PVPh/PMMA blends

Figure 26.7 Comparison of the normalized dielectric loss spectra for the local relaxation process of PVPh/PMMA blends at 60°C. Reprinted with permission from Ref [43].

Figure 5.5 Temperature dependence of the storage (a) and loss (b) moduli, and the loss tangent (c), as determined by DMTAfor PVPh-PMMA blends at 10 Hz (A) pure PMMA, (A) 10 wt% PVPh, ) 30 wt% PVPh, and (O) 54.5 wt% PVPh.

Chang et al. reported the miscibility of poly(vinylphenol) (PVPh) with poly(methyl methacrylate) (I MMA) Figure 1 shows the C CP/MAS spectra of pure PVPh, PMMA, PVPh-co-PMMA, PEG, and PVPh-co-PMMA/ poly(ethylene oxide) (PEO) blends of various compositions with peak assignments. VPh contents of PVPh-co-PMMA is 51 mol% and Mn of PEO is 20,000. The spin lattice relaxation time in the rotating frame (Tip ) was measured to examine the homogeneity of PVPh-co-PMMA/PEO blends on the molecular scale. 

Mirau and White applied the HETCOR pulse sequence to PMA/PVPh, PMMA/PVPh and PC/polycaprolactone (PCL) blends [26, 124]. Figure 10.16(b) shows the HETCOR spectrum for PMA/PVPh = 1/1 cast from methyl ethyl ketone. The combined use of WIM-24 and MAS allows CP for H and C spins in close proximity, therefore, most of the cross-peaks appear between directly bonded C— H pairs. Interestingly, a cross-peak was observed for the nonprotonated carbonyl carbon of PMA. The spectrum shows... 

IPN crosslinked PBA, crosslinked uncrosslinked SAN Poly(p-hydroxy styrene), PVPh and EVAl Acrylic core-shell copolymer and either PBT or PET Poly(allyl methacrylate-co-butyl acrylate-co-butanediol dimethacrylate-co-styrene-co-methyl methacrylate) or poly (aery lonitrile-co-butyl aery late-co-tricy clodeceny 1 aery late-co- styrene) Poly(acrylate-V-cyclohexyl maleimide), PMI, and a copolymer PMMA — core, crosslinked butyl acrylate-styrene copolymer — middle layer, and PMMA shell d = 200-300 nm PEG/atactic PMMA blends were characterized by PVT at T = 20-200°C and P = 0-200 MPa. Free volume fraction was calculated from an equation of state... 

The T of polymer blends can be related to the blend composition by different equations, as shown in Table 12.2. The T of miscible blends of poly(p-dioxa-none) with poly(vinyl phenol) (PPDO/PVPh) [74], as studied using the Fox [75], Gordon-Taylor [76], Couchman-Karasz [77] and Kwei [78] models, showed that the experimental data lay below the Fox equation, suggesting that the free volume of the blends was larger than predicted, assuming free volume additivity. On the other hand, the Gordon-Taylor and the simplified Kwei equations fitted the experimental T values appropriately. Other studies have shown that the Ta of SAN/PMMA blends was also effectively approached by the Gordon-Taylor relationship [79,80]. 

Figure 20.2 Variation of P2/A with composition for various PVPh-based blends. , PEO X=1.5 O, PEOX = 3.0 , PVMEX=1.5 , PVME >l = 3.0 A, PET O, PMMA. Reprinted with permission from Ref [42] 2003, Elsevier.

Figure 14.1 Schematic representation with TEM images of PVPh-h-PS/P4VP blend system showing phase transition from lamellar, gyroid, and hexagonally packed cylinder to body-centered cubic structures with increase in P4VP volume fractions. Undulated and distorted lamellar structures observed in PVPh-h-PS/PMMA blends due to weak hydrogen bonding between PMMA and PVPh. Chen et al. [23]. Reproduced with permission of American Chemical Society.

Figure 5.16 FTIR spectra of hydroxyl vibration region for blends of PMMA with poly(4-vinylphenol) (PVPh). Lines from bottom to top are pure PMMA, blends with increasing PVPh...

Table 1. Tip (ms) values of pure PVPh and various PVPh-co-PMMA/PEO blend compositions...

Table 1 also shows that both pure PVP and PVPh-co-PMMA/PEO blends exhibit only single-exponential relaxation through out all of the blends at... 

A typical value of D is 10 m" s . For Ti of 5 ms, the dimensions of these PVPh-co-PMMA/PEO blends are below 2-3 nm in the amorphous phase. Interestingly, the has a minimum value for the PVPh-cu-PMMA = 40/60 blend showing that the overall chain mobility is maximal at this composition. This observation agrees with the earlier result concerning hydroxyl group association obtained by FTIR and solid-state NMR. In addition, all of the blends show a shorter Ti,/ than that of the pure PVPh-co-PMMA implying that the PVPh-co-PMMA mobility also increases with the increase of PEO content. 

Zumbulyadis et al. [133-135] showed that proton to deuterium CP transfer is also useful to investigate miscibility. For a completely deuterated PMMA (d8-PMMA) homopolymer, a very weak deuterium FID signal, which was created by CP between a small amount of residual protons ( 2%), was detected (Fig. 10.17(a)) [134], For miscible d8-PMMA/PVPh = 18.8/81.2, an appreciable enhancement was observed (Fig. 10.17(c)). However, for the phase-separated blend, the signal enhancement was small as compared to that for the miscible one (Fig. 10.17(b)). They concluded that the signal enhancement in the phase-separated blend comes from interfacial regions (see Section 10.3). 

Fig. 10.17. Time-domain CP/MAS NMR spectra of pure deuterated-PMMA and deuterat-ed-PMMA/PVPh = 18.8/81.2 (a) Only a very weak signal due to CP from residual H is observed for deuterated-PMMA (b) time-domain signal of a partially phase-separated blend cast from tetrahydrofuran and (c) time-domain signal of a homogeneous blend cast from methylethylketone. (Reprinted with permission from Ref. [134]. 1993 American Chemical Society, Washington, DC.)...

Figure 20.18 FTIR spectra recorded at room temperature in the 2700-4000cm region for pure PVPh and various PVPh-co-PMMA/PEO blends, (a) pure PVPh (b) 100/0 (c) 90/10 ...

Figure 21.8 (a) 2D PISEMA spectrum of PMMA/PVPh cast film (b) Cross-sections of the aromatic proton (d 4 116.0 ppm) for Blend-120 (bottom) and cast film (top) at... 

Copolymerization with other vinylic monomers (i.e., styrene, vinyl acetate) allows even further modification. The ease of structural modification to yield desired blend properties (miscibility) is well-documented in the experimental literature. The common acrylate polymer is PMMA and has been noted to be miscible with various other polymers noted in this chapter (PVF2, styrene copolymers, PVC, PVPh, PEO) and thus will not be discussed in this section. 

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