Reinforcing Behaviors of Sulfur-Containing Silane Coupling Agent in Natural Rubber-Based Magnetorheological Elastomers with Various Vulcanization Systems

Effects of Petroleum-Based Oils as Dispersing Aids on Physicochemical Characteristics of Magnetorheological Elastomers

This paper investigated the effects of petroleum-based oils (PBOs) as a dispersing aid on the physicochemical characteristics of natural rubber (NR)-based magnetorheological elastomers (MREs). The addition of PBOs was expected to overcome the low performance of magnetorheological (MR) elastomers due to their inhomogeneous dispersion and the mobility of magnetic particles within the elastomer matrix. The NR-based MREs were firstly fabricated by mixing the NR compounds homogeneously with different ratios of naphthenic oil (NO), light mineral oil (LMO), and paraffin oil (PO) to aromatic oil (AO), with weight percentage ratios of 100:0, 70:30, 50:50, and 30:70, respectively. From the obtained results, the ratios of NO mixed with low amounts of AO improved the material physicochemical characteristics, such as thermal properties. Meanwhile, LMO mixed the AO led to the best results for curing characteristics, microstructure observation, and magnetic properties of the MREs. We found that the LMO mixed with a high content of AO could provide good compatibility between the rubber molecular and magnetic particles due to similar chemical structures, which apparently enhance the physicochemical characteristics of MREs. In conclusion, the 30:70 ratio of LMO:AO is considered the preferable dispersing aid for MREs due to structural compounds present in the oil that enhance the physicochemical characteristics of the NR-based MREs.

Interactions between Different Organosilicons and Archaeological Waterlogged Wood Evaluated by Infrared Spectroscopy

The goal of the study was to characterise chemical interactions between waterlogged archaeological wood and organosilicon compounds applied for its conservation to shed lights on the mechanism of wood dimensional stabilisation by the chemicals. Two alkoxysilanes (methyltrimethoxysilane and (3-mercaptopropyl) trimethoxysilane) and a siloxane (1,3-bis(diethylamino)-3-propoxypropanol)-1,1,3,3-tetramethyldisiloxane) were selected for the research since they already have been proven to effectively stabilise waterlogged wood upon drying. Fourier transform infrared spectroscopy was used for structural characterisation of the degraded wood and evaluation of reactivity of the applied chemicals with polymers in the wooden cell wall. The results obtained clearly show much stronger interactions in the case of alkoxysilanes than the siloxane, suggesting a different mechanism of wood stabilisation by these compounds. The results of this study together with other data obtained in our previous research on stabilisation of waterlogged archaeological wood with organosilicon compounds allow the conclusion that the mechanism of waterlogged wood stabilisation by the used alkoxysilanes is based on bulking the cell wall by silane molecules and wood chemical modification, while in the case of the applied siloxane, it builds upon filling the cell lumina.