is to evaluate the (bio)degradation of low-density polyethylene (LDPE) modified by the incorporation of CESA-BIO PEA0420086-ZN addictive under natural and thermal ageing. The incorporation of the addictive to the LDPE didn't cause any effect on its degradable, but, after a period of either thermal or natural ageing, the functions of ox-degradation were activated and meaningful reductions of the properties analyzed were reached, which are directly proportional to the amount of addictive preset in the composition. The results on the mechanical properties showed that 1% of the addictive caused a reduction of 75% for the compositions exposed to a thermal treatment; meanwhile a 50% reduction was reached by those under a natural treatment.
Biodegradable polymers are an alternative to replace traditional plastics that presents short lif... more Biodegradable polymers are an alternative to replace traditional plastics that presents short lifetime. The aim of this study was to assess the properties of polyhydroxybutyrate (PHB)/low-density polyethylene (LDPE) blends modified by the addition of oxidized polyethylene wax (OPW) and manganese stearate (MnS). The compositions (PHB/LDPE OPW5/MnS2.5 100/0, 75/25, 50/50, 25/75 and 0/100, w/w %) were evaluated by FTIR, MFI, tensile strength, SEM and biodegradation in simulated soil by 3 conditions: a) without previous aging; b) after natural aging and c) after thermal aging, both for 30 days. The biodegradation of the polymers was evaluated by loss of mass after buried in simulated soil. MnS promoted higher intensity to CO linkage of LDPE. MFI were inferior to the blends compared to the pure polymers. LDPE OPW5/MnS2.5 to PHB reduced the tensile strength at break, increased the elongation, and higher amount of PHB increased de Young's modulus. The polymers are immiscible and presents poor interfacial adhesion. Thermal aging promoted the degradation of LDPE OPW5/MnS2.5 , and PHB maintained its biodegradation for all conditions.
Polymer Testing, 2008
Biodegradable polymers represent a promising solution to the environmental problem of plastic was... more Biodegradable polymers represent a promising solution to the environmental problem of plastic waste disposal. Among the candidate polymers, starch, a low-cost natural polymer, can be processed as a thermoplastic. In this work, thermoplastic starch containing glycerol (20, 30 or 40 wt%) was prepared by extrusion. The mechanical properties of the blends were assessed by tensile stress at break, elongation at break and Young's modulus. Nuclear magnetic resonance (NMR), through proton spin-lattice relaxation (T 1 H) measurements, was used to understand the molecular dynamic of the samples. The morphology of the films was assessed by electron scanning microscopy (SEM). The susceptibility to enzymatic degradation was assessed in films incubated with a-amylase in acetate buffer. The loss of mass was determined after 1, 2, 3, 6, 9, 12 and 24 h of enzymatic digestion. The results obtained showed that all of the mechanical properties were improved by the addition of 20% glycerol, but decreased with higher concentrations of glycerol. The amount of free glucose released into the solution during digestion was quantified using a commercial glucose kit. Starch containing 40% glycerol degraded faster than the other blends, because it facilitated the efficiency of the gelatinization process and also the phase separation, as shown by the proton spin-lattice relaxation time. The amount of glucose released was directly proportional to the glycerol content of the samples. These results suggested a short lifetime for this blend, which is in agreement with the values of the T 1 H relaxation parameter that suggests a decrease of the average molecular weight.
Cerâmica, 2006
Cerâmicas porosas têm sido utilizadas em diversas aplicações tecnológicas como coletores de partí... more Cerâmicas porosas têm sido utilizadas em diversas aplicações tecnológicas como coletores de partículas sólidas, isolantes térmicos e acústicos. As áreas de biotecnologia e biomedicina utilizam cerâmicas porosas como reatores em processos de fermentação e em implantes, respectivamente. Adicionalmente, estes materiais apresentam grande aplicação na área de microfiltração de líquidos e emulsões, como a purificação de combustíveis através da separação da água e óleo, e na separação das proteínas do leite. O objetivo deste trabalho é o de produzir tubos de cerâmicas porosas para microfiltração de combustíveis. A primeira etapa compreendeu a produção de tubos cerâmicos porosos por colagem de suspensões e avaliação de suas propriedades físicas, fluidodinâmicas e mecânicas finais. Já a segunda etapa consistiu na análise do desempenho destes tubos durante a microfiltração de combustíveis. As propriedades finais das cerâmicas porosas foram avaliadas em função das variações na composição da su...
