Dielectric relaxations in poly(methyl acrylate), poly(ethyl acrylate), and poly(butyl acrylate)

A comparative study is undertaken of the dielectric relaxation spectra of poly(methyl acrylate), poly(ethyl acrylate), and poly(butyl acrylate), taking into consideration the spectra of the corresponding polymers in the series of the polymethacrylates. The three polymers, PMA, PEA, and PBA, present an α relaxation zone clearly separated from the secondary relaxations. Its shape is not altered with temperature, and it is possible to construct a master curve. With increasing length of the side chain, its distribution of relaxation times broadens and the temperature of the maximum of the relaxation decreases. A β relaxation with decreasing intensity as the length of the side chain increases is clearly perceptible in PMA and PEA, but almost not perceptible at all in PBA. In PEA this relaxation appears split into two peaks. Computer simulation of restricted motions of the side chain discard an origin similar to that of the γ relaxation in PPA or PBA for the lowest temperature component of the relaxation, and suggests the conjunction of two rotation mechanisms in this relaxation for the polyacrylates. For the experimental temperatures of our tests a γ relaxation shows up only in PBA. Its apparent activation energy, higher than in related polymers of the polymethacrylate series, suggests that the tighter packing of monomeric units in polyacrylates leads to a significant increase in the intermolecular contribution to the potential energy barrier responsible for the relaxation.     

Blends containing polymers of epichlorohydrin and ethylene oxide. II. Polyacrylates

The phase behavior of blends of various polyacrylate homopolymers and two commercial ethyl acrylate (EA) and n-butyl acrylate (nBA) copolymers with polyepichlorohydrin (PECH), poly(ethylene oxide) (PEO), and a copolymer of epichlorohydrin and ethylene oxide [P(ECH/EO)] was examined using differential scanning calorimetry and optical indications of phase separation on heating, i.e., lower critical solution temperature (LCST) behavior. Poly(methylacrylate) (PMA) was shown to be miscible with PECH, PEO, and P(ECH/EO) while only PECH was found to be miscible with the higher polyacrylates: poly(ethyl acrylate), EA copolymer, poly(n-propyl acrylate), and nBA copolymer. However, even PECH was found to be only partially miscible with poly(n-butyl acrylate). In general, glass transitions observed by DSC for blends were not as broad as those found in corresponding polymethacrylate blends. All mixtures showed LCST behavior, and, based on this and excess volume measurements, to the extent possible, qualitative conclusions were made concerning the relative strength of the interactions among the various blend pairs. For PECH it appears that the interaction with polyacrylates decreases with increasing size of the alkyl group. The commercial copolymers seem to interact more exothermically with PECH than the corresponding homopolymers. The interaction with PMA is apparently larger for PECH than for PEO or for P(ECH/EO). Interactions for the latter two are about the same. The apparently exothermic interactions between ECH and EO units are not sufficiently strong to preclude miscibility of P(ECH/EO) with PMA. As for the polymethacrylates, it is clear that the chlorine moeity of PECH is needed for miscibility with higher polyacrylates.     

The miscibility of polyacrylates and polymethacrylates with PVC: An interpretation of the heats of mixing of oligomers

Oligomers of various polyacrylates and polymethacrylates and a chlorinated paraffin (as an analogue for PVC) were studied in order to give information relevant to the miscibility of the respective polymers. The heats of mixing of the oligomers with the chlorinated paraffin were measured and showed that those oligomers with the lowest and highest ester group concentration (poly(methyl acrylate) and poly(octadecyl methacrylate)) had unfavourable (positive) heats of mixing whereas oligomers with intermediate ester group concentrations had favourable (negative) heats of mixing. This was consistent with the miscibility of the respective polymers in most cases. The results were interpreted in terms of the summation of the effects of the specific interactions and the dispersive forces. A high concentration of interacting groups leads to a high contribution from the specific interaction, but in the case of poly(methyl acrylate) with the highest concentration of interacting groups this is outweighed by a large unfavourable contribution from the dispersive forces.     

