A series of novel non-crystallizable, low-Tg epoxidized polysiloxane elastomers with excellent low-temperature performance and high degradation temperature were synthesized.

A series of poly(methylvinylsiloxane) elastomer (VMQ) composites with improved oil resistance were prepared by introducing uniform polar polymer phases into VMQ matrix through the in situ reaction of reactive polar monomers—hydroxyethyl methacrylate (HEMA) and hydroxypropyl methacrylate (HPMA)—during peroxide curing. Differential scanning calorimetry and Fourier transform infrared measurements demonstrated that HEMA and HPMA had high reactivity and most of the monomers participated in the in situ reaction during peroxide curing. Transmission electron microscopic images showed that the uniform nanophases with the diameters in the range of 20–50 nm formed in the VMQ vulcanizates. The generated nanophases could interact with silica to form a strong filler network in the VMQ matrix, resulting in a significant increase of the modulus at low elongation of the VMQ vulcanizates. With increasing the content of polar monomers, the tensile strength decreased slightly, the elongation at break, the hardness and the 100% modulus increased, but the 300% modulus decreased significantly due to the decrease of the crosslink density. The incorporation of HEMA or HPMA into VMQ matrix could significantly improve the oil resistance of polysiloxane elastomer, and the oil resistance of the composites containing HEMA was a little better than that of the composites containing HPMA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40983.

The gas-barrier properties of elastomer are of particular importance, especially for airtight applications. Poly(di-isoamyl itaconate-co-isoprene) (PDII) is a newly invented and respectable biobased elastomer, but the barrier properties of PDII and its composites with carbon black and silica are not satisfying at all. Because there are abundant ester groups in PDII macromolecules and these groups can contribute to the homogeneous dispersion of layer silicates, we applied layered silicates, including montmorillonite (MMT) and rectorite (REC), into the PDII matrix to improve the air impermeability. MMT/PDII and REC/PDII composites were prepared by a cocoagulation method, and the air impermeability of the PDII elastomer was highly improved. The smallest gas permeability index reached 1.7 3 10 217 m 2 Pa 21 s 21 at an REC content of 80 phr; this implied a reduction of 85.5%. A comparison of the two types of silicate/PDII composites showed that the MMT/PDII composites had better properties at low filler contents, whereas the REC/PDII composites had better mechanical and gas-barrier properties at high filler contents. Other structures and properties of the composites were investigated by X-ray diffraction, transmission electron microscopy, and dynamic mechanical rheology. V C 2014Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40682.