Natural rubber high molecular weight chain

In any use the addition of 2.5 parts of casein on 100 of reclaim would be expected to improve the compound. A road repair compound is illustrated in Formulation XXVIII. This rubber is conveniently added to the heated asphalt in the form of powdered rubber. Control of the heating process is very important, as overheating degrades the rubber. High molecular weight is essential in the long-chain polymer component, and hence new natural rubber of good quality rather than reclaimed rubber is desirable. 

The high molecular weight and the polymer chain entanglements make the dissolution of natural rubber in solvents difficult. Masticated natural rubber... 

Interdiffusion between a pair of polymers is a demonstration of their thermodynamic miscibility. The adhesion between contacted rubber sheets parallels the extent of any interdiffusion of the polymer chains (Roland and Bohm, 1985). If the contacted sheets are comprised of immiscible rubbers, no interdiffusion occurs. Natural rubber (NR) and 1,2-polybutadiene (1,2-BR) are miscible even at high molecular weights (Roland, 1988a Roland, 1987). When NR is brought into contact with 1,2-BR, they interdiffuse spontaneously. When some form of scattering contrast exists between the materials, interdiffusion will enhance the scattering intensity (either X-ray or neutron) measured from the plied sheets. A variety of spectroscopic methods (Klein, 1981 ... 

The essential concept involved in the statistical theory of rubber elasticity is that a macroscopic deformation of the whole sample leads to a microscopic deformation of individual polymer chains. The microscopic model of an ideal rubber consists of a three-dimensional network with junction points of known functionality greater than 2. An ideal rubber consists of fully covalent junctions between polymer chains. At short times, high-molecular-weight polymer liquids behave like rubber, but the length of the chains needed to describe the observed elastic behavior is independent of molecular weight and is much shorter than the whole chain. The concept of intrinsic entanglements in uncrosslinked polymer liquids is now well established, but the nature of these restrictions to flow is still unresolved. The following discussion focuses on ideal covalent networks. 

Clay reinforcement has already been used in various polymer systems including polyamide, polypropylene, polystyrene and polycarbonate. However, the major challenges in using clay reinforcement in natural rubber are its nonpolar nature, the conventional processing methods used, such as a two-roll mill, and the high molecular weight of natural rubber polymeric chains. 

Once the macromolecular hypothesis of Staudinger was accepted, a basic understanding of the molecular structure was possible. Before cross-linking, rubber (natural rubber in those days) consists of linear chains of high molecular weight. With no molecular bonds between the chains, the polymer may... 

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