Protective effect of the phenyl group in γ‐irradiated compatible blends of poly(methyl methacrylate) and poly(styrene‐co‐acrylonitrile)

Abstract

SynopsisThe sensitivity to radiation of mixtures of poly(methy1 methacrylate) (PMMA) and polystyrene-co-acrylonitrile (SAN) was studied over the entire range of composition. Polystyrene-coacrylonitrile, like polystyrene, is highly resistant to ionizing radiation, having a small G, value for crosslinking (0.077) and an even smaller G, value for main chain scission (0.055). In contrast, PMMA degrades readily under irradiation (with G, = 1.2). In y-irradiated blends, the behavior of each polymer is largely influenced by the presence of the other component. Gel formation in SAN is impeded by PMMA, as a result of a decrease in G,, and a concomitant increase in the ratio C,/C,.Flexural strength measurements, along with molecular weight determinations by gel permeation chromatography, demonstrated that SAN had a marked protective effect on PMMA by decreasing G, (chain scission). This protective effect was not observed in earlier experiments with PMMA-PS blends, in spite of its chemical similarity to the system PMMA-SAN. The difference in behavior between PMMA-PS and PMMA-SAN may be explained on the basis of polymer compatibility. PMMA and SAN form a compatible pair, whereas PMMA and PS are incompatible; thus the short range protective effect of the phenyl groups in PS is inhibited.

Influence of electron beam irradiation on the microrheology of incompatible polymer blends: Thread break‐up and coalescence

“…This implies that the viscosity of LDPE in the blend may be somewhat lower than measured for the irradiated homopolymer. This shielding effect of the phenylrings has been observed by some researchers in a polymer blend with an intimate contact between the two phases [Nguyen and Kausch (1984), Schulz and Mankin (1976)]. Witt (1959) reported that in a blend of immiscible PS and polybutadiene (PB) the radiation induced crosslinking of PB occurred to the same extent as for pure PB.…”

Effect of sequence concentrations on segmented polyurethanes properties

“…The point corresponding to 50 per cent inflection of the enthalpic jump of C p as value of the T g (H) was chosen by most authors. The hard sequence formed from MDI and 1,4‐BDO: ‐(MDI‐BDO) n with a number average molecular weight of 5,000 g/mol has a T g (H) of 93°C, while other authors (Cuvé et al , 1991; Kolodziej et al , 1986; Nguyen and Kausch, 1958) found a slightly higher value (107°C) for this same pure hard sequence, but with more elevated number average molecular weights. This difference is also observed in the case of the melting temperatures ( T m ).…”

“…When the average lengths of the hard sequences increase, their T g (H) values increase too (Nguyen and Kausch, 1958;Yamaguch et al, 1998;Nbeth et al, 1998). …”

A triple‐shape memory material fabricated by in situ crosslinking of poly(butylene adipate‐co‐terephthalate)/ε‐polycaprolactone via electron‐beam irradiation and its triple‐shape memory effects

“…Because the crosslinking induced by E‐B irradiation was more likely to happen within the microphases if heterogeneous system was irradiated according to Dong and Fel . Works by Nguyen and Alexander considered that energy transferred within about 0.6 nm in PMMA, meaning that E‐B irradiation is a strict adjacent or in situ crosslinking method, and more information should be supplied to confirm the formation of bridge molecular at interfaces in this heterogeneous system and resulted interfacial strength.…”

“…This is also verified by Figure (b) where G c and G s increase nonlinearly with PCL. Meanwhile, the ratio G s /G c decreases nonlinearly representing higher probability to be crosslinked as the PCL content increases …”