Green chemistry protocols are proposed to produce high-value chemicals from waste tomatoes. Long-chain hydroxy fatty acids (called cutin acids), in particular the 10,16-dihydroxyhexadecanoic acid and its oligomers, could be innovative building-block chemicals for the synthesis of novel bio-resins and lacquers suitable as internal protective coating for metal food packaging. However, these natural compounds are not currently commercially available. This study investigates the possibility of extracting cutin acids from tomato peels without the use of organic solvents and by an efficient, cost-effective, and environmentally safe method amenable to industrial scale-up. The first route investigated was based on alkaline hydrolysis of the tomato cuticle. The second involved the acid free-selective precipitation of cutin. Finally, cutin was isolated by hydrogen peroxide-assisted hydrolysis. GC-MS analysis revealed the main chemical compound isolated by all methods to be 10,16-dihydroxyhexadecanoic acid, the principal component of tomato cutin, with extraction yields ranging from 81 to 96%. Products are different in terms of appearance, solubility, the degree of crosslinking observed and molecular weight, as shown by GPC analysis. Furthermore, the products extracted were characterized by means of FT-IR spectroscopy and thermal analysis. The cutin obtained through alkaline hydrolysis results the best raw material for bio-resin preparation.
Abstract:This work studies a set of low cost beta alloys with the composition Ti-7Fe, processed by conventional powder metallurgy (PM). The materials were prepared by conventional blending of elemental Ti hydride-dehydride powder with three different Fe powder additions: water atomised Fe, Fe carbonyl and master alloy Fe-25Ti. The optimal sintering behaviour and the best mechanical properties were attained with the use of Fe carbonyl powder, which reached a sintered density of up to 93% of the theoretical density, with UTS values of 800 MPa in the 'as sintered' condition. Coarse water atomised powder particles promoted reactive sintering, and coarse porosity was found due to the coalescence of Kirkendall porosity and by the pores generated during the exothermic reaction between Ti and Fe. The addition of Fe-25Ti produced brittle materials, as its low purity (91·5%) was found to be unsuitable for formulating Ti alloys.
Abstract:The use and development of titanium and titanium alloys have been strongly correlated to high technology industries where costs are not the most important aspect. Titanium could see its market grow by the application of lower cost and more efficient processing methods such as powder metallurgy. This work deals with the characterisation of two types of powders: commercial prealloyed powder and powder produced from master alloy combining mechanical milling and conventional blending to adjust the particle size. The characteristics of the powders, sintering behaviour and final properties of the parts indicate that the master alloy approach leads to better compressibility than the prealloyed powders and, therefore, to lower dimensional change during sintering. The most important result is that it is possible to obtain Ti alloys with properties similar to or better than alloys from prealloyed powders and to obtain homogeneous microstructures, which allows the composition to be adjusted
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