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Dynamic Rheological Properties (dynamic + rheological_property)
Selected AbstractsDynamic rheological and morphological study of the compatibility of thermoplastic polyurethane/ethylene,octene copolymer blendsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Jin Yang Abstract Two grafted ethylene,octene copolymers [POEs; i.e., POE-g-maleic anhydried (MAH) and aminated POE (denoted by POE-g-NH2) were used as compatibilizers in immiscible blends of thermoplastic polyurethane (TPU) and POE. The effects of the compatibilizers on the dynamic rheological properties and morphologies of the TPU/POE blends were investigated. The characteristic rheological behaviors of the blends indicated that the strong interactions between the two phases were due to the compatibilization. Microstructural observation confirmed that the compatibilizers were located at the interface in the blends and formed a stable interfacial layer and smaller dispersed phase particle size. Compared with POE- g -MAH, POE- g -NH2 exhibited a better compatibilization effect in the TPU/POE blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Xanthan Enhances Water Binding and Gel Formation of Transglutaminase-Treated Porcine Myofibrillar ProteinsJOURNAL OF FOOD SCIENCE, Issue 3 2010Yongbiao Shang ABSTRACT:, In this study, the effect of xanthan on dynamic rheological properties, textural profile, and water binding of transglutaminase (TG)-treated myofibrillar protein (MP) gels was investigated. In experiment 1, MP suspensions (40 mg/mL protein, 0.6 M NaCl) at pH 6.45 with or without 0.05% xanthan were treated with 0%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% TG; in experiment 2, MP suspensions (40 mg/mL protein, 0.6 M NaCl) at pHs 6.13, 6.30, 6.45, 6.69 with or without 0.05% xanthan were treated with 0.3% TG. Treated samples were analyzed with differential scanning calorimetry for thermal stability and oscillatory rheometry and Instron penetration tests for gelation properties. The TG treatments lowered the transition temperature (Tm) of MP by as much as 6 °C (P,< 0.05) but increased apparent enthalpy of denaturation. However, there was no detectable thermal stability difference between MP samples with or without xanthan. The shear storage modulus (G,) of MP gels increased markedly upon treatments with ,0.3% TG, and the presence of xanthan further enhanced the gel strength (P,< 0.05). The addition of 0.05% xanthan decreased cooking loss of TG-treated MP gels by 17% to 23% when compared with gels without xanthan at all pH levels evaluated (6.13 to 6.67). Thus, the combination of TG and xanthan offered a feasible means to promote cross-linking and gelation of MP while reducing cooking losses. [source] RHEOLOGY AND MICROSTRUCTURE OF WHEAT DOUGH DEVELOPED WITH CONTROLLED DEFORMATIONJOURNAL OF TEXTURE STUDIES, Issue 1 2000EMILY J. SCHLUENTZ ABSTRACT Undeveloped wheat dough samples were strained in shear and extensional flow between parallel plates to produce a controlled level of development. Dough made in a standard Farinograph, considered developed dough, was used for comparison. Scanning electron microscopy images of deformed dough were subjected to numerical image processing to characterize the protein matrix present. Results were compared to dynamic rheological properties to evaluate the influence of strain deformation on the formation of microstructure. Viscoelastic moduli of wheat dough showed that developed dough had the greatest amount of structure formation, followed by extensionally-strained and shear-strained samples, respectively. Undeveloped dough showed the lowest levels of structure development. Image analysis indicated statistically significant differences between protein matrices in developed and undeveloped samples; however, results were not significantly different between shear- and extension-ally-strained samples. [source] An investigation on the mechanical and dynamic rheological properties of single and hybrid filler/polypropylene composites based on talc and calcium carbonatePOLYMER COMPOSITES, Issue 12 2009Hamed Azizi Some results of experiments on the mechanical and rheological properties of mineral filled polypropylene were presented. Single filler and hybrid filler composites of talc and calcium carbonate (CaCO3) were prepared in a co-rotating twin-screw extruder. The effect of filler type, filler content, and coupling agent on the mechanical and rheological properties of the polypropylene were studied. The coupling agent was maleic anhydride-grafted polypropylene (PP- g -MA). It was found that the mechanical properties are affected by filler type, filler concentration, and the interaction between filler and matrix. The tensile strength of the composite is more affected by the talc while the impact strength is influenced mostly by CaCO3 content. The elongation at break of PP/CaCO3 composites was higher than that of PP/talc composites. The incorporation of coupling agent into PP/mineral filler composites increased the mechanical properties. Rheological properties indicated that the complex viscosity and storage modulus of talc filled samples were higher than those of calcium carbonate filled samples while the tan , was lower. The rheological properties of hybrid-filler filled sample were more affected by the talc than calcium carbonate. The PP- g -MA increased the complex viscosity and storage modulus of both single and hybrid composites. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers [source] Dynamic viscoelasticity of hybrid kevlar and glass fiber reinforced LLDPE in the molten statePOLYMER COMPOSITES, Issue 4 2002S. A. R. Hashmi Kevlar and glass fibers were used to reinforce linear low density polyethylene (LLDPE), and composite sheets of 0.8, 1.5 and 2.5 mm thicknesses were obtained by using a compression molding technique. Dynamic viscoelastic properties of non-hybrid and hybrid composites of various compositions at 200°C are evaluated. Storage modulus (G,) and loss modulus (G,) increase with angular frequency (,) and reinforcement. Replacement of glass fiber by Kevlar at constant loading of fibers in LLDPE increases the value of G,, G, and ,,. The fractured surface of composite shows the gradient orientation of fibers particularly in 2.5 mm thick sheet. Top and bottom layers show relatively two-dimensional orientation as compared to the middle layer, which shows random orientation. The orientation of fibers decreases G, and ,, of Kevlar fiber and hybrid fiber hybrid fiber reinforced LLDPE composites. The effect of change in distance between parallel plate of rheometer (change in strain amplitude) on dynamic rheological properties is studied and reported here. [source] | |||||||||||||