Naruhiko Mashita

Structure formation and dynamic properties of physical gels produced with thermoplastic elastomer and monomer

We propose new non-aqueous polymer physical gels prepared with a small amount of semi-crystalline thermoplastic elastomers (nearly 10% concentration) and a large amount of monomers of low molecular weight. The gels have a three-dimensional continuous polymer network whose unit structure, a spherical cell of a few tens micrometer is mutually connected with holes, i.e. the tunnels. The structure formation initiated as spinodal decomposition but the mechanism changes into the nucleation and growth in an early stage of progression. Droplets of monomer-rich phase are discharged from the homogeneous polymer-rich phase. For operating such a mechanism in the system, it is of importance to be the big difference between the mobility of polymer and monomer. In particular, the molecular weight of the monomer to be less than a few thousands is an essential factor. The super-structure thus formed can be fixed and stabilized only when the system is cooled down below its melting temperature in the semi-crystalline polymer and monomer system. In the non-crystalline polymer and monomer system, although the super-structure is also formed and increases in size, the structure finally collapses and becomes droplets which disperse in the monomer-rich matrix during the cooling process. The physical gels are quite stable thermally and dynamically and give the feel of gelatin, flesh and others depending on species of polymer and oil and their composition. The gels are now applied to industrial products as very soft non-aqueous gels. Copyright

Physical Properties of a Novel Non-Aqueous Physical Gel Having a Comb-Like Polymer

櫛型構造をもつ熱可塑性高分子と低分子量オイルからなる物理ゲルの形態, 熱的, および粘弾性的性質を調べた. 得られたゲルはμmサイズの網状構造を有する. 本ゲルはガラス転移温度が-55℃の系でさえも20℃においてtanδ=0.58 (10Hz, ひずみ10%) を発現する. その融点は136℃付近であり幅広い温度範囲で使用できる新しい熱可塑性の力学的減衰材料となる可能性がある.