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Good Mechanical Properties (good + mechanical_property)
Selected AbstractsRecycling of tire-curing bladder by ultrasonic devulcanizationPOLYMER ENGINEERING & SCIENCE, Issue 1 2006Wenlai Feng The recycling of butyl rubber-based tire-curing bladder was carried out by means of a grooved barrel ultrasonic extruder. Die pressure and ultrasonic power consumption were measured as a function of flow rate and ultrasonic amplitude. Gel fraction and crosslink density of the ultrasonically devulcanized rubber were substantially reduced. In turn, this led to some reduction in gel fraction and crosslink density in the revulcanized rubber. These findings were correlated with dynamic properties and the cure behavior of the devulcanized rubber. The mechanical properties of the revulcanized rubber, dependent on processing conditions during devulcanization, were compared with that of the virgin vulcanizate. Good mechanical properties of revulcanized rubber was achieved with 86 and 71% retention of the tensile strength and the elongation at break respectively, and with modulus increased by 44%. The devulcanized rubber was found to contain tiny gel particles of a wide size distribution with a predominant size of <4 ,m. POLYM. ENG. SCI., 46:8,18, 2006. © 2005 Society of Plastics Engineers [source] In Situ Damage Detection With Acoustic Emission Analysis During Cyclic Loading of Wire Reinforced EN AW-6082,ADVANCED ENGINEERING MATERIALS, Issue 7 2010Kay André Weidenmann In the field of lightweight construction, hybrid structures such as reinforced metal matrix composites are highly qualified materials. The direct composite extrusion process allows for continuous manufacturing of wire reinforced aluminum matrix profiles. The aim is to increase the stiffness and specific strength in a way that the composite material shows better mechanical properties than the single matrix material. To determine and locate damage evolution during cyclic loading of spring steel reinforced EN AW-6082 matrix the acoustic emission analysis is used. Furthermore it allows for getting more information about the damage mechanisms during fatigue of the matrix and the final failure of the reinforcing element. The current work also includes the determination of damage evolution using strain measuring methods. [source] A novel route for preparation of PVC sheets with high UV irradiation resistanceJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Xianke Ye Abstract A novel acrylonitrile acrylate copolymer coating was proposed to improve the UV irradiation resistance of poly(vinyl chloride) (PVC) sheets. Its effect on the photoageing properties of the sheets was evaluated by means of Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), yellowness index test, and the oxygen permeability coefficient and mechanical properties measurement. The experimental results show that the novel acrylonitrile acrylate copolymer coating significantly improves the UV irradiation resistance of PVC sheets. Compared with the PVC sheets without coating, the coated PVC sheets show better mechanical properties, lower yellowness index, and smaller oxygen permeability coefficient after UV irradiation. The analysis on the SEM images of the PVC sheets indicates that the coating acts as a film to prevent the PVC sheets from UV energy and oxygen that can accelerate the photochemical reactions of PVC. The FTIR analysis confirms that the coating can slow down the microstructures development of the PVC sheets, also indicating that the coating impeded the photochemical reactions of PVC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Compatibilization and development of layered silicate nanocomposites based of unsatured polyester resin and customized intercalation agentJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Luigi Torre Abstract In this study a procedure for the preparation of compatibilized nanoclays was used to produce effective nanocomposites based on unsatured polyester (UP) resin. A compatibilization procedure of the filler with a selected surfactant has been developed and optimized, the effect of organic modifiers on the synthesized nanocomposites properties was studied. Moreover, polyester/clay nanocomposites were prepared. In particular, samples were prepared using two different mixing methods. The properties and formation processes of the nanocomposites obtained using the two methods were compared. X-ray diffraction studies revealed the formation of intercalated/exfoliated nanocomposites structures. The effect of processing parameters, used for both the compatibilization procedure and the preparation of nanocomposites, was studied. Dynamic mechanical, thermal analysis, and rheological tests were performed to investigate the formation mechanism of UP/montmorillonite nanocomposite. In particular, mechanical properties of nanocomposites were studied using dynamic mechanical analysis and tensile tests. Mechanical, rheological, and thermal characterization have confirmed the validity of the used approach to compatibilize the nanoclay and to produce nanocomposites. Tensile