PMA/PVAc

Figure 3.18. dCp/dr versus temperature data for different PMA/PVAc blend compositions. 

Figure 3.18 shows the dCp/dT signal versus temperature for different PMA/PVAc blend compositions. The dCp/dT signal showed a high degree of symmetry, which implies that the miscibility level is high. Compare this with the behaviour of PVC/poly(ethyl methacrylate) (PEMA) blends. 

Figures 3.21 and 3.22 show the changes of TgS and ACp versus composition for some PMA/PVAc blends. The following relations hold for Tg and...

Figure 3.22. Plot of ACp versus composition for PMA/PVAc blends.

Table 3.4. STgValues for PECH/PMMA, PS/PPO and PMA/PVAc blends...

The PMA-PVAc blends are miscible, but show no specific interactions. The interdiffusion coefficient will be as follows. 

Figure 3.31 shows dCp/dT versus time at 100°C for the PMA/PVAc combination. The dCp/dT signal shows clearly that an interface is formed by thermal diffusion. This is shown by the increase in the dCp/dT signal between the two glass transitions. It can also be seen that the PMA, PVAc and interface signals overlap. A peak-resolution technique, with the condition that ACp (observed) = ACp (calculated), can be used to deal with this problem. Figure 3.32 shows the result for the sample annealed for 130 h. 

Figure 3.32. Comparison of the multi-peak resolution results with the experimental data ( ) for the PMA-PVAc combination annealed at 100°C for 130 h.

Figure 3.33. Weight fraction of the interface versus diffusion time for the PMA-PVAc...

To evaluate this model, an experiment with a four-component system was conducted This system was a poly(methyl acrylate)/poly(vinyl acetate) (PMA/PVAc) physical blend, or mixture, consisting of four individual blends (PMA/PVAc (80/20) + PMA/PVAc (60/40) + PMA/PVAc (40/60) - -PMA/PVAc (20/80)). PMA is miscible with PVAc. The open squares in Figure 3.49 are the experimental dCp/dT data. The difference between glass transition temperatures of PMA and PVAc is about 33°C. In the glass transition region, the four-component mixture showed an acceptable fit to the experimental data, see Figure 3.49. The solid lines shown in Figure 3.49... 

The first patent on PAB was granted to Parkes in 1846 for two natural polymers co-vulcanized during blending in the presence of CS2, i.e., a natural rubber (NR = amorphous c/s-polyisoprene, IR) with gutta-percha (GP = semicrystalline trans-polyisoprene, IR). Thus, mbber PAB predates that of synthetic polymers by ca. 80 years (PMA/PVAc 1929). Notably, while the early plastics were bio-based, their usage fell to <5 wt% nowadays slowly recovering from the absolute dominance of synthetic, petroleum-based plastics. 

Available evidence suggests that the main reaction accounting for transfer to vinyl polymers (e.g., PMA, PVAc, PVC, PVF) usually involves ahstraaion of a methine hydrogen (Scheme 61). However, definitive evidence for the mechanism is currently only available for a few polymers (e.g., PVAc PVF). 

Figure 11 Arrhenius plots of the slow component of nonradiative decay times of MG in (A) PVAc, (B) PMA, and (C) PEMA as functions of temperature. Below Tg the plots show two regions of Arrhenius temperature dependence. (From Refs. 1, 12.)...

Fig. 13 es -17 for polymeric monolayers at A/W. The symbols correspond to data for PtBMA ( ), PMMA (A), PVAc (o), PMA ( A ), PEO ( 0 ). PTHF ( ). The initial slopes in both are drawn in for the good solvent limit (solid line) and the theta limit (dashed line)... 

We present the viscoelastic characterization of these polymers as deduced from SLS. By means of the scheme outlined with Fig. 4, we demonstrate in Fig. 14 that two groups of polymers are well differentiated in terms of their polar profile , that is their progression of e and k with increasing 77. In the figure, those under the good solvent condition with y fa 3, PVAc, PMA, PEO and PTHF, are shown in (A) and those under the poor solvent condi-... 

