Characterization and evaluation of UV-irradiation aging of urushi by micro-UV/Py-GC/MS system

Lacquer is the main raw material of lacquerware,while UV-irradiation is an important factor leading to its aging.In order to investigate the aging behavior of urushi lacquer film under UV-irradiation,and to propose parameters that can be used to evaluate its aging degree,the micro-UV/Py-GC/MS system has been applied in the present work to enrich and identify volatile products released by urushi film during aging on the one hand,and to investigate micro-amount and conventional urushi films with different aging degrees on the other hand,in addition,representative historical samples have also been investigated.Volatile products released by urushi film demonstrate that during UV-irradiation,polysaccharides wrapping urushiol polymer would be first degraded to generate furans and alcohols,and then urushiol polymer would undergo photo-oxidation and break of molecular chain,mainly generating oxidation products including aldehydes,organic acids,and ketones,as well as a small number of alkyl benzenes and hydrocarbons.Py-GC/MS analysis of micro-amount urushi films with different aging degrees indicates that UVirradiation is more destructive to aliphatic chains in urushiol polymer,but it also can accelerate the polymerization of microamount urushi film.Py-GC/MS analysis of conventional urushi films indicates that with the increase of aging degree,the total chromatographic peak area ratio of hydrocarbons to benzene derivatives gradually increases,the peak area ratio of 3-pentadecenyl-catechol to 3-pentadecyl-catechol gradually decreases,and the peak area ratio of aging products of urushiol to 3-pentadecyl-catechol gradually increases.The above parameters were further used to evaluate the aging degree of two urushicontained samples separately collected from the surface and interior of a carved lacquer panel in the Forbidden City,and evaluation results are in accord with the natural aging law and further verify the reliability of the proposed parameters.Research results of the present work can lay a foundation for the in-depth study of the UV-irradiation aging mechanism of urushi.

Evaluation of Layered Inorganic Nano-powder Modified Bitumen

Thermal oxidative and aging as an inevitable process in the practical application of road asphalt has great effect on the properties of asphalt. In this paper,the influences of short-term thermal oxidative ageing and ultraviolet radiation(UV) aging on the dynamic viscosity,penetration,softening point and rheological properties of two kinds of layered inorganic nano-powder including organo-modified montmorillonite (OMMT) and nanometer brucite (Mg(OH)2) modified asphalts were studied respectively. The rheological properties of these binders have been determined using a dynamic shear rheometer (DSR) through temperatures sweep tests.The rheological and physical analysis showed the two major influences of ageing on the properties for two kinds of layered inorganic nano-powder modified bitumens. On one hand,ageing decreased the viscous behaviors of modified binders,on the other hand,ageing improved the elastic behaviors of modified binders. The performances of binders after aging depended on the combined effect between the modifier and the bitumen. Both the two modifiers resisted the aging of bitumens and the effect of OMMT was better.