The storage of post-consumer unsaturated polyester/glass fibre composites impacts negatively on t... more The storage of post-consumer unsaturated polyester/glass fibre composites impacts negatively on the environment due to its persistence (long lifetime of both the glass fibre and the resin) as well as the high volume/weight ratio of the residues. In this work we introduce a new approach for the recycling process of artefacts made of these polyester/glass fibre composites that involves the dispersion of the ground, not powdered, composite in raw polyester resin. Room temperature resin curing was employed. Flexural and impact tests were performed to optimize the processing conditions and the manufacturing process. Significant improvement in texture, flexural strength and impact resistance of sheets were achieved by pressing and heating the sheets at 40∞C and 50∞C during curing. The artefacts utilized in our work were post-consumer public telephone weather protector caps, which, in Brazil, are manufactured with a composite of unsaturated polyester/glass fibre. Although we used this specific artefact, the methodology can be extended to different types of post-consumer materials or industrial scraps.
Journal of Composite Materials, 2014
Cardanol–formaldehyde thermoset resin was reinforced with raw and chemically modified fibers of b... more Cardanol–formaldehyde thermoset resin was reinforced with raw and chemically modified fibers of bamboo ( Bambusoideae). Modified fibers were treated with alkali solutions of NaOH (5% and 10%) and bleached with sodium hypochlorite NaClO/H2O (1:1) at 60℃–75℃. The biocomposites were fabricated with a hand lay-up technique. This study investigated the fibers microstructure before and after alkali treatment, as the interaction between matrix and reinforce by scanning electron microscopy. The Fourier transform infrared spectra allowed the identification of characteristic stretching frequencies attributed to the methyl groups of lignin. A considerable increase in thermal stability was observed in the materials studied, which was verified by thermogravimetric analysis and confirmed by X-ray diffraction. The tensile tests showed that the mechanical properties (tensile modulus, tensile strength, and elongation at break) of bamboo fibers improved after alkali treatment, as well as the increase...
Journal of Vinyl and Additive Technology, 2015
ABSTRACT Despite poly(vinyl chloride) (PVC) being one of the most useful materials available to t... more ABSTRACT Despite poly(vinyl chloride) (PVC) being one of the most useful materials available to the fabricator, its inadequate disposal has contributed to strong noneconomic issues based on the allegedly evil effects of chlorine. In this study, we examined the influence of adding starch, a biodegradable bioplastics, to mixtures of PVC plasticized with di(2-ethylhexyl) adipate (which is susceptible to fungal attack). PVC and its mixtures were assessed by mechanical properties, differential scanning calorimetry, Fourier-transform infrared spectroscopy, low-field nuclear magnetic resonance, thermogravimetric analysis, optical microscopy, and degradation in simulated soil. Increasing the amount of starch in the mixtures resulted in greater material stiffness, with a reduction in tensile strength at break (σ) and elongation at break (ɛ). Fourier-transform infrared spectroscopy and nuclear magnetic resonance showed that there was limited interfacial interaction between components of the PVC mixtures, which agreed with slight phase separation (breakage of the interfaces) and the decrease in the values of σ and ɛ for the mixtures. Samples containing a larger content of starch showed little weight loss after 2, 4, and 6 months in simulated soil, possibly because the starch was encapsulated by the PVC resin. J. VINYL ADDIT. TECHNOL., 2015. © 2015 Society of Plastics Engineers
Polímeros Ciência e Tecnologia, 2013
Resumo: O interesse por polímeros biodegradáveis tem aumentado devido ao baixo impacto ambiental ... more Resumo: O interesse por polímeros biodegradáveis tem aumentado devido ao baixo impacto ambiental dos mesmos. No entanto, muitos desses produtos disponíveis no mercado são frágeis, difíceis de processar e têm alto custo. Uma das técnicas para superar essas deficiências é através de blenda com outros polímeros. Este trabalho avaliou várias composições de blenda PHB/PP, utilizando-se um aditivo pró-degradante deste último, de forma a tornar a formulação oxibiodegradável em solo simulado (ASTM D6003). O comportamento mecânico, térmico e químico de corpos de prova de tração das amostras enterradas foi acompanhado através de medidas de resistência à tração, DSC, FTIR, GPC e SEM. Parte das amostras foi envelhecida em estufa a 90 °C por 10 dias, de forma a acelerar a oxidação do PP pelo aditivo. A blenda composta por 56 wt% de PP / 40 wt% de PHB / 3 wt% de GMA / 1 wt% de MnSt foi a mais susceptível à oxibiodegradação, tendo reduzido depois de 180 dias de enterramento em solo, a tensão de tração em 40%, alongamento na ruptura em 46% e a massa em 24%. Estes valores foram superiores ao próprio PHB puro e o efeito sinérgico ocorrido nestas blendas foi atribuído à aceleração da degradação do PHB pelo PP oxidado.
