The effects of compatibility on the mechanical properties and fatigue resistance of butyl/EPDM rubber blends

In this study, compatibility of butyl/ethylene‐propylene‐diene rubbers in different ratios was investigated byviscometric technique. For evaluating polymer compatibility, the parameters Δb suggested by Krigbaum&Wall, ΔB and μ that were suggested by Chee were calculated. Data obtained from viscometric study were used for preparing new compound recipe. Mechanical and rheological properties of the new compounds were measured and the changes in the properties before and after thermal aging were determined. Replacement of ethylene‐propylene‐diene rubber with butyl rubber in appropriate ratio improved the fatigue resistance of the vulcanizates. Improvement of dynamic mechanical properties of polymer blends is expected only in the case of blending compatible polymers in appropriate ratios. The compatibility of blends in different ratios has been studied by viscometric technique and mechanical measurements and obtained very similar results. It has been concluded that viscometric determination of butyl/ethylene‐propylene‐diene rubbers compatibility could be used as a simple technique for predicting the mechanical properties of the same rubber blend that was related with solid phase compatibility. POLYM. COMPOS., 31:1869–1873, 2010. © 2010 Society of Plastics Engineers.     

Synthesis and Characterization of Biodegradable Polymer – Used as a Pour Point Depressant for Lubricating Oil

Additives based on polymers of alkyl methacrylate used in lubricant composition improve the viscometric and rheological properties of the lubricant and provide fuel economy. They are also looked upon to provide additional performance characteristics such as improved low temperature fluidity, dispersancy and thickening. However, the recent demand for eco-friendly technology guided us to incorporate the sunflower chemistry into the acrylate skeleton through the process of copolymerization in anticipation of getting an ideal blend of performance as well as eco-friendly chemistry. The present investigation comprises the homo and copolymerization of sunflower oil with different mass fraction of methyl methcrylate (MMA), decyl acrylate (DA) and styrene, characterizations and their evaluations as a pour point depressant in base oils.     

Contribution of Chain Ends and Chain Stiffness on the Solution Properties of Polysulfone

This paper is concerned with the conformational characteristics of polysulfone in dilute solutions of N,N-dimethylformamide, as evidenced by viscometric data, in order to use these results in more complicated structures with different properties and applications. The dependencies of the solution properties on the molecular weight oligomers and in higher molecular weight regions were quantitatively explained, by considering the effects of chain ends and chain stiffness, according to Yamakawa theory.     

Expansion coefficients and conformational properties of heterodisperse poly(acrylamide-co-sodium acrylate)

Calculations of expansion coefficients from light scattering and viscometric data on heterodisperse samples of poly(acrylamide-co-sodium-acrylate) satisfactorily describe the solution properties of these polymers across the entire copolymer range, from polyacrylamide to poly(sodium acrylate). Light scattering results correlate well with the viscosity data provided that corrections are made for polymer heterodispersity and that a modified Krigbaum equation is used to estimate the unperturbed dimensions of the molecules. The expansion coefficients deduced from light scattering and Flory–Fox hydrodynamic theory were inaccurate and insensitive to fluctuations in charge density and molecular weight.     

Dipolar polymeric compounds and their properties in the aqueous medium

Reactions between poly(4-vinylpyridine) and acrylic acid as well as poly(vinylimidazole) and the same acid led to polymers containing carboxybetaine repeating units with a percentage higher than 90%. Chemical structures and compositions of chemically modified polymers were established from their ¹H NMR and IR spectra. The solution properties of the two poly(carboxybetaines) were analyzed by potentiometric titrations and viscometric measurements. Deionized water as well as CaCl₂ and NaCl aqueous solutions of different concentrations were used as solvents. From potentiometric titrations with 0.5 M HCl, the apparent pK_a values were determined using Henderson–Hasselbach equation. These values are strongly depended of the solvent nature. Thus, both poly(carboxybetaines) have the lowest pK_a values when deionized water was used as solvent. Therefore, the lowest binding ability of the H⁺ by COO⁻ groups occurs in this solvent.The viscometric measurements revealed that reduced viscosity values are non-responsive towards the polymer solution concentrations irrespective of the used solvent (i.e., deionized water or NaCl and CaCl₂ aqueous solutions). Therefore, the behaviour of these carboxybetaine macromolecules in the above-mentioned solvents is that of hung up hard spheres. Consequently, the intrinsic viscosity values were calculated according to the Einstein–Simha equation applicable for such systems. The [η] versus salt solution concentration plots show a decreasing part in the concentration range from 0 to 0.05 M that is followed by a slow [η] increasing.In 0.5 M HCl both poly(carboxybetaines) exhibit the viscometric polyelectrolyte behaviours because of their shift to the corresponding cationic polyelectrolytes.     

