Mechanical properties of siliceous earth/natural rubber composites

Siliceous earth (SE), which has a special morphology and structure, was selected as filler of natural rubber (NR) and mechanical properties of compounds were analyzed. Two processes were employed to prepare SE/NR compounds described as mechanical mixing method and latex method, respectively. Cure characteristics, mechanical properties of the vulcanizates prepared from the masterbatches were compared with those prepared by mechanical mixing method. X‐ray diffraction results of NR/SE vulcanizations indicated that mechanical mixing above the latex process facilitated the intercalation of NR into the galleries of SE. The results of mechanical properties show that SE has good reinforcing properties on NR both by latex or mechanical mixing process. By comparison, H samples show slightly higher crosslink density, tensile strength, 300% modulus, and lower elongation at break than M sample in same loading. But in the aspect of dynamic properties there exist obviously difference between latex and mechanical mixing process. Rubber processing analyzer (RPA) results showed that uncured M samples showed obviously higher storage modulus than that of H samples. The heat build‐up of M30 is much lower than that of H30. These behaviors indicated better dynamitic properties when the masterbatches prepared by the predispersing method was utilized. POLYM. ENG. SCI., 58:1043–1052, 2018. © 2017 Society of Plastics Engineers