The Final Frontier of Sustainable Materials: Current Developments in Self-Healing Elastomers

It is impossible to describe the recent progress of our society without considering the role of polymers; however, for a broad audience, “polymer” is usually related to environmental pollution. The poor disposal and management of polymeric waste has led to an important environmental crisis, and, within polymers, plastics have attracted bad press despite being easily reprocessable. Nonetheless, there is a group of polymeric materials that is particularly more complex to reprocess, rubbers. These macromolecules are formed by irreversible crosslinked networks that give them their characteristic elastic behavior, but at the same time avoid their reprocessing. Conferring them a self-healing capacity stands out as a decisive approach for overcoming this limitation. By this mean, rubbers would be able to repair or restore their damage automatically, autonomously, or by applying an external stimulus, increasing their lifetime, and making them compatible with the circular economy model. Spain is a reference country in the implementation of this strategy in rubbery materials, achieving successful self-healable elastomers with high healing efficiency and outstanding mechanical performance. This article presents an exhaustive summary of the developments reported in the previous 10 years, which demonstrates that this property is the last frontier in search of truly sustainable materials.     

Calumet.

Comments on an article by Hans J. Eysenck (1954). The author providing these comments states that if he had an "erroneous impression" of Eysenck's main conclusions, it is his further impression that he was not alone in this reaction to his paper. He states that the implicit tone as well as the explicit statement work together in the process of communication. Furthermore, the commentator states that it is good to see that Eysenck has troubled to correct the false impression his paper created. Lastly, the commentator states that it is particularly gratifying that he reiterates the subjective basis of the judgments he found it necessary to make in summarizing the literature. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanical and thermal properties of polypropylene/montmorillonite nanocomposites using stearic acid as both an interface and a clay surface modifier

The effects of stearic acid treatment on the crystallization, morphology, thermal, and mechanical properties of polypropylene (PP)/montmorillonite (Mm) nanocomposites were investigated. Stearic acid was used as a new surface modifier for Mm, and also small amounts of this acid were used as a new interface modifier. Nanocomposites containing 1.5, 2.5, 5, and 10% in weight of the unmodified and modified Mm were prepared by melt blending. The tensile and impact properties of nanocomposites were evaluated. Wide‐angle X‐ray diffraction was used to study both the generated PP β crystals and the dispersion state of the nanocomposites. Differential scanning calorimeter was used to detect the melting and crystallization behavior of the samples. The toughness of some nanocomposites was higher than the pure PP. β phase of PP was observed with the addition of Mm. Stearic acid favored the dispersion of the nanocomposites when used as interface modifier. Nanocomposites with better dispersion exhibited crystallization temperatures similar to pure PP. POLYM. COMPOS., 35:1–9, 2014. © 2013 Society of Plastics Engineers