Morphological evolution and mechanical property enhancement of natural rubber/polypropylene blend through compatibilization by nanoclay

Abstract

Nanocomposites of natural rubber (NR)/polypropylene (PP) (80/20 wt %) blends filled with 5 phr pristine clay were prepared by melt-mixing process. Effects of clay incorporation technique via conventional melt-mixing (CV) and masterbatch mixing (MB) methods on nanostructure and properties of the blend nanocomposites were investigated. The XRD, SAXS, WAXD, and TEM results showed that the clays in the NR/PP blend nanocomposites were presented in different states of dispersion and were locally existed at the interface between NR and PP as well as dispersed in the NR matrix. The presence of clay caused unique morphological evolution such as fine fibrillar PP domains. The tensile strength was improved over the unfilled NR/PP blends by 53% and 224%, and the storage modulus at 25 8C was increased by 78% and 120% for the NR/PP/clay nanocomposites prepared by CV and MB methods, respectively. Significant improvement in both properties was particularly obtained from the MB method due to finer dispersion fibrillar PP phase in the NR matrix and stronger interfacial adhesion between NR and PP fibers, as suggested from DMA. The oil resistance of blend nanocomposites was also improved over that of the unfilled NR/PP blend, and this property was further progressed by the masterbatch mixing method.

Assessment of compatibilization role of nanoclay in immiscible polystyrene/ethylene–octene copolymer blends via wide‐angle X‐ray scattering, microstructure, rheological analyses, and mechanical properties

“…The main factors responsible for the morphology modification observed for the blends, due to nanoclay inclusion, include: (1) a suppression of the coalescence phenomenon during the blending process, (2) an improvement of the interfacial properties of the blends, and (3) the changes in the component rheological properties. It is well known that the presence of the nanoparticles in immiscible blends could suppress the coalescence phenomenon occurring between the dispersed‐phase domains during the blending process . Of course, this is recognized for the blend nanocomposites where the nanoparticles are localized in their matrix phase and/or interface, as confirmed for both PS‐rich and EOC‐rich blend nanocomposites.…”

“…In this way, the nanoparticles between the dispersed‐phase domains act as a barrier against their coagulation during their collision under the flow field. The reduced interfacial tension in filled blends with the nanoparticles localized at interface may also suppress the coalescence and intensify the deformation and breakup phenomena of the dispersed domains under the flow stress field . The later could be more pronounced if the nanoparticles localized at the interface of the blend strengthen the interfacial interactions between the components, as deduced by the XRD (Figure ) and rheological results (Figures and ).…”

“…Data were recorded from1.5 to 10°, and the scanning rate was 1 min −1 with a step size of 0.1. The basal spacing of the organically modified layer silicate before and after intercalation was estimated from the position of the ( d 001 ) peak in the scattering patterns, according to the Bragg's law: where d is the basal spacing of the nanoclay and θ is the ( d 001 ) peak angle.…”

“…Among the various kinds of nanoparticles, the nanoclay with a high performance, easy availability, and a relatively low cost has been more applied to make the polymer nanocomposites. On the other hand, the observations obtained from the researchers' studies showed the nanoclay could act as a compatibilizer in the immiscible polymer blends . Three known mechanisms of the nanoclay compatibilization include: (1) acting the nanoclay organic surfactant miscible in the both blend components, (2) achieving the free energy profit by the solid‐melt adsorption, and (3) localizing the nanoclay in the interface of the blend.…”

“…Masa et al observed that nanoclay localization in the interface as well as the natural rubber (NR) matrix phase of NR/PP blend resulted in the formation of a fine fibrillar morphology of PP dispersed phase, reinforcement of the interfacial adhesion, and therefore a remarkable improvement of the mechanical properties. 8 Canto investigated the effects of blending sequence and residence time on the efficiency of the nanosilica as a interfacial compatibilizer of PP/poly(ethylenevinyl acetate) blend. 3 It was revealed that the nanoclay compatibilization efficiency was strongly dependent on the mixing time, and the blending sequence was less important.…”