Transparent halopolymer film such as poly(vinyl chloride) containing leuco dye formed color image by UV irradiation. Combinations of six kinds of polymers and five kinds of leuco dyes were investigated as photo coloring systems. A stable coloration of the leuco dye can be obtained if halopolymer is used as a matrix film. The transparent film of poly(vinyl chloride) (PVC) which contained leuco auramine benzotriazole (1-ABT) changed to greenish blue by UV irradiation for about 10sec. Photo-sensitivity of 1-ABT depended on the kind of halopolymer films. Poly(vinyl chroride-co-acrylonitrile) gave high photosensitivity for color formation of 1-ABT.
Color formation of 1-ABT in poly(2-chloroacrylonitrile)(PCAN) by UV light was very fast, and was observed during casting the film under room light. Therefore only photobleaching was observed in film state. Color formation of 1- ABT with PCAN was also investigated in acetonitrile solution and in dimethylformamide solution. Color formation in dimethylformamide was faster than in acetonitrile. Photochemical reaction of fluoran lactone (FL) in PCAN film gave interesting result. Slightly greenish film of the FL-PCAN system colored quickly to red by irradiation, followed by changing to black by continuous irradiation. The UV and IR spectra of the PCAN film containing FL under UV light suggested formation of poly(cyanoacetyle).

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UV Curing behavior of acrylate monomers in the presence of resol is described. A thin layer consist of resol, monofunctional acrylate (ECA), and hexafunctional acrylate (DPCA-60) gives the crosslinked polymer under UV irradiation. IR spectra of the crosslinked polymer show characteristic absorptions due to both resol and acrylate with a decrease of v C=C′ which indicates the additional polymerization takes place in this system. The curing is accelerated by addition of alkali, which suggests the phenol structure is active site for the polymerization. Among several kinds of alkali investigated, Ba(OH)₂ is most effective for the reaction from the point of insoluble polymer yield. Consumption of acrylate double bond in the insoluble polymer ranges above 60% which decreases slowly with an increase in the DPCA-60 content due to steric hindrance. The synergic effect of Ba(OH)₂ appears when it is added 0.1mol% for hydroxy group in the resol. UV irradiation leads to color change of the cured layer from pale yellow to reddish violet (λ_max =570nm) with an appearance of ESR signal at g =2.004, which indicates the formation of phenoxy radical. The phenoxy radical formed in the resol should be an active site for UV polymerization of this system.

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Nonlinear optical susceptibility X⁽³⁾ of polydiacetylenes has been evaluated by third harmonic generation. First, in order to obtain the X⁽³⁾ tensor component along the polymer main chain, thin single crystals of two representative polydiacetylenes, poly-PTS and poly-DCHD were made by utilization of sampling technique in microscopy, i.e., the microtome cutting of single crystal embedded in plastic resin. The THG intensity observed was proportional to cos⁸θ, where θ was the angle between the polymer main chain and the polarization of laser light. The X⁽³⁾ value of poly-DCHD was found to be rather higher than that of poly-PTS. At resonant wavelength of 1.97μm, the X⁽³⁾ of poly-DCHD attained 8×10^-10 esu. Furthermore, it was confirmed that when geometrical correction were properly made, the X⁽³⁾ obtained from polycrystalline thin film of poly-PTS well agreed with that from thin single crystals. Secondary, regarding oly-diphenyldiacetylene derivatives, it was found that the π-conjugation between the polymer main chain and aromatic substituents was effective on the improvement of X⁽³⁾ values. The X⁽³⁾ magnitudes of poly-BTFP and poly-DFMP well reflect the dihedral angles between polymer main chain and the phenyl substituents (58^o for poly-BTFP and 67^o for poly-DFMP) as a measure of π-conjugation. Especially, at non-resonant region of 2.1μm the X⁽³⁾ of poly-BTFP is about 5 times greater than that of poly-PTS.

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This work has made an exploratory study on photocrosslinking of low density polyethylene (LDPE) as an insulating material. The kinetic character, efficiency and mechanism of photocrosslinking of LDPE in the melt, and the main parameters affecting the crosslinking processes have been studied, The crosslinking density, homogeneity and some properties of the crosslinked products(XLPE) were examined.
Our results show that (1) by optimizing the reaction conditions LDPE sheets as thick as 2-3mm were readily photocrosslinked with the gel content of more than 70% in the irradiation time of 15 seconds; (2) The use of multifunctional crosslinker (e.g. triallyl cyanurate, TAC) was crucial for both the crosslinking rate and the homogeneity of crosslinks of the thick sample; (3) Temperature had a profound effect on photocrosslinking process, the rate of which increased considerably around the melting point of LDPE ; (4) The rate of photocrosslinking was found to be second order to light intensity; (5)Some physical properties of XLPE including crosslinking density, homogeneity of crosslinks, mechanical and electrical properties show that the technique of photocrosslinking of LDPE in the melt is quite promising for the manufacture of wires and cables.

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