Mechanical Results (mechanical + result)

Distribution by Scientific Domains

Selected Abstracts

A study of the recycling and stability of flexographic photopolymer plates

Cristina C. Cordeiro
Abstract Flexographic photopolymer plates have a wide range of commercial applications despite the fact that recycling of such materials is difficult. In consequence, there is a large bulk of leftover material around the world. In this research, the photopolymer plate waste products, identified as styrene-butadiene rubber (SBR)/polyester are blended into common polypropylene (PP) and ethylenevinylacetate (EVA) resins at different loading percentages. PP and EVA are used as the polymer matrix and the recovered styrene-butadiene rubber (SBR) material as the filler. Evaluation of the mechanical, spectroscopic, thermal and chemical properties, as well as morphology, is done by means of scanning electron microscopy (SEM). Mechanical results show that elongation strongly depends on the matrix polymer: the greater the amount of solid-sheet photopolymer (SSP), the smaller the elongation. No specific interactions were detected; however, thermal degradation and transitions were displaced, suggesting some miscibility. More homogeneity is seen for EVA blends, with no significant chemical attack detected. It is possible to reuse these recycled materials in blends with PP and EVA resins. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Acrylic Bone Cements Modified With Bioactive Filler

Carlos Federico Jasso-Gastinel
Abstract Bioactive cuttlebone Sepia officinalis particles that contain collagen were used to fill poly (methyl methacrylate- co -styrene) bone cements, varying size and concentration of filler particles. Cuttlebone was characterized by X-ray diffraction and plasma atomic emission spectrophotometer. Maximum reaction temperature and cement setting time were determined for composites and reference (copolymer without filler), along with NMR determination of residual monomer concentration. Mechanical properties characterization included stress-strain, bending, compression, fracture toughness and storage modulus tests. Mechanical results for composites filled with 10 and 30% weight of cuttlebone, complied with norm requirements which opens the possibility for using cuttlebone particles as bioactive filler. [source]

Structures and properties of ternary blends of recycled poly(ethylene terephthalate)/bisphenol-A polycarbonate/(E/nBA/GMA)

Yong Peng
Abstract Recycled poly(ethylene terephthalate)/bisphenol-A polycarbonate/PTW (ethylene, butylacrylate (BA), and glycidylmethacrylate (E/nBA/GMA) terpolymer) were blended in different sequence through low temperature solid state extrusion (LTSSE) was studied. R-PET/PC blends were toughened by PTW, resulting in the improvement of impact strengths. In tensile test, the (PC/PTW)/r-PET blends made by mixing r-PET with the preblend of PC/PTW had noticeable strengthening effect on its tensile properties, which was not impaired by the rubber content due to its strain-hardening occurred following its necking at the constant load. Morphological study by scanning electron microscopy (SEM) was in conformity with the mechanical result. For the (PC/PTW)/r-PET blends, the PC particles were well embedded in the PET matrix and the smooth morphology exhibited. The DSC thermographs for heating and cooling run indicated that the crystallinity of PET rich phase was affected by different blending sequence. In the FTIR test, the different absorption intensity of PC aromatic carbonate carbonyl band was clearly illustrated. The results indicated different blending sequence led to different blending effect. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Effect of quasi-carbonization processing parameters on the mechanical properties of quasi-carbon/phenolic composites

Donghwan Cho
Abstract In this work, quasi-carbon fabrics were produced by quasi-carbonization processes conducted at and below 1200°C. Stabilized polyacrylonitrile (PAN) fabrics and quasi-carbon fabrics were used as reinforcements of phenolic composites with a 50 wt %/50 wt % ratio of the fabric to the phenolic resin. The effect of the quasi-carbonization process on the flexural properties, interfacial strength, and dynamic mechanical properties of quasi-carbon/phenolic composites was investigated in terms of the flexural strength and modulus, interlaminar shear strength, and storage modulus. The results were also compared with those of a stabilized PAN fabric/phenolic composite. The flexural, interlaminar, and dynamic mechanical results were quite consistent with one another. On the basis of all the results, the quasi-static and dynamic mechanical properties of quasi-carbon/phenolic composites increased with the applied external tension and heat-treatment temperature increasing and with the heating rate decreasing for the quasi-carbonization process. This study shows that control of the processing parameters strongly influences not only the mechanical properties of quasi-carbon/phenolic composites but also the interlaminar shear strength between the fibers and the matrix resin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Characterization of end-functionalized styrene,butadiene,styrene copolymers and their application in modified asphalt

Qiang Wang
Abstract End amino, carboxylic acid, and hydroxyl functionalized styrene,butadiene,styrene (SBS) triblock copolymers were prepared with 1,5-diazabicyclo[3.1.0]hexane, carbon dioxide, and epoxy ethane as capping agents, respectively. The effects of the end polar groups on the morphology and dynamic mechanical properties were investigated. Transmission electron microscopy images suggested that the group at the end of the polystyrene (PS) segment made the morphology of the PS domains disordered and incompact. Dynamic mechanical results showed that the storage and loss modulus increased after SBS was end-functionalized. End amino and carboxylic acid groups improved the compatibility and storage stability of SBS-modified asphalt. However, the effect of the end-hydroxyl group on the improvement of the storage stability of SBS-modified asphalt was not obvious. The differential scanning calorimetry analysis of SBS-modified asphalt further showed that the compatibility and storage stability of SBS-modified asphalt were improved by the attachment of amino or carboxylic acid groups through the anionic polymerization method. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 8,16, 2007 [source]