Polymer Testing, 2008
Biodegradable polymers represent a promising solution to the environmental problem of plastic was... more Biodegradable polymers represent a promising solution to the environmental problem of plastic waste disposal. Among the candidate polymers, starch, a low-cost natural polymer, can be processed as a thermoplastic. In this work, thermoplastic starch containing glycerol (20, 30 or 40wt%) was prepared by extrusion. The mechanical properties of the blends were assessed by tensile stress at break, elongation at break
Polímeros, 2009
RESUMO Polímeros sintéticos são largamente utilizados em diversos produtos devido às suas proprie... more RESUMO Polímeros sintéticos são largamente utilizados em diversos produtos devido às suas propriedades físicas, químicas e facilidade de transformação. O poli (cloreto de vinila), conhecido como PVC, é um dos polímeros mais versáteis desenvolvidos pelo homem, de ...
Polymers for Advanced Technologies, 2005
ABSTRACT
Polymer Testing, 2004
The biodegradation of poly-β-(hydroxybutyrate) (PHB) and poly-β-(hydroxybutyrate-co-β-valerate) (... more The biodegradation of poly-β-(hydroxybutyrate) (PHB) and poly-β-(hydroxybutyrate-co-β-valerate) (PHB-V) was assessed by the loss of mass, tensile strength and roughness of the polymer. The melting temperature and crystallinity were also determined. Both polymers showed similar biodegradation in soil composting medium at 46°C and at room temperature (24°C) and in a soil simulator. PHB-V had the lowest crystallinity values and PHB had the highest. Soil composting medium at 46°C favoured the biodegradation of PHB and PHB-V based on the loss of mass. After ageing in soil composting medium at 46°C for 86 days, both polymers showed a decrease in the tensile strength at break (76% for PHB and 74% for PHB-V). In agreement with this, the roughness of both polymers increased faster in soil composting medium at 46°C. These results suggest that roughness may be a useful parameter for evaluating the biodegradation of polymers.
Polymer Testing, 2000
Sample preparation and test conditions are parameters recognised to influence Oxidative Induction... more Sample preparation and test conditions are parameters recognised to influence Oxidative Induction Time (OIT) results obtained by Differential Scanning Calorimetry (DSC). Therefore, many laboratory practices have been written to prevent this interference. However, quantitative results on the variability of OIT as a function of these parameters have not been presented systematically in the literature. The following parameters were investigated using a two level factorial design and High Density Polyethylene samples: (1) sample shape-pulverising and cutting pieces of sample; (2) amount of sample-2 and 8 mg; (3) heating rates to reach the isotherm-fast and 10°C/min; (4) oxygen flow-20 and 60 ml/min. Sample shape, amount of sample and heating rate were the parameters that showed significant variability. Higher order interactions were considered negligible. Finally, the variation of the parameters under assessment was described by a linear model obtained with the aide of the chemometric method of Yates' Algorithm.
Effects of the compatibilizer PE‐g‐GMA on the mechanical, thermal and morphological properties of... more Effects of the compatibilizer PE‐g‐GMA on the mechanical, thermal and morphological properties of virgin and reprocessed LDPE/corn starch blends
The inappropriate storage of solid wastes, particularly those containing polymeric materials, is ... more The inappropriate storage of solid wastes, particularly those containing polymeric materials, is a serious cause of environmental pollution and has led to much investigation on the use of biodegradable polymers. In this work, we examined the biodegradation properties of different blends of the binary system poly(?-caprolactone) (PCL) and cellulose acetate (CA). The parameters assessed included the change in mass during aging in simulated soil, the occurrence of morphological alterations and the tensile strength at break. The incorporation of PCL improved the biodegradation rates of the blends, with those that had the highest phase separations also showing the greatest morphological alterations, probably because of polymer chain hydrolysis.
