Poly acrylics temperature

In a study of the transition in conformation from random coil to stiff rod by poly(acrylic acid), it was found that the point of transition depended on a number of factors, including the nature of the solvent, the temperature, the particular counterion used and the degree of dissociation (Klooster, van der Trouw Mandel, 1984). 

Poly(acrylic acid) is not soluble in its monomer and in the course of the bulk polymerization of acrylic acid the polymer separates as a fine powder. The conversion curves exhibit an initial auto-acceleration followed by a long pseudo-stationary process ( 3). This behaviour is very similar to that observed earlier in the bulk polymerization of acrylonitrile. The non-ideal kinetic relationships determined experimentally in the polymerization of these two monomers are summarized in Table I. It clearly appears that the kinetic features observed in both systems are strikingly similar. In addition, the poly(acrylic acid) formed in bulk over a fairly broad range of temperatures (20 to 76°C) exhibits a high degree of syndiotacticity and can be crystallized readily (3). 

Monomer and initiator must be soluble in the liquid and the solvent must have the desired chain-transfer characteristics, boiling point (above the temperature necessary to carry out the polymerization and low enough to allow for ready removal if the polymer is recovered by solvent evaporation). The presence of the solvent assists in heat removal and control (as it also does for suspension and emulsion polymerization systems). Polymer yield per reaction volume is lower than for bulk reactions. Also, solvent recovery and removal (from the polymer) is necessary. Many free radical and ionic polymerizations are carried out utilizing solution polymerization including water-soluble polymers prepared in aqueous solution (namely poly(acrylic acid), polyacrylamide, and poly(A-vinylpyrrolidinone). Polystyrene, poly(methyl methacrylate), poly(vinyl chloride), and polybutadiene are prepared from organic solution polymerizations. 

Carbon Chain Backbone Polymers. These polymers may be represented by (4) and considered derivatives of polyethylene, where n is the degree of polymerization and R is (an alkyl group or) a functional group hydrogen (polyethylene), methyl (polypropylene), carboxyl (poly(acrylic acid)), chlorine (poly(vinyl chloride)), phenyl (polystyrene) hydroxyl (poly(vinyl alcohol)), ester (poly(vinyl acetate)), nitrile (polyacrylonitrile), vinyl (polybutadiene), etc. The functional groups and the molecular weight of the polymers, control their properties which vary in hydrophobicity, solubility characteristics, glass-transition temperature, and crystallinity. 

Fig. 19. Effect of the volume fraction of water on the temperature dependence of the shear loss modulus of poly-(acrylic add) 1 = traces ...

Recently, Muller et al. studied block and graft copolymers poly(n-butyl acrylate)-Wocfc/gra/f-poly(acrylic acid), PnBA-h/g-PAA [136]. The non-polar block/backbone has a low glass transition temperature, thus dynamic micelles were expected the ionic block/side-chains are weak anionic polyelectrolytes, thus a strong dependence of micellization on pH could be expected. The graft copolymers were synthesized by ATRP copolymerization of poly(-ferf-butyl acrylate) macromonomers with n-butyl acrylate, followed by hydrolysis of the terf-butyl acrylate side-chains to PAA [137]. The length of the PAA side chains was varied from 20 to 85 monomer units and their number from 1.5 to 10, whereas the length of the backbone was kept at ca. 130 units. 

Abbreviations y x AFM AIBN BuMA Ca DCP DMA DMS DSC EGDMA EMA EPDM FT-IR HDPE HTV IPN LDPE LLDPE MA MAA MDI MMA PA PAC PB PBT PBuMA PDMS PDMS-NH2 interfacial tension viscosity ratio atomic force microscopy 2,2 -azobis(isobutyronitrile) butyl methacrylate capillary number dicumyl peroxide dynamic mechanical analysis dynamic mechanical spectroscopy differential scanning calorimetry ethylene glycol dimethacrylate ethyl methacrylate ethylene-propylene-diene rubber Fourier transform-infra-red high density polyethylene high temperature vulcanization interpenetrating polymer network low density polyethylene linear low density polyethylene maleic anhydride methacrylic acid 4,4 -diphenylmethanediisocyanate methyl methacrylate poly( amide) poly( acrylate) poly(butadiene) poly(butylene terephtalate) poly(butyl methacrylate) poly(dimethylsiloxane) amino-terminated poly(dimethylsiloxane)... 

Graft copolymers of poloxamers and either poly(acrylic acid) or chitosan change from a sol to a gel at temperature above 37 °C. The appearing gel forms a stable matrix that can retain a drag for its sustained release. The triblock copolymer consisting of polyethylene oxide)-poly(/-lactide)-poly(ethylene oxide) (PEO-PLLA-PEO) is also temperature-sensitive but shows an opposite gellation property. At low... 

The first mention of the a(x) dependence was in experimental work [265], The dielectric relaxation data of water in mixtures of seven water-soluble polymers was presented there. It was found that in all these solutions, relaxation of water obeys the CC law, while the bulk water exhibits the well-known Debye-like pattern [270,271], Another observation was that a is dependent not only on the concentration of solute but also on the hydrophilic (or hydrophobic) properties of the polymer. The seven polymers were poly(vinylpyrrolidone) (PVP weight average molecular weight (MW) = 10,000), poly (ethylene glycol) (PEG MW = 8000), poly(ethylene imine) (PEI MW = 500,000), poly(acrylic acid) (PAA MW = 5000), poly(vinyl methyl ether) (PVME MW = 90,000), poly(allylamine) (PA1A MW = 10,000), and poly(vinyl alcohol) (PVA MW = 77,000). These polymers were mixed with different ratios (up to 50% of polymer in solution) to water and measured at a constant room temperature (25°C) [265]. 

II-6) (Table 6, entries 1 and 3). This indicates an enhanced stability, and consequently a higher state of order for the liquid crystalline phase. This is confirmed by the fact that polymers with a higher number of Z-double bonds (Table 6, entries 4 and 5) show a smectic mesophase. Smectic mesophases were also found in polymers with poly(acrylate) A, poly(methacrylate) B, poly(silox-ane) C, and poly(vinylcyclopropene) D backbones (Table 6 entries 13,15,17, 19). The isotropization temperatures of these polymers were approximately the same. 

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