strength and Young's modulus were modified by the loading of the organoclays. Furthermore, the rheology of the nanocomposite formulation provided processing information, while mechanical and dynamic mechanical characterization was performed on the nanocomposites produced with the newly compatibilized formulation. The results have shown that nanocomposites with better mechanical properties can be obtained through the selection of an appropriate compatibilization process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Preparation of sheath,core bicomponent composite ion-exchange fibers and their propertiesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Zhi-Jia Ding Abstract Based on sheath,core bicomponent composite ion-exchange fibers with modified polystyrene and modified polypropylene, composite fibers were further crosslinked and sulfonated with chlorosulfonic acid to produce strongly acidic cation-exchange fibers. The optimal technology of the obtained fibers was examined, and the structures of the fibers were investigated with Fourier transform infrared spectrophotometry, differential scanning calorimetry, and so forth. The properties were measured with chemical titration, filament strength instrumentation, scanning electron microscopy, and so forth. The results showed that cation-exchange fibers with better mechanical properties and a higher exchange capacity were obtained, and they had higher practicability. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Rigid PVC/(layered silicate) nanocomposites produced through a novel melt-blending approach,JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 2 2009Laurent M. Matuana On the basis of the fusion behavior of poly(vinyl chloride) (PVC), the influence of compounding route on the properties of PVC/(layered silicate) nanocomposites was studied. Four different compounding addition sequences were examined during the melt compounding of PVC with montmorillonite (MMT) clay, including (a) a direct dry mixing of PVC and nanoclay, (b) an addition of nanoclay at compaction, (c) an addition of nanoclay at the onset of fusion, and (d) an addition of nanoclay at equilibrium torque. Both unmodified sodium montmorillonite (Na+ -MMT) and organically modified montmorillonite (Org.-MMT) clays were used, and the effect of the addition sequence of the clay during compounding on its dispersion in the matrix was evaluated by X-ray diffraction and transmission electron miscroscopy. The surface color change, dynamic mechanical analysis, and flexural and tensile properties of PVC/clay nanocomposites were also studied. The experimental results indicated that both the extent of property improvement and the dispersion of nanoparticles in PVC/(layered silicate) nanocomposites are strongly influenced by the degree of gelation achieved in PVC compounds during processing. The addition of nanoclay to PVC must be accomplished at the onset of fusion, when PVC particles are reduced in size, in order to produce nanocomposites with better nanodispersion and enhanced mechanical properties. Overall, rigid PVC nanocomposites with unmodified clay (Na+ -MMT) were more thermally stable and exhibited better mechanical properties than their counterparts with organically modified clay (Org.-MMT). J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers [source] Copolymers of Poly(2,5-benzimidazole) and Poly[2,2,-(p -phenylene)-5,5,-bibenzimidazole] for High-Temperature Fuel Cell ApplicationsMACROMOLECULAR MATERIALS & ENGINEERING, Issue 11 2008Sung-Kon Kim Abstract Copolymers of poly(2,5-benzimidazole) (ABPBI) and poly[2,2,-(p -phenylene)-5,5,-bibenzimidazole] (pPBI) were synthesized for use as fuel cell membranes to take advantage of the properties of both constituents. The composition of the copolymers were controlled by changing the feed ratio of 3,4-diaminobenzoic acid and terephthalic acid with 3,3,-diaminobenzidine in the polycondensation reaction. The copolymer membranes showed higher conductivities, better mechanical properties, and larger acid absorbing abilities than commercial poly[2,2,-(m -phenylene)-5,5,-bibenzimidazole] membranes. [source] Effects of stearic acid on the interface and performance of polypropylene/superfine down powder compositesPOLYMER COMPOSITES, Issue 12 2009Xin Liu To manufacture the hygroscopic sheets available for functional application, superfine down powder (SDP) and stearic acid modified superfine down powder (MSDP) were, respectively, blended and extruded with polypropylene (PP) to produce composite pellets, and the extruded pellets were hot-pressed into composite sheets. The chemical reaction between SDP and stearic acid was characterized using the attenuated total reflection attachment on the Fourier transform infrared. PP/MSDP composites showed more uniform powder dispersion in PP matrix, higher compatibility, and better mechanical properties than that of PP/SDP composites, which showed an evident decrease in tensile strength and elongation at break compared with pure PP. It was worth noting that the Young's modulus of PP/SDP composites was higher than that of pure PP, but lower than that of PP/MSDP composites. The addition of SDP led to a large increase in water absorption of PP/SDP composites. However, the water absorption of PP/MSDP composites decreased slightly compared with that of PP/SDP composites. Furthermore, the effects of SDP and MSDP on the microstructural and thermal properties of different composites were also investigated, respectively. