Parameterization of silica-filled silicone rubber morphology: A contrast variation SANS and TEM study

Size characterization of nanomaterials in environmental and biological matrices through non-electron microscopic techniques

Engineered nanomaterials (ENs) can enter the environment, and accumulate in food chains, thereby causing environmental and health problems. Size characterization of ENs is critical for further evaluating the interactions among ENs in biological and ecological systems. Although electron microscope is a powerful tool in obtaining the size information, it has limitations when studying nanomaterials in complex matrices. In this review, we summarized non-electron microscope-based techniques, including chromatography-based, mass spectrometry-based, synchrotron radiation- and neutron-based techniques for detecting the size of ENs in environmental and biological matrices. The advantages and disadvantages of these techniques were highlighted. The perspectives on size characterization of ENs in complex matrices were also presented.

Decoupling the Contributions of ZnO and Silica in the Characterization of Industrially-Mixed Filled Rubbers by Combining Small Angle Neutron and X-Ray Scattering

Scattering techniques with neutrons and X-rays are powerful methods for the investigation of the hierarchical structure of reinforcing fillers in rubber matrices. However, when using only X-ray scattering, the independent determination of the filler response itself sometimes remains an issue because of a strong parasitic contribution of the ZnO catalyst and activator in the vulcanization process. Microscopic characterization of filler-rubber mixtures even with only catalytic amounts of ZnO is, therefore, inevitably complex. Here, we present a study of silica aggregates dispersed in an SBR rubber in the presence of the catalyst and show that accurate partial structure factors of both components can be determined separately from the combination of the two scattering probes, neutrons, and X-rays. A unique separation of the silica filler scattering function devoid of parasitic catalyst scattering becomes possible. From the combined analysis, the catalyst contribution is determined as well and results to be prominent in the correction scheme. The experimental nano-structure of the ZnO after the mixing process as the by-product of the scattering decomposition was found also to be affected by the presence or absence of silica in the rubber mixture, correlated with the shear forces in the mixing and milling processes during sample preparation. The presented method is well suited for studies of novel dual filler systems.

Cyclic tensile machine with wide speed range for in situ neutron/X-ray scattering study on elastomers

A tensile machine is designed for in situ scattering investigation of elastomers in the cyclic tensile process. The specimen is stretched by two linearly moving clamps in the opposite direction; thus, the center of the specimen is kept stationary during the tensile test. With this configuration, either X-ray scattering or neutron scattering can be carried out easily. A high speed direct current motor is used to drive the machine, providing a wide tensile speed range from 1.28 × 10^-3 mm/s to 102.4 mm/s. Cyclic tension is achieved by program controlled motor rotation, and the engineering stress-strain curve can be saved automatically in each cycle. Moreover, an independent displacement sensor is used to check the possible accumulative error of position during cyclic tension. The orientation change of multiwall carbon nanotube filled silicon rubber is investigated by small angle neutron scattering to test the machine, which shows that the machine is capable of combining the cyclic tensile test with in situ scattering measurement.

Three-dimensional direct visualization of silica dispersion in polymer-based composites

We present a novel strategy for realizing the three-dimensional direct visualization of silica dispersion by the fluorescence modification of a silica filler.

Study on the preparation and performance of low gas permeability trifluoropropyl phenyl silicone rubber

Low gas permeability coating can prevent oxygen and sulphur vapour from permeating into silicone rubber and protect electronic components, chips, electrodes, medicines, etc. from oxidation and sulfuration.