Polystyrene rheology

Because of this interaction, PVP has found appHcation in surfactant formulations, where it functions as a steric stabilizer for example to generate uniform particle-size polystyrene emulsions (110—112). In a variety of formulations, a surfactant s abiHty to emulsify is augmented by PVP s abiHty to stabilize coUoids stericaHy and to control rheology. 

The advances in polymer blending and alloying technology have occurred through three routes (1) similar-rheology polymer pairs, (2) miscible polymers such as polyphenylene oxide and polystyrene, or (3) interpenetrating polymer networks (IPNs). All these systems were limited to specific polymer combinations that have an inherent physical affinity for each other. However with... 

Antony, P., Puskas, J.E., and Kontopoulou, M. The Rheological and Mechanical Properties of Blends Based on Polystyrene-Polyisobutylene-Polystyrene Triblock Copolymer and Polystyrene. Proceedings of MODEST, International Symposium on Polymer Modification, Degradation and Stabilization, Budapest, Hungary, 2002. 

Winter, H.H. Evolution of rheology during chemical gelation. Prog. Colloid Polym. Scl,15,104—110,1987. Hempenius, M.A. et al. Melt rheology of arborescent graft polystyrenes. Macromolecules, 31, 2299, 1998. 

Hong, B. K. and Jo, W. H. (2000) Effects of molecular weight of SEBS triblock copolymer on the morphology, impact strength, and rheological property of syndiotactic polystyrene/ ethylene-propylene rubber blends. Polymer, 41, 2069-2079. 

Stabilizing agents are used to maintain drilling fluid rheological properties at highly elevated downhole temperatures. Chromium and chromium-free lignosulfonates, polyglycol ethers, sodium polystyrene sulfonate-co-maleic anhydride), and a melanin polymer have been used in this application. Additives such as sodium diethyldi-thiocarbamate have been used to stabilize aqueous polysaccharides such as xanthan gum (18). 

Rheological Studies of Aqueous Concentrated Polystyrene Latex Dispersions with Adsorbed Poly(vinyl alcohol) Layers... 

Any fundamental study of the rheology of concentrated suspensions necessitates the use of simple systems of well-defined geometry and where the surface characteristics of the particles are well established. For that purpose well-characterized polymer particles of narrow size distribution are used in aqueous or non-aqueous systems. For interpretation of the rheological results, the inter-particle pair-potential must be well-defined and theories must be available for its calculation. The simplest system to consider is that where the pair potential may be represented by a hard sphere model. This, for example, is the case for polystyrene latex dispersions in organic solvents such as benzyl alcohol or cresol, whereby electrostatic interactions are well screened (1). Concentrated dispersions in non-polar media in which the particles are stabilized by a "built-in" stabilizer layer, may also be used, since the pair-potential can be represented by a hard-sphere interaction, where the hard sphere radius is given by the particles radius plus the adsorbed layer thickness. Systems of this type have been recently studied by Croucher and coworkers. (10,11) and Strivens (12). 

In this paper we report some rheological studies of aqueous concentrated polystyrene latex dispersions, in the presence of physically adsorbed poly(vinyl alcohol). This system has been chosen in view of its relevance to many practical systems and since many of the parameters needed for interpretation of the rheological results are available (15-18). The viscoelastic properties of a 20% w/w latex dispersion were investigated as a function of polymer coverage, using creep measurements. 

B., 37, 362 (1995). The authors claimed that acetone solutions (5, 10 and 20%, specifically) of a sample that had gel permeation chromatography retention time close to that of a linear polystyrene of 1.1 x 106 molecular mass, had four decades lower viscosity than the corresponding solutions of flexible-chain linear poly(butyl methacrylate). However, in our opinion, neither the examined sample was characterized satisfactorily enough to be referred to as a dendrimer, nor the rheology was described sufficiently enough to draw any conclusions about the solution s flow behavior. Therefore, we refer to this paper here only for reasons of curiosity. 

The lack of mechanical strength for thermoplastic hyperbranched polymers makes them more suitable as additives in thermoplast applications. Hyperbranched polyphenylenes have been shown to act successfully as rheology modifiers when processing linear thermoplastics. A small amount added to polystyrene resulted in reduced melt viscosity [31]. (Sect> 3.1). 

S. Chang, T. Xie, and G. Yang, Effects of polystyrene-encapsulated magnesium hydroxide on rheological and flame-retarding properties of HIPS composites, Polym. Degrad. Stab., 91(12) 3266-3273, December 2006. 

Ballman,R.L Rademacher,L.E., Farnham,W.H. Visualization of polystyrene melt flow. Presented at 1972 August U.S.-Japan joint seminar on polymer processing and rheology, Knoxville, Tenn. See J. Appl. Polymer Symp. 20 (1973). 

Onogi,S., Masuda,T., Kitagawa,K. Rheological properties of anionic polystyrenes. 

Ashare, E. Rheological properties of monodisperse polystyrene solutions, Ph.D. Thesis, University of Wisconsin (1968). Trans. Soc. Rheol. 12,535-557 (1968). 

Mieras,H.J.M.A. Elastic or normal-stress behavior of monodisperse polystyrene melts or solutions. Paper presented at the conference Advances in Rheology, Glasgow, September 1969. 

Onogi,S., Masuda,T., Kitagawa,K. Rheological properties of anionic polystyrenes. I. Dynamic viscoelasticity of narrow-distribution polystyrenes. Macromolecules 3, 109-116 (1970). 

---