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] Studies on mechanical properties of sisal fiber/phenol formaldehyde resin in-situ compositesPOLYMER COMPOSITES, Issue 2 2009Qiuhong Mu Phenol formaldehyde resin (PF) reinforced with short sisal fibers (SF) were obtained by two methods, direct-mixing and polymerization filling. Impact and bending properties of resulting composites were compared. Under the same compression molding conditions, polymerization filled composites showed better mechanical properties than those of direct-mixed composites. The influences of fiber modifications on the mechanical properties of SF/PF in-situ (polymerization filled) composites have been investigated. Treated-SF-reinforced composites have better mechanical properties than those of untreated-SF-reinforced composites. The effects of SF on water absorption tendencies of SF/PF composites have also been studied. In addition, sisal/glass (SF/GF) hybrid PF composites of alkali-treated SF were prepared. Scanning electron microscopic studies were carried out to study the fiber-matrix adhesion. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] The influence of chemical surface modification on the performance of sisal-polyester biocompositesPOLYMER COMPOSITES, Issue 2 2002S. Misra This article concerns the effectiveness of various types and degrees of surface modification of sisal fibers involving dewaxing, alkali treatment, bleaching cyanoethylation and viny1 grafting in enhancing the mechanical properties, such as tensile, flexural and impact strength, of sisal-polyester biocomposites. The mechanical properties are optimum at a fiber loading of 30 wt%. Among all modifications, cyanoethylation and alkali treatment result in improved properties of the biocomposites. Cyanoethylated sisal-polyester composite exhibited maximum tensile strength (84.29 MPa). The alkali treated sisal-polyester composite exhibited best flexural (153.94 MPa) and impac strength (197.88 J/m), which are, respectively, 21.8% and 20.9% higher than the corresponding mechanical properties of the untreated sisal-polyester composites. In the case of vinyl grafting, acrylonitrile (AN)-grafted sisal-polyester composites show better mechanical properties than methyl-methacrylate (MMA)-grafted sisal composites. Scanning electron microscopic studies were carried out to analyze the fiber-matrix interaction in various surface-modified sisal-polyester composites. [source] Influence of the processing conditions on a two-phase reactive blend system: EVA/PP thermoplastic vulcanizatePOLYMER ENGINEERING & SCIENCE, Issue 11 2002Catherine Joubert The elaboration of a TPV based on copolymer of ethylene and vinyl acetate (EVA) and polypropylene (PP) as thermoplastic phase was investigated in a batch mixer. The crosslinking reaction is carried out through a transesterification reaction between ester groups of EVA and alcoxysilane groups of the crosslinker agent tetrapropoxyorthosilicate (TPOS). The main advantage of this crosslinking reaction is that it can be well controlled and suitable for different processing conditions. The aim of the present study is to get a better understanding of the dispersion mechanism and of the phase inversion of the EVA major phase during its dynamic vulcanization into the PP minor phase. It was proved that the initial viscosity ratio, , = ,pp/,EVA, between EVA and PP plays an important part in the morphology development of the reactive blend. The viscosity ratio must be close to the critical ratio expressed by Utracki's model of phase inversion mechanism. Furthermore, the influence of different processing parameters on the variation of the morphology and on the mechanical properties of the ultimate TPV was investigated. The main conclusion of this study is that the characteristic time of crosslinking must be of the same order than the time of mixing. Indeed, better mechanical properties are obtained when a progressive phase inversion occurred and when it is controlled by rheological aspects and transient morphology equilibrium of the two phases and not by the mechanical fragmentation of the crosslinked EVA. For example, in our experimental conditions (concerning the amounts of catalyst and crosslinker reagents), high shear rates can be avoided ( < 80 s,1) as the self-heating of the blend under shear considerably increases (,T , 50°C for = 225 s,1), leading to faster kinetics and consequently to a phase inversion controlled by the fragmentation of the crosslinked EVA phase. [source] Structure-property relationship in polyurethane elastomers containing starch as a crosslinkerPOLYMER ENGINEERING & SCIENCE, Issue 5 2000Sonal Desai Polyurethane elastomers were synthesized using polypropylene glycol (PPG 2000) as the polyol and starch as the multifunctional