A contribution to the UV degradation of polyurethanes

The effects of the nature of the polyols used in polyurethane (PUR) synthesis on the structural transformations after ageing by UV irradiation has been studied. The investigations were performed on PUR prepared from polyester and polyether diol oligomers. The characterization of the samples before and after ageing in view of the structural changes, which influence the course of the photooxidative degradation and photocrosslinking as well as in view of changes of mechanical properties has been done. Comparative investigations were performed by spectroscopic and viscometric measurements. The results show pronounced heterogeneity of the degradative reactions, including the existence of crosslinking processes and producing thus very inhomogeneous polymeric material. The course and the intensity of photooxidative degradation of PUR differ together with changes of mechanical properties depending whether polyester or polyether polyol have been used. The processes of photooxidative degradation is less expressed in polyesterurethane then in polyurethane based on polyether, under the same conditions of experiments. Different structures of polyester diols caused the various ageing behaviour of PUR too.     

Water-soluble copolymers: 22. Copolymers of acrylamide with 2-acrylamido-2-methylpropanedimethylammonium chloride: Aqueous solution properties of a polycation

The viscometric, turbidimetric and potentiometric properties of copolymers of acrylamide (AM) with 2-acrylamido-2-methylpropanedimethylammonium chloride (AMPDAC) were studied in aqueous solutions. The AMPDAC polymers exhibit poor salt tolerance and large, negative viscosity/temperature coefficients. Furthermore, the polymers were found to be sensitive to changes in pH. The AMPDAC polymers undergo phase separation in the presence of dianions as a function of temperature and AMPDAC composition.     

Versuche zur charakterisierung eines polystyrol-gepfropften zellstoffes

A graft copolymer of cellulose (wood-pulp) and polystyrene is made soluble by carbanilation. The dioxane-solutions are used for viscometric and UV-spectrophotometric investigations, as well as for a fractionated precipitation. The material is a genuine graft copolymer. Fractions with low limiting viscosity number carry more, but shorter branches of polystyrene than such ones with high limiting viscosity number.     

Synthesis and fluorescence in solution of polybenzimidazolylphenylenephthalamides

Six polybenzimidazolylphenylenephthalamides (PBIPPA), two meta/para isomers, and four meta/para isomers that had different distances between a benzimidazolyl and the adjacent benzimidazolyl in a polymer chain were synthesized. They were soluble in N,N‐dimethylacetamide. In addition to the fluorescence from the π → π* transition of isolated phenylbenzimidazole, a fluorescence from a chromophore complex in the grand state appeared in the fluorescence spectra, which was observed at higher concentrations. The concentration dependence of the intensity of the fluorescence was investigated in order to learn whether the chromophore complex was intermolecular or intramolecular. It was concluded that the chromophore complex is intramolecular, a conclusion supported by the viscometric results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1412–1416, 2003     

Characterization of the rheological behavior of fiber-filled polypropylene melts under steady and oscillatory shear using cone-and-plate and rotational parallel plate rheometry

Utilization of cone-and-plate and rotational parallel plate rheometry to characterize the rheological behavior of fiber-filled polymer melts at low shear rates was evaluated. The effect of flow geometry and dimensions on the viscoelastic and viscometric functions was considered. Stress growth functions were found to be dependent on the dimensions of the flow channel. However, viscometric functions were not affected by the dimensions or the geometry of the flow channel. The initial state of orientation was found to be an important factor in determining the flow found to be an important factor in determining the flow behavior. Oscillatory shear tests yielded highly strain-dependent loss and storage moduli even at very small strain amplitudes. However, the stress response was found to be sinusoidal in most cases, although the properties were strain dependent.     

Rheological properties of cement mixes: IV. Effects of superplasticizers on viscosity and yield stress

The effect of sulfonated naphthalene- and melamine-formaline condensates upon the viscometric properties of cement pastes and slurries has been investigated. Plastic viscosity and yield stress were determined from coaxial cylinder viscometer measurements. These were related to admixture type and concentration, cement type, and to the volume concentration of cement in the mix.     

Lyotropic liquid crystalline solutions of hydroxypropyl cellulose in water: Effect of salts on the turbidity and viscometric behavior

Effect of addition of salt on the viscometric behavior of the dilute or concentrated aqueous solution of hydroxypropyl cellulose (HPC) was determined by means of an Ubbelohde or a cone-plate viscometer. That effect on the turbidity of the dilute system was also determined. As salts, NaCl, LiCl, and thiourea were chosen. The turbidity and viscometric behavior for the dilute system, and the viscometric behavior for the concentrated system were greatly affected by salt type and concentration. With increasing NaCl or LiCl concentration, the cloud point decreased, [η] showed a maximum, Huggins' constant k′ showed a minimum, and the shear viscosity for concentrated isotropic solutions showed a maximum. The 45 wt % solution with no salt showed a viscometric behavior which was characteristic of lyotropic liquid crystals; however, with increasing NaCl concentration, a critical temperature at which the shear viscosity showed a maximum with respect to temperature shifted to lower temperature. This behavior was due to an increase in the turbidity, not due to a phase transformation. On the other hand, an addition of thiourea did not affect so greatly the turbidity and viscometric behavior as an addition of NaCl or LiCl did. We speculated different actions of NaCl and thiourea.     