Fig. 14 A/SjC>eq vs. /s>eq for PEO, PTFiF, PMA and PVAc up to es>max for all four polymers, with the symbols identical to those in Fig. 13 (A). The same plots for PMMA and PtBMA are shown in (B), where the open symbols stand for 17 < 2 mN nr1 and the filled symbols for n > 2 mN nr1. The solid and dashed curves are the same as in Fig. 4, and the surface pressure increases counterclockwise, starting from 77 = 0, Limit I, in Fig. 4. PMMA shows a discontinuous change with can be explained by the coalescence of PMMA patches existing as a heterogeneous film prior to the monolayer state. Error bars, not shown for clarity, are 0.5% and 5% for/s>eq and A/SjC>eq, respectively...

Scheme 2 Proposed McLafferty-type rearrangement via intermolecular proton transfer from the CH3 of PVAc to the ester group of PMMA in the welt-mixed coalesced PVAc/PMMA blend. Note that only the conversion of PMMA to PMA is depicted in the proton-transfer from PVAc...

Acrylic polymers are recognized for their miscibility with a variety of polymers, viz. miscibility of PMA with PVAc [Kem, 1957]. PMMA is miscible with standard PC at T < LCST - 140°C. The miscibility range can be greatly increased by modifying the PC chain ends (LCST < 300°C) [Kambour, 1988]. Demixing PMMA/PC blends by the spinodal decomposition mechanism generated alloys with excellent mechanical properties [Kyu, 1990]. 

Poly(4-vinyl phenol) with PVAc, EVAc, PCL, PPL, PMA, PEA, PBA, The amount of free and bonded C=0 vibrations were determined fort the PVPh/hydrogen bonding polymer blends, using a curve fitting procedure Coleman et al., 1989... 

For most polymer pairs to be miscible, an exothermic interaction is required. Nandi et al. [40] studied the miscibility of poly(methyl acrylate) (PMA) and poly(vinyl acetate) (PVAc) in several solvents by the inverse... 

Figure 3.33 shows how the weight fraction of the interface increases with time, whilst Figure 3.34 shows how >a and co, the weight fractions of PMA and PVAc, respectively, in the interface change with time. The changes of (Op, and (o with time are similar, which indicates that interdiffusion in this particular polymer pair is symmetrical. The change of thickness of the interface with diffusion time is shown in Figure 3.35. Here, the room temperature densities of PMA and PVAc were used to calculate the average density, p. Thus, for both symmetrical and asymmetrical interfaces, the growth of interfacial thickness can be described by Eq. (22).

Figure 1 Polymer interpretation chart. PAI, polyamideimide PC, polycarbonate UP, unsaturated polyester PDAP, diarylate phtalate resin VC-VAc, vinyl chloride-vinyl acetate copolymer PVAc, polyvinyl acetate PVFM, polyvinyl formal PUR, polyurethane PA, polyamide PMA, methacrylate ester polymer EVA, ethylene-vinyl acetate copolymer PF, phenol resin EP, epoxide resin PS, polystyrene ABS, acrylonitrile-butadiene-styrene copolymer PPO, polyphenylene oxide P-SULFONE, poly-sulfone PA, polyamide UF, urea resin CN, nitrocellulose PVA, polyvinyl acetate MC, methyl cellulose MF, melamine resin PAN, polyacrylonitrile PVC, polyvinyl chloride PVF, polyvinyl fluoride CR, polychloroprene CHR, polyepichlorohydrin SI, polymethylsiloxane POM, polyoxy-methylene PTFE, polytetrafluoroethylene MOD-PP, modified PP EPT, ethylene-propylene terpolymer EPR, ethylene-propylene rubber PI, polyisoprene BR, butyl rubber PMP, poly(4-methyl pentene-1) PE, poly(ethylene) PB, poly(butene-l). (Adapted from Ref. 22, p. 50.)...

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