Viscosity , Relaxation and Stability of Natural Rubber
Mooney viscosity and Mooney relaxation of unaged and oven aged SMR L natural rubber samples were studied. The viscosity was characterized by ML (1+4) 100°C and the rate of stress relaxation by the exponent a in a power law M = k (t) a . With the increasing time of oven aging at 140°C the decrease of both viscosity and stress relaxation rate exponent were observed. Aging of raw natural rubber can therefore be studied by Mooney viscosity and Mooney relaxation tests and obtained results are sensitive enough to be used for characterization of raw natural rubber stability.
Rubber Technology: Compounding and Testing for Performance
Narrow Fabric WeavingRubber TechnologyRubber TechnologyPolymer Science and TechnologyRubber Technology A Think BookRubber TechnologyScience and Technology of RubberHand Book of Rubber FormulationsCompounding Precipitated Silica in ElastomersRubber CompoundingThe Rubber FormularyKey Engineering MaterialsTire EngineeringHigh-Performance Elastomeric Materials Reinforced by NanoCarbonsRubber TechnologyRubber ProcessingRubber CompoundingThe Complete Book on Rubber Processing and Compounding Technology (with Machinery Details) 2nd Revised EditionHow to Improve Rubber CompoundsPlastics Technology Handbook, Fourth EditionBasic Rubber TestingThe Mixing of RubberEssential Rubber Formulary: Formulas for PractitionersConstitutive Models for Rubber VIIIHandbook of Thermoplastic ElastomersRubberRubber TechnologyRubber Technologist's HandbookAnticorrosive Rubber LiningRubber Products Manufacturing TechnologyThe Complete Book On Rubber Processing And Compounding TechnologyRubber as a Construction Material for Corrosion ProtectionElastomers and Rubber Compounding MaterialsScience and Technology of RubberTyre Compounding for Improved PerformanceRubber TechnologyAn Introduction to Rubber TechnologyRubber Technology and ManufactureReverse Engineering of Rubber ProductsRubber Technology
Intramolecular Contributions to Stretched-Exponential Relaxation Behavior in Polymers
Theoretical and experimental evidence for the occurrence of multiple relaxation regimes in polymers far above the glass transition temperature is presented and interpreted in terms of the Kohlrausch- Williams-Watts (KWW) stretched exponential expression. Intramolecular effects responsible for the observation of stretched exponential decay of correlation functions are discussed in relation to four different theoretical models: The kinetic Ising model of Glauber, the Shore-Zwanzig model of linear fluctuating dipoles, the Hall-Helfand model of bistable oscillators, and the dynamic rotational isomeric state model. A decrease in the KWW exponent is predicted with increasing intramolecular coupling. Chain connectivity appears as a major factor underlying the stretched exponential behavior observed in an intermediate time regime covering a time span of 2-3 orders of magnitude. In the short time limit, a single exponential decay of correlations is approached in all models. At long times, on the other hand, different KWW exponents are observed depending on the degree of intramolecular cooperativity. Results of depolarized Rayleigh scattering measurements by Tandem Fabry-Perot interferometry on poly(methylphenylsi1oxane) at high temperatures are observed to be insensitive to variations in temperature and concentration, which lends support to the notion that intramolecular interactions play a fundamental role in ascribing the apparent KWW behavior.