Institute for Polymers and Composites

Portugal

Institute for Polymers and Composites

Portugal
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Cunha M.,Institute for Polymers and Composites | Berthet M.-A.,Montpellier University | Covas J.A.,Institute for Polymers and Composites | Hilliou L.,Institute for Polymers and Composites
Polymer Composites | Year: 2014

The high cost, narrow processing window, and poor mechanical properties of polyhydroxyalkanoates hamper their use as films for food packaging applications. We report the preparation, characterization, and film blowing of polyhydroxybutyrate-valerate (PHBV)/beer spent grain fibers (BSGF) composites. Beer spent grains are by-products of the beer industry submitted to an acid/caustic treatment and to successive grinding to achieve fibers with typical size of 30 microns. PHBV/BSGF compounds were extruded and successfully subjected to draw down ratios as high as 50. However, processability was lost for BSGF contents above 10 wt%, due to their percolation within the PHBV matrix. Two PHBV/BSGF compounds were processed into blown films. The resulting mechanical, structural, and barrier properties depend on processing parameters and BSGF content. The fully bio-sourced and compostable PHBV based thin films produced under processing conditions scalable to industrial production show gas and water vapor barrier properties attractive for food packaging applications. © 2014 Society of Plastics Engineers.


Cunha M.,Institute for Polymers and Composites | Covas J.A.,Institute for Polymers and Composites | Hilliou L.,Institute for Polymers and Composites
Journal of Applied Polymer Science | Year: 2015

Poly(hydroxy butyrate-co-valerate) (PHBV) is a biodegradable polymer that is difficult to melt process into films. Such difficulty is mirrored in the lack of literature on film blowing of PHBV- or PHBV-based materials. To circumvent this problem, 70/30 wt % blends of PHBV with a biodegradable compound (PBSebT), or with poly(butylene adipate-co-terephtalate) (PBAT), were prepared and tested for extrusion film blowing. Both blends showed a similar rheological pattern at 175°C, which is the maximum processing temperature with tolerable thermal degradation. Blending stabilized the film bubbles, thus widening the processing window. However, film properties such as tensile modulus, strain at break and tear resistance remained isotropic and crystallinity characteristics in the machine and transverse directions were generally similar. To bypass the thermal degradation associated with polymer blending, PHBV/PBAT films were coextruded. These showed enhanced functional properties when compared with films blown from blends. The mechanical properties of bilayered films matched those of films blown from commercial PBAT designed for food packaging. © 2015 Wiley Periodicals, Inc.


Hilliou L.,Institute for Polymers and Composites | Machado D.,Institute for Polymers and Composites | Oliveira C.S.S.,UCIBIO | Gouveia A.R.,UCIBIO | Reis M.A.M.,UCIBIO
Journal of Applied Polymer Science | Year: 2015

The effects of recovered residues on the characteristics of polyhydroxy(butyrate-co-valerate) (PHBV) produced from mixed microbial cultures (MMCs) fed with cheese whey, olive oil mill wastewater, or a synthetic mixture of acetic and propionic acid were investigated. The different types of MMC PHBVs were extracted and purified with different downstream routes; this enabled the recovery of polymers with different hydroxyvalerate contents and different residue types and levels, ranging from 0 to 11%. The results indicate overall that the recovery of residues together with the biopolymer brought benefits to the melt processability of these MMC PHBVs. Impurities triggered thermal degradation at smaller temperatures, promoted melting at lower temperatures, acted as thermal stabilizers, improved the melt viscosity, and enhanced the shear thinning. The degree of crystallinity of the aged samples was not affected by the impurities, but the crystallites size increased. MMC PHBVs recovered with residues containing more proteins showed better thermal stability, whereas MMC PHBVs containing more inorganic residues showed better melt viscoelastic properties. The results of this study show that impurities recovered together with the MMC PHBVs introduced changes to their thermal, semicrystalline, and rheological properties; these changes, in some cases, were detrimental, but they were also potentially advantageous to the processing and conversion of these materials into products such as packages. © 2015 Wiley Periodicals, Inc.


Almeida H.A.,Institute for Polymers and Composites | Bartolo P.J.,Institute for Polymers and Composites
Methods in Molecular Biology | Year: 2012

Rapid prototyping technologies were recently introduced in the medical field, being particularly viable to produce porous scaffolds for tissue engineering. These scaffolds should be biocompatible, biodegradable, with appropriate porosity, pore structure, and pore distribution on top of presenting both surface and structural compatibility. This chapter presents the state-of-the-art in tissue engineering and scaffold design using numerical fluid analysis for optimal vascular design. The vascularization of scaffolds is an important aspect due to its influence regarding the normal flow of biofluids within the human body. This computational tool also allows to design either a scaffold offering less resistance to the normal flow of biofluids or reducing the possibility for blood coagulation through forcing the flow toward a specific direction. © 2012 Springer Science+Business Media, LLC.


Almeida H.A.,Institute for Polymers and Composites | Bartolo P.J.,Institute for Polymers and Composites
Methods in Molecular Biology | Year: 2012

Rapid prototyping technologies were recently introduced in the medical field, being particularly viable to produce porous scaffolds for tissue engineering. These scaffolds should be biocompatible, biodegradable, with appropriate porosity, pore structure, and pore distribution, on top of presenting both surface and structural compatibility. Surface compatibility means a chemical, biological, and physical suitability with the host tissue. Structural compatibility corresponds to an optimal adaptation to the mechanical behaviour of the host tissue. This chapter presents a computer tool to support the design of scaffolds to be produced by rapid prototyping technologies. The software enables to evaluate scaffold mechanical properties as a function of porosity and pore topology and distribution, for a wide rage of materials, suitable for both hard and soft tissue engineering. © 2012 Springer Science+Business Media, LLC.

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