Introduction of Internetwork Grafting

System PU/PBMA, mass % Compati- bilizer Time of the onset of separation, min Conversion degree at the onset of separation, a PU PBMA PU, PBMA, °C °C 

Really, the temperature dependence of the loss maximum tan 5 for IPN components and semi-IPNs (75 25) show the existence of two expressed maxima with glass transition temperatures of - 5 °C for the PU phase and 60 °C for the PBMA phase. This means that the IPN is typically a two-phase system. 

For IPNs containing 5 mass % of HEMA, Fig. 79a shows only one broad maximum. The existence of only one maximum may be the result of either compatibilization leading to the formation of a one-phase system or to the formation of a heterogeneous system with broad interphase regions between two phases and with small dimensions of domains of one of the phases. As microphase separation for the systems with introduced HEMA begins much faster than that for the IPN without additive, it is evident that this system 

---

These samples, simultaneous PU/PS IPNs, were synthesised by a one-short route. The IPN topology appears to restrict phase separation, which results in materials with broad transition regions. By variation of the crosslink level in either or both polymer networks, the controlled introduction of internetwork grafting or the incorporation of compatibilisers into the PS network, the compatibility of the two polymer networks can be increased. For simultaneous IPNs, it has been found [129] that the network which is first formed... 

---