Springer Science and Business Media LLC Acta Medica Okayama 0032-3896 55 12 2023 Effect of the blend ratio of cyclic and linear polyethylene blends on isothermal crystallization in the quiescent state 1393 1398 EN Keiko Kobayashi Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Hironori Atarashi Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Shinichi Yamazaki Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Kunio Kimura Graduate School of Environmental, Life, Natural Science and Technology, Okayama University The role of entanglements that form between cyclic and linear polymers in crystallization is of particular interest, but it is not fully understood. We investigated the crystallization behaviors of blends of cyclic polyethylene (C-PE) and linear polyethylene (L-PE) in a quiescent state to elucidate the role of this novel entanglement in crystallization. The samples were prepared by mixing the prepared C-PE and L-PE specimens at L-PE weight fraction (ΦL-PE) values of 0–100 wt%, with the weight average molecular weights of C-PE and L-PE being 175 × 103 and 154 × 103, respectively. The isothermal crystallization behaviors were analyzed through polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The morphology observed through POM was similar to that of ΦL-PE. From the time evolution of the heat flow measured via DSC, we obtained the half-crystallization time (t1/2) values as functions of ΦL-PE at different degrees of supercooling (ΔT). The 1/t1/2 values of the C-PE and L-PE homopolymers were approximately the same at ΔT = 25.5 and 26.5 K. At a larger ΔT value, the 1/t1/2 value of C-PE was significantly larger than that of L-PE. In contrast, 1/t1/2 reached a minimum value at ΦL-PE = 30–40 wt%, irrespective of ΔT. As the entanglement density increased with increasing ΦL-PE, the crystallization rate was expected to decrease monotonically. By considering the experimental relationship between 1/t1/2 and ΦL-PE, we speculated that the suppression of crystallization in the blended system was caused by a novel entanglement formed by the penetration of the L-PE chain into the C-PE chain. No potential conflict of interest relevant to this article was reported.

岡山大学環境管理センター Acta Medica Okayama 0917-1533 23 2001 編集後記 61 EN Kunio Kimura No potential conflict of interest relevant to this article was reported.

岡山大学環境理工学部 Acta Medica Okayama 1341-9099 1 1 1996 重合過程を利用した芳香族高分子の高次構造形成 221 227 EN Yuhiko Yamashita Kunio Kimura Hiroshi Tsugita Fumiyoshi Yokoyama 10.18926/fest/11649 Morphology and formation mechanism of poly (4'-oxy-4-biphenylcarbonyl) (POBP) crystals obtained by solution polymerization were firstly treated. It was concluded that the formation mechanism of the bundlelike aggregates of fibrillar crystals in POBP was fundamentally simillar to that in POB whiskers. Secondly the copolymerization effects of m-acetoxybenzoic acid and 4-(4-acetoxyphenyl) benzoic acid on the morphology of POB whiskers were studied. The experimental results strongly supported our proposal for the formation mechanism of whiskers which was consisted of crystallization of oligomers with a critical length as lamellae from solution and solid state polymerizationof oligomers between lamellae. Finally, the formation mechanism of poly (p-oxycinnamoyl) spherical products during solution polymerization was treated. The formation of these spherical products could be understood by overlapped phase diagram of melting depression curve and consolute curve of oligomers-solvent system. No potential conflict of interest relevant to this article was reported.

岡山大学環境理工学部 Acta Medica Okayama 1341-9099 11 1 2006 New Attempt at Preparation of Fluorine-containing Poly(ether ketone)s in Supercritical Carbon Dioxide 93 97 EN Kunio Kimura Shinichi Yamazaki 10.18926/fest/11482 Fluorine-containing poly(ether ketone)s was synthesized by the nucleophilic aromatic substitution reaction of 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane and 4,4'-bis(2,3,4,5,6-pentafluorobenzoyl) diphenyl ether in super-critical CO(2). Polymerizations were carried out at 80℃ for 6 hours under 5000 psi of CO(2) pressure, which was super-critical phase. Polymerization concentration was 0.5 g of polymer in 10 - 12 mL of CO(2). The polymer was not obtained in CO(2) due to the insolubility of both the potassium bisphenoxide and the polymer into CO(2). However, the polymer was formed by an addition of DMAc and NMP in CO(2), even though molecular weight was not so high. Very small amount of co-solvents which were immiscible with CO(2) was effective, and it was 1/20 - 1/25 amount of the solvent used in the conventional poly(ether ketone) synthesis. The polymerization mechanism was also discussed. No potential conflict of interest relevant to this article was reported.

岡山大学環境理工学部 Acta Medica Okayama 1341-9099 12 1 2007 結晶化処理を用いたポリブチレンテレフタレートの効果的鎖延長反応の開発 167 171 EN Seiji Ihara Hisashi Shiroma Shinichi Yamazaki Kunio Kimura 10.18926/fest/11477 Plastics are quite important materials for not only industrial usages but also our daily life. Many plastics are difficult to reuse because they are susceptible to UV, hydrolysis and so on leading to the reduction of molecular weight. Among them, poly (butylenes terephthalate) (PBT) is a valuable materials prepared by polycondensation reaction, and PBT has the same limitation to reuse. Hence, efficient chain extension reaction for recovered PBT has been needed to improve the properties damaged by chain scission. In this study, new chain extension reaction had been examined by using crystallization as pre-treatment. Isothermal crystallization at 161℃ concentrated the chain end-groups on the surface of the crystals, and chain extension reaction at 210℃, which was lower than the melting temperature of PBT, enhanced the molecular weight significantly compared with the reaction over the melting temperature. It concluded that the pre-treatment of crystallization was favorable for the efficient chain extension reaction and this result provided the new technology for the effective reuse of the plastics. No potential conflict of interest relevant to this article was reported.

岡山大学環境理工学部 Acta Medica Okayama 1341-9099 12 1 2007 流動場結晶化における異形微粒子添加によるshish構造形成の促進 157 160 EN Shinichi Yamazaki Kanji Wakabayashi Kenta Mizuma Kunio Kimura 10.18926/fest/11473 We have shown that the shish was formed from the oriented melt composed of the elongated chains caused by dust particles within the melt via bundle typed nucleation under flow with low shear rate (γ=5s(-1)). This implies that dust particles effectively cause the elongation of chains within the melt. In this work, we observed the crystallization of polypropylene added with irregular shaped particles under shear flow by means of polarizing optical microscope. We prepared various shaped particles such as confetti-like, spherical and rock-like. We found that the size and asymmetric shape of additive particles play an important role for the acceleration of formation of shish. No potential conflict of interest relevant to this article was reported.