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Mechanical Analysis (mechanical + analysis)
Kinds of Mechanical Analysis Terms modified by Mechanical Analysis Selected AbstractsEffect of long-term natural aging on the thermal, mechanical, and viscoelastic behavior of biomedical grade of ultra high molecular weight polyethyleneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2010H. Fouad Abstract In the total joint prostheses, Ultra High Molecular Weight Polyethylene (UHMWPE) may undergo an oxidative degradation in the long term. The overall properties of UHMWPE are expected to be altered due to the oxidative degradation. The goal of this study is to investigate the effects of natural aging up to 6 years in air on the thermal, mechanical, and viscoelastic properties of UHMWPE that was used in total joint replacement. The changes in UHMWPE properties due to aging are determined using Differential Scanning Calorimetry (DSC), uniaxial tensile tests, and Dynamic Mechanical Analysis (DMA). The DSC results show that the lamellar thickness and degree of crystallinity of UHMWPE specimens increase by 38% and 12% due to aging. A small shoulder region in the DSC thermograms is remarked for aged specimens, which is an indication of formation of new crystalline forms within their amorphous region. The tensile properties of aged and nonaged UHMWPE specimens show a significant decrease in the elastic modulus, yield, fracture stresses, and strain at break due to aging. The DM testing results indicate that the storage modulus and creep resistance of UHMWPE specimens decrease significantly due to aging. Also, it is remarked that the , relaxation peak for aged UHMWPE specimens occurs at lower temperature compared to nonaged ones. The significant reduction in the strength and creep resistance of UHMWPE specimens due to aging would affect the long-term clinical performance of the total joint replacement and should be taken into consideration during artificial joint design. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] On the Interrelationship of Transreactions with Thermal Properties and Dynamic Mechanical Analysis of PTT/PEN BlendsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 16 2009Seyed-Hassan Jafari Abstract An attempt was made to explore the effects of interchange reactions on the crystallization, melting, and dynamic mechanical behavior of binary blends based on poly(trimethylene terephthalate) (PTT)/poly(ethylene 2,6-naphthalate) (PEN). 1H NMR spectroscopy is used to verify the occurrence of interchange reactions at the interface, which are increased upon an increase in the melt processing time and temperature. The crystallinity of PTT was reduced while that of PEN was increased on blending. In addition, the crystallization temperatures of both phases showed depression. A single composition-dependent glass transition temperature (Tg) was detected in the second and subsequent heating thermograms of the blends, which is indicative of miscibility. The cold crystallization of the PTT phase was observed to increase while that of PEN was suppressed on blending. Each phase crystallized individually and a melting point depression was evident, which suggests a certain level of miscibility. Dynamic mechanical thermal analysis corroborated differential scanning calorimetry results. A constructive synergism was observed in the glassy state storage moduli of the blends, which is suggestive of a reduced specific volume of the system because of enhanced interactions and crystallinity. [source] Effect of EPDM on Morphology, Mechanical Properties, Crystallization Behavior and Viscoelastic Properties of iPP+HDPE BlendsMACROMOLECULAR SYMPOSIA, Issue 1 2007Nina Vranjes Abstract Summary: Blends of isotactic polypropylene (iPP) and high density polyethylene (HDPE) with and without ethylene-propylene-diene (EPDM) terpolymer as compatibilizer were systematically investigated to determine the influence of the EPDM on blends properties. The morphology was studied by Scanning Electron Microscopy (SEM). Mechanical properties of investigated systems: tensile strength at break, elongation at break, yield stress and Izod impact strength were determined. Crystallization behavior was determined by Differential Scanning Calorimetry (DSC). Dynamic Mechanical Analysis (DMA) was used to determined the storage modulus (E,), loss modulus (E,), and loss tangent (tan ,). The PP+HDPE blend revealed poor adhesion between PP and HDPE phases. Finer morphology was obtained by EPDM addition in PP+HDPE blends and better interfacial adhesion. Addition of HDPE to PP decreased tensile strength at break, elongation and yield stress. Decrease of tensile strength and yield stress is faster with EPDM addition in PP+HDPE blends. Elongation at break and impact strength was significantly increased with EPDM addition. The addition of EPDM in PP+HDPE blends did not significantly change melting points of PP phase, while melting points of HDPE phase was slightly decreased in PP+HDPE+EPDM blends. The EPDM addition increased the percentage of crystallization (Xc) of PP in PP+HDPE blends. The increase of Xc of HDPE was found in the blend with HDPE as matrix. Dynamical mechanical analysis showed glass transitions of PP and HDPE phase, as well as the relaxation transitions of their crystalline phase. By addition of EPDM glass transitions (Tg) of HDPE and PP phases in PP+HDPE blends decreased. Storage modulus (E,) vs. temperatures (T) curves are in the region between E,/T curves of neat PP and HDPE. The decrease of E, values at 25,°C with EPDM addition in PP+HDPE blends is