crosslinker in varying concentrations. Thermal and mechanical properties were measured by DSC, DMA and tensile tests. The morphology was examined by SEM. The swelling behavior of the polyurethanes in various solvents was investigated and the solubility parameter was determined. All these properties were compared with those of polyurethanes containing 1,1,1 -trimethylol propane (TMP) as the crosslinker. Starch-based polyurethanes exhibited better mechanical properties. The effect of varying the starch:TMP ratio on the mechanical strength was also studied. With increasing starch content, the tensile strength and elongation increased. The starch-based PUs exhibited two glass transitions, whereas TMP-based PUs exhibited one Tg. No significant difference in the Tgs of the two PUs was observed. The activation energy of St-PU calculated from DMA was 69 kcal/mol. Soil degradation tests indicated greater biodegradability in polyurethanes containing starch than in those containing TMP. [source] Synthesis of sub-micrometer core,shell rubber particles with 1,2-azobisisobutyronitrile as initiator and deformation mechanisms of modified polystyrene under various conditionsPOLYMER INTERNATIONAL, Issue 10 2009Rujun Dai Abstract BACKGROUND: Sub-micrometer core-shell polybutadiene- graft -polystyrene (PB- g -PS) copolymers with various ratios of polybutadiene (PB) core to polystyrene (PS) shell were synthesized by emulsion grafting polymerization with 1,2-azobisisobutyronitrile (AIBN) as initiator. These graft copolymers were blended with PS to prepare PS/PB- g -PS with a rubber content of 20 wt%. The mechanical properties, morphologies of the core-shell rubber particles and deformation mechanisms under various conditions were investigated. RESULTS: Infrared spectroscopic analysis confirmed that PS could be grafted onto the PB rubber particles. The experimental results showed that a specimen with a ,cluster' dispersion state of rubber particles in the PS matrix displayed better mechanical properties. Transmission electron micrographs suggested that crazing only occurred from rubber particles and extended in a bridge-like manner to neighboring rubber particles parallel to the equatorial plane at a high speed for failure specimens, while the interaction between crazing and shear yielding stabilized the growing crazes at a low speed in tensile tests. CONCLUSION: AIBN can be used as an initiator in the graft polymerization of styrene onto PB. The dispersion of rubber particles in a ,cluster' state leads to better impact resistance. The deformation mechanism in impact tests was multi-crazing, and crazing and shear yielding absorbed the energy in tensile experiments. Copyright © 2009 Society of Chemical Industry [source] Effect of the type of nylon chain-end on the compatibilization of PP/PP-GMA/nylon 6 blendsPOLYMER INTERNATIONAL, Issue 2 2002Adriana Tedesco Abstract Polyamide and polypropylene (PP) are two important classes of commercial polymers; however, their direct mixing leads to incompatible blends with poor properties. Polypropylene functionalized with glycidyl methacrylate (PP-GMA) was used as a compatibilizer in blends of PP and nylon 6, because of the possible reaction of NH2 and COOH groups with the epoxide group of GMA. Two types of nylon 6 with different ratios between NH2 and COOH groups were used. The one with higher concentration of COOH groups was less compatible with PP in a binary blend. When PP-GMA was used as a compatibilizer, a better dispersion of nylon in the PP matrix was obtained together with better mechanical properties for both nylons used in this work. © 2001 Society of Chemical Industry [source] Processing, properties and stability of biodegradable composites based on Mater-Bi® and cellulose fibresPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 11-12 2003D. Puglia Abstract In this work, the behaviour of biocomposites obtained by the addition of flax cellulose pulp to Mater-Bi®, a commercial thermoplastic matrix based on starch, has been studied in comparison with traditional glass fibre composites. The composites were produced by compounding with a twin-screw extruder. Depending on the kind of fibre, reinforcement contents of 10,40% were obtained. The mechanical behaviour, both in normal conditions and after water absorption, was analysed. It has been noted that the addition of cellulose pulp increases the composite modulus more than glass fibre: in fact, a poor adhesion of the interface between the glass fibre and Mater-Bi® has been observed. The thermal degradation behaviour of the composite has been studied by thermogravimetric analysis (TGA). Different degradation peaks have been observed and the activation energies, related to the main peak, have been calculated. The addition of cellulose pulp produces better mechanical properties and higher thermal stability. Copyright © 2003 John Wiley & Sons, Ltd. [source] Recycled PCB flour reinforced linear low-density polyethylene composites enhanced by water cross-linking reactionASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2009Chen-Feng Kuan Abstract Recycled printed circuit board (PCB) flour