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Carvalho M.T.,University of Lisbon | Ferreira C.,University of Lisbon | Santos L.R.,PIEP Innovation in Polymer Engineering | Paiva M.C.,PIEP Innovation in Polymer Engineering | Paiva M.C.,University of Minho
Polymer Engineering and Science | Year: 2012

This article addresses the separation of polyethylene terephthalate (PET) from ternary blends with polyvinyl chloride (PVC) and polystyrene (PS) by froth flotation. The experimental work was carried out with representative samples from post-consumer waste packages collected at drop-off-points. Previous to froth flotation, PET selective wetting was achieved by alkaline treatment followed by surfactant adsorption. For this purpose, an aqueous solution of NaOH and an industrial detergent commonly used for waste plastic washing were tested as alkaline treatment, and calcium lignosulphonate and Hostaphat were tested as surfactants. An enriched product with 98.9% grade in PET and only 0.6% in PVC was recovered in the nonfloated product. The PET recovery in this product was 97% while ∼96% of PVC and 91% of PS were recovered in the floated product. An analytical method was developed for the quantification of the waste plastic composition. The method was based on the selective dissolution of the plastics in the mixture. © 2011 Society of Plastics Engineers. Source

Gonzalez D.,University of Vigo | Campos A.R.,PIEP Innovation in Polymer Engineering | Cunha A.M.,University of Minho | Santos V.,University of Vigo | Parajo J.C.,University of Vigo
Journal of Chemical Technology and Biotechnology | Year: 2011

BACKGROUND: Cytisus scoparius samples were processed with hot, compressed water (autohydrolysis treatments) to obtain both fiber-containing solids (suitable as reinforcements for composites) and a liquid phase containing sugar oligomers derived from hemicelluloses. The solid phase from autohydrolysis, mainly made up of cellulose and lignin, was employed for manufacturing polylactic acid (PLA)-based biodegradable composites. The mechanical properties, water uptake and thermal properties of composites were assessed. RESULTS: The hydrolysis of the major hemicellulose polysaccharide components of Cytisus scoparius was interpreted using kinetic models based on sequential pseudo-homogeneous first-order, irreversible reactions. Operating under non-isothermal conditions, the autohydrolysis experiment carried out at up to 215 °C led to the maximum concentration of sugar oligomers (accounting for about 71% of the initial xylan). These compounds can be employed for a variety of purposes, including applications as prebiotics. Composites containing autohydrolyzed fibers presented both improved impact strength and reduced water absorption ability. CONCLUSIONS: Autohydrolysis of Cytisus scoparius led to a liquid phase containing xylooligosacharides with commercial value, and to a solid phase suitable as a reinforcement for PLA-based composites with reduced water retention ability. © 2010 Society of Chemical Industry. Source

Gonzalez D.,University of Vigo | Gonzalez D.,Transfer and Innovation Center | Campos A.R.,PIEP Innovation in Polymer Engineering | Cunha A.M.,University of Minho | And 3 more authors.
Collection of Czechoslovak Chemical Communications | Year: 2011

Cellulose fibres were employed as reinforcement agent for biodegradable composites using polylactic acid (PLA) as a polymer matrix. PLA can be obtained from renewable resources, and it is attracting much interest owing to its favourable physico-mechanical properties and biodegradability. Prior to composite compounding, two commercial PLA from different suppliers were characterized for apparent density, flow index, crystallinity, thermal properties, melt flow rheology and intrinsic viscosity for comparison. In experiments performed with an integrated compounding-injection moulding machine (ICIM), the effects of the processing conditions on the mechanical properties of composites (tensile strength, stiffness and strain at break) were analyzed using a Taguchi experimental design. Other properties of the composites, such as surface morphology and fibre length distribution, were also considered. ICIM technology provided composites with better mechanical properties and lower fibre degradation than the conventional sequential extrusion and injection moulding (SEIM) technology. © 2011 Institute of Organic Chemistry and Biochemistry. Source

Gonzalez D.,University of Vigo | Gonzalez D.,Transfer and Innovation Center | Campos A.R.,PIEP Innovation in Polymer Engineering | Cunha A.M.,University of Minho | And 4 more authors.
BioResources | Year: 2010

Broom (Cytisus scoparius) samples were processed in media containing formic acid and hydrogen peroxide (MILOX process) to obtain celluloseenriched solids. The chemical processing of broom samples was assessed by means of a centered, second order factorial design of experiments. Empirical models derived from the experimental data gave a close interpretation of the experimental patterns, and enabled the selection of operational conditions for achieving extensive delignification and hemicellulose removal, while minimizing the dissolution of cellulose. Broom samples processed under the selected conditions were employed to reinforce PLA composites, which were characterized mechanically and by DSC, SEM, and water absorption experiments. Source

Simoes C.L.,PIEP Innovation in Polymer Engineering | Simoes C.L.,University of Minho | Xara S.M.,Catholic University of Portugal | Bernardo C.A.,University of Minho
Waste Management and Research | Year: 2011

The present study aims at evaluating the potential environmental impact of using recycled high-density polyethylene (HDPE) in the production of an anti-glare lamella (AGL), a road safety device currently manufactured from virgin (not recycled) polymer. The impact was evaluated using the life cycle assessment (LCA) technique and comparing two alternative systems: current AGL, manufactured from virgin HDPE, and optional AGL, made with recycled HDPE obtained from post-consumer packages. The AGL manufacturing phase was found to be responsible for most of the impacts in both systems, with the production of the raw material being the largest contributor for that phase. The present study makes a contribution to the problem of developing value-added products made from post-consumer polymeric recyclates. © The Author(s) 2010. Source

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