New thermoset systems based on disulfide bonds were synthesized with self-healing capabilities. The self-healing mechanism is not related to disulfide–disulfide exchange reactions, but to thiol–disulfide exchange reactions that are pH-dependent. Stress relaxation experiments showed large relaxation for systems having PTM2 as a curing agent, which indicates that the system can rearrange its molecular structure as a mechanism to release stress. However, relaxation rates decreased for samples tested longer after production. This indicates the disappearance of thiol-groups probably caused by thiol–thiol oxidation.

The melt viscosity of poly(propylene) is found to reduce dramatically through the addition of a minute amount of silica nanoparticles. We attribute this unique effect to “selective adsorption of high molar mass polymer chains” on the surface of the nanofillers. This represents a paradigm shift regarding commonly accepted relations between the molar mass and viscosity of molten polymers. This strong viscosity decrease provides major advantages for polymer processing, and materials with improved properties are obtained.

The influence of the number-averaged rubber particle size (d_n) on the mechanical and rheological properties of thermoplastic/cross-linked elastomer blends was studied, with the focus on thermoplastic vulcanizates (TPVs) based on poly(propylene) (PP) and ethylene-propylene-diene (EPDM) rubber. Time-resolved small-angle X-ray scattering measurements revealed that the criteria to obtain tough behavior are very different for TPVs than for traditional rubber-toughened thermoplastics, since the deformation mechanism of TPVs under tensile conditions is dominated by yielding of the semi-crystalline, thermoplastic matrix without the occurrence of matrix crazing and internal rubber cavitation. The formation of interlamellar voids, as occurs in the unfilled thermoplastic during deformation, is more effectively suppressed with decreasing d_n, which leads to a significant enhancement of the ultimate tensile properties. Additionally, the decrease in d_n leads to an enhanced elastic recovery, but also increases the melt viscosity. These results demonstrate that d_n is an important parameter to control the balance between the mechanical properties and the melt processability of blends based on thermoplastics and cross-linked elastomers.