more pronounced. [source] Characterization of a Novel Fiber Composite Material for Mechanotransduction Research of Fibrous Connective TissuesADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Hazel R. C. Screen Abstract Mechanotransduction is the fundamental process by which cells detect and respond to their mechanical environment, and is critical for tissue homeostasis. Understanding mechanotransduction mechanisms will provide insights into disease processes and injuries, and may support novel tissue engineering research. Although there has been extensive research in mechanotransduction, many pathways remain unclear, due to the complexity of the signaling mechanisms and loading environments involved. This study describes the development of a novel hydrogel-based fiber composite material for investigating mechanotransduction in fibrous tissues. By encapsulating poly(2-hydroxyethyl methacrylate) rods in a bulk poly(ethylene glycol) matrix, it aims to create a micromechanical environment more representative of that seen in vivo. Results demonstrated that collagen-coated rods enable localized cell attachment, and cells are successfully cultured for one week within the composite. Mechanical analysis of the composite indicates that gross mechanical properties and local strain environments could be manipulated by altering the fabrication process. Allowing diffusion between the rods and surrounding matrix creates an interpenetrating network whereby the relationships between shear and tension are altered. Increasing diffusion enhances the shear bond strength between rods and matrix and the levels of local tension along the rods. Preliminary investigation into fibroblast mechanotransduction illustrates that the fiber composite upregulates collagen I expression, the main protein in fibrous tissues, in response to cyclic tensile strains when compared to less complex 2D and 3D environments. In summary, the ability to create and manipulate a strain environment surrounding the fibers, where combined tensile and shear forces uniquely impact cell functions, is demonstrated. [source] Microstructure and mechanical properties related to particle size distribution and composition in dark chocolateINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2009Emmanuel Ohene Afoakwa Summary Composition in dark chocolate was varied and the effects determined on microstructure, using light microscopy, and mechanical properties of molten and tempered chocolates, using a TA.HD Plus Texture Analyser. Compositional parameters were particle size distribution (PSD) (D90 of 18, 25, 35 and 50 ,m), fat (25%, 30% and 35%) and lecithin (0.3% and 0.5%) contents. Micrographs revealed wide variations in sugar crystalline network structure and inter-particle interaction strengths related to PSD and fat level. Samples containing 25% fat had more crystal agglomerates, well flocculated with greater particle-to-particle interaction strengths than those with higher (30% and 35%) fat contents. Increasing the D90 to 35,50 ,m caused broadening of the PSD, with particles becoming coarser, which were similar at all fat levels. Mechanical analysis showed that PSD, fat and lecithin content significantly influenced firmness of molten chocolate and hardness of solid (tempered) chocolate with significant interactions among factors. Particle size was inversely correlated with firmness (1235,173 g) and hardness (7062,5546 g). Greatest effect of PSD was with 25% fat and 0.3% lecithin. With higher fat and lecithin contents, the PSD influence was reduced. It was concluded that PSD, fat and lecithin contents and their interactions were central to mechanical properties of dark chocolates. [source] Effects of eccentric treadmill running on mouse soleus: degeneration/regeneration studied with Myf-5 and MyoD probesACTA PHYSIOLOGICA, Issue 1 2003A.-S. Armand Abstract Aim:, The aim of this report is to show that eccentric exercise under well-controlled conditions is an alternative model, to chemical and mechanical analyses, and analyse the process of degeneration/regeneration in mouse soleus. Methods:, For this, mice were submitted to a single bout of eccentric exercise on a treadmill down a 14° decline for 150 min and the soleus muscle was analysed at different times following exercise by histology and in situ hybridization in comparison with cardiotoxin-injured muscles. Results:, We analyse the regenerative process by detection of the accumulation of transcripts coding for the two myogenic regulatory factors, Myf-5 and MyoD, which are good markers of the activated satellite cells. From 24 h post-exercise (P-E), clusters of mononucleated Myf-5/MyoD-positive cells were detected. Their number increased up to 96 h P-E when young MyoD-positive myotubes with central nuclei began to appear. From 96 to 168 h P-E the number of myotubes increased, about 10-fold, the new myotubes representing 58% of the muscle cells (168 h P-E). Conclusion:, These results show that this protocol of eccentric exercise is able to induce a drastic degeneration/regeneration process in the soleus muscle. This offers the opportunity to perform biochemical and molecular analyses of a process of regeneration without muscle environment defects. The advantages of this model are discussed in the context of fundamental and therapeutical perspectives. [source] A fast implementation of the FETI-DP method: FETI-DP-RBS-LNA and applications on large scale problems with localized non-linearitiesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2005Jun Sun Abstract As parallel and distributed computing gradually becomes