Effectiveness of copolymers

The effect of copolymer composition on gas permeability is shown in Table 9. The inherent barrier in VDC copolymers can best be exploited by using films containing Htde or no plasticizers and as much VDC as possible. However, the permeabiUty of even completely amorphous copolymers, for example, 60% VDC—40% AN or 50% VDC—50% VC, is low compared to that of other polymers. The primary reason is that diffusion coefficients of molecules in VDC copolymers are very low. This factor, together with the low solubiUty of many gases in VDC copolymers and the high crystallinity, results in very low permeabiUty. PermeabiUty is affected by the kind and amounts of comonomer as well as crystallinity. A change from PVDC to 50 wt °/ VC or 40 wt % AN increases permeabiUty 10-fold, but has Httle effect on the solubiUty coefficient. 

Synthesis and mechanical and morphological characterization of (AB)n, ABA and BAB type copolymers of m-phenylene-isophthalamide and polydimethylsiloxane have been reported241 242>. The effect of copolymer type, chemical composition and segment molecular weights on phase separation and the solution behavior of these systems have also been discussed. 

Deschamps AA, Grijpma DW, and Feijen J. Poly(ethylene oxide)/poly(butylenes terephthalate) segmented block copolymers The effect of copolymer composition on physical properties and degradation behavior. Polymer, 2001, 42, 9335-9345. 

TABLE VI. EFFECTIVENESS OF COPOLYMERS AS MINERAL FINES STABILIZERS... 

Bhatt, G. M. and Filke, L., Effect of copolymer content on tackiness of PET chips during SSP, presentation given at the Polyester 2000 5th World-Congress-The Polyester Chain, Zurich, Switzerland, 28 November-1 December, 2000. 

Zhang, L., Ma, C. and Mukerjee, S. 2005. Effect of copolymer composition on the oxygen transport properties of sulfonated poly(arylene ether sulfone) and sulfonated poly(sulfide sulfone) PEMs. Journal of the Electrochemical Society 152 A1208-A1216. 

M. Fowler, J. Barlow, and D. Paul, Effect of copolymer composition on the miscibility of blends of styrene-acrylonitrile copolymers with poly (methyl methacrylate), Polymer, 28(7) 1177-1184, June 1987. 

The effect of copolymer sequence on coil-to-globule transition was also studied using Langevin molecular dynamics [103]. The method for estimation of the quality of reconstruction of core-shell globular structure after chain collapse was proposed. It was found that protein-like sequences exhibit better reconstruction of initial globular structure after the cooling procedure, as compared to purely random sequences. 

Hill, A.J., Winhold, S Stack, G.M., Tant, M.R. (1996) Effect of copolymer composition on free volume and gas permeability in polyethylene terephthalate) -poly(l,4 cyclohexylenedimethylene terephthalate) copolymers . Eur. Polym. J. 32(7), 843. 

Fig. 34 Colour effects of copolymer P23 at pH 1 (no shift) and at pH 10 (bathochromic shift)...

Fig. 16.7 Summary of the in-vitro release of lysozyme from a series of biodegradable copolymers. (a) Effect of copolymer block lengths (all 30% (w/v)) (b) Effect of polymer concentration (all for copolymer 4)...

If there are more than two components in a mixture (as in a blend of a homopolymer with a copolymer), binary interaction parameters can be combined into a composite % parameter to describe the overall behavior of the system. For example, Choi and Jo [11] showed how the effects of copolymer sequence distribution in blends of polyethylene oxide) with poly(styrene-co-acrylic acid) can be described by an atomistic simulation approach to estimate the binary intermolecular interaction energies which are combined into a total interaction parameter for the blend. Their paper [11] also provides a list of the many preceding publications attempting to address the effects of copolymer composition, tacticity, and copolymer sequence distribution on polymer blend miscibility. In addition to the advances in computational hardware and software which have made atomistic simulations much faster and hence more accessible, work in recent years has significantly improved the accuracy of the force fields [12] used in such simulations. 

Lyatskaya Y, Gersappe D, Balazs AC. Effect of copolymer architecture on the efficiency of compatibilizers. Macromolecules 1995 28 6278-6283. 

Figure 3. Effect of copolymer composition on chain scissioning yield, G(s).

Meilchen, M. A., B. M. Hasch, and M. A. McHugh. 1991. Effect of copolymer composition on the phase behavior of mixtures of poly(ethylene-co-methyl acrylate) with propane and chlorodifluoromethane. Macromolecules 24 4874-4882. 

D. Freilich and G.B. Tanny, Hydrodynamic and microporous support pore size effects on the properties and structure of dynamically formed hydrous Zr(IV)-polyacrylate membranes, Desalination, 1978, 27, 233-251 A.J. van Reenen and R.D. Sanderson, Dynamically formed hydrous zirconium(IV) oxide-polyelectrolyte membranes, VI. Effect of copolymer composition on the stability of poly(acrylic acid - covinyl acetate) and poly(acrylic acid - covinyl alcohol) membranes, Desalination, 1989, 72, 329-338. 

Emulsifying Effect of Copolymers in the Solid State. The next step was to ascertain if the findings for two nonmiscible liquids are applicable to two incompatible polymers such as PS and PI, and if a block copolymer also functions as an emulsifier. 

The morphology of commercial blends usually is far from equilibrium. Preparation of the alloys must take thermodynamic and kinetic parameters into account if the desired effects are to be achieved. The effects of copolymer addition of the dispersion size and blend performance have been studied [Hobbs et al., 1983 Fayt et al., 1986 Armat and Moet, 1993]. 

Figure 4. Effect of copolymer to rhodium molar ratio for the hydrogenation of 1-octene at 70°C and 172 bar.

Figure 7. Effect of copolymer composition in the hydrogenation ofl octene at 70 C and 172 bar. (0) RhCl(TAN2oDPPA) (a) RhCKTANisDPPA) (o ) RhCKTANjDPPA)...

Un-cross-linked semicrystalline poly vinyl alcohol) hydrogels were prepared by solvolysis of the corresponding vinyl trifluoroacetate polymers and copolymers. The relationships between polymer crystallinity, hydrogel structure, and mechanical properties in the subject hydrogels were examined. Evidence was presented that comonomers acted to disrupt crystal structure and increase water content. The effects of copolymer structure on surface characteristics important to biomedical applications were examined, and the importance of hydrogel nonionic character was demonstrated through protein binding studies. 

Effects of Copolymer Composition. Figure 3 illustrates the effect of changes in Cg hydrophobe composition on the apparent viscosity versus... 

Figure 3. Effect of copolymer concentration on the apparent viscosity of copolymers of acrylamide with octylacrylamide in 0,342 M NaCl at 25 °C and a shear rate of 1.28 s. ...

The effect of copolymer composition on the rate of the hydroquinone oxidation reaction has been studied using IVI-AA copolymers. Curves of the change of the oxidized hydroquinone concentration as a function of reaction time in the presence of polyampholyte-copper(II) complexes are presented in Fig. 10. An increase in the amount of basic groups in the copolymers leads to an increase in the rate of hydroquinone oxidation. Copolymers in which maleic and methacrylic acids are used as a second comonomer of IVI, exhibit lower activity than IVI-AA. 

Qiao M, Chen D, Ma X, Liu Y. Injectable biodegradable temperature-responsive PLGA PEG-PLGA copolymers Synthesis and effect of copolymer composition on the drug release from the copolymer-based hydrogels. Int J Pharm 2005 294 103 112. 

---