放射光小角広角X練散乱および振動分光から眺めた高分子の等温結晶化現象における規則構造発展過程

摘要

結晶性高分子の溶融状態からの等温結晶化過程における規則構造発展の様子を，赤外スペクトル，広角および小角X線散乱高速測定データに基づき，分子レベルから結晶格子，高次組織に至るさまざまのレベルから検討した．対象としてイソタクチ、ソクポリプロピレン（iPP），ナイロン10/10，ポリオキシメチレン（POM）を選択した．iPPの場合，赤外スペクトルにおける臨界連鎖長の概念を利用し，融状態の中での規則的らせん鎖セグメントの形成ならびに成長過程を措いた．またSAXS，WAXDデータからは，規則的らせんセグメントが集合した孤立ドメインの生成，ドメインどうしの接近および相関の増大，そして，ついには積層ラメラ構造への発達と，らせん状分子鎖の形成と発達に平行して生じる高次構造の発展プロセスを明らかにした．ナイロン10/10の場合，溶融状態でも弱いながら水素結合がアミド基間で形成されており，等温結晶化が始まる時点で既に，水素結合で結ばれた分子鎖集合体が系全体にわたって不均一に形成されていることを明らかにし，iPPの場合との大きな相違点を指摘した．POMについては，伸びきり鎖結晶（ECC）や折れたたみ鎖結晶（FCC）の存在を敏感に反映する赤外バンドを利用し，ラメラ構造形成に至るプロセスの中でのFCCおよびECCモルホロジー発生の様子を観察するとともに，それが，親ラメラの間の非晶部分で起こる子ラメラの発生と強く関わっていることを明らかにした．%The evolution processes of regular structure in isothermal crystallization phenomena of crystalline polymers have been investigated from the viewpoints of molecular level, crystal lattice, and higher-order structure on the basis of time-dependent infrared spectral data and synchrotron small- (SAXS) and wide-angle X-ray scattering (WAXD) data. The polymers treated here were isotactic polypropylene (iPP), nylon 10/10 and polyoxymethylene (POM). In the case of iPP, the formation and growing processes of regular helical segments in the molten state are described by utilizing the concept of critical sequential length for infrared bands. Combination of these spectroscopic data with the SAXS and WAXD data clarifies the formation process of domains consisting of regular helical segments, the increment of correlation of neighboring domains, and the development of stacked lamellar structure, during which the remarkable growth of crystal lattices consisting of regular helices occurs in parallel. In the case of nylon 10/10, weak hydrogen bonds are formed between amide groups even in the molten state. Once the isothermal crystallization starts to occur, these more-or-less correlated domains built up by the hydrogen bonds are formed followed by the formation of crystal lattices consisting of relatively regular methylene segments. Such growth is quite different from the case of iPP crystallization. The study of POM is based on the observation of infrared bands intrinsic to the folded chain crystals (FCC) and extended chain crystals (ECC). From the time-resolved measurements of these infrared bands as well as the SAXS and WAXD in the isothermal crystallization process of POM, we clarified that the lamellar structure of FCC morphology is formed at first. Then some new lamellae are formed in between these original lamellae, resulting in the formation of ECC parts in which the regular helices pass through the several neighboring lamellae as taut tie chains.