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Tuning of the crosslink density (CLD) in the rubber compounds is very crucial for optimizing the physical and mechanical properties of the ultimate rubber products. Conventionally, CLD can be measured via rheological methods such as moving die rheometer (MDR), via mechanical tests such as temperature scanning stress relaxation analysis (TSSR), or via direct swelling experiments using Flory–Rehner approach. In the current study, two novel techniques, focused ion beam - scanning electron microscopy (FIB-SEM) processing, with simultaneous energy dispersive X-ray spectrometry (EDS) mapping analysis and scanning acoustic microscopy (SAM) were combined and correlated to conventional methods on a model recipe of ethylene propylene diene monomer (EPDM) compound having different sulphur contents. Depending on the applied technique, the increase in the crosslink density with sulphur content was found to be 1.7 fold for the Flory–Rehner approach and 1.2 fold for both TSSR and MDR. It is directly monitored from the FIB-SEM-EDS analysis that the sulphur distribution and agglomeration behavior increased in line with ZnO content, which is an indirect indication of the rise in crosslink density. The impedance maps of the crosslinked samples obtained through SAM analysis revealed that the impedance of the samples increased with the increasing sulphur content, which can be attributed to higher level of crosslink density. A quantified correlation was obtained between SAM images and the crosslink density of the samples. It was shown that SAM is a promising tool for practical and non-destructive analysis for determining the formation of crosslink density of the rubbers. [ABSTRACT FROM AUTHOR]

The emphasis of biocompatible polymer applications in medical sciences and biotechnology has remarkably increased. Developing new low-cost, low-toxicity and lightweight composite forms of biopolymers has become even more attractive since the addition of new species into polymer matrices assist to improve biomedical activities of such materials to a higher extend. Developments in nanoscience and nanotechnology recently contribute to controlled fabrication and ultraprecise diagnosis of such materials. This study concerns the observation of solution processing effects in the fabrication of porous PLA/AGNWs bionanocomposite coatings using electron and ion processing based serial cross-sectioning and high-resolution imaging. The nanostructuring and characterization were both performed in a focused ion-beam-scanning electron microscope (FIB-SEM) platform. HR-SEM imaging was conducted on-site to track solvent based morphological property alterations of PLA and PLA/AgNWs structures. Simultaneous SEM-EDS analyses revealed the elemental distribution and the chemical composition along the cross-sectioned regions of the samples. Accordingly, it was observed that, in case of acetone dissolved materials, both pristine PLA and PLA/AgNWs samples sustained their foamy structure. When chloroform was used as the solvent, the porosity of the polymer matrices was less and the resulting structure was found to be denser than samples dissolved in acetone with a lower surface area ratio inside the material. This can be attributed to the rapid volatilization of acetone compared to chloroform, and hence the formation of interconnected pore network. For both nanocomposite biopolymers dissolved in acetone and chloroform, silver nanowires were homogeneously distributed throughout PLA matrices. [ABSTRACT FROM AUTHOR]