Methyl acetate solubility parameter

The solubility of commercial poly(methyl methacrylate) is consistent with that expected of an amorphous thermoplastic with a solubility parameter of about 18.8 MPa. Solvents include ethyl acetate (8 = 18.6), ethylene dichloride (8 = 20.0), trichloroethylene (8 = 19), chloroform (8 = 19) and toluene (8 = 20), all in units ofMPa. Difficulties may, however, occur in dissolving cast poly(methyl methacrylate) sheet because of its high molecular weight. 

Figure 8.1. Relation of solubility parameters (solpars or Hildebrand 8 values) and carbon numbers in various homologous series of solvents. (4) Normal alkanes, (B) normal chloroalkanes, (C) methyl esters, (D) alkyl formates and acetates, (E) methyl ketones, (F) alkyl nitriles, ) normal alkanols, (H) alkyl benzenes, and (I) dialkyl phthalates.

Prior to Harwood s work, the existence of a Bootstrap effect in copolymerization was considered but rejected after the failure of efforts to correlate polymer-solvent interaction parameters with observed solvent effects. Kamachi, for instance, estimated the interaction between polymer and solvent by calculating the difference between their solubility parameters. He found that while there was some correlation between polymer-solvent interaction parameters and observed solvent effects for methyl methacrylate, for vinyl acetate there was none. However, it should be noted that evidence for radical-solvent complexes in vinyl acetate systems is fairly strong (see Section 3), so a rejection of a generalized Bootstrap model on the basis of evidence from vinyl acetate polymerization is perhaps unwise. Kratochvil et al." investigated the possible influence of preferential solvation in copolymerizations and concluded that, for systems with weak non-specific interactions, such as STY-MMA, the effect of preferential solvation on kinetics was probably comparable to the experimental error in determining the rate of polymerization ( 5%). Later, Maxwell et al." also concluded that the origin of the Bootstrap effect was not likely to be bulk monomer-polymer thermodynamics since, for a variety of monomers, Flory-Huggins theory predicts that the monomer ratios in the monomer-polymer phase would be equal to that in the bulk phase. 

New copolymer membranes of acrylonitrile for the separation of benzene-CYH mixtures by PV were developed by Ray et al. (1997). The monomers in the copolymers were selected on the basis of their solubility parameter values relative to those of benzene and CYH. These were styrene, methyl methacrylate, and vinyl acetate. Copolymers of acrylonitrile with methyl methacrylate and vinyl acetate showed good selectivity and moderate flux 60-70 and 0.075 kg/m h, respectively, with a membrane of 10 pm thickness for a feed mixture containing 5% benzene. Copolymer of acrylonitrile with styrene showed comparatively higher flux but lower selectivity. Ray et al. claimed that the selectivities obtained with these membranes were better than those reported in the literature. 

A solubility parameter of 24.5-24.7 MPa / [12.0-12.1 (cal/cm ) ] has been calculated for PVF using room temperature swelling data (52). The polymer lost solvent to evaporation more rapidly than free solvent alone when exposed to air. This was ascribed to reestablishment of favorable dipole-dipole interactions within the polymer. Infrared spectral shifts for poly(methyl methacrylate) in PVF have been interpreted as evidence of favorable acid-base interactions involving the H from CHF imits (53). This is consistent with the greater absorption of pyridine than of methyl acetate, despite a closer solubiUty parameter match with methyl acetate. 

Another method involves excimer fluorescence as a molecular probe see Section 2.9. The question may be raised as to whether polymer blends will become more miscible if the differences in their solubility parameters are reduced. Excimer fluorescence provides some evidence see Rgure 4.14 (52). Here, 0.2 wt.% of poly(2-vinyl naphthalene), P2VN, is dispersed in a series of poly (alkyl methacrylates). These include the following, which are identified in Figure 4.14 by acronym methyl, PMMA ethyl, PEMA n-propyl, PnPMA isopropyl, PiPMA n-butyl, PnBMA isobutyl, PiBMA . yec-butyl, PsBMA ferf-butyl, PtBMA phenyl, PPhMA, isobomyl, PiBoMA benzyl, PBzMA and cyclohexyl, PCMA. Two other host polymers were polystyrene, PS, and poly(vinyl acetate), PVAc. 

Poly(methyl methacrylate) prepared by free radical polymerization is amorphous and is therefore soluble in solvents of similar solubility parameter. Effective solvents include aromatic hydrocarbons such as benzene and toluene chlorinated hydrocarbons such as chloroform and ethylene dichloride and esters such as ethyl acetate and amyl acetate. Some organic materials, although not solvents for the polymer, cause crazing and cracking, e.g., aliphatic alcohols and amines. Poly(methyl methacrylate) has very good resistance to attack by water, alkalis, aqueous inorganic salts and most dilute acids. Some dilute acids such as hydrocyanic and hydrofluoric acids, however, do attack the polymer, as do concentrated oxidizing acids. Poly(methyl methacrylate) has much better resistance to hydrolysis than poly(methyl acrylate), probably by virtue of the... 

Terpene resins will be effective as solid solvents for an elastomer when their Hildebrand solubility parameters are close to the Hildebrand solubility parameters of the respective polymer. For example, from Table 22.4 it can be seen that pure polyterpene resins are suitable tackifiers for poly(ethylene) (PE), natural rubber, and polybutadiene polymers. Further, terpene phenol resins are suitable tackifiers for poly(vinyl acetate), poly(methyl methacrylate), and poly(ethylene terephthalate). 

The role of solvents is to reduce the viscosity of adhesives and to improve fluidity. That can provide the adhesives wettability to create an intimate contact with the surface of adherends. Solvents must be able to dissolve the components of adhesives. Solubility parameter is an index to show the soliditivity of solvents. A solvent can dissolve a high amount of materials whose solubility parameters are close to that of the solvent. Water, alcohols, aromatic hydrocarbons (e.g., toluene and xylene), ketones (e.g., methyl ethyl ketone and cyclohexanone), acetate esters (e.g., ethyl acetate and butyl acetate), n-hexane, cyclohexane, methylene chloride are used due to their solubility, dehydration rate, noncombustibility, and workability. To meet the demands concerning environmental issues, the use of some solvents such as toluene, xylene, ethylbenzene, and styrene is restricted bylaws such as the air pollution control law legislated by Ministry of the Environment in Japan (The Ministry of the Environment 1996). 

Azad and Fitch (5) investigated the effect of low molecular weight hydrocarbon additives on the formation of colloidafr particles in suspension polymerization of methyl methacrylate and vinyl acetate. It was found that the additives n-octane, n-dodecane, n-octadecane, n-tetracosane and mineral oil exerted a thermodynamic affect depending upon water-solubility and molecular weight. Since these effects on emulsion polymerization have not been considered by the earlier investigators, we have chosen n-pentane and ethyl benzene as additives with limited water-solubility and n-octadecane, and n-tetracosane as water-insoluble ones. Seeded emulsion polymerization was chosen so that the number of particles could be kept constant throughout the experiments and only the effect of the other parameters on the rate could be determined. 

Symmetric SBS block copolymers covering a wide range of compositions and molecular weights have been synthetized and studied by the same techniques as symmetric BSB copolymers In solution in methylethyl ketone, methyl methacrylate, vinyl acetate, or styrene they exhibit a behaviour similar to that of SB and BSB copolymers with respect to the effect of temperature, concentration, and postpolymerization of the solvent. The effect of the molecular weight of the soluble and insoluble blocks on the geometrical parameters of the hex onal and lamellar structures is however different for BSB and SBS copolymers. For SBS copolynKrs, there is a reciprocal interaction between soluble and insoluble blocks. 

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