the computing standard for large scale problems, the domain decomposition method (DD) has received growing attention since it provides a natural basis for splitting a large problem into many small problems, which can be submitted to individual computing nodes and processed in a parallel fashion. This approach not only provides a method to solve large scale problems that are not solvable on a single computer by using direct sparse solvers but also gives a flexible solution to deal with large scale problems with localized non-linearities. When some parts of the structure are modified, only the corresponding subdomains and the interface equation that connects all the subdomains need to be recomputed. In this paper, the dual,primal finite element tearing and interconnecting method (FETI-DP) is carefully investigated, and a reduced back-substitution (RBS) algorithm is proposed to accelerate the time-consuming preconditioned conjugate gradient (PCG) iterations involved in the interface problems. Linear,non-linear analysis (LNA) is also adopted for large scale problems with localized non-linearities based on subdomain linear,non-linear identification criteria. This combined approach is named as the FETI-DP-RBS-LNA algorithm and demonstrated on the mechanical analyses of a welding problem. Serial CPU costs of this algorithm are measured at each solution stage and compared with that from the IBM Watson direct sparse solver and the FETI-DP method. The results demonstrate the effectiveness of the proposed computational approach for simulating welding problems, which is representative of a large class of three-dimensional large scale problems with localized non-linearities. Copyright © 2005 John Wiley & Sons, Ltd. [source] Polyhedral Oligomeric Silsesquioxane (POSS) Nanoscale Reinforcement of Thermosetting Resin from Benzoxazine and BisoxazolineMACROMOLECULAR RAPID COMMUNICATIONS, Issue 23 2005Qiao Chen Abstract Summary: The reaction between octaaminophenyl polyhedral oligomeric silsesquioxane (OAPS) and 2,2,-(1,3-phenylene)-bis(4,5-dihydro-oxazoles) (PBO) over different temperature ranges was confirmed by FT-IR spectroscopy. The OAPS was used to modify benzoxazine (BZ) in the presence of PBO. The novel polybenzoxazine (PBZ)-PBO/OAPS hybrid nanocomposite was prepared by solvent methods. Dynamic mechanical analyses indicated that the nanocomposites exhibited much higher Tg values than the pristine PBZ and PBZ-PBO resin, and the storage modulus of the nanocomposites was maintained at higher temperatures, although only a small amount of OAPS was incorporated into the systems. Dynamic thermogravimetric analysis showed that the thermal stability of the hybrid was also improved by the inclusion of OAPS. DMA of PBZ (a), PBZ-PBO (b), and PBZ-PBO/OAPS nanocomposites (c,e). [source] In situ reinforcement of poly(butylene terephthalate) and butyl rubber by liquid crystalline polymerPOLYMER COMPOSITES, Issue 5 2009S. Kumar Ternary in situ butyl rubber (IIR)/poly(butylene terephthalate) (PBT) and liquid crystalline polymer (LCP) blends were prepared by compression molding. The LCP used was a versatile Vectra A950, and the matrix material was IIR/PBT 50/50 by weight. Morphological, thermal, and mechanical properties of blends were investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimetry, and thermogravimetric analysis (TGA). Microscopy study (SEM) showed that formation of fibers is increasing with the increasing amount of LCP A950. Microscopic examination of the fractured surface confirmed the presence of a polymer coating on LCP fibrils. This can be attributed to some interactions including both chemical and physical one. The increased compatibility in polymer blends, consisting of IIR/PBT, by the presence of LCP A950 may be explained by the adsorption phenomena of the polymer chains onto the LCP fibrils. SEM and AFM images provided the evidence of the interaction between IIR/PBT and the LCP. Dynamic mechanical analyses (DMA) and TGA measurements showed that the composites possessed a remarkably higher modulus and heat stability than the unfilled system. Storage modulus for the ternary blend containing 50 wt% of LCP exhibits about 94% increment compared with binary blend of IIR/PBT. From the above results, it is suggested that the LCP A950 can act as reinforcement agent in the blends. Moreover, the fine dispersion of LCP was observed with no extensional forces applied during mixing, indicating the importance of interfacial adhesion for the fibril formation. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] Silicone,Poly(hexylthiophene) Blends as Elastomers with Enhanced Electromechanical Transduction Properties,ADVANCED FUNCTIONAL MATERIALS, Issue 2 2008F. Carpi Abstract Dielectric elastomers are progressively emerging as one of the best-performing classes of electroactive polymers for electromechanical transduction. They are used for actuation devices driven by the so-called Maxwell stress effect. At present, the need for high-driving electric fields limits the use of these transduction materials in some areas of potential application, especially in the case of biomedical disciplines. A reduction of the driving fields may be achieved with new elastomers offering intrinsically superior electromechanical properties. So far, most attempts in this direction have been focused on the development of composites between elastomer matrixes and high-permittivity ceramic fillers, yielding limited results. In this work, a different approach was adopted for increasing the electromechanical response of a common type of dielectric elastomer. The