Polyester–polycarbonate blends. V. Linear aliphatic polyesters

Polycarbonate blends with the linear aliphatic polyesters poly(ethylene succinate) (PES), poly(ethylene adipate) (PEA), poly(1,4-butylene adipate) (PBA), and poly(hexamethylene sebacate) (PHS) were prepared by solution casting. Blends containing PES, PEA, and PBA exhibited a single T_g by DSC and thus form a single, miscible amorphous phase with polycarbonate. However, blends containing PHS exhibited only partial miscibility. Crystallinity of the polyesters was reduced by mixing with polycarbonate; however, plasticization by the polyesters induced crystallization of the polycarbonate. Miscibility in these systems is the result of an exothermic heat of mixing stemming from an interaction of the carbonyl dipole of the ester group with the aromatic carbonate. The effect of polyester structure on miscibility with polycarbonate is interpreted by and correlated with heats of mixing obtained by direct calorimetry of low molecular weight liquid analogs of the polymers.     

CO2-solubility of oligomers and polymers that contain the carbonyl group

Poly(vinyl acetate) (PVAc) is miscible with CO₂ over a broad range of molecular weights at 298 K. The cloud-point pressures needed to dissolve ∼5 wt% poly(methyl acrylate) (PMA) at 298 K are significantly greater than those needed to dissolve PVAc, even though a PMA repeat group has the same number of carbon, hydrogen, and oxygen atoms as in PVAc. This large difference in dissolution pressures is attributed to the lack of accessibility of the carbon dioxide to the carbonyl group in PMA. In addition, experimental data for poly(dimethyl siloxane) (PDMS) copolymers with readily accessible side groups suggest that an acetate group is slightly more CO₂-philic than an acrylate group. PVAc is more CO₂-soluble than other hydrocarbon homopolymers, including poly(propylene oxide) (PPO) and poly(lactide) (PLA). However, PVAc is significantly less miscible with CO₂ than PDMS and poly(fluoroalkyl acrylate) (PFA).     

Vibrational analysis of functionalized polyolefins/poly(vinylchloride) blends

Polyolefins functionalized with diethylmaleate were mixed with poly(vinylchloride) (PVC) in different compositions. Intermolecular interactions involving the carbonyl groups of the side chains of the functionalized polyolefins and methine hydrogens of PVC were investigated by means of infrared spectroscopy. The major flexibility of the ester groups attached to the backbone chains, with respect to polyesters, seems to increase the capability of such groups to interact with groups of more polar polymers, thus allowing prediction of easier miscibility, which however also depends on the starting polyolefin structure and function-alization degree.     

The miscibility of polyacrylates and polymethacrylates with PVC: In situ polymerization and the miscibility of poly(methyl acrylate) and poly(ethyl acrylate) with PVC

The in situ polymerization of vinyl chloride with various polyacrylates and polymethacrylates has been studied. The products were examined by dynamic mechanical analysis. Poly(methyl acrylate) and poly(ethyl acrylate) had previously produced two-phase blends with poly(vinyl chloride) (PVC) by solvent casting, but poly(ethyl acrylate) was shown to be miscible with PVC when blends were produced by in situ polymerization. Poly(methyl acrylate) and poly(octyl acrylate) were found to be immiscible with PVC whereas other polyacrylates and polymethacrylates with intermediate ester group concentrations were found to be miscible, confirming previous studies. The glass transition temperatures of the blends were measured and the deviations from the expected mean of the two base polymers were calculated as an indication of the strength of interaction between the polymers. The polymers having intermediate ester group concentrations showed the strongest interactions and the results correlated well with previously measured interaction parameters.     

Rheological characteristics of synthetic road binders

Most adhesives and binders, including binders for asphalt mixture production, are presently produced from petrochemicals through the refining of crude oil. The fact that crude oil reserves are a finite resource means that in the future it may become necessary to produce these materials from alternative and probably renewable sources. Suitable resources of this kind may include polysaccharides, plant oils and proteins. This paper deals with the synthesis of polymer binders from monomers that could in future be derived from renewable resources. These binders consist of polyethyl acrylate (PEA) of different molecular weight, polymethyl acrylate (PMA) and polybutyl acrylate (PBA), which were synthesised from ethyl acrylate, methyl acrylate and butyl acrylate, respectively, by atom transfer radical polymerization (ATRP). The fundamental rheological properties of these binders were determined by means of a dynamic shear rheometer (DSR) using a combination of temperature and frequency sweeps. The results indicate that PEA has rheological properties similar to that of 100/150 penetration grade bitumen, PMA similar rheological properties to that of 10/20 penetration grade bitumen, while PBA, due to its highly viscous nature and low complex modulus, cannot be used on its own as an asphalt binder. The synthetic binders were also combined with conventional penetration grade bitumen to produce a range of bitumen–synthetic polymer binder blends. These blends were batched by mass in the ratio of 1:1 or 3:1 and subjected to the same DSR rheological testing as the synthetic binders. The blends consisting of a softer bitumen (70/100 pen or 100/150 pen) with a hard synthetic binder (PMA) tended to be more compatible and therefore stable and produced rheological properties that combined the properties of the two components. The synthetic binders and particularly the extended bitumen samples (blends) produced rheological properties that showed similar characteristics to elastomeric SBS PMBs, although their precise viscoelastic properties were not identical.     

