Low-density polyethylene in benzene, toluene, and o-dichlorobenzene was irradiated by UV light to clarify the roles of solvents in the polymer photochemical degradation. Irradiation was done for 50 h at 25 and 50°C in air, oxygen, and nitrogen atmospheres. Reaction products were analyzed by FT-IR, GPC, ¹³C NMR. Carbonyl groups, double bonds, and hydroperoxide groups in the polyethylene irradiated for 50 h were detected by FT-IR and ¹³C NMR. The molecular weight changed a little. Quantities of the functional groups and gels increased in the order of benzene, toluene, and o-dichlorobenzene. Oxygen molecules play an important role in this kind of photochemical reaction.

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Microporous sheets were prepared by biaxial stretching of polypropylene (PP) sheets filled with calcium carbonate (CaCO₃) and silica (SiO₂). Pore volume and water vapor transmission (WVTR) increase for higher degrees of biaxial stretching. Maximum pore size (D_max), WVTR and air permeability increase with increasing of the content of filler. Maximum pore size is positively correlated with average pore size, and negatively correlated with water resisting pressure. Average pore sizes of sheet increase with increasing of particle size of filler. Air permeability, D_max and water resisting pressure are different for different kinds of fillers. Between one surface and the other surface of the sheet, there are many large voids and micropores. Micropores are located in the stretched PP layer, they connect with large voids.

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Several mechanical properties and morphology of epoxy resins filled with various carbon powders such as natural graphite (NG), man-made graphite (MG), and petroleum coke (PC) were studied by using a Rheovibron, an Instron tensile tester, a Vickers hardness tester, and a SEM. PC was added to the epoxy resin up to 50 wt%, and NG and MG powders up to 85 wt%. The carbon powders were dispersed randomly in all the specimens. The glass transition temperature (T_g) and storage modulus (E') for all series of the specimens increased with increasing content of carbon powders. The effect of fillers on the storage modulus was evident in the order of NG>MG>PC. The compressive strength (σ_c) and Vickers hardness (H_v) were influenced very strongly by the morphological factor of the carbon powders and their content. The σ_c values of the specimens filled with PC were larger than those of the other specimens. Theσ_c, values of the NG- and MG-filled specimens decreased with increasing carbon content. The H_v values of all the specimens, PC-filled specimens in particular, increased remarkably.

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Polymers containing pendant epoxide or vinyl ether groups were synthesized by radical copolymerization of glycidyl vinyl ether (GVE) with N-phenylmaleimide (NPM) and N-phenoxycarbonyloxymaleimide (NPCM), or by ring-opening alternating copolymerization of GVE with phthalic anhydride (PAn). In the photo-induced cross-linking reaction, the pendant vinyl ether groups in poly (GEV-PAn) showed higher reactivity than the pendant epoxide groups in poly (GVE-NPM), and poly (GVE-PAn) was readily cross-linked by various dithiols with or without benzophenone. In the electron beam (EB) -induced cross-linking reaction, the sensitivity of poly (GVE-NPCM), which has pendant eprxide and carbonate groups, was higher than that of poly (GVE-NPM) containing only pendant epoxide groups. Furthermore, the EB-sensitivity of poly (GVE-PAn) was even higher than that of poly (GVE-NPM) or poly (GVE-NPCM).

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A novel crosslinkable diacetylene-polyimide was prepared from 4, 4'- (1, 3-butadiyne-1, 4-diyl) -bis (phthalic anhydride) and p-phenylenediamine in order to develop a high temperature material with multidimensional high modulus. The polyimide crosslinked thermally about 250°C. The extent of crosslinking was 85%. The storage modulus of the resulting crosslinked polyimide was about twice larger than that of non-crosslinked polyimides. The plateau storage modulus of the crosslinked polyimide increased with increasing temperature as a result of crosslinkage of the diacetylene groups till higher temperatures than that of polyimides without diacetylene groups.