technique consisted in blending, rather than loading, the elastomer (poly(dimethylsiloxane)) with a highly polarizable conjugated polymer (undoped poly(3-hexylthiophene)). The resulting material was characterised by dielectric spectroscopy, scanning electron microscopy, tensile mechanical analysis, and electromechanical transduction tests. Very low percentages (1,6 wt %) of poly(3-hexylthiophene) yielded both an increase of the relative dielectric permittivity and an unexpected reduction of the tensile elastic modulus. Both these factors synergetically contributed to a remarkable increase of the electromechanical response, which reached a maximum at 1 wt % content of conjugated polymer. Estimations based on a simple linear model were compared with the experimental electromechanical data and a good agreement was found up to 1 wt %. This approach may lead to the development of new types of materials suitable for several types of applications requiring elastomers with improved electromechanical properties. [source] Integration of geometric design and mechanical analysis using B-spline functions on surfaceINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 14 2005Hee Yuel Roh Abstract B-spline finite element method which integrates geometric design and mechanical analysis of shell structures is presented. To link geometric design and analysis modules completely, the non-periodic cubic B-spline functions are used for the description of geometry and for the displacement interpolation function in the formulation of an isoparametric B-spline finite element. Non-periodic B-spline functions satisfy Kronecker delta properties at the boundaries of domain intervals and allow the handling of the boundary conditions in a conventional finite element formulation. In addition, in this interpolation, interior supports such as nodes can be introduced in a conventional finite element formulation. In the formulation of the mechanical analysis of shells, a general tensor-based shell element with geometrically exact surface representation is employed. In addition, assumed natural strain fields are proposed to alleviate the locking problems. Various numerical examples are provided to assess the performance of the present B-spline finite element. Copyright © 2005 John Wiley & Sons, Ltd. [source] A finite element model for thermomechanical analysis of sheet metal formingINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2004G. Bergman Abstract A thermal model based on explicit time integration is developed and implemented into the explicit finite element code DYNA3D to model simultaneous forming and quenching of thin-walled structures. A staggered approach is used for coupling the thermal and mechanical analysis, wherein each analysis is performed with different time step sizes. The implementation includes a thermal shell element with linear temperature approximation in the plane and quadratic in the thickness direction, and contact heat transfer. The material behaviour is described by a temperature-dependent elastic,plastic model with a non-linear isotropic hardening law. Transformation plasticity is included in the model. Examples are presented to validate and evaluate the proposed model. The model is evaluated by comparison with a one-sided forming and quenching experiment. Copyright © 2004 John Wiley & Sons, Ltd. [source] Nanofilled polyethersulfone as matrix for continuous glass fibers composites: Mechanical properties and solvent resistance,ADVANCES IN POLYMER TECHNOLOGY, Issue 3 2010M. Aurilia Abstract Polyethersulfone (PES) is high performance thermoplastic polymer; however, its applications are limited by the poor resistance to several classes of solvents. Fumed silica and expanded graphite nanoparticles were used to prepare nanofilled PES by a melt-compounding technique with the view to improve the barrier properties. Solvent uptake at equilibrium and solvents resistance of nanofilled PES compounds were investigated by three different methodologies: (1) weight increase by methylene chloride absorption in a vapor-saturated atmosphere, (2) solvent uptake of acetone at equilibrium, and (3) decay of storage modulus induced by acetone diffusion. The storage modulus decay was measured by means of dynamic mechanical analysis on samples immersed in an acetone bath. The collected data were fitted to an ad hoc model to calculate the diffusion coefficient. The produced nanofilled PES showed a significant improvement in barrier properties and considerable reduction in acetone uptake at equilibrium, in comparison with the neat PES. Nanofilled PES compounds were also used to produce continuous glass fiber composites by the film-stacking manufacturing technique. The composites exhibited, by and large, improvements in flexural and shear strength. Their solvent resistance was evaluated by measuring the variation of mechanical properties after exposure to acetone for 1 and 5 days. These tests showed that the composites produced with the nanocomposite matrix did not exhibit higher solvent resistance than those prepared with neat PES, probably because of the deterioration of the fiber/nanocomposite-matrix interfacial bond in the wet state. