Toru Masuko

Single crystal of poly[bis(3,4-dimethylphenoxy)phosphazene]

We studied structural features on a single crystal of poly[bis(3,4-dimethylphenoxy)phosphazene] (PB(dM)PP) and examined its lattice constants. Also wide-angle X-ray diffraction (WAXD) work for the bulk film of the polymer are described in comparison with the results of electron diffraction (ED) for the single crystal

Crystal structure of poly[bis(3,4-dimethylphenoxy)phosphazene]

The crystal structure and chain conformation of poly[bis(3,4-dimethylphenoxy)phosphazene] — PB (dMe) PP — have been studied by X-ray diffraction techniques. The unit cell of this polymer shows an orthorhombic form with the crystallographic parameters a=2.05, b=1.49, c (chain axis)=0.998 nm. Its space group is determined as Pbcn-D2h14where the molecular chains are located at the centre and each corner of the unit cell, which contains eight monomeric units; these molecular chains possibly have a — (trans3cis)2-conformation. The R factor calculated from the final crystal structure was estimated as 16.9%. As with other types of polyorganophosphazenes, the thermotropic transformation in PB (dMe) PP takes place from the three-dimensionally ordered state to its two-dimensional psuedohexagonal form (ah = 1.49 nm), accompanied by a latent heat change at 96 °C.

Solution-grown crystal of poly[bis(4-ethylphenoxy)phosphazene]

The lattice parameters of polyorganophosphazenes are considered to involve significantly important information for understanding molecular chain packings in both their crystalline and mesomorphic states [1]. Since Kojima and Magill [2] first reported on the lattice constants of poly[bis(2,2,2-trifluoroethoxy)phosphazene] from its well-defined solutiongrown crystal, several works along these lines have already been published [3-7], calling attention to structural similarities between phosphazene polymers and organic flexible polymers. To substantiate various qualities of these inorganic polymers in terms of material characterization, further approaches on solution-grown crystals of other crystallizable polyphosphazenes will be necessary. In this study we investigated the structural features of solution-grown crystals of poly[bis(4ethylphenoxy)phosphazene] [PB(4-Et)PP] and examined the lattice constants using a transmission electron microscope. The thermotropic transition behaviour of the polymer was previously reported by Tanaka et al. [8] by solid-state 31p-nuclear magnetic resonance spectroscopy. Well-purified hexachlorocyclotriphosphazene was polymerized in 1,2,4-trichlorobenzene with sulphamic acid to polydichlorophosphazene [9]; the polymer was then reacted with sodium 4-ethylphenoxide in a toluene-di(ethyleneglycol dimethyl ether) mixture at 115 °C for 48 h [10], yielding the PB(4-Et)PP polymer. The purified polymer indicated the following results of elemental analysis (theoretical values): C 66.84% (66.90%), H 6.33% (6.30%) and N 4.91% (4.88%). The residual chlorine content was <0.01%. Infrared spectroscopy for the polymer showed very strong absorption at 1321 cm -1, assigned to the asymmetric stretching vibration mode of P N bonds. The weight average molecular weight and molecular weight distribution index of the polymer were characterized as Mw = 4.65 x 105 and Mw/M n --4.49, respectively, by a gel-permeation chromatography method. Solution-grown crystals of PB(4-Et)PP were made by dissolving the polymer in N,N-dimethylformamide at 140 °C just below the boiling point of this solvent. The final solution concentration was designed to be 0.005wt% by adding n-propyl alcohol into the solution at 90 °C and the solution was then slowly cooled to room temperature. In this case n-propyl alcohol played the role of a poor

Dynamic Viscoelastic Properties of Surface-Treated Ni Powder/Epoxy Resin Composite Materials.

金属Ni粉/エポキシ樹脂複合材料において, 金属Ni粉末表面に各種カップリング剤処理を行うことにより, マトリックス樹脂との接着力を向上させて力学的物性の改善を計った. Ni粉末の体積分率を0.245とし, カップリング剤としてシラン系, チタネート系, アルミニウム系を用いた. 各複合材料の動的粘弾性の温度依存性を周波数100Hzで30～320℃の温度範囲で測定し, カップリング剤処理の効果を評価した. この結果, エポキシ官能基を持つシラン系カップリング剤でNi粉末を処理した場合, 複合材料の貯蔵弾性率が急激に低下する温度は約240℃であり, 未処理試料の示す190℃に対して大幅に向上することが認められた. このとき, カップリング剤量はNi粉末に対し1w%で十分な効果があった. また, 複合材料のガラス転移に関連した活性化エネルギーを求めることによって, 粒子表面とマトリックスとの親和性を相対的に評価可能であった. それによると, カップリング剤による表面改質効果はシラン系>チタネート系>アルミニウム系の順に現れた.