Polystyrene weight, effect

Molecular weight effects are illustrated in Figs. 1 and 2, showing the increasing DR effectiveness of higher-MW polystyrene samples at all concentrations regardless of solvent type. ... 

Gupta RK, Nguyen DA, Sridhar T (1991) Extensional viscosity of dilute polystyrene solutions effect of concentration and molecular weight. Phys Fluid 12 1296-1318... 

Casper, C.L., Stephens, J.S., Tassi, N.G., Chase, D.B. and Rabolt, J.F. 2004. Controlling surface morphology of electrospun polystyrene fibers Effect of humidity and molecular weight in the electro spinning process. Macromolecules 37 573-578. 

Tanaka et al. used NPLC and RPLC to determine CCD of PMMA- -PS with different compositions and conversions synthesized from the copolymerization of methyl methacrylate and co-p-vinylbenzyl polystyrene macro monomer [ 158]. The good agreement between CCD obtained by both HPLC modes showed that the molecular weight effect on the CCD is negligible. As the macromonomer content increases, the CCD becomes sharper. These results are in accordance with the theoretical predictions. As the conversion increases at the same feed composition, the CCD becomes broader towards the low macromonomer content side, which is in contrast to the CCD of the samples obtained previously from oo-methacryloyl polystyrene macro monomer [159]. They also showed that the CCD is broadened as the graft length increases, in copolymer samples with a similar composition, in accordance with the theoretical prediction [159]. 

Jones DM, Walters K, WilUams PR (1987) The Extensional Viscosity of Mobile Polymer Solutions. Rheol Acta 26 20-30 McKineley GH, Sridhar T (2002) Filament-Stretching Rheome-try of Complex Huids. Annu Rev Huid Mech 34 375-415 Li L, Larson RG, Sridhar T (2000) Brownian Dynamics Simulation of Dilute Polystyrene Solutions. J Rheol 4 291-322 Gupta RK, Nguyen DA, Sridhar T (1991) Extensional Viscosity of Dilute Polystyrene Solutions Effect of Concentration and Molecular Weight. Phys Huid 12 1296-1318... 

Casper, C. L., J. S. Stephens, N. G. Tassi, D. B. Chase, and J. F. Rabolt (2004). Controlling surface morphology of electrospun polystyrene fibers effect of humidity and molecular weight in the electrospinning process. Macromolecules 37(2) 573-578. 

Zhao, B., Haasch, R. T., Maclaren, S. (2004). Solvent-induced self-assembly of mixed poly(methyl methacrylate)/polystyrene brushes on planar silica Substrates molecular weight effect. Journal of the American Chemical Society, 126, 6124-6134. 

Schellenberg, J. Melting properties of syndiotactic polystyrenes and effect of hydrogen on molecular weight distribution. Macrom. Mat. Eng., 290, 675-680 (2005). 

Fig, 13 - Comparison of the observed and calculated matrix molecular weight effect on the orientation of an anthracene-labelled polystyrene chain. The full curves represent the calculated behaviour... 

A method for the polymerization of polysulfones in nondipolar aprotic solvents has been developed and reported (9,10). The method reUes on phase-transfer catalysis. Polysulfone is made in chlorobenzene as solvent with (2.2.2)cryptand as catalyst (9). Less reactive crown ethers require dichlorobenzene as solvent (10). High molecular weight polyphenylsulfone can also be made by this route in dichlorobenzene however, only low molecular weight PES is achievable by this method. Cross-linked polystyrene-bound (2.2.2)cryptand is found to be effective in these polymerizations which allow simple recovery and reuse of the catalyst. 

It should be noted that polystyrene with a number average molecular weight of 50000 has a Tg only about 2°C less than would be expected of a polystyrene of infinitely high molecular weight. Hence increasing the molecular weight beyond this point in order to raise the Tg would not be very effective and at the same time it would lead to large increases in melt viscosity. 

Optical properties of the blends are somewhat dependent on the molecular weight of the polystyrene, presence of additives such as lubricant in the polystyrene, ratio of polystyrene to SBS, processing conditions and mixing effectiveness of the extruder. It is stated that the optical properties of the sheets are similar whether linear or radial type stereoblock polymers are used. 

The main experimental techniques used to study the failure processes at the scale of a chain have involved the use of deuterated polymers, particularly copolymers, at the interface and the measurement of the amounts of the deuterated copolymers at each of the fracture surfaces. The presence and quantity of the deuterated copolymer has typically been measured using forward recoil ion scattering (FRES) or secondary ion mass spectroscopy (SIMS). The technique was originally used in a study of the effects of placing polystyrene-polymethyl methacrylate (PS-PMMA) block copolymers of total molecular weight of 200,000 Da at an interface between polyphenylene ether (PPE or PPO) and PMMA copolymers [1]. The PS block is miscible in the PPE. The use of copolymers where just the PS block was deuterated and copolymers where just the PMMA block was deuterated showed that, when the interface was fractured, the copolymer molecules all broke close to their junction points The basic idea of this technique is shown in Fig, I. 

Class and Chu demonstrated that if a tackifier is chosen that is largely incompatible with the elastomer, a modulus increase due to the filler effect is observed and little change in Ta results, and once again a PSA would not be obtained. This was observed for mixtures of low molecular weight polystyrene resin and natural rubber. The same polystyrene resin did tackify SBR, a more polar elastomer that is compatible with the resin. Hydrogenating the polystyrene to the cycloaliphatic polyvinylcyclohexane changed the resin to one now compatible with the less polar natural rubber and no longer compatible with SBR. These authors also provide... 

Another serious effect occurs with liquids which are not in themselves solvents but which may wet the polymer surfaces. These facilitate relief of frozen-in stresses by surface cracking which can be a severe problem in using many injection and blow mouldings with specific chemicals. Examples of this are white spirit with polystyrene, carbon tetrachloride with polycarbonates and soaps and silicone oils with low molecular weight polyethylenes. 

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