Extensional flow of non-newtonian fluids—A review

Extensional flows have been the object of study in several laboratories in recent years. Polymeric systems have been studied in most cases because of their interesting behaviour and also because of the importance of their rheological properties to the plastics engineer. Controlled, steady elongation is more difficult to achieve in the laboratory than the more traditional viscometric flows. Moreover, it is not in general possible to predict the response of a viscoelastic material to steady extension based on knowledge of its viscometric functions. This review begins by presenting some useful expressions describing the kinematics of extensional flows. Then some results of interest from rational mechanics are presented and the behaviour predicted by a number of constitutive equations for viscoelastic fluids are discussed. After presenting the pertinent relations of linear viscoelasticity for extensional flows, experimental methods and results for steady simple extension are reviewed and some possible implications for the processing of molten polymers are discussed.     

含氨甲酸铁络合物光敏剂的聚乙烯膜光降解性能的研究

合成了以二烷基二硫代氨基甲酸为配体的一系列铁络合物光敏剂,测试了光敏剂的红外和紫外光谱。通过人工加速紫外光降解试验和自然曝露试验,测定了含光敏剂的LDPE膜的力学性能、粘均相对分子质量、红外吸收及羰基指数的变化。结果表明：加入了0．1％二异丙基氨基甲酸铁（FeDIPC)的LDPE膜的光降解效果明显优于含其它敏剂的LDPE膜。     

Complex formation of polymethacrylic acid with random copolymer of vinylpyrrolidone and vinylamine in solutions

Summary By IR-Spectroscopic, conductometric, potentiometric and viscometric methods the formation of interpolymer complexes in polymethacrylic acid-random copolymer of vinylpyrrolidone and vinylamine (VP/VAm, 88 mol.% of VP) systems in water and methanol have been shown. The properties of copolymer complexes (PMAA-VP/VAm) are compared with ones of homopolymer complexes of polymethacrylie acid-polyvinylpyrrolidone (PMAA-PVP).     

Huggins viscometric constant of semirigid and rigid-chain aromatic polyamides

The absolute values of the Huggins viscometric constant for semirigid- and rigid-chain aromatic polyamides are high, but not very high in comparison to the values for flexible-chain polymers. The Huggins viscometric constant virtually does not change with some, at least two-fold, change in the molecular weight of semirigid- and rigid-chain polyamides, which is similar to the results known for flexible-chain polymers. Either the thermodynamic rigidity of the macromolecules or the thermodynamic affinity between polymer and solvent as a function of the nature of the solvent have the predominant effect on the values of the Huggins viscometric constant in solutions of aromatic polyamides. Translated from Khimicheskie Volokna, No. 1, pp. 3–7, January–February, 1998.     

The numerical simulation of boger fluids: A viscometric approximation approach

A general-purpose finite element program has been used to simulate the flow of nonshear-thinning, highly elastic polymer solutions (Boger fluids). In particular, the creeping flow through an abrupt 4:1 circular and planar contraction is studied, as well as the flow at the exit of a capillary die for the determination of extrudate swell. Experimentally measured normal stress and viscosity data are included in a simple rheological model, based on the viscometric simplification of the CEF constitutive equation. Vortex size and intensity in the die entry and extrudate swell at the die exit increase rapidly, with elasticity level, in general agreement with experimental findings. It is shown that despite the limitations of the model, the viscometric approximation can be used to study the effect of normal stresses in cases where a main flow direction can unambiguously be defined. In die exit Flows, it can also provide an upper limit for the determination of extrudate swell, while Tanner's theory of elastic recovery provides the lower limit.     

Rheological properties of cement mixes: II. Zeta potential and preliminary viscosity studies

The effects of superplasticizing admixtures upon rheological properties of cement mixes have been investigated. Their effects upon the zeta potential generated at the interface between cement particle surfaces and the admixture-containing liquid were studied by electrophoretic and streaming potential techniques. Comparisons were made between the above results and the results of mortar flow measurements; the results of rotational viscometric measurements on slurries also revealed a strong influence of the admixtures upon the apparent viscosity. Significant correlations are made among the results of zeta potential, flow properties and adsorption isotherm measurements.     

Effect of mica addition on the properties of natural rubber and polybutadiene rubber vulcanizates

The rheometric, mechanical, and dynamic mechanical properties as well as fracture surfaces of natural rubber–mica and polybutadiene rubber–mica vulcanizates were studied. Mica was used in the range of 0–30 phr and the rheometric study was carried out at 160°C. The results indicate that the mechanical properties are improved as filler addition increases. Dynamic mechanical testing was used to analyze the observed mechanical behavior. The two elastomers showed different fracture behaviors. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2156–2162, 2003