Mechanical behaviors of two types of polypropylene (PP) blend mixed with linear low density polyethylene (LLPE) and elastic styrene-ethylene-butylene-styrene (SEBS) terpolymer were analyzed by Finite Element Method (FEM). Although pure PP was broken immediately after the yielding point under the uniaxial drawing, the breaking strain of PP/SEBS blend increased with increasing SEBS content. However, the elongation was not increased by mixing with LLDPE. From FEM analysis, the stress distribution in PP existed around SEBS particles was relatively uniform. However, PP/LLPE blend showed a similar stress distribution formed by voids, that was, the stress in PP were concentrated to the equatorial direction by LLPE. The stress distribution in PP was responsible for the increase of breaking strain of PP/SEBS blend.
Mechanical and structural changes of silk fibers caused by stretch after treatment with LiBr aqueous solution were investigated. The mechanical properties of degummed silk depended upon the temperature of treatment with 8M LiBr aqueous solution. The strength and elongation increased with treatment temperature whereas the Young's modulus decreased. The X-ray diffraction pattern showed that the crystalline orientation was disturbed by the treatment at 80°C whereas the destruction of the crystallites did not occur. The stretch up to 160% was possible after the treatment at 80°C for 1h in 8M LiBr aqueous solution. The strength and Young's modulus increased while the elongation decreased. On the basis of the X-ray diffraction and SEM observations, the crystal orientation was found to become higher with increasing draw ratio.
Methyl methacrylate (MMA) was efficiently graft-copolymerized in aq. FeCl3 solution onto cellulose by the UV irradiation from a high-pressure mercury lamp. While the oxygen removal from the system by means of vigorous evacuation caused the drastic decrease of percent grafting. In this connection PMMA chains prepared in FeCl3-saccharide systems by the UV irradiation were found to scarcely contain saccharide residues at the chain ends, irrespective of the species of the saccharides used. The formation of both Fe2+ and hydrogen peroxide as a result of the irradiation on the reaction systems was confirmed by conducting model reactions. It was suggested from these results that the homopolymerization is initiated with free radicals resulted from the redox reaction between Fe2+ and H2O2, and followed by the grafting via the transfer reaction of the growing homopolymer radicals to cellulose molecules.
Methyl methacrylate (MMA) was graft-copolymerized onto cellulose in an aq. FeCl3 solution by the irradiation of UV light. The copolymerization was found to proceed even after the interruption of the irradiation. The addition of the monomer into the polymerization system, which had been beforehand preirradiated in the absence of the monomer, was not followed by the copolymerization. The after effect also increased the molecular weight of the graft PMMA, being isolated from graft product by means of complete hydrolysis of trunk cellulose molecules. However, the increase was not always proportional to the weight increase observed after the interruption. On the other hand, the increase of kinetic chain length caused by the after effect in the AIBN-sensitized grafting systems was found to be nearly proportional to the weight increase of the graft PMMA, The chain lengths were calculated from the number-average molecular weight of the graft PMMA and the weight fraction of truly grafted PMMA chain in the graft PMMA which was determined by subjecting the graft PMMA to thin-layer chromatography. These results may imply that the propagating polymeric free radicals are long-lived ones. In the case of the graft copolymerization by chemical method initiated with AIBN, a linear relationship between the reciprocal of number-average molecular weights of graft PMMA and the first power of the AIBN concentrations shows that the termination mechanism of graft copolymerization is not bimolecular one.
An investigation involving 6000m/min spinning process is undertaken on poly (ethylene terephthalate) in this study. Experimental results indicate that the physical properties of the as-spun filaments spun at 6000m/min are close to that of the commercially available yarn, except for the property of break elongation. The break elongation of 6000m/min highly oriented yarn (HOY) is around 50%, i.e., twice that of commercially available yarn. Additionally, yarn with a high break elongation (6000m/min HOY) can generally not be directly used for fabrics in the weaving process. Furthermore, an on-line heat treatment device is designed in this study for reducing the break elongation of the fibers. Some physical properties, fiber structure, DSC analysis and dynamic modulus of on-line heat treated yarn are also investigated. These results confirm that the break elongation of yarn heat treated at 250°C corresponds with the acceptable level of commercially available yarn, thereby implying that on-line heat treatment exerts a significant effect on reduction of break elongation for a yarn spun at 6000m/min. Consequently, the on-line heated yarn can be directly used in weaving process and the post drawing process can be omitted.
For faster evaluation of durability of polytetrafluoroethylene-coated glass fiber fabric (PTFE-glass membrane), the specimen was immersed in hot water and the effects of water and heat on the specimen were studied. The changes in tensile strength of the PTFE-glass membrane and its base fabric (glass fiber fabric) were dependent on the duration as well as the temperature of hot water treatment test. The retained tensile strength of the glass fiber fabric immersed in water at 90°C for 14 days was 31%. Micro holes, micro cracks and partial failures on the surface of the glass fibers of the treated fabric were observed by a scanning electron microscopy (SEM). When the glass fiber fabric was immersed in hot water, it degraded due to erosion and its tensile strength decreased. On the other hand, in the latter case the retained tensile strength of the PTFE-glass membrane immersed in water at 90°C for 14 days was 62%, the effect of protection of the PTFE coating against hot water was confirmed. When the PTFE-glass membrane was immersed in hot water, water infiltrated from its surface into the glass fiber fabric and affected the glass fibers causing a decrease of the tensile strength.
The ami of this study is to evaluate hand feeling properties (the Fu-ai indecies) of sample fabrics, treated by the inner carboxymethylation, with the KES method, and to compare the results with those obtained for the starting fabric and the whole-carboxymethylated fabrics. It was recognized that, in addition to appreciable enhancement of their water absorbency, the inner-carboxymethylated fabrics showed Fu-ai indecies fairly colse to those of the starting fabric, so far as the extent of carboxymethylation was low.