Compatibilizing effects of poly(styrene-graft-ethylene oxide) in blends of polystyrene and butyl acrylate polymers

The compatibilizing effect of poly(styrene-graft-ethylene oxide) in polystyrene (PS) blends with poly(n-butyl acrylate) (PBA) and poly(n-butyl acrylate-co-acrylic acid) (PBAAA) was investigated. No significant effects of the graft copolymer on the domain size were found in the PBA blends. By functionalizing PBA with acrylic acid, the average size of the polyacrylate domains was reduced considerably by the graft copolymer. Thermal and dynamic mechanical analysis of the PS/PBAAA blends revealed that the PBAAA glass transition temperature (T_g) decreased with increasing graft copolymer content. The effect of the graft copolymer in the PS/PBAAA blends can be explained by interactions across the interface due to the formation of hydrogen bonds between the poly(ethylene oxide) (PEO) side chains in the graft copolymer and the acrylic acid segments in the PBAAA phase. Hydrogen bonding was confirmed by IR analysis of binary blends of PEO and PBAAA. Partial miscibility in the PEO/PBAAA blends was indicated by a PEO melting point depression and by a T_g reduction of the PBAAA phase. The thermal properties of the PEO/PBA blends indicated only very limited miscibility. © 1996 John Wiley & Sons, Inc.     

Interpenetrating polymer networks with controllable intermolecular hydrogen bonding

Summary The effect of introducing simultaneously crosslinking and intermolecular hydrogen bonding into blends of poly(styrene) and poly(butyl acrylate) on miscibility was studied by DSC, TEM and IR. Incorporation of strong proton-donor groups into PS apparently promotes its miscibility with PBA due to hydrogen bonding. Single phase IPN can be prepared but much higher content of the proton-donor is needed in comparison with the corresponding blend without crosslinking. The interlocking structure of the networks appears unfavourable to forming real miscible IPNs.     

Phase behavior of ternary polymer blends with hydrogen bonding

Atactic poly (methyl methacrylate) (aPMMA) was found to be almost completely immiscible with poly(vinyl acetate) (PVAc). Both aPMMA and PVAc are known to be miscible with poly(vinyl phenol) (PVPh) according to literature. Adding of PVPh into immiscible aPMMA/PVAc mixtures is likely to improve their miscibility. Therefore, PVPh can be used as cosolvent to cosolubilize aPMMA and PVAc. A ternary blend consisting of aPMMA, PVAc, and PVPh was prepared and determined calorimetrically in this article. According to the calorimetry data, the ternary blend was determined to be miscible. The reason for the observed miscibility is because the interactions between PVAc and PVPh are similar to those between aPMMA and PVPh. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2797–2802, 2004     

A review of miscibility enhancement via ion-dipole interactions

It is shown that ion-dipole interactions induce considerable miscibility enhancement in blends of styrene ionomers with poly(alkylene oxides). Dynamic mechanical studies, in conjunction with transparency and brittleness of the samples, are used to evaluate miscibility. The effect is clearly thermodynamics in that phase separation can be induced in miscible samples by raising the temperature, with miscibility reestablished ons cooling. The miscibility enhancement in these systems is compared with that resulting from hydrogen bonding. In addition to the styrene/alkylene oxide system, ion-dipole interactions are found to be effective in enhancing the miscibility of many ionic polymer/polar polymer pairs. The ionomers used in this study were styrene lithium methacrylate and ethyl acrylate lithium acrylate copolymers, while polyethers, polysulfides, polyesters, polyimines, and substituted polyethylenses served as polar polymers.     

