Formation kinetics and viscoelastic properties of semi-interpenetrating networks based on crosslinked polyurethane and poly(butyl methacrylate)

Interpenetrating Polymer Networks Based on Polyurethane and Poly(butyl methacrylate): Interrelation Between Reaction Kinetics and Microphase Structure

“…It was found that segregation degree is higher for sequential IPNs than for simultaneous ones. The experimental data for semi-IPNs and full IPNs [5,6,231 show that the way of formation of IPN reflects on the segregation degree and microheterogeneous structure. A higher segregation degree for full sequential IPNs is the result of separation in time of two reactions.…”

Phase-Separated Interpenetrating Polymer Networks

“…Some features of the phase structure, which follow from IPN viscoelastic properties, can be pointed out. The continuous medium for samples 2-6 is the phase enriched in PU network, which is evidenced by a plateau on the elastic- [202] ity curve at temperatures above 343 K. A drastic decrease of the elastic modulus above this temperature for the semi-IPN containing 44 mass % PBMA (curve 7) unambiguously indicates a high PBMA content in the continuous phase. As for many full and semi-IPNs, the inversion of phases enriched in one of the components occurs in the region of intermediate compositions [155].…”

“…The T g of the PU network shifts from 251 to 265 K, while the T g of PBMA remains practically unchanged. The observed changes in the relaxation behavior of the semi-IPNs seem quite logical when considered from the [202] standpoint of concepts of formation of phases enriched in one of the components of a two-phase system. In the above-considered series, the increase in T g of the PU-enriched phase appears to be associated with the decrease in the reaction system viscosity, which results in the formation of a more regular structure of the PU network.…”

“…The relaxation properties of semi-IPNs are characterized by the same general features as for full IPNs [199][200][201][202]. The investigation of the temperature dependence of the shear modulus and of the mechanical losses for semiIPNs based on linear PMMA or polyacrylonitrile and cross-linked PU has shown that the transition temperatures inherent to PU are shifted to higher values when its content is increased.…”

“…It is important that the viscoelastic properties of IPNs depend on the kinetic conditions and on the method of IPN synthesis [202]. This question was thoroughly investigated for semi-IPNs based on cross-linked PU and linear PBMA.…”