Progress in Rubber, Plastics and Recycling Technology
The storage of post-consumer unsaturated polyester/glass fibre composites impacts negatively on t... more The storage of post-consumer unsaturated polyester/glass fibre composites impacts negatively on the environment due to its persistence (long lifetime of both the glass fibre and the resin) as well as the high volume/weight ratio of the residues. In this work we introduce a new approach for the recycling process of artefacts made of these polyester/glass fibre composites that involves the dispersion of the ground, not powdered, composite in raw polyester resin. Room temperature resin curing was employed. Flexural and impact tests were performed to optimize the processing conditions and the manufacturing process. Significant improvement in texture, flexural strength and impact resistance of sheets were achieved by pressing and heating the sheets at 40∞C and 50∞C during curing. The artefacts utilized in our work were post-consumer public telephone weather protector caps, which, in Brazil, are manufactured with a composite of unsaturated polyester/glass fibre. Although we used this spec...
The polymer polyethylene (PE) is a flexible, light, transparent and impermeable material, which i... more The polymer polyethylene (PE) is a flexible, light, transparent and impermeable material, which it takes it more than a hundred years to be degraded. One of the possible solutions for this low rate of degradability is applying the biodegradable polymer, that is, polymers that present their chemical structure modified by the action of the microorganisms. The main of this work is to evaluate the (bio)degradation of low-density polyethylene (LDPE) modified by the incorporation of CESA-BIO PEA0420086-ZN addictive under natural and thermal ageing. The incorporation of the addictive to the LDPE didn't cause any effect on its degradable, but, after a period of either thermal or natural ageing, the functions of ox-degradation were activated and meaningful reductions of the properties analyzed were reached, which are directly proportional to the amount of addictive preset in the composition. The results on the mechanical properties showed that 1% of the addictive caused a reduction of 75% for the compositions exposed to a thermal treatment; meanwhile a 50% reduction was reached by those under a natural treatment.
Biodegradable polymers are an alternative to replace traditional plastics that presents short lif... more Biodegradable polymers are an alternative to replace traditional plastics that presents short lifetime. The aim of this study was to assess the properties of polyhydroxybutyrate (PHB)/low-density polyethylene (LDPE) blends modified by the addition of oxidized polyethylene wax (OPW) and manganese stearate (MnS). The compositions (PHB/LDPE OPW5/MnS2.5 100/0, 75/25, 50/50, 25/75 and 0/100, w/w %) were evaluated by FTIR, MFI, tensile strength, SEM and biodegradation in simulated soil by 3 conditions: a) without previous aging; b) after natural aging and c) after thermal aging, both for 30 days. The biodegradation of the polymers was evaluated by loss of mass after buried in simulated soil. MnS promoted higher intensity to CO linkage of LDPE. MFI were inferior to the blends compared to the pure polymers. LDPE OPW5/MnS2.5 to PHB reduced the tensile strength at break, increased the elongation, and higher amount of PHB increased de Young's modulus. The polymers are immiscible and presents poor interfacial adhesion. Thermal aging promoted the degradation of LDPE OPW5/MnS2.5 , and PHB maintained its biodegradation for all conditions.
Polymer Testing, 2008
Biodegradable polymers represent a promising solution to the environmental problem of plastic was... more Biodegradable polymers represent a promising solution to the environmental problem of plastic waste disposal. Among the candidate polymers, starch, a low-cost natural polymer, can be processed as a thermoplastic. In this work, thermoplastic starch containing glycerol (20, 30 or 40 wt%) was prepared by extrusion. The mechanical properties of the blends were assessed by tensile stress at break, elongation at break and Young's modulus. Nuclear magnetic resonance (NMR), through proton spin-lattice relaxation (T 1 H) measurements, was used to understand the molecular dynamic of the samples. The morphology of the films was assessed by electron scanning microscopy (SEM). The susceptibility to enzymatic degradation was assessed in films incubated with a-amylase in acetate buffer. The loss of mass was determined after 1, 2, 3, 6, 9, 12 and 24 h of enzymatic digestion. The results obtained showed that all of the mechanical properties were improved by the addition of 20% glycerol, but decreased with higher concentrations of glycerol. The amount of free glucose released into the solution during digestion was quantified using a commercial glucose kit. Starch containing 40% glycerol degraded faster than the other blends, because it facilitated the efficiency of the gelatinization process and also the phase separation, as shown by the proton spin-lattice relaxation time. The amount of glucose released was directly proportional to the glycerol content of the samples. These results suggested a short lifetime for this blend, which is in agreement with the values of the T 1 H relaxation parameter that suggests a decrease of the average molecular weight.