Compatibility of polyacrylates and polymethacrylates with poly(vinyl chloride): 2. Measurement of interaction parameters

Interactions of various solvents with poly(vinyl chloride) and a series of polyacrylates and polymethacrylates have been studied by inverse gas chromatography. Values of the interaction parameters χ₁₂ have been calculated and show the importance of specific interactions between the polymers and the solvents. Low values of χ₁₂ indicating a strong interaction were found for the polyacrylates and polymethacrylates with a proton donating solvent, chloroform, and for the poly(vinyl chloride) with some proton accepting solvents, especially butan-2-one. Interactions of solvents, with mixtures of poly(vinyl chloride) with some compatible polyacrylates and polymethacrylates, have also been studied. From this, and using the values of χ₁₂ found above, values of the polymer-polymer interaction parameters χ₂₃ have been calculated. Low values of χ₂₃, indicating a strong interaction were found, especially for polymethacrylates and polyacrylates with shorter ester side chains. Lower values were obtained for polymethacrylates than polyacrylates again indicating greater interactions. These results fit in well with the results of a previous paper where we found that the polymers with longer ester side chains were not compatible with PVC or phase separated on heating, and that fewer acrylates than methacrylates are compatible with PVC.     

Miscibility and lower critical solution temperature type phase behavior of poly(ethyl acrylate)/poly(vinylidene fluoride-cohexafluoro acetone) blends

Summary The miscibility of mixtures of poly(ethyl acrylate) (PEA) with poly (vinylidene fluoride-co-hexafluoro acetone) (P(VDF-HFA)) was investigated with optical microscopy and differential scanning calorimetry (DSC). In PEA/P(VDF-HFA) blends with P(VDF-HFA) content of 50 and 70(wt%), the heterogeneous phase morphology was observed on optical micrographs at 210°C. It was found that PEA/P(VDF-HFA) blends showed the lower critical solution temperature type (LCST) phase behavior. The endothermic peak for PEA / P(VDF-HFA) blend observed on DSC thermogram near 200°C corresponded to the liquid-liquid phase transition temperature as shown in the heterogeneous phase morphology with optical microscopy. It was expected that the endothermic peak is the transition temperature from miscibility to immiscibility.     

Prediction and experiment of core–shell particle morphology of vinyl acetate and butyl acrylate

In this article, the particle morphology in emulsion polymerization of the poly(vinyl acetate) (PVAc)/poly(butyl acrylate) (PBA) system is investigated. With the use of the basic data in literature, the relevant interface tensions and viscosity are estimated with the equation proposed in literature. The time achieved to equilibrium morphology is predicted with cluster dynamics proposed by Gonzalez. The experiment result is consistent with that of prediction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2930–2937, 2002; DOI 10.1002/app.10297     

Miscibility and mechanical properties of poly(styrene-co-4-vinylpyridine) and poly(butyl acrylate-co-acrylic acid) ionomer blends

The miscibility of polystyrene with poly(butyl acrylate) is very poor. Ionic interactions have been utilized recently as miscibility enhancers. In this paper, dynamic mechanical studies indicate that ion pair–ion pair interactions can be utilized to achieve miscibility in blends of polystyrene and poly(butyl acrylate). The styrenes contain 0–15mol% quaternary ammonium salt of 4-vinylpyridine, while the butyl acrylates contain 0–15mol% potassium acrylate groups. The miscibility increases with increase of ion content. When the ion content exceeds 11mol%, the polymers can be completely miscible. The mechanical properties of the ionomers and their blends were also studied. The results indicate that the tensile strength of ionomer blends is higher than that of corresponding poly(butyl acrylate-co-potassium acrylate)s (PBA-AA-K). The elongation at break of ionomer blends is higher than that of the corresponding poly(styrene-co-N-methyl-4-vinylpyridinium iodide) (PS-4VP-Q). © 1998 SCI.     

