Tetra-hydroxymethyl phosphonium chloride （THPC） has been considered as an important chrome-free tanning agent. To understand the THPC tanning mechanism, the structure, charge distribution, activity and tanning abili...Tetra-hydroxymethyl phosphonium chloride （THPC） has been considered as an important chrome-free tanning agent. To understand the THPC tanning mechanism, the structure, charge distribution, activity and tanning ability of each phosphorous compound in THPC tanning system were studied, by ^31p NMR, FT-IR spectroscopy, differential scanning calorimetry （DSC） and computational chemistry method, etc. When pH raised to 6.0, the decomposition of THPC would take place, which results in a production of free formaldehyde, tri-hydroxymethyl phosphonium （TrHP） and tri-hydroxymethyl phosphine oxide （TrHPO）. At pH 9.0, THPC will be converted completely to TrHP and most TrHP is further oxidized into TrHPO. It is possible that, in reaction of phosphorous compounds and collagens, both P-C and C-O bonds would break simultaneously or individually. From molecular charge distribution and bond polar properties, it is deduced that, if P-C bonds break, the activity is in order of TrHPO 〉 THPC 〉 TrHE whereas if C--O bonds break, the order is TrHP 〉 THPC 〉 TrHPO. It is more possible that P--C bonds will break in reaction with collagen, and TrHPO may be more active in the THPC tanning system. The results of tanning and DSC also prove the above conclusion. Furthermore, the fact that the shrinkage temperature of THPC tanned leather was below 70℃ when basified to pH 5.0 or lower suggests that the hydroxymethyl groups of THPC and TrHP are less possible to combine directly with amino groups of collagen.展开更多
Polycrystalline TiN/TaN multilayers were grown by reactive magnetron sputtering on WC-Co sintered hard alloy Substrates. Multilayer structure and composition modulation amplitudes were studied using X-ray diffraction ...Polycrystalline TiN/TaN multilayers were grown by reactive magnetron sputtering on WC-Co sintered hard alloy Substrates. Multilayer structure and composition modulation amplitudes were studied using X-ray diffraction method. Hardness and elastic modulus were measured by nanoindentation tester. For A>8.0 nm, hardness is lower than rule-of mixtures value of individual single layer, and increased rapidly with decreasing A, peaking at hardness values≈33% higher than that at A=4.3 nm. As a result of analysing the inclination of applied load for indenter displacement on P-h curve (△P/△h), this paper exhibits that the enhancement of the resistance to dislocation motion and elastic anomaly due to coherency strains are responsibie for the hardness change展开更多
基金the National Basic Research Program (2007CB616909)Startup Foundation of Applied Chemistry of the Key Discipline of Zhejiang University of Technology and Zhejiang Provincial Science and Technology Plan (2006C21107)
文摘Tetra-hydroxymethyl phosphonium chloride （THPC） has been considered as an important chrome-free tanning agent. To understand the THPC tanning mechanism, the structure, charge distribution, activity and tanning ability of each phosphorous compound in THPC tanning system were studied, by ^31p NMR, FT-IR spectroscopy, differential scanning calorimetry （DSC） and computational chemistry method, etc. When pH raised to 6.0, the decomposition of THPC would take place, which results in a production of free formaldehyde, tri-hydroxymethyl phosphonium （TrHP） and tri-hydroxymethyl phosphine oxide （TrHPO）. At pH 9.0, THPC will be converted completely to TrHP and most TrHP is further oxidized into TrHPO. It is possible that, in reaction of phosphorous compounds and collagens, both P-C and C-O bonds would break simultaneously or individually. From molecular charge distribution and bond polar properties, it is deduced that, if P-C bonds break, the activity is in order of TrHPO 〉 THPC 〉 TrHE whereas if C--O bonds break, the order is TrHP 〉 THPC 〉 TrHPO. It is more possible that P--C bonds will break in reaction with collagen, and TrHPO may be more active in the THPC tanning system. The results of tanning and DSC also prove the above conclusion. Furthermore, the fact that the shrinkage temperature of THPC tanned leather was below 70℃ when basified to pH 5.0 or lower suggests that the hydroxymethyl groups of THPC and TrHP are less possible to combine directly with amino groups of collagen.
文摘Polycrystalline TiN/TaN multilayers were grown by reactive magnetron sputtering on WC-Co sintered hard alloy Substrates. Multilayer structure and composition modulation amplitudes were studied using X-ray diffraction method. Hardness and elastic modulus were measured by nanoindentation tester. For A>8.0 nm, hardness is lower than rule-of mixtures value of individual single layer, and increased rapidly with decreasing A, peaking at hardness values≈33% higher than that at A=4.3 nm. As a result of analysing the inclination of applied load for indenter displacement on P-h curve (△P/△h), this paper exhibits that the enhancement of the resistance to dislocation motion and elastic anomaly due to coherency strains are responsibie for the hardness change
