engleski

Effect of Rubber Inhomogeneity on Molecular Dynamics

Rubber is known as an inhomogeneous material because of very wide molar mass distribution and its specific (inhomogeneous) gel structure. Electron spin resonance (ESR) – spin probe method is an extremely sensitive tool in studying local segmental motions in various polymer systems. This method is based on the use of free nitroxide radicals that are incorporated in a polymer matrix by diffusion. Their motion is determined by the local matrix structure and dynamics of chain segments. Analysis of composite ESR spectra of natural rubber show two types of molecular motions: fast and slow motions, attributed to the sol and gel components, respectively. Rotational correlation times calculated from ESR spectra and the ratio between fast and slow spectral components give useful information about matrix structure and its structural and dynamic inhomogeneity. This information is directly related to mechanical properties of a rubber material. Particularly, difference in the (in)homogeneity of natural rubber and its synthetic analogues will be discussed.

Natural rubber; dynamics; inhomogeneity; spin probe; ESR (EPR)

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