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The structural development and morphology in unvulcanized and vulcanized (both pre- and postvulcanized) natural rubber latex were studied in a relaxed state and under deformation by multiple-quantum (MQ) NMR and in situ wide-angle X-ray diffraction (WAXD), respectively. Vulcanization was carried out using both sulfur and peroxide, showing important differences on the spatial distribution of cross-links according to the source of vulcanizing agents. Sulfur prevulcanization promotes the formation of highly homogeneous networks in the dispersed rubber particles, whereas peroxide vulcanization makes broader spatial cross-link distributions. The latter is compatible with the formation of core–shell network structures. Molecular orientation and strain-induced crystallization were analyzed by both stress–strain relations and WAXD. An increase in the vulcanizing agent concentration led to an increase in modulus and crystalline fractions. For sulfur vulcanization, the additional heat treatment (postvulcanization) increased the interactions between rubber particles and unreacted vulcanizing agents. For peroxide vulcanization, the additional heat treatment led to chain scission reactions and degradation of network points.

The cure of polybutadiene rubber (BR) with sulfur donor dipentamethylene thiuram tetrasulfide (DPTT) does not show reversion reaction, in contrast with similar natural rubber compounds. No polysulfure links are formed; whereas a great amount of À ÀCÀ ÀCÀ À crosslinks are produced. The addition of tetramethyl thiuram monosulfidic (TMTM) strongly affects the crosslinking process. Mechanical properties of the cured compounds are poor. In DPTT, curing of BR the radical species produced through homolitic cleavage of DPTT molecule seems to have sufficient energy to produce crosslinking, via allylic abstraction, and also initiate the polymerization of double bonds producing areas of high crosslinking density that induce early material failure.

The natural rubber (NR) latex consists of polymer particles charged negatively due to the adsorbed phospholipids and proteins molecules. The addition of stable aqueous suspension of thermally reduced graphite oxide (TRGO) stabilized by ionic surfactants to NR latex can favor the occurrence of interaction between the stabilized TRGO and NR particles. Herein, the use of two surfactants of different nature, namely, sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB), for the preparation of (TRGO)/NR nanocomposites, is reported. Zeta potential and particle size measurements indicated that the use of DTAB as cationic surfactant results in the flocculation of NR particles and promoted the formation of ion-pair interactions between TRGO and the proteins and/or phospholipids present on the NR surface. This indicates that the use of DTAB can promote a self-assembly phenomenon between TRGO with adsorbed DTAB molecules and NR particles. The occurrence of self-assembly phenomenon allows obtaining homogenous dispersion of TRGO particles in the polymer matrix. The TRGO/NR nanocomposites prepared by the use of DTAB exhibited superior mechanical properties and excellent electrical conductivities reaching values of stress at 500% strain of 3.02 MPa and 10−4 S/cm, respectively.