星型の絡み合い高分子の末端架橋における粘弾性挙動：分岐高分子に対する粘弾性計算の拡張

抄録

Viscoelastic behaviour for entangled star polymer of 3 arms was investigated before and after the end-linking using computational linear rheology system of Branch-On-Branch(BOB) Rheology. The object of this study as an experimental system was poly(propylene sulfide) star (PPS star) with different arm length. The results of calculation were compared with the experimental data which has already been published and was supplied by the author of the original article. An additional function was incorporated into BOB-rheology which enables the calculation for polymers with the end-linking. The progress of end-link reaction was analysed by formulating the consumption of reactive groups in PPS star. The formulation produced the relation between the fraction of PPS star monomer and the connectivity extent in the end-link reaction. By comparing the experimental data with the calculation data for the monomer fraction, the unequal reactivity of end groups, also known as the substitution effect, was turned out to be negligible. As a result of calculation before the end-linking, the experimental data could be well reproduced by the viscoelasticity of 3 arm star polymer mixed with H-polymer rather than 3 arm star polymer alone. The results of calculation after the end-linking showed vertical shifts between the calculation and experimental data. The shifts were almost constant through the frequency range investigated and independent of the connectivity extent. Therefore, the expression of the plateau modulus (G₀ = (4/5)·(dRT/M_e), d:density, M_e: the entanglement molar mass) is considered to underestimate the modulus appeared in the experimental data. Other features such as the cross point of G' and G", plateau region and terminal flow region were well reproduced by the calculation data.