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 29:146,160, 2010; View this article online at wileyonlinelibrary. DOI 10.1002/adv.20187 [source] Polymer characterization by ultrasonic wave propagationADVANCES IN POLYMER TECHNOLOGY, Issue 2 2008Francesca Lionetto Abstract The propagation of low-intensity ultrasound in polymers, acting as a high-frequency dynamic mechanical deformation, can be successfully used to monitor changes in the modulus of polymers associated with glass transition, crystallization, cross-linking, and other chemical and physical phenomena related to changes in the viscoelastic behavior, such as gelation phenomena. The velocity of sound is related to the polymer storage modulus and density, whereas the absorption of ultrasonic waves is related to the energy dissipation in the material and, therefore, to the loss modulus. Accordingly, ultrasonic measurements have been used by several authors to monitor the evolution of the viscoelastic moduli of polymers as a function of time or temperature and, recently, become a characterization technique of its own right, generally known as ultrasonic dynamic mechanical analysis (UDMA). Often the technique is used in conjunction with rheological methods as a means of providing a better insight into the viscoelastic behavior of polymer systems. As yet UDMA is underutilized primarily because of the low operating temperatures (usually below 100,C) of commercially available ultrasonic transducers, and also due to the requirement of a coupling medium to ensure an efficient energy transfer mechanism between the transducer and the test material. Despite these limitations, this paper shows that the use of ultrasonics is potentially a powerful method for the characterization of polymers, particularly as a tool for online monitoring of events occurring during polymer processing and in the manufacture of polymer matrix composites. The aim of this paper is to review the progress made in recent years, highlighting the potential and reliability of UDMA for monitoring physical transitions in polymers such as glass transition, melting, crystallization, as well as physical changes taking place during curing of thermosetting resins. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:63,73, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20124 [source] Investigation of the gelatinization and extrusion processes of corn starchADVANCES IN POLYMER TECHNOLOGY, Issue 1 2002Roberta C. R. Souza Abstract The gelatinization and extrusion processes of corn starch were studied. Differential scanning calorimetry was used to determine the gelatinization temperature as a function of the water content. Plasticized corn starch was processed in single- and twin-screw extruders to produce thermoplastic materials. The mechanical properties of the films obtained in the twin-screw extruder with the addition of different quantities of water were evaluated. Dynamic mechanical analysis applied to thermoplastic starch samples obtained with 33% (w/w) total plasticizers showed two transitions, attributed to the presence of two phases in the starch,glycerol,water system. © 2002 John Wiley & Sons, Inc. Adv Polym Techn 21: 17,24, 2002; DOI 10.1002/adv.10007 [source] Gellan,adipic acid blends crosslinked by means of a dehydrothermal treatmentJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Niccoletta Barbani Abstract Blends of gellan gum (GE) and adipic acid (ADA), at various ratios, were manufactured in the form of films by casting from aqueous solutions and crosslinked by a dehydrothermal treatment (DHT). The materials, before and after DHT, were characterized by both physicochemical tests and cellular adhesion and growth on the film surfaces. The total reflection and spotlight Fourier transform infrared (FTIR) spectroscopy and optical and scanning electron microscopy showed the presence of both GE-rich and ADA-rich regions and the formation of ester groups after DHT. Differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis (DMA) showed that the crosslinking by DHT made the materials more thermally stable. The swelling in water, which diminished in the films subjected to DHT, confirmed that the crosslinking enhanced the whole stability of the material. DMA also showed that the behavior of the GE,ADA blends was quite similar to that of some living tissues, such as the skin. The cell cultures indicated that the materials, especially that with a 6 : 10 ADA-to-GE ratio, were very able to promote cellular adhesion and proliferation. In conclusion, the GE,ADA crosslinked blends appeared very suitable for a use as biomaterials; in particular, the cell cultures indicated that they might be useful as scaffolds for tissue reconstruction. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Influence of processing conditions and physicochemical interactions on morphology and fracture behavior of a clay/thermoplastic/thermosetting ternary blendJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010M. Hernandez Abstract This study provides information on the mechanical behavior of epoxy-poly(methyl methacrylate) (PMMA)-clay ternary composites, which have been prepared using the phase separation phenomenon of PMMA and the introduction of organophilic-modified montmorillonites (MMTs), the continuous matrix being the epoxy network. Two dispersion processing methods are used: a melt processing without any solvent and an ultrasonic technique with solvent and a high-speed stirrer. TEM analysis shows that phase separation between PMMA and the epoxy network was obtained in the shape of spherical nodules in the presence of the clay in both process methods used. Nanoclay particles were finely dispersed inside thermosetting matrix predominantly delaminated when ultrasonic blending was used; whereas micrometer-sized aggregates were formed when melt blending was used. The mechanical behavior of the ternary nanocomposites was characterized using three-point bending test, dynamic mechanical analysis (DMA), and linear elastic fracture mechanics. The corresponding fracture surfaces were examined by scanning electron microscopy to identify the relevant fracture mechanisms involved. It was evidenced that the better dispersion does not give the highest toughness because ternary nanocomposites obtained by melt blending present the highest fracture parameters (KIc). Some remaining disordered clay tactoids seem necessary to promote some specific toughening mechanisms. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Curing behavior and mechanical properties of hollow glass microsphere/bisphenol a dicyanate ester compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010Jinhe Wang Abstract Hollow glass microsphere (HGS)/bisphenol A dicyanate ester (BADCy) composites have been prepared by mechanical mixing, followed by a stepped curing process. The effect of HGS on the curing behavior of BADCy was studied using differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The mechanical properties of the composites were examined by mechanical tests, and the improvements of the mechanical properties were investigated by scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA). The results show that HGS is catalytic for the polycyclomerization of the BADCy, which is advantageous to reduce the maximal processing temperature. The impact strength, flexural strength, flexural modulus and storage modulus of BADCy are improved. The improvements of the mechanical properties without sacrificing thermal properties, the ability of lowing processing temperature and the low cost make HGS good filler for cyanate ester resin. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Effect of wood flour loading and thermal annealing on viscoelastic properties of poly(lactic acid) composite filmsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010M. Hrabalova Abstract Poly(lactic acid) (PLA) films filled with up to 50 wt % softwood flour were prepared by melt compounding and thermocompression. Thermal annealing of the melt was performed at temperatures from 90°C to 120°C, for 45 min. Responses on polymer-filler interactions, viscoelastic properties, crystallinity of PLA as well as PLA-wood flour-filled films were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). The effectiveness of fillers on the storage moduli (C) was also calculated. The results reveal that wood flour (WF) in conjunction with thermal annealing affected the melting behavior of PLA matrix, and the glass transition temperature. It was further found that the effectiveness of the wood filler in biocomposites widely improved with thermal annealing as well as with higher WF concentration. Finally, it was found that the compatibility between WF and the PLA matrix can be improved when suitable annealing conditions are applied. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Synthesis and characterization of a cured epoxy resin with a benzoxazine monomer containing allyl groupsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Shiao-Wei Kuo Abstract Vinyl-terminated benzoxazine (VB-a), which can be polymerized through ring-opening polymerization, was synthesized through the Mannich condensation of bisphenol A, formaldehyde, and allylamine. This VB-a monomer was then blended with epoxy resin and then concurrently thermally cured to form an epoxy/VB-a copolymer network. To understand the curing kinetics of this epoxy/VB-a copolymer, dynamic differential scanning calorimetry measurements were performed by the Kissinger and Flynn,Wall,Ozawa methods. Fourier transform infrared (FTIR) analyses revealed the presence of thermal curing reactions and hydrogen-bonding interactions of the epoxy/VB-a copolymers. Meanwhile, a significant enhancement of the ring-opening and allyl polymerizations of the epoxy was observed. For these interpenetrating polymer networks, dynamic mechanical analysis and thermogravimetric analysis results indicate that the thermal properties increased with increasing VB-a content in the epoxy/VB-a copolymers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Synthesis and characterization of biodegradable crosslinked polymers from 5-hydroxylevulinic acid and ,,,-diolsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Yan Zhang Abstract Novel biodegradable chemically crosslinked polymers, poly(5-hydroxylevulinic acid- co -,,,-diol)s (PHLA-diols), were synthesized from 5-hydroxylevulinic acid and ,,,-diols and characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. The gel content, swelling ratio, tensile properties, and hydrolytic degradation behaviors were also measured and assessed. The glass-transition temperature of the PHLA-diols could be adjusted within a wide range (,50 to 30°C) by the type and feed ratio of the diol. Because of the low glass-transition temperature and crosslink structure, they exhibited certain elastic properties. The tensile modulus, strength, and elongation at break measured at 37°C were 1.4,6.3 MPa, 0.8,1.6 MPa, and 10,25%, respectively. These polymers could be hydrolytically degraded. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Systematic study of interfacial interactions between clays and an ionomerJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Yan Gao Abstract To study the interfacial interactions between an ionomer [poly(ethylene- co -acrylic acid) neutralized by zinc salts (PI)] and clays, PI,clay nanocomposites were prepared using a solution method. Two types of commercially available montmorillonite clays respectively K10 and KSF were used, and were modified with organic modifiers with chain lengths of 12,18 carbons. The interactions between the PI, clays, and modifiers were evaluated through study of the structure, morphology, and properties of the PI,clay nanocomposites. We found that the modifiers were successfully intercalated into the clay layers (Fourier transform infrared spectroscopy). The clay modified with a long-chain agent showed an exfoliated nature in the nanocomposite. The thermal stability and storage modulus of PI were improved greatly by the addition of the clays, especially when the long-chain modifier was used (thermogravimetric analysis and dynamic mechanical analysis). The differential scanning calorimetry results show that clay layers are inserted into the clusters because of solvent-directed morphological evolution, so the transition of the ionic domains and the crystallinity of PI are changed. The interaction between PI, the modifier, and the silicate layer played an important role in the determination of the properties of the nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Highlight of a compensation effect between filler morphology and loading on dynamic properties of filled rubbersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Franck Sosson Abstract This investigation highlighted the equivalence between carbon black (CB) loading and structure influences on dynamic mechanical properties in the linear behavior of several filled synthetic rubber compounds. Different morphologies (specific surface area and structure) of CB incorporated at different loadings were formulated to modulate the filler-rubber matrix interphase content, usually named "tightly bound rubber." Both reinforcement level and tightly bound rubber content were measured on each compound by dynamic mechanical analysis (DMTA) and by Soxhlet extraction and thermogravimetry (TGA) respectively. Then, a systematic description of their evolution was made against CB loading and morphology. These evolutions were attributed to the hydrodynamic effect which could be evaluated by the effective filler volume fraction. A new parameter , is defined, representing the effective filler volume fraction for each compound and it was calculated on the basis of experimental parameters. Results show good correspondences between , included both the hydrodynamic effects of the filled carbon black rubbers and dynamic mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] The effect of water-soluble polymers on rheology of microfibrillar cellulose suspension and dynamic mechanical properties of paper sheetJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Arja-Helena Vesterinen Abstract Rheological properties of fiber/polymer suspensions and dynamic mechanical analysis (DMA) of paper sheets containing the same polymers were measured. Correlations between viscoelastic properties of suspensions and strength of paper sheet are presented. Rheological properties of suspensions of microfibrillar cellulose (MFC) and a set of water soluble polymers were measured. Rheological properties of these complex fluids vary considerably depending on the added polymer. A suspension of fiber and carboxymethyl cellulose (CMC) exhibits a viscosity higher than the sum of the viscosity of the individual components in the suspension. In contrast, when cationic starch (CS) is used together with the fiber, the yielding behavior rather than the viscosity is characteristic of the suspension. Dynamic mechanical properties of paper sheets containing CMC or CS as additives were studied at different humidity levels. Different yielding behavior observed in oscillatory rheology can be correlated with straining behavior in dynamic mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Compatibility studies with blends based on poly(n -butyl methacrylate) and polyacrylonitrileJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Zhaogang Ge Abstract In this study, poly(n -butyl methacrylate) (PBMA) was prepared by a suspension polymerization process, and blending with polyacrylonitrile (PAN) in N,N -dimethyl acetamide to prepare PAN/PBMA blends in various proportions. Hansen's three dimensional solubility parameters of PAN and PBMA were calculated approximately through the contributions of the structural groups. The compatibility in these blend systems was studied with theoretical calculations as well as experimental measurements. Viscometric methods, Fourier transform infrared spectroscopy, dynamic mechanical analysis, scanning electron microscopy, and thermogravimetric analysis were used for this investigation. All the results showed that a partial compatibility existed in PAN/PBMA blend system, which may be due to the intermolecular interactions between the two polymers. And, the adsorption experiment results showed that the addition of PBMA contributed to the enhancing adsorptive properties of blend fibers, which lays the foundation for further studying PAN/PBMA blend fibers with adsorptive function. