Sythesis and characterization of biodegradable grafted copolymers

This work aimed to prepare biodegradable copolymers based on ethylene vinyl acetate and polylactic acid using transesterification reactions. The materials were prepared in the melt and then characterized by elemental analysis, infrared spectroscopy, X-ray, scanning electron microscopy, gel permeation chromatography and rheology. Selective extractions for all samples were made, and the results indicate that a maximum of 25% of EVA-g-PLA copolymer was synthesized by this method. Biodegradation tests were carried out using the standard ISO 14851 (1999), which specifies a method for determining the biochemical oxygen demand in a closed respirometer. The results demonstrate that the procedure used allowed the synthesizes of biodegradable copolymers with mechanical properties similar to conventional polymers

Influence of EVA molar mass on preparation of EVA-g-PCL biobased copolymers

The rapid growth of plastic production is considered as a serious source of environment pollution. Approximately 100 million tons of plastics are produced each year and within a short period of time almost half are disposed to the environment. A way to overcome this problem would be the use of biodegradable polymers. Several attempts are made to replace synthetic polymers by biodegradable ones. Nevertheless, they did not prove yet to be useful for commercial applications due to their high price or limitations in terms of thermal and mechanical properties. Alternative to biodegradable polymers are biobased polymers, which can be prepared by blending or copolymer formation of a biodegradable and a synthetic polymer. Thus, the present work aims to prepare copolymers of ethyl vinyl acetate (EVA) and poly(ξ-caprolactone) (PCL), EVA-g-PCL, and to study the influence of the molar mass of EVA on copolymer formation and its properties. The materials were prepared in a internal batch mixer using titanium propoxide (Ti(OPr)4) as catalyst. Characterization was performed by selective extraction of the formed copolymers, SEM, FTIR, rheology, DSC, TGA and tensile properties. Morphological results by SEM evidence copolymer formation, the particle size of the dispersed phase decreases as the EVA molar mass decreases. The tensile properties of the prepared materials are similar to the ones of synthetic polymers. The biodegradability, evaluated based on biochemical oxygen demand method, showed that biodegradability increases as the EVA molar mass increases.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/29802/200

Morphology development in EVA/PDMS blends by carbonyl hydrosylilation

International audienc

Morphology development in EVA/PDMS blends by carbonyl hydrosylilation

International audienc

Influence of a non-polar medium (alkane and molten polypropylene) on the titanium n-butoxide hydrolysis-condensation reactions

International audienceStudy of hydrolysis-condensation reactions of titanium n-butoxide precursor into an unusual medium and non-classical conditions was carried out. Kinetic data were reached in a temperature range of 130-250A degrees C from FTIR, TGA-GC-MS and rheological techniques. These results were obtained into an alkane dispersing medium, (Squalane: 2,6,10,15,19,23-hexamethyltetracosane), and compared to the ones determined from the hydrolysis-condensation reactions of the titanium dioxide precursor carried in molten polypropylene (PP) during extrusion process. The transposition of these knowledge to the in situ synthesis of titanium dioxide in molten PP matrix by reactive extrusion lead to the formation of a fine dispersion of few nanometer diameter (similar to 5 nm) of TiO2 particles. Finally, the viscoelastic behaviour of the nanocomposite has been strongly altered in the terminal relaxation zone as permanent secondary plateau (solid-like behavior), attributed to some fractal arrangement of the inorganic domains was observed

A simple method for tuning the glass transition process in inorganic phosphate glasses

International audienceThe physical modification of glass transition temperature (T-g) and properties of materials via blending is a common practice in industry and academia and has a large economic advantage. In this context, simple production of hitherto unattainable new inorganic glass blends from already existing glass compositions via blending raises much hope with the potential to provide new glasses with new and improved properties, that cannot be achieved with classical glass synthesis, for a plethora of applications such as computers screens, glass-to-metal seals, and storage materials for nuclear wastes. Here, we demonstrate that blends of the specific glass compositions studied are miscible in all proportions, an unreported phenomenon in hard condensed matter like glass. Interestingly, excellent agreement was found between the obtained data and calculated T(g)s from theoretical equations (Supplementary information) for predicting the composition dependence of T-g for miscible blends with weak but significant specific interactions between the blend components. That this blending method is at present not applied to inorganic glasses reflects the fact that water and chemically resistant phosphate glasses with relatively low T(g)s have become available only recently

Synthesis of biodegradable copolymers

This work aimed to prepare biodegradable copolymers based on ethylene vinyl acetate and polylactic acid using transesterification reactions. The materials were characterized by elemental analysis, infrared spectroscopy, rheology, scanning electron microscopy and gel permeation chromatography. Selective extractions for all samples were made, and the results indicate that a maximum of 25% of EVA-g-PLA copolymer was synthesized by this method. Biodegradation tests were carried out using the standard ISO 14851 (1999) which specifies a method for determining the biochemical oxygen demand in a closed respirometer. This procedure allowed the synthesizes biodegradable copolymers with mechanical properties similar to conventional materials

Synthesis of biodegradable copolymers based on ethylene vinyl acetate and polylactic acid

In the present study biodegradable copolymers of ethylene vinyl acetate and polylactic acid were synthesized using transesterification reactions, the structure, morphology, mechanical properties and biodegradability of the produced materials were characterized. Ethylene vinyl acetate was modified with polylactic acid in an internal mixer using titanium propoxide as transesterification catalyst. The graft copolymers were characterized by elemental analysis, infrared spectroscopy, rheology, scanning electron microscopy and thermal analysis. Selective extractions for all copolymers were made, and the results indicate that a maximum of 25 % of EVA-g-PLA copolymer was synthesized by this method. Biodegradation tests were carried out using the standard ISO 14851 (1999), which specifies a method for determining the biochemical oxygen demand in a closed respirometer. This procedure allowed to synthesize biodegradable copolymers with mechanical properties similar to conventional polymers

Effect of PCL and EVA molar mass on the development of sustainable polymers

Biodegradable grafted copolymers, EVA-g-PCL, have been synthesized by reactive extrusion, through transesterification reaction between ethylene-vinyl acetate copolymer (EVA) and poly(ε-caprolactone) (PCL) using titanium propoxide (Ti(OPr)4) as catalyst. The effect of EVA and PCL molar mass on the amount of grafted copolymer and materials properties was investigated. The prepared blends were characterized by several analytical techniques, such as, selective extractions, rheology, TGA, DSC, SEM, mechanical properties, and the biodegradability was evaluated based on biochemical oxygen demand method. The results showed that the amount of copolymer increases as the amount of catalyst increases. Moreover, using EVA and PCL with high and low molar mass, respectively, allowed to obtain a material exhibiting properties similar to conventional polymers and higher biodegradability.The authors acknowledge the financial support given by FCT through the project PTDC/AMB/73854/2006 and the PhD grant SFRH/BD/29802/2006

Grafting of PCL to EVA by reactive processing: effect of PCL molar mass

Biobased graft copolymers, EVA-g-PCL, has been synthesized by transesterification reaction between EVA and PCL, using titanium propoxide Ti(OPr)4 as catalyser. The extent of the grafting reaction was estimated from the amount of copolymer extracted. Characterization of the copolymer formation was also performed using several analytical techniques, such as, SEM, TGA, DSC and XPS. Oxygen measurements were carried out to monitor the biodegradability of the prepared materials. The results obtained showed this method is an efficient way to enhance EVA biodegradability.Fundação para a Ciência e a Tecnologia (FCT