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Polypropylene (PP) filled with calcium carbonate (CaCO₃) was extruded to sheets using a T-Die extruder with chill rollers. The effects of several factors on uniaxial stretching uniformity at three times stretching were investigated. These factors included CaCO₃ content, CaCO₃ particle size, kinds and contents of dispersing additives, and preliminary low ratio stretching at low temperature. (1) With increasing CaCO₃ content, the uniform stretching temperature range is elevated. Smaller fillers need higher content of dispersing additives. (2) The nonionic surfcatant content of 0.05-0.07 g/m²·CaCO₃ is effective for improving uniform stretching ability. (3) Adipic acid, a polyester plasticizer, enhances uniform stretchability. (4) Dispersing additives aid CaCO₃ to disperse in the PP matrix. The boundary of PP/CaCO₃ is peeled under the stretching stress, by this uniform stretching is achieved. (5) Preliminary low ratio stretching at low temperatures is more effective than mormal high ratio stretching at high temperature.

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Y-Ba-Cu-O superconducting thick films were prepared with poly (glycygyl methacrylate) (PGMA) as a polymeric binder by a screen method. In this paper, influences of the binder on the superconducting properties are discussed. The superconducting ceramic thick film was obtained throughvery slow thermal decomposition of the binder. But T_c, where resistance becomes O, was lowered with increasing the amount of the binder. SEM observations and X-ray analyses showed that the loweringof T_c was caused by structure strained due to the thermal decomposition of binder followed by the inhomogeneous sintering and by the thermal expansion difference between a substrate and the conducting layer. Moreover, XMA analyses suggested that the very slight amount of carbon, which remained even after the sintering was related to the lowering of T_c.

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A cooperative GPC test on a polystyrene sample polymerized radically was carried out by 21 laboratories using identical procedures. The variation of the average molecular weights obtained was studied in detail. The average coefficients of variation (standard deviations divided by mean values) of number average, weight average, and z-average molecular weights are 11.0, 11.3, and 21.1%, respectively. The calculation method, the type of detector and the number of divisions of chromatogram do not affect remarkably the average molecular weights obtained. The average molecular weights obtained by different laboratories using the identical columns show variations greater than 20%. In order to reduce the average coefficients of variation to less than 10%, it is necessary to pay much attention to slight changes of operative conditions such as the resolving power of the column and the flow rate of solvent.

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Highly elastic and high water-content hydrogels were prepared from coagulation obtained by blending of concentrated aqueous solutiopns of poly (vinyl alcohol) (PVA) and poly (sodium ^L-glutamate) (PSLG) in an autoclave under 2 atm pressure at 120°C, and dehydration of the resulting coagulate followed by swelling. The elastic moduli of the hydrogels increase with increasing PSLG content and are higher than those of the hydrogels obtained by repeated freezing and thawing. This is primarily due to formation of rigid segments by the interaction of PVA chains with PSLG chains and formation of the bound water.

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The bluing mechanism of amylose-iodine complexes was investigated by simultaneous stopped-flow measurements of circular dichroism (CD) and absorption spectra, using an amylase with an average degree of polymerization (DP) of ca. 20. A two-step process of complexation was observed under the conditions that the bound species of iodine is only I^-₃ and the concentration of amylose was much larger than that of I^-₃. The first step was the formation of achromic complex of amylose with intrinsic I^-₃, accompanied by the appearance of induced positive CD bands around 288 and 353 nm. In the second step, the formation of a dimer I^-₃·I^-₃ responsible for the coloring of the complex was observed. On the other hand, under the conditions that the coloring species of iodine was I₂·I^-₃ in the absence of KI, the complexation proceeded by apparent one-step reaction. The apparent initial rate for the formation of I^-₃·I^-₃ was estimated to be smaller than that of I₂·I^-₃. Consequently, it was suggested that the formation of I₂·I^-₃ is facilitated by the more cooperative interaction between I₂ and I^-₃, than that between the two I^-₃ ions.

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