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Methyl acrylic acid/zinc oxide (MAA/ZnO) was introduced to modify styrene- butadiene rubber/waste rubber powder (SBR/WRP) composites by blending. The enhanced mechanical properties and processing ability were presumably originated from improved compatibility and interfacial interaction between WRP and the SBR matrix by the in situ polymerization of zinc dimethacrylate (ZDMA). A refined interface of the modified SBR/WRP composite was observed by scanning electron microscopy. The formation of ZDMA significantly increased the ionic bond content in the vulcanizate, resulting in exceptional mechanical performance. The comprehensive mechanical properties including tensile strength, tear strength and dynamic heat-building performance reached optimum values with 16 phr MAA.

By adopting the isoconversional method, subtle changes in the curing activation energy (E?) among epoxy resin/graphite composites by the inclusion of expanded graphite (EG), ionic liquid of 1-butyl-3-methyl-imidazolium hexafluorophosphate ([BMIm]PF6) or their combination are shown in the whole conversion range. At lower concentrations (1?phr) of EG, compared with the E? of the neat epoxy resin, the composite with EG has a lower E? before the gelation, and a higher E? after the gelation. At higher concentrations of EG, however, in the whole conversion range, the composite with EG shows a higher E? compared with the neat epoxy resin. As the curing proceeded, a peculiar increase in E? is found in systems containing [BMIm]PF6. Due to the formation of hydrogen bonding between [BMIm]PF6 and the hardener (Jeffamine), the reactivity of Jeffamine is considerably decreased, leading to a much higher E? in [BMIm]PF6-containing systems, especially at higher conversion. In systems containing a combination of [BMIm]PF6 and EG, due to the interactions between EG and [BMIm]PF6, the shielding effect provided by the well-dispersed EG sheets constrains the formation of the hydrogen bonding between [BMIm]PF6 and Jeffamine, leading to lowered E? compared with that for the system containing [BMIm]PF6 only.

2,5-bis(2-benzoxazolyl) thiophene (BBT) included polypropylene (PP)/halloysite nanotubes (HNTs) composites showed substantially increased mechanical properties and this was attributed to the changed crystallinity of the PP matrix by BBT (Liu et al 2007 Nanotechnology 18 455703). This paper intends to give a detailed study on the influence of BBT hybrid fibrils on the crystallization of the PP matrix by using the observations of polarized optical microscopy (POM) and scanning electron microscopy, together with the comparisons of the activation energy of crystallization. The POM results show that PP crystals could epitaxially grow on the BBT and hybrid fibril substrates, indicating the nucleating ability of BBT. Oriented PP ribbon-like crystals with a thickness of 200 nm around BBT fibrils are observed. The formation of this unique crystal morphology is attributed to the epitaxial crystallization under the shearing orientation effect. A new transition peak well above the glass transition of PP is observed, which is attributed to the glass transition of the confined amorphous PP in the ribbon-like crystal layers around the fibrils. The fold-surface free energy of the BBT included composites is substantially decreased, suggesting facilitated crystallization in the presence of hybrid fibrils.

Many types of clay tend to absorb organics via electron transferring interactions between the clay and the organics. This may be utilized to design clay incorporated polymer composites with better interfacial properties. In the present paper, 2,5-bis(2-benzoxazolyl) thiophene (BBT), capable of donating electrons, is selected as the interfacial modifier for polypropylene (PP)/halloysite nanotube (HNTs) composites. The electron transfer between HNTs and BBT are confirmed. The mechanical properties and the unique morphology of the nanocomposites are examined. Formation of fibrils of BBT in the presence of HNTs is found in the nanocomposites. The chemical composition of the fibrils in the nanocomposites is found to be composed of largely BBT and a small amount of HNTs. The formation mechanism of BBT fibrils are elucidated to be the strong interactions between BBT and HNTs under melt shearing. The formation of the BBT fibrils leads to much higher crystallinity compared with previously reported PP nanocomposites. The nanocomposites with BBT show substantially increased tensile and flexural properties, which are attributed to the enhanced crystallinity of the nanocomposites.

A naturally occurred microtubullar silicate, halloysite nanotubes (HNTs), was co-cured with epoxy/cyanate ester resin to form organic–inorganic hybrids. The coefficient of thermal expansion (CTE) of the hybrids with low HNT concentration was found to be substantially lower than that of the plain cured resin. The moduli of the hybrids in the glassy state and rubbery state were significantly higher than those for the plain cured resin. The dispersion of HNTs in the resin matrix was very uniform as revealed by the transmission electron microscopy (TEM) results. The interfacial reactions between the HNTs and cyanate ester (CE) were revealed by the results of Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). The substantially increased properties of the hybrids were attributed to the covalent bonding between the nanotubes and the matrix.