New genre of antioxidants from renewable natural resources:synthesis and characterisation of rosemary plant-derived antioxidants and their performance in polyolefins

Several ester derivatives of rosmarinic acid (rosmarinates) were synthesised, characterised (1D and 2D NMR, UV and FTIR spectroscopy) and tested for their potential use as antioxidants derived from a renewable natural resource. The intrinsic free radical scavenging activity of the rosmarinates was assessed, initially using a modified DPPH (2, 2-diphenyl-1-picrylhydrazyl radical) method, and found to be higher than that of commercial synthetic hindered phenol antioxidants Irganox 1076 and Irganox 1010. The thermal stabilising performance of the rosmarinates in polyethylene (PE) and polypropylene (PP) was subsequently examined and compared to that of samples prepared similarly but in the presence of Irganox 1076 (in PE) and Irganox 1010 (in PP) which are typically used for polyolefin stabilisation in industrial practice. The melt stability and the long-term thermo-oxidative stability (LTTS) of processed polymers containing the antioxidants were assessed by measuring the melt flow index (MFI), melt viscosity, oxidation induction time (OIT) and long-term (accelerated) thermal ageing performance. The results show that both the melt and the thermo-oxidative stabilisation afforded by the rosmarinates, and in particular the stearyl derivative, in both PE and PP, are superior to those of Irganox 1076 and Irganox 1010, hence their potential as effective sustainable bio-based antioxidants for polymers. The rosmarinic acid used for the synthesis of the rosmarinates esters in this study was obtained from commercial rosemary extracts (AquaROX80). Furthermore, a large number of different strains of UK-grown rosemary plants (Rosmarinum officinalis) were also extracted and analysed in order to examine their antioxidant content. It was found that the carnosic and the rosmarinic acids, and to a much lesser extent the carnosol, constituted the main antioxidant components of the UK-plants, with the two acids being present at a ratio of 3:1, respectively.

Rosemary : a raw material for a new genre of bio-based antioxidants for sustainable applications

The potential replacement, partially or fully, of synthetic additives by bio-based alternatives derived from indigenous renewable non-food crop resources offers a market opportunity for a green supply of raw materials for different industrial and health products, with greater involvement of the farming community in crop production while addressing the ever more stringent environmental and pollution laws that now require the use of less potentially toxic/harmful ingredients, even if they are present in relatively small quantities. The work presented here relates to developing a new genre of environmentally-sustainable bio-based antioxidants (AO) for industrial uses that are obtained from extracts of UK-grown rosemary (Rosmarinus officinalis) plant. The performance of these AOs was tested, and their efficacy compared with some common and benchmark synthetic AOs from the same chemical class, in different products including polymers especially for packaging, as well as lubricants, cosmetics and health products. One of the main active ingredients in rosemary is Rosmarinic acid which is a water-soluble compound. This was chemically transformed into a number of ester derivatives, Rosmarinates, targeted for different applications. The parent and the modified antioxidants (the rosmarinates) were characterised and their antioxidancy were examined and tested in linear low-density polyethylene (LLDPE) and in polypropylene (PP) and compared with compounds of similar structure and with other well known synthetic antioxidants used commercially in polyolefins. The results show that antioxidants sourced from rosemary have the added benefit of being highly efficient and intrinsically more active than many synthetic and bio-based alternatives.

Investigation of the potential antibacterial activity of Buddlja Madagascariensis extracts

DUE TO COPYRIGHT RESTRICTIONS ONLY AVAILABLE FOR CONSULTATION AT ASTON UNIVERSITY LIBRARY AND INFORMATION SERVICES WITH PRIOR ARRANGEMENT

Some historical extracts relevant to the discovery and application of the diffraction of X-rays by crystals to contribute to the centennial celebration and the International Year of Crystallography

Illustrative extracts from the writings of Paul P. Ewald and of Max von Laue are presented. The latter in turn contains extensive text contributions from William Lawrence Bragg. These selections we have chosen so as to indicate the nature of the discovery of X-ray diffraction from crystals (experiments undertaken by Friedrich, Knipping and von Laue) and its early and prompt application in crystal structure analyses (by William Henry Bragg and William Lawrence Bragg). The platform for these discoveries was provided by a macroscopic physics problem dealt with by Ewald in his doctoral thesis with Arnold Sommerfeld in the Munich Physics Department, which is also where von Laue was based. W.L. Bragg was a student in Cambridge who used Trinity College Cambridge as his address on his early papers; experimental work was done by him in the Cavendish Laboratory, Cambridge, and also with his father, W.H. Bragg, in the Leeds University Physics Department. Of further historical interest is the award of an Honorary DSc (Doctor of Science) degree in 1936 to Max von Laue by the University of Manchester, UK, while William Lawrence Bragg was Langworthy Professor of Physics there. © 2012 Copyright Taylor and Francis Group, LLC.