reinforced linear low-density polyethylene (LLDPE) composites were prepared successfully. Water cross-linking technique was adopted to improve the physical characteristics of the composites. Composites were compounded using a twin-screw extruder and treated with a coupling agent (vinyltrimethoxysilane, VTMOS) and a compatibilizer (polyolefin elastomer grafted with melaic acid, POE-g-MA). They were then moisture-cross-linked in hot water. The composite that was cross-linked in water exhibited better mechanical properties than the noncross-linked composite because of strong chemical bonding between the filler and the polyolefin matrix. When the PCB flour content reaches 60 wt% following 4 h of water cross-linking, the tensile strength and the flexural strength are increased by 18.8% (12.8,15.2 MPa) and 13.2% (21.9,24.8 MPa) respectively. Scanning electron microscopy (SEM) images of the fracture surfaces of water cross-linked composites indicated that good interfacial strength existed between the filler and the polyolefin matrix. Thermal analyses of water cross-linked composites indicated that the thermal degradation temperature and the heat deflection temperature (HDT) of the composite increased with the increasing of water cross-linking time. The HDT of the composite rose from 55.8 to 83 °C. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Enhanced photodegradation efficiency of polyethylene-TiO2 nanocomposite film with oxidized polyethylene waxJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2010Wenjun Fa Abstract A novel photodegradable polyethylene-oxidized polyethylene wax-TiO2 (PE-OPW-TiO2) nanocomposite film was prepared by embedding the organically modified TiO2 nanoparticles into commercial PE in the presence of OPW. The photocatalytic degradation behavior under ultraviolet light or solar light was investigated by examining the weight loss of the composite films, UV,vis transmittance spectrum, scanning electron microscope (SEM), and gel permeation chromatogram (GPC). The results show that OPW, as a dispersant and a compatibiliser, markedly improves the dispersion and compatibility of TiO2 nanoparticles in PE resins. The PE-OPW-TiO2 composite film demonstrates much higher photodegradation efficiency and much better mechanical property than either the PE-TiO2 composite film or the pure PE film. The weight-average molecular weight (Mw) of the PE-OPW-TiO2 composite film decreased 94.3% and the number-average molecular weight (Mn) decreased 84.5% after 38 days solar light irradiation. The photocatalytic degradation mechanism of the film is briefly discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Analysis of Superplastic Deformation of AZ31 Magnesium Alloy,ADVANCED ENGINEERING MATERIALS, Issue 9 2007K. Abu-Farha AZ31 is a magnesium alloy possessing good mechanical properties, which makes it particularly attractive for automotive applications. Yet, in order to advance the utilization of this alloy, a broad database of its superplastic behavior is needed. This work presents the results of a comprehensive study on the elevated temperature superplastic behavior of the AZ31 magnesium alloy. Flow stress, fracture strain and strain sensitivity index maps were constructed over a wide range of strain rates, covering temperatures between 325 and 450 °C. [source] Towards Thermoconductive, Electrically Insulating Polymeric Composites with Boron Nitride Nanotubes as FillersADVANCED FUNCTIONAL MATERIALS, Issue 12 2009Chunyi Zhi Abstract Ultilizing boron nitride nanotubes (BNNTs) as fillers, composites are fabricated with poly(methyl methacrylate), polystyrene, poly(vinyl butyral), or poly(ethylene vinyl alcohol) as the matrix and their thermal, electrical, and mechanical properties are evaluated. More than 20-fold thermal conductivity improvement in BNNT-containing polymers is obtained, and such composites maintain good electrical insulation. The coefficient of thermal expansion (CTE) of the BNNT-loaded polymers is dramatically reduced because of interactions between the polymer chains and the nanotubes. Moreover, the composites possess good mechanical properties, as revealed by Vickers microhardness tests. This detailed study indicates that BNNTs are very promising nanofillers for polymeric composites, allowing the simultaneous achievement of high thermal conductivity, low CTE, and high electrical resistance, as required for novel and efficient heat-releasing materials. [source] Tribology,Structure Relationships in Silicon Oxycarbide Thin FilmsINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 5 2010Joseph V. Ryan Silicon oxycarbide is a versatile material system that is attractive for many applications because of its ability to tune properties such as chemical compatibility, refractive index, electrical conductivity, and optical band gap through changes in composition. One particularly intriguing application lies in the production of biocompatible coatings with good mechanical properties. In this paper, we report on the wide range of mechanical and tribological property values exhibited by silicon oxycarbide thin films deposited by reactive radio frequency