Characterization of First-Stage Silicon Nitride Components After Exposure to an Industrial Gas Turbine

H.-T. Lin
This paper provides a summary of recent efforts undertaken to examine the mechanical properties and microstructural stability of first-stage silicon nitride blades and nozzles after field testing in an industrial gas turbine. Two commercially available silicon nitrides, i.e., Kyocera SN282 vanes and SN281 blades, were successfully evaluated in the 100 h final phase engine test at Solar Turbines Incorporated. The turbine rotor inlet temperature was increased from 1010° to 1121°C at 100% speed during the engine test with efficiency increasing from 28.8% to 30.1%. Results of scanning electron microscopy showed that apparent materials recession still occurred during the 100 h engine test, especially in the leading and trailing edge regions where the gas pressure or velocity was the highest. The apparent material recession of the airfoils resulted from the volatilization of the normally protective silica layer, evidenced by the increased surface roughness and porous Lu2Si2O7 surface layer features. On the other hand, mechanical results generated using a ball-on-ring test technique showed that little strength degradation was measured after the 100 h engine test. [source]

Mechanical behavior of recycled reinforced polyamide railway fasteners

José Antonio Casado
Modern railway tracks use short-fiber glass reinforced polyamide to inject insulating and mechanically resistant fasteners to connect the rails to the sleepers. Some of this material is later withdrawn, due either to defective production or to breakage in service. The recovery of the material for its later re-use would lead to a great saving, from both an environmental and an economic viewpoint. Mechanical recycling is a simple, economic process that only requires the crushing of the material and its subsequent molding, without the need for any chemical treatments. However, it has some drawbacks; as with any kind of recycling, there is a certain loss of material quality with some degradation of its properties. In this work, the physical and mechanical results for fasteners injected with recycled material are compared to others injected with pure material. The results show that the use of recycled fasteners is limited in-service by working conditions that increase the thermoplastic material temperature above its critical glass transition temperature, Tg. POLYM. COMPOS., 31:1142,1149, 2010. © 2009 Society of Plastics Engineers [source]

Influence of the degree of grafting on the morphology and mechanical properties of blends of poly(butylene terephthalate) and glycidyl methacrylate grafted poly(ethylene- co -propylene) (EPR)

SL Sun
Abstract Poly(ethylene- co -propylene) (EPR) was functionalized to varying degrees with glycidyl methacrylate (GMA) by melt grafting processes. The EPR- graft -GMA elastomers were used to toughen poly(butylene terephthalate) (PBT). Results showed that the grafting degree strongly influenced the morphology and mechanical properties of PBT/EPR- graft -GMA blends. Compatibilization reactions between the carboxyl and/or hydroxyl of PBT and epoxy groups of EPR- graft -GMA induced smaller dispersed phase sizes and uniform dispersed phase distributions. However, higher degrees of grafting (>1.3) and dispersed phase contents (>10 wt%) led to higher viscosities and severe crosslinking reactions in PBT/EPR- graft -GMA blends, resulting in larger dispersed domains of PBT blends. Consistent with the change in morphology, the impact strength of the PBT blends increased with the increase in EPR- graft -GMA degrees of grafting for the same dispersion phase content when the degree of grafting was below 1.8. However, PBT/EPR- graft -GMA1.8 displayed much lower impact strength in the ductile region than a comparable PBT/EPR- graft -GMA1.3 blend (1.3 indicates degree of grafting). Morphology and mechanical results showed that EPR- graft -GMA 1.3 was more suitable in improving the toughness of PBT. SEM results showed that the shear yielding properties of the PBT matrix and cavitation of rubber particles were major toughening mechanisms. Copyright © 2006 Society of Chemical Industry [source]

Models of S/, interactions in protein structures: Comparison of the H2S,benzene complex with PDB data

PROTEIN SCIENCE, Issue 10 2007
Ashley L. Ringer
Abstract S/, interactions are prevalent in biochemistry and play an important role in protein folding and stabilization. Geometries of cysteine/aromatic interactions found in crystal structures from the Brookhaven Protein Data Bank (PDB) are analyzed and compared with the equilibrium configurations predicted by high-level quantum mechanical results for the H2S,benzene complex. A correlation is observed between the energetically favorable configurations on the quantum mechanical potential energy surface of the H2S,benzene model and the cysteine/aromatic configurations most frequently found in crystal structures of the PDB. In contrast to some previous PDB analyses, configurations with the sulfur over the aromatic ring are found to be the most important. Our results suggest that accurate quantum computations on models of noncovalent interactions may be helpful in understanding the structures of proteins and other complex systems. [source]