11 documents found, page 1 of 2
Ellagic acid as stabilizer in the thermo-oxidative degradation of thermoplastic...
Gama, Nuno; Evtyugin, Dmitry D.; Lourenço, Ana; Lopes, Célia; Evtuguin, Dmitry V.Ellagic acid (EA) is a plant polyphenol with strong antioxidant properties. The stabilizing effect of EA on the thermo-oxidative degradation of the commercial thermoplastic poly(ester-ether urethane) (TPU) was studied for the first time and compared with effect of kraft lignin (KL), butylated hydroxytoluene (BHT) and pentaerythritol tetrakis (Irganox 1010). TPUs doped with antioxidants (ca. 20,000 ppm), were an...
Development of a functional prototype for recovery of recycled expanded polysty...
Leite, Pedro; Correia, Carlos M.; Araújo, Raquel; Tinoco, João; Gama, Nuno; Ferreira, Paula; Gonçalves, Idalina; Neto, Victor; Zhiltsova, TatianaExpanded polystyrene (EPS) is composed of 98% air and 2% polystyrene (PS). EPS parts are made up of PS beads that contain a blowing agent, typically pentane, entrapped into their interior, allowing them to expand and form a honeycomb-similar cellular structure. The expandable PS beads allow for efficient storage and transportation while also providing control over density in separate steps (pre-expansion and mo...
Ellagic acid as stabilizer in the thermo-oxidative degradation of thermoplastic...
Gama, Nuno; Evtyugin, Dmitry D.; Lourenço, Ana; Lopes, Célia; Evtuguin, Dmitry V.Ellagic acid (EA) is a plant polyphenol with strong antioxidant properties. The stabilizing effect of EA on the thermo-oxidative degradation of the commercial thermoplastic poly(ester-ether urethane) (TPU) was studied for the first time and compared with effect of kraft lignin (KL), butylated hydroxytoluene (BHT) and pentaerythritol tetrakis (Irganox 1010). TPUs doped with antioxidants (ca. 20,000 ppm), were an...
Modified cork/SEBS composites for 3D printed elastomers
Gama, Nuno; Ferreira, Artur; Evtuguin, Dmitry; Barros‐Timmons, AnaThree dimensional (3D) printed elastomers is a challenge which can be overcome using fillers. With that in perspective, cork was chemically modified via a two-step reaction, aiming to achieve better compatibility with styrene-ethylene-butylene-styrene (SEBS). In the first step, the OH groups of cork surface were grafted with succinic acid, while in the second step the free acid groups were reacted with a polyol...
New poly(lactic acid) composites produced from coffee beverage wastes
Gama, Nuno; Ferreira, Artur; Evtuguin, Dmitry V.In this study, aiming to reduce the environmental impact of plastics, new composite materials containing recycled fibers from used paper coffee cups and oil extracted from spent coffee grounds (SCG) were produced. Accordingly, the cellulose fibers were chemically modified using lactic acid to be used as poly(lactic acid) filler reinforcement. The obtained results revealed that its addition improved the mechanic...
Different methods of synthesizing poly(glycerol sebacate) (PGS): a review
Godinho, Bruno; Gama, Nuno; Ferreira, ArturPoly(glycerol sebacate) (PGS) is a biodegradable elastomer that has attracted increasing attention as a potential material for applications in biological tissue engineering. The conventional method of synthesis, first described in 2002, is based on the polycondensation of glycerol and sebacic acid, but it is a time-consuming and energy-intensive process. In recent years, new approaches for producing PGS, PGS bl...
Insights into PU/EVA blends produced using industrial residues towards eco-effi...
Gama, Nuno; Godinho, B.; Barros-Timmons, Ana; Ferreira, ArturAiming at minimizing the issues associated with the disposal of polymers, in this study, elastomeric materials derived from 100% recycled feedstocks were produced. Residues of polyurethane (PU) foams (from 0 to 100%) were blended with residues of ethylene–vinyl acetate (EVA) derived from the shoe-soles industry (from 0 to 100%) to produce films by hot compression. The experimental values obtained by the charact...
PU/lignocellulosic composites produced from recycled raw materials
Gama, Nuno; Godinho, Bruno; Barros-Timmons, Ana; Ferreira, ArturLignocellulosic composites are biodegradable, have low cost, neutrality to CO2 emission, easily processed, easily available and pause no health risks, therefore these materials have been the subject of an increase of interest. In addition, there is a continuous demand of materials obtained from renewable resources and waste recycling. In that sense, in this study polyurethane (PU) residues were mixed with resid...
Cure and performance of castor oil polyurethane adhesive
Gama, Nuno; Ferreira, Artur; Barros-Timmons, Anaiming at the development of sustainable materials, in this study, a biobased wood polyurethane adhesive (PUA), derived from castor oil (CO), was synthetized and its properties were compared with a conventional wood adhesive. Different NCO/OH ratios have been used to assess its effect on the properties of the ensuing adhesives. FTIR, and DMA were used to monitor the extent of reaction and the glass transition te...
Spent coffee grounds as a renewable source for ecopolyols production
Soares, Belinda; Gama, Nuno; Freire, Carmen S. R.; Barros-Timmons, Ana; Brandao, Ines; Silva, Rui; Pascoal Neto, Carlos; Ferreira, ArturBACKGROUNDBased on the biorefinery concept, the main focus of this work was the increase in value of spent coffee grounds via an acid liquefaction process using polyhydric solvents in the presence of sulfuric acid, at moderate temperature. For that purpose the effect of temperature, sulfuric acid concentration and time on biomass conversion was studied using design of experiments combined with statistical analy...