Premium
Structure of natural rubber/emulsion butadiene rubber (NR/EBR) vulcanizates
Author(s) -
Jurkowska B.,
Olkhov Y. A.,
Jurkowski B.
Publication year - 2000
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/1097-4628(20001024)78:4<732::aid-app60>3.0.co;2-7
Subject(s) - natural rubber , glass transition , curing (chemistry) , materials science , amorphous solid , emulsion , composite material , dynamic mechanical analysis , polymer chemistry , polymer , chemical engineering , crystallography , chemistry , engineering
Diblock amorphous topological structure of a filled vulcanizate network made of natural rubber (NR) and Emulsion Butadiene Rubber (EBR) was found. These blocks differ in the transition temperatures about 200°C. Dual transitions of such rubbers have been assigned as a motion of the mixed soft block [low glass transition temperature ( T g )] in the glassy state and the motion in elements of a network around physical and chemical crosslinking sites in a rigid block (high T g ), respectively. Compaction of the topological structure of a high‐temperature block during curing (manifested by the growth of T g ) was noticed. The molecular weight distribution of the chains between the junctions of the network and shares of these amorphous blocks in the structure of the rubber network vs curing time were calculated using the methodology shown. Introduction of Perkalink 900 at constant quantity of sulfur changes a structure of the junctions in the tested rubber network from mixed (10–15% of chemical bonds, and remaining are cluster type and topological junctions) into practically all chemical bonds. Optimal curing time evaluated by the thermomechanical analysis, at which molecular structures formed in both blocks reflect the equilibrium state of adsorption layers of two rubbers introduced into the compound, is close to that evaluated by the vulcametric tests. The location of the molecular weight distribution curve in both blocks one against another depends on rubber formulation. Also, a fact that crosslinks are gathered, as was predicted by Vilgis and Heinrich calculations, was confirmed experimentally. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 732–742, 2000