magnetron sputtering. Through a change in oxygen partial pressure in the sputtering plasma, the composition of the films was controlled to produce relatively pure SiO2, carbon-doped SiC, and compositions between these limits. Hardness values were 8,20 GPa over this range and the elastic modulus was measured to be between 60 and 220 GPa. We call attention to the fit of the mechanical data to a simple additive bond-mixture model for property prediction. Tribological parameters were measured using a ball-on-disk apparatus and the samples exhibited the same general trends for friction coefficient and wear rate. One film is shown to produce variable low friction behavior and low wear rate, which suggests a solid-state self-lubrication process because of heterogeneity on the nanometer scale. [source] Mechanical behavior of carbon nanofibre-reinforced epoxy compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2010Sohel Rana Abstract Epoxy resins are widely used in a variety of applications because of their high chemical and corrosion resistance and good mechanical properties. But few types of epoxy resins are brittle and possess low toughness which makes them unsuitable for several structural applications. In this work, carbon nanofibres have been dispersed uniformly into the epoxy resin at a very low concentration (0.07 vol. %). Improvement of 98% in Young modulus, 24% in breaking stress and 144% in work of rupture was achieved in the best sample. The emphasis is on achieving uniform dispersion of carbon nanofibers into epoxy resin using a combination of techniques such as ultrasonication, use of solvent and surfactants. The fracture surfaces of the specimens were studied under scanning electron microscope to see the fracture mechanism of nanocomposites under tensile load and correlate it to the enhancement in their properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Physicochemical and biological evaluation of plasma-induced graft polymerization of acrylamide onto polydimethylsiloxaneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008A. Parvin Abstract Polydimethylsiloxane (PDMS) rubbers exhibit good mechanical properties for biomedical and industrial applications, but their inherently high hydrophobicity limits biomedical applications of this material despite its favorable mechanical properties. In this work, surface modification of PDMS by radio-frequency glow discharge and subsequently graft polymerization of acrylamide was studied. PAAm-grafted, oxygen plasma-treated, and control (untreated) PDMS rubbers were characterized using attenuated total reflectance Fourier transform infrared, scanning electron microscopy, dynamic mechanical thermal analyses, zeta potential, and contact angle techniques. Fibroblast (L929) cell attachment and growth onto these surfaces were examined by optical microscopy. The data from in vitro assays showed that cell attachment onto control surface was very negligible while significant cell attachment and growth was observed onto oxygen plasma-treated and PAAm-grafted PDMS surfaces. The method developed in this work offers a convenient way of surface modifications of biomaterials to improve attachment of cells onto substrates. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source] Contribution of the Starch, Protein, and Lipid Fractions to the Physical, Thermal, and Structural Properties of Amaranth (Amaranthus caudatus) Flour FilmsJOURNAL OF FOOD SCIENCE, Issue 5 2007D. Tapia-Blácido ABSTRACT:, Amaranth protein,lipid (PL) and protein (P) films were elaborated and compared with amaranth flour films in order to determine the contribution of the interactions between the biopolymer (starch and protein) and the lipids to the film properties. The films were made by the casting method, using the same glycerol concentration (0.9 g glycerol/100 g solution). A separation of the lipid fraction in the PL films and a polymorphic transformation of the corresponding fatty acids were observed by differential scanning calorimetry (DSC) and verified by an analysis of the microstructure by scanning electron microscopy (SEM). The flour films showed no separation of the lipid fraction, evidence that the lipids were strongly associated with the proteins and homogenously distributed throughout the starch network, contributing to the good mechanical properties when compared to the PL films and to the excellent barrier properties when compared to both the PL and P films. The protein-protein interactions also contributed to the mechanical properties of the flour films. The presence of proteins and lipids in the flour films had an important effect on film solubility, and also on the color and opacity of the films. This study showed that the flour film properties depended on the interactions formed by their polymers (starches and proteins) and by the lipid, on the distribution of these interactions within the film matrix and on the concentrations of each component in the film. [source] A novel aromatic,aliphatic copolyester consisting of poly(1,4-dioxan-2-one) and poly(ethylene- co -1,6-hexene terephthalate): Preparation, thermal, and mechanical propertiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2010Jie Gong Abstract A novel multiblock aromatic,aliphatic copolyester poly(ethylene- co -1,6-hexene terephthalate)-copoly(1,4-dioxan-2-one) (PEHT-PPDO) was successfully synthesized via the chain-extension reaction of dihydroxyl teminated poly(ethylene- co -hexane terephthalate) (PEHT-OH) with dihydroxyl teminated poly(1,4-dioxan-2-one) (PPDO-OH) prepolymers, using toluene-2,4-diisocyanate as a chain extender. To produce PEHT-OH prepolymer with an appropriate melting point which can match the reaction temperature of PEHT-OH prepolymer with PPDO-OH prepolymer, 1,6-hexanediol was used to disturb the regularity of poly(ethylene terephthalate) segments. The chemical structures and molecular weights of PEHT-PPDO copolymers were characterized by 1H NMR, FTIR, and GPC. The DSC data showed that PPDO-OH segments were miscible well with PEHT-OH segments in amorphous state and that the crystallization of copolyester was predominantly contributed by PPDO segments. The TGA results indicated that the thermal stability of PEHT-PPDO was improved comparing with PPDO homopolymer. The novel aromatic,aliphatic copolyesters have good mechanical properties and could find applications in the field of biodegradable polymer materials. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2828,2837, 2010 [source] Photopolymerization of ternary thiol,ene/acrylate systems: Film and network propertiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2007Huanyu Wei Abstract Photocurable, ternary-component mixtures of a 1:1 molar multifunctional thiol,ene (trithiol and triallyl ether) blend and a 16-functional acrylate based monomer have been photopolymerized, and the final film properties of the ternary crosslinked networks have been measured. The photopolymerization kinetics, morphology, and mechanical and physical properties of the films have been investigated with real-time infrared, atomic force microscopy, and dynamic mechanical analysis. The photopolymerization process is a combination of acrylate homopolymerization and copolymerizations of thiol with allyl ether and acrylate functionalities. The tan , peaks of the photopolymerized ternary systems are relatively narrow and tunable over a large temperature range. The morphology is characterized by a distinct phase-separated nanostructure. The photocured thiol,ene/acrylate ternary systems can be made to exhibit good mechanical properties with enhanced energy absorption at room temperature by the appropriate selection of each component concentration. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 822,829, 2007. [source] Novel thermally stable poly(amine hydrazide)s and poly(amine-1,3,4-oxadiazole)s for luminescent and electrochromic materialsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2005Guey-Sheng Liou Abstract We describe the preparation, characterization, and luminescence of four novel electrochromic aromatic poly(amine hydrazide)s containing main-chain triphenylamine units with or without a para-substituted N,N -diphenylamino group on the pendent phenyl ring. These polymers were prepared from either 4,4,-dicarboxy-4,- N,N -diphenylaminotriphenylamine or 4,4,-dicarboxytriphenylamine and the respective aromatic dihydrazide monomers via a direct phosphorylation polycondensation reaction. All the poly(amine hydrazide)s were amorphous and readily soluble in many common organic solvents and could be solution-cast into transparent and flexible films with good mechanical properties. These poly(amine hydrazide)s exhibited strong ultraviolet,visible absorption bands at 346,348 nm in N -methyl-2-pyrrolidone (NMP) solutions. Their photoluminescence spectra in NMP solutions or as cast films showed maximum bands around 508,544 and 448,487 nm in the green and blue region for the two series of polymers. The hole-transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. All obtained poly(amine hydrazide)s and poly(amine-1,3,4-oxadiazole)s exhibited two reversible oxidation redox couples at 0.8 and 1.24 V vs. Ag/AgCl in acetonitrile solution and revealed excellent stability of electrochromic characteristics, changing color from original pale yellow to green and then to blue at electrode potentials of 0.87 and 1.24 V, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3245,3256, 2005 [source] Novel family of triphenylamine-containing, hole-transporting, amorphous, aromatic polyamides with stable electrochromic propertiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2005Tzy-Hsiang Su Abstract We report the preparation and characterization of a series of novel electrochromic, aromatic poly(amine amide)s with pendent triphenylamine units. The synthesis proceeded via direct phosphorylation polycondensation between a novel diamine, N,N -bis(4-aminophenyl)- N,,N,-diphenyl-1,4-phenylenediamine, and various aromatic dicarboxylic acids. All the poly(amine amide)s were amorphous and readily soluble in many common organic solvents and could be solution-cast into transparent, tough, and flexible films with good mechanical properties. They exhibited good thermal stability and 10% weight-loss