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Polypropylene nanocomposite film: A critical evaluation on the effect of nanoclay on the mechanical, thermal, and morphological behaviorJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010S. K. Sharma Abstract Polypropylene (PP)/clay nanocomposites prepared by melt blending technique using different percentages of clay with and without maleic anhydride grafted PP (MA-PP) were studied. The intercalated and exfoliated structure of nanocomposites was characterized by X-Ray Diffraction (XRD) and transmission electron microscopy (TEM). Because of the typical intercalated and exfoliated structure, the tensile modulus of the nanocomposites were improved significantly as compared to virgin PP. The viscoelastic behavior of the nanocomposites was studied by dynamical mechanical analysis (DMA) and the results showed that with the addition of treated clay to PP there was substantial improvement in storage modulus increases. The thermal stability and crystallization of the PP nanocomposites as studied by differential scanning calorimeter (DSC) and thermo gravimetric analysis (TGA) were also improved significantly compared to PP. © 2009 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] Nano-AlN functionalization by silane modification for the preparation of covalent-integrated epoxy/poly(ether imide) nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Jingkuan Duan Abstract Aluminum nitride nanoparticle (nano-AlN) organically modified with the silane-containing epoxide groups (3-glycidoxypropyltrimethoxy silane, GPTMS) was incorporated into a mixture of poly(ether imide) (PEI), and methyl hexahydrophthalic anhydride-cured bisphenol A diglycidyl ether grafted by GPTMS was prepared for nanocomposite. Scanning electron microscopy, transmission electron microscopy, and atomic force microscopy were used to investigate the microscopic structures of nanocomposites. According to experimental results, it was shown that addition of nano-AlN and PEI into the modified epoxy could lead to the improvement of the impact and bend strengths. When the concentrations of nano-AlN and PEI were 20 and 10 pbw, respectively, the toughness/stiffness balance could be achieved. Dynamic mechanical analysis (DMA) results displayed that two glass transition temperatures (Tg) found in the nanocomposites were assigned to the modified epoxy phase and PEI phase, respectively. As nano-AlN concentration increased, Tg value of epoxy phase had gradually increased, and the storage modulus of the nanocomposite at the ambient temperature displayed an increasing tendency. Additionally, thermal stability of the nanocomposite was apparently improved. The macroscopic properties of nanocomposites were found to be strongly dependent on their components, concentrations, dispersion, and resulted morphological structures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Glass transition and cold crystallization in carbon dioxide treated poly(ethylene terephthalate)JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2009Yeong-Tarng Shieh Abstract An amorphous poly(ethylene terephthalate) (aPET) and a semicrystalline poly(ethylene terephthalate) obtained through the annealing of aPET at 110°C for 40 min (aPET-110-40) were treated in carbon dioxide (CO2) at 1500 psi and 35°C for 1 h followed by treatment in a vacuum for various times to make samples containing various amount of CO2 residues in these two CO2 -treated samples. Glass transition and cold crystallization as a function of the amount of CO2 residues in these two CO2 -treated samples were investigated by temperature-modulated differential scanning calorimetry (TMDSC) and dynamic mechanical analysis (DMA). The CO2 residues were found to not only depress the glass-transition temperature (Tg) but also facilitate cold crystallization in both samples. The depressed Tg in both CO2 -treated poly(ethylene terephthalate) samples was roughly inversely proportional to amount of CO2 residues and was independent of the crystallinity of the poly(ethylene terephthalate) sample. The nonreversing curves of TMDSC data clearly indicated that both samples exhibited a big overshoot peak around the glass transition. This overshoot peak occurred at lower temperatures and was smaller in magnitude for samples containing more CO2 residues. The TMDSC nonreversing curves also indicated that aPET exhibited a clear cold-crystallization exotherm at 120.0°C, but aPET-110-40 exhibited two cold-crystallization exotherms at 109.2 and 127.4°C. The two cold crystallizations in the CO2 -treated aPET-110-40 became one after vacuum treatment. The DMA data exhibited multiple tan , peaks in both CO2 -treated poly(ethylene terephthalate) samples. These multiple tan , peaks, attributed to multiple amorphous phases, tended to shift to higher temperatures for longer vacuum times. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Study of PET/PP/TiO2 microfibrillar-structured composites, part 1: Preparation, morphology, and dynamic mechanical analysis of fibrillized blendsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2009Wenjing Li Abstract The objective of this study was to manufacture and investigate a novel microfibrillar-reinforced material based on fibrillized blends of polyethyleneterephthalate (PET), polypropylene (PP), and TiO2 nanoparticles (300 nm and 15 nm in size). The uncompatibilized and compatibilized blends (polypropylene grafted maleic anhydride as compatibilizer) were extruded and subsequently cold-drawn into strands with a draw ratio of 10. The effects of compatibilizer and TiO2 particles on the structure and properties of drawn strands were investigated. Upon addition of compatibilizer, the preferential location of TiO2 particles shifted from the PET-dispersed phase to the PP matrix, which brought about different structures of the drawn strands. Differential scanning calorimetry study provided indications for a heterogeneous nucleation effect of the PET fibrils on the PP matrix and of the TiO2 particles on the PET fibrils. Dynamic mechanical analysis demonstrated that the mechanical properties of the drawn strands are strongly dependent on the strand structures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] | ||||||||||||||||||||||||||||||||||