Cerâmica, 2006
Cerâmicas porosas têm sido utilizadas em diversas aplicações tecnológicas como coletores de partí... more Cerâmicas porosas têm sido utilizadas em diversas aplicações tecnológicas como coletores de partículas sólidas, isolantes térmicos e acústicos. As áreas de biotecnologia e biomedicina utilizam cerâmicas porosas como reatores em processos de fermentação e em implantes, respectivamente. Adicionalmente, estes materiais apresentam grande aplicação na área de microfiltração de líquidos e emulsões, como a purificação de combustíveis através da separação da água e óleo, e na separação das proteínas do leite. O objetivo deste trabalho é o de produzir tubos de cerâmicas porosas para microfiltração de combustíveis. A primeira etapa compreendeu a produção de tubos cerâmicos porosos por colagem de suspensões e avaliação de suas propriedades físicas, fluidodinâmicas e mecânicas finais. Já a segunda etapa consistiu na análise do desempenho destes tubos durante a microfiltração de combustíveis. As propriedades finais das cerâmicas porosas foram avaliadas em função das variações na composição da su...
The storage of post-consumer unsaturated polyester/glass fibre composites impacts negatively on t... more The storage of post-consumer unsaturated polyester/glass fibre composites impacts negatively on the environment due to its persistence (long lifetime of both the glass fibre and the resin) as well as the high volume/weight ratio of the residues. In this work we introduce a new approach for the recycling process of artefacts made of these polyester/glass fibre composites that involves the dispersion of the ground, not powdered, composite in raw polyester resin. Room temperature resin curing was employed. Flexural and impact tests were performed to optimize the processing conditions and the manufacturing process. Significant improvement in texture, flexural strength and impact resistance of sheets were achieved by pressing and heating the sheets at 40∞C and 50∞C during curing. The artefacts utilized in our work were post-consumer public telephone weather protector caps, which, in Brazil, are manufactured with a composite of unsaturated polyester/glass fibre. Although we used this specific artefact, the methodology can be extended to different types of post-consumer materials or industrial scraps.
Journal of Composite Materials, 2014
Cardanol–formaldehyde thermoset resin was reinforced with raw and chemically modified fibers of b... more Cardanol–formaldehyde thermoset resin was reinforced with raw and chemically modified fibers of bamboo ( Bambusoideae). Modified fibers were treated with alkali solutions of NaOH (5% and 10%) and bleached with sodium hypochlorite NaClO/H2O (1:1) at 60℃–75℃. The biocomposites were fabricated with a hand lay-up technique. This study investigated the fibers microstructure before and after alkali treatment, as the interaction between matrix and reinforce by scanning electron microscopy. The Fourier transform infrared spectra allowed the identification of characteristic stretching frequencies attributed to the methyl groups of lignin. A considerable increase in thermal stability was observed in the materials studied, which was verified by thermogravimetric analysis and confirmed by X-ray diffraction. The tensile tests showed that the mechanical properties (tensile modulus, tensile strength, and elongation at break) of bamboo fibers improved after alkali treatment, as well as the increase...
