PU/PBMA

Sample Preparation. For each of the xx, lx, and xl mixtures, three PU PBMA compositions, 3 7, 5 5, and 7 3, were made with the 11 mixture, only the 5 5 composition was prepared. An equivalent weight ratio of 0.95 for OH NCO was maintained for the PU components a 3.5 1 (by weight) BD TMP mixture was used for the PU(x) samples. Samples containing PBMA(x) were made with a 60 1 (mole ratio) BMA TMGDM mixture. These ratios yield a calculated Me of 1700 and 4200 g/mol for the PU(x) and PBMA(x), respectively. In each mixture, 0.05 wt.%... 

The effect of fillers on the reaction of polymer formation was discussed in Chapter 4. It is evident that introducing a filler during IPN formation should also lead to its influence on the rates of the IPN formation. This influence should affect the possibility of microphase separation. This question was studied " for simultaneous semi-lPN based on a crosslinked polyurethane and linear PBMA. The ratio PU PBMA was 3 1, the ratio IPN flller was 60 40 and 80 20 by weight. It was established that the onset of auto-acceleration of the butyl methacrylate polymerization increases from 160 min without filler to 220 min in the presence of a filler (talc). After the onset of auto-acceleration, the reaction rate of butyl methacrylate pol5mierization decreases with the increase of amount of filler. The filler influence on the reaction kinetics was explained based on the so-called... 

Using the proposed method, the free volume distribution was determined for simultaneous semi-IPNs based on cross-linked PU and PBMA (simultaneous curing of PU and polymerization of BMA) [126]. The PU/PBMA ratio was 1 1. The gel chromatographic experiments were performed using as a test molecule the standard polystyrene (Du Pont) with MM from 1800000 to 800 at Mw/Mn < 1.05, toluene and styrene being also used as low molecular mass substances. The transition from the molecular masses to the mean-square dimensions of the coils for PS were done using the relation = 0.065 M / ... 

A theoretical method was proposed [240] to calculate the interphase amount in IPNs from the data on modulus-temperature behavior. For PU/PBMA IPNs the interfacial concentration was estimated and a wide interfacial region between the phase domains was discovered. 

Fig. 69 Kinetics of PU formation and BMA polymerization in semi-IPNs at various component ratios a—PU in IPN, b—PBMA in IPN. PU/PBMA 17-85/15, 18-75/25, 19-65/35 by mass % [202]...

Microphase separation also depends on the PU/PBMA ratio. Indeed, for the ratio 85 15 mass% (Table 13) the conversion degree before the onset of microphase separation is higher for both components than for the ratio 75 25, while the values for the ratios 65 35 and 75 25 are close to each other. At the same time the PU mass fraction corresponding to fmps turned out to be the... 

Table 13 Compositions and microphase separation parameters for PU-PBMA semi-IPNs [285]...

PU/PBMA ratio, mass % moM PBMA rate constant -10, S Onset of separation time, min Conversion degree at the separation onset, PU Conversion degree at the separation onset, PBMA... 

The kinetics of the formation of these systems was studied [202] for the PU/PBMA IPNs. As distinct from the preceding results, in this work the phase separation resulting from kinetic changes was estimated by the glass transition temperatures of two evolved phases, which characterize their composition and hence the conditions of phase separation. Table 14 shows some parameters of semi-IPN PU/PBMA 85 15 mass % obtained by introduction of Hnear PBMA into the reaction mixtme. The main criterion of phase separation in this work is the shift of glass transition temperature of the two evolved phases, each of which is enriched by one of the components. 

Table 18 Some features of the compatibilizer action on the formation and properties of IPNs based on PU-PBMA [341]...

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... 

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