Effect of the miscibility between a silane and a sizing agent on silanol condensation

The miscibility between a hydrolyzed silane coupling agent, which had chemically nonreactive organofunctional groups such as propyl groups, and a film‐forming polymer [poly(vinyl acetate) PVAc] and its effect on silanol condensation were studied. A mixture consisting of a silane hydrolyzate and PVAc obtained from an alcoholic aqueous solution was investigated with Fourier transform infrared spectroscopy and size exclusion chromatography. Hydrogen bonding between the SiOH groups of the silane and the C?O groups of PVAc and silanol condensation affected by PVAc were examined. The hydrogen bonding and condensation reaction were influenced by the miscibility between the organofunctional group of the silane and PVAc. The miscibility of each system was estimated from the calculated Hildebrand solubility parameter of the organofunctional group. A correlation between the miscibility and the integrated absorbance of the hydrogen‐bonded C?O, obtained by least‐squares curve fitting, was established. On the basis of the molecular weight of the silane and the number of hydrogen‐bonded C?O groups, a micellelike phase was proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 589–598, 2003     

Migration resistant polymeric plasticizer for poly(vinyl chloride)

Flexible films of poly(vinyl chloride) (PVC) and linear or branched poly(butylene adipate) (PBA), synthesized from 1,4‐butanediol and adipic acid or dimethyl ester of adipic acid, were aged in an aqueous environment for 10 weeks to study how branching, molar mass, and end‐group functionality affect the leaching of polyester plasticizer from thin films. Principal component analysis was applied to reveal patterns and correlations between mechanical properties, material characteristics, and aging behavior. Introduction of branches in the polyester structure increased the miscibility between PVC and the polyester, resulting in improved mechanical properties and lower water absorption. Methyl ester end‐group in PBA polyester stabilized the polymeric plasticizer toward hydrolysis, and reduced the formation and migration of monomeric degradation products from the blends during aging in water. The combination of branched structure with methyl ester end‐groups resulted in a migration resistant polymeric plasticizer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2458–2467, 2007     

Compatibility of polyacrylates and polymethacrylates with poly(vinyl chloride): 1. Compatibility and temperature variation

Mixtures of a series of polymethacrylates and polyacrylates with PVC were prepared by solvent casting from methyl ethyl ketone. Some mixtures were also prepared by mechanical mixing and in situ polymerization (polymerization of vinyl chloride monomer in the presence of the other polymer). The mixtures were assessed for compatibility by dynamic mechanical measurements and optical clarity. It was found that all polymethacrylates from poly(methyl methacrylate) to poly(n-hexyl methacrylate) were compatible with PVC as were poly(n-propyl acrylate) and poly(n-butyl acrylate). Higher chain polyacrylates are incompatible. Poly(methyl acrylate) and poly(ethyl acrylate) appear incompatible with PVC when mixtures are prepared by solvent casting, but compatible when prepared by in situ polymerization, and mechanical mixtures show some sign of compatibility. It seems possible that in this case the solvent interferes with the compatibility. Mixtures of PVC with poly(n-hexyl methacrylate), poly(n-butyl acrylate) and poly(n-propyl acrylate) phase separate when heated in the region between 100°C and 160°C indicating the existence of a lower critical solution temperature.     

Effect of initiator on morphology in poly(vinyl acetate)/polystyrene and poly(butyl acrylate)/polystyrene composite latexes

Summary A simple method of related sensitivity range to predict thermodynamic equilibrium morphology of a core-shell latex particle (J Appl Polym Sci. 2004, 92, 3144), is recently explored. The article proposed that it is necessary to classify core-shell latex systems as sensitivity and no-sensitivity by their equilibrium morphology sensitivity to initiator and emulsifier. As for the sensitivity system, the final morphology may change by adjusting initiator and emulsifier, whereas, for the no-sensitivity system, it is hard to change its final morphology in this way. Equilibrium morphologies in system poly(vinyl acetate) (PVAc)/polystyrene (PSt) and poly(butyl acrylate) (PBA)/ PSt composite latexes particles were observed by changing initiator. Composite latexes of the two systems were synthesized by two-stage semi-continuous emulsion polymerization. The types or/and concentration of initiator changed in two stages in which the oil-soluble initiator 2,2-azobis(isobutyronitrile) (AIBN) and the water-soluble initiator potassium persulfate (KPS) were used respectively, the concentration of which was 0.5% or 2% based on the weight of monomer. The results showed that the two systems had different characteristics. At different experiment conditions designed, the same equilibrium morphologies with PSt as core and PVAc as shell were obtained in system PVAc/PSt, whereas, three different equilibrium morphologies, core-shell, inverted core-shell and hemisphere, were obtained in system PBA/PSt. The equilibrium morphology in system PVAc/PSt is no-sensitive to initiator, and the equilibrium morphology in system PBA/PSt is sensitive to initiator.