Effect of different types of peroxides on rheological, mechanical, and morphological properties of thermoplastic vulcanizates based on natural rubber/polypropylene blends

Influences of various types and concentrations of peroxides on the properties of thermoplastic vulcanizates based on natural rubber/polypropylene (PP) blends were investigated. The objective was to find a proper balance between the influences of degree of crosslinking of the rubber and degradation of the PP phase on the rheological, mechanical, and morphological properties. The typical crosslinking temperature and crosslink efficiency and also relative amounts of decomposition products of each peroxide play an important role in the properties of the TPVs. In this work, the TPVs prepared with DCP or DTBPIB give a superior overall balance of properties relative to the TPVs crosslinked with DTBPH or DTBPHY

Potent Application of Scrap from the Modified Natural Rubber Production as Oil Absorbent

The production of raw natural rubber always ends up with leftover latex. This latex is later collected to produce low grades of rubber. The collection of this latex also depends on the latex’s quality. However, reproducing the latex may not be applicable if the latex contains many specks of dirt which will eventually be discarded. In this work, an alternative solution was to utilize such rubber in a processable form. This scrap rubber (SR) from the production of natural rubber grafted with polymethyl methacrylate (NR-g-PMMA) production was recovered to prepare an oil-swellable rubber. The rubber blends were turned into cellular structures to increase the oil swellability. To find the suitable formulation and cellular structure of the foam, the foams were prepared by blending SR with virgin natural rubber (NR) at various ratios, namely 0/100, 20/80, 30/70, 50/50, 70/30, 80/20, and 100/0 (phr/phr). The foam formation strongly depended on the SR, as it prevented gas penetration throughout the matrix. Consequently, small cells and thick cell walls were observed. This structure reduced the oil swellability from 7.09 g/g to 5.02 g/g. However, it is interesting to highlight that the thermal stability of the foam increased over the addition of SR, which is likely due to the higher thermal stability of the NR-g-PMMA waste or SR. In summary, the blending NR with 30 phr of SR provided good oil swellability, processability, and morphology, which benefit oil recovery application. The results obtained from this study will be used for further experiments on the enhancement of oil absorbency by applying other key factors. This work is considered a good initiative for preparing the oil-absorbent material based on scrap from modified natural rubber production

Effect of Ground Tyre Rubber Devulcanisates on the Properties of a Passenger Car Tyre Tread Formulation

Extensive research on recycling processes, in particular for waste tyre material, is necessary due to increasing raw material costs, diminishing resources and growing awareness of environmental issues. One of the preferred methods is devulcanisation, in which only sulphur cross-links are broken, while the polymer chains remain intact. In this study, optimised processing conditions for the devulcanisation of whole passenger car tyres using diphenyldisulphide (DPDS) as a devulcanisation aid were applied. The devulcanised ground tyre rubber (D-GTR) obtained from the process was blended on top of the original tyre tread formulation at different concentrations. The cure characteristics and mechanical properties of the re-vulcanised blends are evaluated in comparison to the original compound. The results so far indicate that the addition of D-GTR influences the properties of the blend, but to a lesser extent than the commercially used powder or reclaim types do, for which loadings less than 5% can be applied. The main reason for the influence of D-GTR on the rubber properties is inhomogeneities in the D-GTR/virgin rubber blen