temperatures above 540 °C. Their glass-transition temperatures were 263,290 °C. These polymers in N -methyl-2-pyrrolidinone solutions exhibited strong ultraviolet,visible absorption peaks at 307,358 nm and photoluminescence peaks around 532,590 nm in the green region. The hole-transporting and electrochromic properties were studied with electrochemical and spectroelectrochemical methods. Cyclic voltammograms of poly(amine amide) films prepared by the casting of polymer solutions onto an indium tin oxide coated glass substrate exhibited two reversible oxidation redox couples at 0.65 and 1.03 V versus Ag/AgCl in an acetonitrile solution. All the poly(amine amide)s showed excellent stability with respect to their electrochromic characteristics; the color of the films changed from pale yellow to green and then blue at 0.85 and 1.25 V, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2085,2098, 2005 [source] Synthesis and properties of novel soluble polyamides having ether linkages and laterally attached p -terphenyl unitsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2004Sheng-Huei Hsiao Abstract A new ether-bridged aromatic dicarboxylic acid, 2,,5,-bis(4-carboxyphenoxy)- p -terphenyl (3), was synthesized by the aromatic fluoro-displacement reaction of p -fluorobenzonitrile with 2,,5,-dihydroxy- p -terphenyl in the presence of potassium carbonate, followed by alkaline hydrolysis. A set of new aromatic polyamides containing ether and laterally attached p -terphenyl units was synthesized by the direct phosphorylation polycondensation of diacid 3 with various aromatic diamines. The polymers were produced with high yields and moderately high inherent viscosities (0.44,0.79 dL/g). The polyamides derived from 3 and rigid diamines, such as p -phenylenediamine and benzidine, and a structurally analogous diamine, 2,,5,-bis(4-aminophenoxy)- p -terphenyl, were semicrystalline and insoluble in organic solvents. The other polyamides were amorphous and organosoluble and could afford flexible and tough films via solution casting. These films exhibited good mechanical properties, with tensile strengths of 91,108 MPa, elongations to break of 6,17%, and initial moduli of 1.95,2.43 GPa. These polyamides showed glass-transition temperatures between 193 and 252 °C. Most of the polymers did not show significant weight loss before 450 °C, as revealed by thermogravimetric analysis in nitrogen or in air. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4056,4062, 2004 [source] Synthesis and characterization of novel soluble triphenylamine-containing aromatic polyamides based on N,N,-bis(4-aminophenyl)- N,N,-diphenyl-1,4-phenylenediamineJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2002Guey-Sheng Liou Abstract A new triphenylamine-containing aromatic diamine, N, N,-bis(4-aminophenyl)- N, N,-diphenyl-1,4-phenylenediamine, was prepared by the condensation of N,N,-diphenyl-1,4-phenylenediamine with 4-fluoronitrobenzene, followed by catalytic reduction. A series of novel aromatic polyamides with triphenylamine units were prepared from the diamine and various aromatic dicarboxylic acids or their diacid chlorides via the direct phosphorylation polycondensation or low-temperature solution polycondensation. All the polyamides were amorphous and readily soluble in many organic solvents such as N, N -dimethylacetamide and N -methyl-2-pyrrolidone. These polymers could be solution cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with relatively high glass-transition temperatures (257,287 °C), 10% weight-loss temperatures in excess of 550 °C, and char yields at 800 °C in nitrogen higher than 72%. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2810,2818, 2002 [source] Synthesis of biodegradable copolymers with low-toxicity zirconium compounds.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2002Abstract The aim of this article is to show a new method of copolymerizing glycolide and caprolactone with the low-toxicity zirconium(IV) acetylacetonate and zirconium(IV) chloride as initiators. Such initiators enabled us to obtain copolymers with very good efficiency and good mechanical properties. The reactivity of the initiators was defined, and the chain-propagation process was examined. On the basis of an NMR examination and differential scanning calorimetry thermograms, we found that the samples obtained at 100 °C with the initiators were characterized by a segmental chain microstructure, which provided good mechanical properties. When the synthesis was carried out at 150 °C, a more randomized structure was obtained, which caused crucial changes in the properties of the copolymers and decreases in the mechanical properties. Because of their properties, the obtained copolymers could be successfully applied as degradable surgical implants or drug carriers. The results show that the copolymers obtained with zirconium(IV) acetylacetonate and chloride could successfully replace ones obtained in the presence of tin compounds as far as medical applications are concerned. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1379,1394, 2002 [source] | |||||||||||||||||||||||||||||||