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Optimum Amount (optimum + amount)
Selected AbstractsRheological, morphological, mechanical, and barrier properties of PP/EVOH blendsADVANCES IN POLYMER TECHNOLOGY, Issue 3 2001Jong Ho Yeo Using the biaxially oriented film process, polypropylene (PP)/ethylene-vinyl alcohol copolymer (EVOH) blends with an improved barrier property could be obtained by generating a laminar structure of the dispersed phase in the matrix phase. This laminar morphology, induced by biaxial orientation, was found to result in a significant increase in the oxygen barrier property of PP/EVOH (85/15) blends by about 10 times relative to the pure PP. In this study, compatibility in the PP/EVOH blend system was evaluated by investigating the influence of compatibilizer on the rheological, morphological, and mechanical properties of the blends. In addition, the effects of compatibilizer content, draw ratio, and draw temperature on the oxygen permeability and morphology of biaxially drawn blend films were also studied. It was revealed that an optimum amount of compatibilizer, maleic anhydride grafted PP, should be used to improve the barrier property of the PP/EVOH blends with a well-developed laminar structure. The draw ratio and draw temperature had a significant influence on the permeability of the blends. The blend films exhibited a more pronounced laminar structure when the blends were stretched biaxially under processing conditions of higher draw ratio and draw temperature, resulting in higher barrier properties. © 2001 John Wiley & Sons, Inc. Adv Polym Techn 20: 191,201, 2001 [source] SENSORY EVALUATION OF COOKED RICE IN RELATION TO WATER-TO-RICE RATIO AND PHYSICOCHEMICAL PROPERTIESJOURNAL OF TEXTURE STUDIES, Issue 1 2007WEENA SRISAWAS ABSTRACT The effects of cooking water-to-rice (W/R) ratio on the sensory characteristics of cooked rice eating quality of 14 varieties of Thai rice were investigated in relation to their physicochemical properties. Milled rice samples were cooked with five W/R ratios ranging from 1.3 to 2.5 on a weight basis and presented to 12 trained panelists for sensory evaluation. A three-way analysis of variance and a principal component analysis identified the intensity of sensory hardness as the main characteristic of cooked rice. It decreased with increasing W/R ratio whereas sensory stickiness decreased. The overall acceptability based on appearance, texture and flavor attributes reached peak levels corresponding to optimum W/R ratios for different rice varieties, and was highly correlated with sensory hardness and stickiness. Partial least squares regression models of optimum W/R ratio and peak overall acceptability gave coefficients of determination of 0.991 and 0.980, respectively, thus indicating that the optimum W/R ratio and the acceptability ratings of cooked rice could be reliably predicted from the physicochemical properties such as the apparent amylose content, protein content, gel consistency, alkali-spreading value and grain elongation ratio of milled rice. PRACTICAL APPLICATIONS Sensory evaluation of cooked rice eating qualities is a difficult task to carry out routinely on a day-to-day basis. Presently, rice varieties are categorized according to grain dimensions and selective physicochemical traits that reflect on the eating quality of cooked rice. Though it has been long realized that the amount of water used for cooking and rice physicochemical properties highly influence the eating quality of cooked rice, no information is currently available on the quantitative evaluation of these factors. Results of this study showed that models could be developed to quantify the optimum amount of water for cooking rice of different varieties with the most desirable sensory eating qualities. The prediction of peak overall sensory acceptability scores that correspond to the optimum cooking water-to-rice ratio could be useful for categorizing rice varieties based on their impact on sensory eating quality and for the development of baseline information for consumers by the rice industry. [source] Surface modification of bagasse fibers by silane coupling agents through microwave oven and its effects on physical, mechanical, and rheological properties of PP bagasse fiber compositePOLYMER COMPOSITES, Issue 6 2007S.A. Hashemi Polypropylene/bagasse fiber composites were prepared by compounding polypropylene (PP) with bagasse fibers as reinforcing filler. Surfaces of fibers were modified through the use of silane coupling agents (Vinyltrimethoxysilane and ,-Glycidoxypropyltrimethoxysilane). The fiber coating was performed by mixing of silane with fibers and cured through microwave oven in presence of catalyst. It was found that modification of surface fiber will change the physical, mechanical, morphological, and rheological properties of composite. It was observed from scanning electron microscopy that fiber adhesion to matrix has been improved and so as dispersion. Addition of fibers increases the melt viscosity in unmodified fibers but reduced the melt viscosity for modified fibers and even the viscosity is lower at higher loading compared with unmodified fibers. The tensile strength and tensile modulus increased in modified fibers compared with the unmodified on the same loading, but elongation at break decreased. The effect of coupling agent on properties of filled PP depend on the content of coupling agents and