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properties on the coating formation, the latter interactions are the subject of more fundamental study in future.
Figure 1. Rheological properties of natural rubber suspensions with different fillers at different concentrations, relative to the unfilled natural rubber suspension (purple curve), ( a ) Kaolinite, ( b ) SMI nanoparticles, ( c ) Talc. 3.2. Microstructural Properties The effects of fillers on the microstructure of the natural rubber latex are evidenced by results of DSC analysis, as summarized in Figure 2. The pure natural rubber is characterized by a low glass transition temperature of T g = ƺ 64.53 °C and no further thermal transitions were noticed over the temperature range up to 180 °C as no specific vulcanization agents were added. The change in heat capacity NJ c p = 0.4940 J/(g°C) over the glass transition is a measure for the change in the molecular mobility in the amorphous phase during the glass transition and may indicate variations in molecular structure induced—e.g., by chain interactions or cross-linking reactions in the amorphous phase.
Figure 2. DSC results of natural rubbers with a detail on the glass transition in the presence of different types and concentrations of fillers, listing glass transition temperature T g and heat capacity change NJ c p (compositions in wt.-%). The slight but consistent variations in T g and NJ c p were noticed in the presence of fillers to different extents, depending on the filler type and concentration. A detail of the glass transition step during heating indeed shows either a shift in the temperature T g and/or a reduction in the value NJ c p in the presence of fillers. The natural rubber composites with fillers show a reduction in NJ c p , relative to the pure natural rubber, which progressively decreases further as a function of higher filler concentrations: the reduction is the highest for the SMI nanoparticles (to a final value of NJ c p = 0.3996
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