High voltage atmospheric cold plasma (HVACP) treatment generates reactive gas species that induce inter and intramolecular reactions in soybean oil. The goal of this study is to analyze the effect of HVACP treatment on the chemical structure of soybean oil in a hydrogen gas environment at atmospheric pressure. HVACP was used to treat soybean oil (15g), for up to 6h by triplicate. Plasma generated reactive gas species interact with the sample producing three distinct fractions identified as a liquid, gel, and solid. Fatty acid profile, FTIR, 1H-NMR/13C-NMR, GPC, thermal properties and peroxide value, were used to characterize the chemical structure. Results indicated a lower content of polyunsaturated fatty acids, increased content of saturated fatty acids, and the presence of isomers. An insoluble portion was observed in the solid fraction and increase with treatment time up to 42% in the 6h treated samples. Plasma species may cause two main reactions: polymerization and hydrogenation.
The goal of the present study is to demonstrate 1H LF-NMR time relaxation measurements for efficient and rapid evaluation of Omega-3 polyunsaturated fatty acids (PUFA)-rich linseed oil (LSO) oxidative aging mechanisms, by monitoring primary chemical and structural changes occurring during thermal oxidative stress. The LF NMR monitors the different proton spin-spin coupling energy relaxation times, T2 within LSO molecular segments, from the initiation of free radical generation and hydroperoxide formation to the propagation of alkoxy radicals, and alpha, beta-unsaturated aldehydes formation, and a termination phase of crosslinked polymerization end products. The 1H LF NMR T2 values monitors both the covalent and secondary bonding interactions (e.g., electrostatic and hydrogen bonding) during the different oxidation phases. The present paper shows that LSO tail segments mobility in terms of T2 multi-exponential relaxation decays, generated by data reconstructing of 1H transversal relaxation components are providing a clear, sharp and informative understanding of LSO sample’s autoxidation aging processes. This is supported by high field band selective 1H NMR pulse excitation for hydroperoxide and aldehydes quantification of the same LSO samples at 25, 40, 60, 80, 100, and 120oC with pumped air for 168 h. Peroxide value, viscosity and self-diffusion, as well as fatty acids profile and by- products determined by GC-MS were also carried out, and correlated with the LSO tail T2 relaxation results. In conclusion the selective determination of LSO alkyl tail T2 energy relaxation time domain values was demonstrated as a rapid evaluation marker for following omega-3 PUFA-rich oils oxidative aging.
Quantitative analyses on the coefficient of friction of common coating waxes are necessary and essential for designing systems for coating, conveying, packaging operations, transporting and storing of papers and paperboards, while analyses on wear behavior can be helpful for predicting performance durability of the coating surface. In this study, we investigated the friction and wear behaviors of six waxes including four commercial waxes and two soybean oil-based wax developed in our lab for bulk coating on cardboard. The effect of normal load, sliding velocity, and environmental temperature was evaluated. The friction coefficient of different waxes varies with sliding conditions. Higher normal load, sliding velocity, and environmental temperature resulted in significantly greater wear loss. Crystalline morphology and crystallinity were affected by environmental temperature, and they correlate to the variations in friction coefficient and wear loss of these materials. Overall, the Estercoat developed in our lab had comparable frictional properties and much less wear than paraffin wax under tested conditions and can be a good substitute for paraffin wax.