optimum amount was achieve through measurement of water absorption. Two types of coupling agents were used, one as A-171 [CH2CHSi (OCH3)3] and second one as A-187 [CH2OCHCH2O (CH2)3Si(OCH3)], the first one shows better adhesion to the fibers and improvements in mechanical properties are much better compared with the second one. POLYM. COMPOS., 28:713,721, 2007. © 2007 Society of Plastics Engineers [source] Reactive extrusion of poly(ethylene terephthalate),(ethylene/methyl acrylate/glycidyl methacrylate),organoclay nanocompositesPOLYMER COMPOSITES, Issue 2 2007Elif Alyamac This study was conducted to investigate the effects of component concentrations and addition order of the components on the final properties of ternary nanocomposites composed of poly(ethylene terephthalate), organoclay, and an ethylene,methyl acrylate,glycidyl methacrylate (E-MA-GMA) terpolymer acting as an impact modifier for PET. In this context, first, the optimum amount of the impact modifier was determined by melt compounding binary PET-terpolymer blends in a corotating twin-screw extruder. The amount of the impact modifier (5 wt%) resulting in the highest Young's modulus and moderate elongation at break was selected owing to its balanced mechanical properties. Thereafter, by using 5 wt% terpolymer content, the effects of organically modified clay concentration and addition order of the components on the properties of ternary nanocomposites were systematically investigated. Mechanical testing revealed that different addition orders of the materials significantly affected the mechanical properties. Among the investigated addition orders, the best sequence of component addition (PI-C) was the one in which poly(ethylene terephthalate) was first compounded with E-MA-GMA. Later, this mixture was compounded with the organoclay in the subsequent run. In X-ray diffraction analysis, extensive layer separation associated with delamination of the original clay structure occurred in PI-C and CI-P (Clay + Impact Modifier followed by PET) sequences with both 1 and 3 wt% clay contents. X-ray diffraction patterns showed that at these conditions exfoliated structures resulted as indicated by the disappearance of any peaks due to the diffraction within the consecutive clay layers. POLYM. COMPOS., 28:251,258, 2007. © Society of Plastic Engineers [source] Thermal properties of biaxially deformed in situ compositesPOLYMER ENGINEERING & SCIENCE, Issue 8 2004Youngwook P. Seo The thermal properties of biaxially blown poly(etherimide) (PEI) films containing a thermotropic liquid crystalline polymer (TLCP) were studied using differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction and dynamic mechanical thermal analysis. The effects of the compatibilizer and thermal annealing on the thermal properties of biaxially oriented TLCP films were investigated. Though the compatibilizer (poly(ester imide)) improved deformation of the TLCP phase (poly ester amide) and adhesion between the matrix and the TLCP phase, which improved mechanical properties, it did not significantly affect the thermal properties of the in situ composite films. The film degradation behavior corroborated the role of the compatibilizer. Since a relatively small amount of TLCP (10 wt%) was added to the matrix and the matrix PEI was amorphous, the effect of annealing on the TLCP structure was not obvious. By the same token, while the effect of the deformation in the circumferential direction (a change in the blow-up ratio) was manifest in mechanical property improvements, its effect on the thermal properties was not obvious. All films showed similar thermal expansion behaviors, regardless of the thermal history and of the compatibilizer addition. Thus, there is an optimum amount of the compatibilizer required to obtain optimal mechanical properties for in situ composite films without causing a deterioration of their thermal properties. Polym. Eng. Sci. 44:1419,1428, 2004. © 2004 Society of Plastics Engineers. [source] Trust and creativity: understanding the role of trust in creativity-oriented joint developmentsR & D MANAGEMENT, Issue 3 2009Francis Bidault In this article we report on the design, prototyping and results of a research effort aimed at identifying whether and how trust affects the innovativeness of a partnership between two players. The methodology combined an experiment and two questionnaires. The research aimed to increase our understanding of trust and its impact on the innovative outcome of cooperation and to derive some guidance for economic actors, namely R&D managers and executives who intend to build innovation-oriented relationships with their business partners. Specifically, we investigated the effect of trust on partners' creativity and willingness to invest financially in a joint development. Our results show that more trustful partners invest higher amounts in the alliance, while there seems to be an optimum amount of mutual trust between partners who maximize their joint creativity and innovativeness; if the level of mutual trust is below or above this threshold, their joint creativity seems to increase less or even to decrease. Our findings suggest that joint development projects should always include explicit trust development activities at the beginning of the project, and that the amount of trust in the joint team should be monitored to avoid the negative consequences of excessive trust. [source] | |||||||||||||