Sulfur-Cured Natural Rubber Elastomer Networks: Correlating Cross-Link Density, Chain Orientation, and Mechanical Response by Combined Techniques

Abstract

We present a combination of independent techniques in order to characterize vulcanized natural rubber elastomer networks. We combine solid state proton multiplequantum NMR, equilibrium swelling, mechanical experiments, and in-situ tensile X-ray scattering measurements, all of them giving access to the segmental orientation effects in relation to the cross-linking of the systems. By means of the combination of these techniques, we investigate a set of unfilled natural rubber networks with different levels of cross-linking. The relevance of this work is the application of this approach in order to study the reinforcement effect in filled elastomers with nanoparticles in a following work.

Epoxy resin curing reaction studied by proton multiple-quantum NMR

“…Nevertheless, due to its selectivity, double-quantum (DQ) or more generally multiple-quantum (MQ) NMR is nowadays considered as the most precise and effective experimental approach for the quantification of weak RDCs of soft polymers, 8 and thus one of the most powerful and successful tools for the quantitative characterization of dynamics in polymer melts, [17][18][19] the gel point, 20 vulcanization kinetics, 21 and the complete and quantitative characterization of polymer network structures. [22][23][24][25] In those studies, MQ experiments are based upon the lengthy but quite robust Baum-Pines (B-P) sequence 8,26,27 (shown in Fig. 1), which shows ideal performance for studying soft (weaker dipolar-coupled) polymers systems such as elastomers [23][24][25]28,29 and gels.…”

“…[22][23][24][25] In those studies, MQ experiments are based upon the lengthy but quite robust Baum-Pines (B-P) sequence 8,26,27 (shown in Fig. 1), which shows ideal performance for studying soft (weaker dipolar-coupled) polymers systems such as elastomers [23][24][25]28,29 and gels. 22,30 Nevertheless, the use of B-P sequence is limited for characterizing high dipolar coupled polymers (epoxy resins would belong to this type of samples), as it was recently demonstrated in the study of ionic elastomers.…”

Effect of entanglements in the microstructure of cured NR/SBR blends prepared by solution and mixing in a two-roll mill

“…The subsequent analysis of I nDQ by using a numerical inversion procedure based on a modified Fast Tikhonov Regularization [31], has been used to obtain a quantitative picture of the actual distribution function of residual couplings. Regularization procedure and data analysis for NR and SBR samples were widely explained in a cursory way elsewhere [16][17][18][19]21,31].…”

Stepwise cure and properties of silicone resin for high‐ultraviolet‐transmission optical elements

“…18 According to the Flory-Rehner theory, 19 the crosslinking density (m e ) of the cured sample was estimated by the following equation:…”

“…where q is the density of the (un-swollen) sample (1.115 g/ cm 3 ), M c (g/mol) the average molecular weight between crosslinking points, u the volume fraction of silicone resin in the swollen sample, v (here 0.465) 18 the Flory-Huggins interaction parameter between the solvent and the sample, and V 0 the molar volume of toluene (1.0654 3 10 21 L/mol). The u in eq.…”