Encontrados 18 documentos, a visualizar página 1 de 2
Integrated compounding and injection moulding of short fibre reinforced composites
Sousa, R. A.; Reis, R. L.; Cunha, A. M.; Bevis, M. J.Composites of high density polyethylene (HDPE) and carbon fibre (C fibre) were compounded and moulded into tensile test bars in compounding injection moulding (CIM) equipment that combines a twin-screw extruder and an injection moulding unit. Two HDPE grades exhibiting different rheological behaviours were used as matrices. The mechanical properties of the moulded parts were assessed by both tensile and impact ...
Coupling of HDPE/hydroxyapatite composites by silane-based methodologies
Sousa, R. A.; Reis, R. L.; Cunha, A. M.; Bevis, M. J.Several coupling treatments based on silane chemicals were investigated for the development of high density (HDPE)/hydroxyapatite (HA) composites. Two HA powders, sintered HA (HAs) and non sintered HA (HAns), were studied in combination with five silanes, namely y-methacryloxy propyltrimethoxy silane (MEMO), 3-(2-aminoethyl)aminopropyltrimethoxy silane (DAMO), vinyltrimethoxy silane (VTMO), 3-aminopropyltrietho...
Bi-composite sandwich moldings : processing, mechanical performance and bioacti...
Sousa, R. A.; Oliveira, A. L.; Reis, R. L.; Cunha, A. M.; Bevis, M. J.Two composite systems composed of high-density polyethylene (HDPE) filled with hydroxyapatite (HA) and carbon fiber (C fiber) were compounded in a co-rotating twin screw extruder and subsequently molded in a two component injection molding machine in order to produce test bars with a sandwich-like morphology. These moldings are based on a HDPE/HA composite outer layer and a HDPE/C fiber composite core. The mech...
Processing and properties of bone-analogue biodegradable and bioinert polymeric...
Sousa, R. A.; Reis, R. L.; Cunha, A. M.; Bevis, M. J.This paper summarizes the processing and properties of bone-analogue composites aimed to be used in temporary or permanent orthopaedic applications. The studied matrices were two biodegradable starch based blends (with ethylene-vinyl alcohol copolymer or with cellulose acetate) and three high density polyethylene (HDPE) grades. Composites of these materials with hydroxyapatite (HA—the main inorganic constituent...
Structural development of HDPE in injection molding
Sousa, R. A.; Reis, R. L.; Cunha, A. M.; Bevis, M. J.This study investigated some relevant structure/properties relationships in shear-controlled orientation in injection molding (SCORIM) of high-density polyethylene (HDPE). SCORIM was used to deliberately induce a strong anisotropic character in the HDPE microstructure. Three grades with different molecular weight characteristics were molded into tensile test bars, which were subsequently characterized in terms ...
Shear controlled orientation in injection moulding of starch based blends inten...
Altpeter, H.; Bevis, M. J.; Gomes, Manuela E.; Cunha, A. M.; Reis, R. L.Biodegradable polymeric implants are considered to be good alternatives to metallic implants in several temporary applications. Aliphatic polyesters have been extensively investigated and have been employed in several biomedical applications. More recently, biodegradable starch based polymeric blends have also been considered as alternative materials. In this study, the effect of shear controlled orientation in...
Reinforcement and structure development in injection molding of bone-analogue c...
Sousa, R. A.; Reis, R. L.; Cunha, A. M.; Bevis, M. J.Composites of high density polyethylene (HDPE) with hydroxyapatite (HA—the main inorganic constituent of human bone) were produced by extrusion compounding and subsequent injection molding. Shear controlled orientation in injection molding (SCORIM) was used deliberately to induce a strong anisotropic character in the composite materials. Bi-composite moldings featuring a sandwich like morphology were also produ...
Relationships between processing and mechanical properties of injection molded ...
Reis, R. L.; Cunha, A. M.; Oliveira, M. J.; Campos, A. R.; Bevis, M. J.We apply a macromolecular-orientation approach to produce high molecular weight polyethylene (HMWPE) + hydroxyapatite (HA) ductile composites with the stiffness and strength within the range of human cortical bone. Our composites are produced with different amounts (10 to 50% by weight) of the reinforcement by two procedures: bi-axial rotating drum and twin screw extrusion (TSE). The processing is by convention...
Injection molding of a starch/EVOH blend aimed as an alternative biomaterial fo...
Sousa, R. A.; Kalay, G.; Reis, R. L.; Cunha, A. M.; Bevis, M. J.Biodegradable polymers show great potential to be used as materials for temporary implants and bone replacement applications in orthopedics. However, its use in high load-bearing applications will depend on the successful development of biodegradable implants with a mechanical performance matching that of human bone. This article describes the optimization of the injection molding process of an alternative biod...
The enhancement of the mechanical properties of a high-density polyethylene
Kalay, G.; Sousa, R. A.; Reis, R. L.; Cunha, A. M.; Bevis, M. J.This paper describes the process optimization in injection molding of high-density polyethylene (HDPE). Both conventional injection molding and shear controlled orientation (SCORIM) were employed in processing. The process optimization was based on design of experiments and complemented with analysis of variance. Mechanical characterization was carried out by tensile testing. Wide-angle X-ray diffraction and di...
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