Journal of Vinyl and Additive Technology, 2015
ABSTRACT Despite poly(vinyl chloride) (PVC) being one of the most useful materials available to t... more ABSTRACT Despite poly(vinyl chloride) (PVC) being one of the most useful materials available to the fabricator, its inadequate disposal has contributed to strong noneconomic issues based on the allegedly evil effects of chlorine. In this study, we examined the influence of adding starch, a biodegradable bioplastics, to mixtures of PVC plasticized with di(2-ethylhexyl) adipate (which is susceptible to fungal attack). PVC and its mixtures were assessed by mechanical properties, differential scanning calorimetry, Fourier-transform infrared spectroscopy, low-field nuclear magnetic resonance, thermogravimetric analysis, optical microscopy, and degradation in simulated soil. Increasing the amount of starch in the mixtures resulted in greater material stiffness, with a reduction in tensile strength at break (σ) and elongation at break (ɛ). Fourier-transform infrared spectroscopy and nuclear magnetic resonance showed that there was limited interfacial interaction between components of the PVC mixtures, which agreed with slight phase separation (breakage of the interfaces) and the decrease in the values of σ and ɛ for the mixtures. Samples containing a larger content of starch showed little weight loss after 2, 4, and 6 months in simulated soil, possibly because the starch was encapsulated by the PVC resin. J. VINYL ADDIT. TECHNOL., 2015. © 2015 Society of Plastics Engineers
Polímeros Ciência e Tecnologia, 2013
Resumo: O interesse por polímeros biodegradáveis tem aumentado devido ao baixo impacto ambiental ... more Resumo: O interesse por polímeros biodegradáveis tem aumentado devido ao baixo impacto ambiental dos mesmos. No entanto, muitos desses produtos disponíveis no mercado são frágeis, difíceis de processar e têm alto custo. Uma das técnicas para superar essas deficiências é através de blenda com outros polímeros. Este trabalho avaliou várias composições de blenda PHB/PP, utilizando-se um aditivo pró-degradante deste último, de forma a tornar a formulação oxibiodegradável em solo simulado (ASTM D6003). O comportamento mecânico, térmico e químico de corpos de prova de tração das amostras enterradas foi acompanhado através de medidas de resistência à tração, DSC, FTIR, GPC e SEM. Parte das amostras foi envelhecida em estufa a 90 °C por 10 dias, de forma a acelerar a oxidação do PP pelo aditivo. A blenda composta por 56 wt% de PP / 40 wt% de PHB / 3 wt% de GMA / 1 wt% de MnSt foi a mais susceptível à oxibiodegradação, tendo reduzido depois de 180 dias de enterramento em solo, a tensão de tração em 40%, alongamento na ruptura em 46% e a massa em 24%. Estes valores foram superiores ao próprio PHB puro e o efeito sinérgico ocorrido nestas blendas foi atribuído à aceleração da degradação do PHB pelo PP oxidado.
Polymer Testing, 2008
Biodegradable polymers represent a promising solution to the environmental problem of plastic was... more Biodegradable polymers represent a promising solution to the environmental problem of plastic waste disposal. Among the candidate polymers, starch, a low-cost natural polymer, can be processed as a thermoplastic. In this work, thermoplastic starch containing glycerol (20, 30 or 40wt%) was prepared by extrusion. The mechanical properties of the blends were assessed by tensile stress at break, elongation at break
Polímeros, 2009
RESUMO Polímeros sintéticos são largamente utilizados em diversos produtos devido às suas proprie... more RESUMO Polímeros sintéticos são largamente utilizados em diversos produtos devido às suas propriedades físicas, químicas e facilidade de transformação. O poli (cloreto de vinila), conhecido como PVC, é um dos polímeros mais versáteis desenvolvidos pelo homem, de ...
Polymers for Advanced Technologies, 2005
ABSTRACT
Polymer Testing, 2004
The biodegradation of poly-β-(hydroxybutyrate) (PHB) and poly-β-(hydroxybutyrate-co-β-valerate) (... more The biodegradation of poly-β-(hydroxybutyrate) (PHB) and poly-β-(hydroxybutyrate-co-β-valerate) (PHB-V) was assessed by the loss of mass, tensile strength and roughness of the polymer. The melting temperature and crystallinity were also determined. Both polymers showed similar biodegradation in soil composting medium at 46°C and at room temperature (24°C) and in a soil simulator. PHB-V had the lowest crystallinity values and PHB had the highest. Soil composting medium at 46°C favoured the biodegradation of PHB and PHB-V based on the loss of mass. After ageing in soil composting medium at 46°C for 86 days, both polymers showed a decrease in the tensile strength at break (76% for PHB and 74% for PHB-V). In agreement with this, the roughness of both polymers increased faster in soil composting medium at 46°C. These results suggest that roughness may be a useful parameter for evaluating the biodegradation of polymers.