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
The radical polymerization of maleic anhydride（MA）,styrene（ST）with the vinyl groups introduced onto the surface of the nano-sized silica via solution polymerization method was developed.The methacryloxypropyl nano...The radical polymerization of maleic anhydride（MA）,styrene（ST）with the vinyl groups introduced onto the surface of the nano-sized silica via solution polymerization method was developed.The methacryloxypropyl nano-sized silica（MPNS）was used as macromonomer and polymerized with maleic anhydride and styrene by initiating with BPO in toluene.The structure and properties of MPNS/SMA nano-composite were characterized by FT-IR spectra and TEM.Meanwhile,it was applied as tanning agent compared with the traditional styrene-maleic anhydride copolymer in leather.It was found that the applied leather had better quality characteristics with the addition of the nano-sized silica.展开更多
Traditional chrome tanning technology is still widely used today. In this technology, chrome shaving as well as chrome contained effluent in tanning and retanning processes is a big issue in the industry. Wet white ta...Traditional chrome tanning technology is still widely used today. In this technology, chrome shaving as well as chrome contained effluent in tanning and retanning processes is a big issue in the industry. Wet white tanning technology has been gaining in importance in recent years, but in general, the comprehensive performance of chrome-free tanned leather is not comparable with that of chrome tanned leather. In the present work, chrome-free tanning and chrome tanning are combined in a reversed procedure, which produces leather with chrome tanned leather quality without chrome tanned leather waste problems. In this procedure, a special amphoteric organic compound, no pickle, no salt chrome-free tanning agent TWT was used to tan delimed hides （no pickle） making wet white with shrinking temperature at 80-85 ~C. Then, new method called reversed tanning further process the wet white into chrome-tanned crust. In this reversed method, retanning, fatliquoring and coloring processes were carried out before chrome tanning. This technology eliminates chrome waste issue in tanning, shaving, post tanning processes. The chrome contained effluent is only concentrated in the last chrome tanning process. The leather made with this technology has complete conventional chrome-tanned leather quality. In this way, chrome leather quality without chrome waste problems was achieved. So, it is a new clean tanning technology.展开更多
A promising and practical chrome-free tanning system has been developed based on a novel Al–Zr bimetal complex tanning agent.However,to achieve satisfactory resultant leather,the retanning process that is compatible ...A promising and practical chrome-free tanning system has been developed based on a novel Al–Zr bimetal complex tanning agent.However,to achieve satisfactory resultant leather,the retanning process that is compatible with this emerging tannage needs to be investigated systematically.This paper aims to explore the interaction between the bimetal complex tanned wet white and retanning agents.The isoelectric point(pI)of wet white was 7.2,which was nearly the same as wet blue.The electropositivity of wet white was even higher than that of wet blue during post-tanning processes,resulting in higher uptake rate of retanning agents.The distribution of various retanning agents in wet white was analyzed by pI measurement of layered leather and fluorescent tracing technique.The retanning agents were unevenly distributed throughout the cross-section,which might be an important restriction factor in obtaining satisfactory organoleptic properties of the crust leather.This fact is mainly due to the strong electrostatic interaction between anionic retanning agents and wet white.Applying a high dosage of multiple retanning agents in a proper sequence of addition benefited the full penetration of retanning agents in leather matrix and thus improved the organoleptic properties of crust leather.This work provides guidance for optimizing retanning process of the wet white leather.展开更多
The use of vegetable tanning materials in leather processing has drawn attention as an alternative to basic chromium sulphate for its natural abundance and environmental aspects.In this work,an attempt has been made t...The use of vegetable tanning materials in leather processing has drawn attention as an alternative to basic chromium sulphate for its natural abundance and environmental aspects.In this work,an attempt has been made to extract vegetable tannins from Xylocarpus granatum bark using different solvents(e.g.,water,methanol,ethanol,and chloroform)and compare with conventional vegetable tanning agents such as mimosa and quebracho.The highest extraction efficiency was observed 31.22%by methanol.The presence of tannin content and polyphenolic compounds,e.g.(-)epicatechin(503 mg/100 g dry extract),catechin hydrate(218 mg/100 g dry extract),catechol(29 mg/100 g dry extract)were ensured by UV-Vis,FT-IR spectroscopy and HPLC.Again,condensed tannins,moisture content,and pH of the methanol extracted tannin were found 47.80%,5.82%,and 3.97 respectively.The leather tanned by Xylocarpus granatum tannin showed a shrinkage temperature of 86.34±1.52℃.Other properties such as tensile strength,tear strength,grain cracking load,and distention at grain cracking were comparable to conventional vegetable-tanned leather.The cross-sectional morphology of the tanned leathers was also characterized by scanning electron microscopy(SEM)which revealed a compact structure of the leather fibers.In light of the findings from the study,X.granatum bark tannin could be a well alternative to chromium and a new source of vegetable tannin for the leather industry.展开更多
The use of vegetable tanning materials in leather processing has drawn attention as an alternative to basic chromium sulphate for its natural abundance and environmental aspects. In this work, an attempt has been made...The use of vegetable tanning materials in leather processing has drawn attention as an alternative to basic chromium sulphate for its natural abundance and environmental aspects. In this work, an attempt has been made to extract veg-etable tannins from Xylocarpus granatum bark using different solvents (e.g., water, methanol, ethanol, and chloroform) and compare with conventional vegetable tanning agents such as mimosa and quebracho. The highest extraction efficiency was observed 31.22% by methanol. The presence of tannin content and polyphenolic compounds, e.g. (-)epicatechin (503 mg/100 g dry extract), catechin hydrate (218 mg/100 g dry extract), catechol (29 mg/100 g dry extract) were ensured by UV-Vis, FT-IR spectroscopy and HPLC. Again, condensed tannins, moisture content, and pH of the methanol extracted tannin were found 47.80%, 5.82%, and 3.97 respectively. The leather tanned by Xylocar-pus granatum tannin showed a shrinkage temperature of 86.34 ± 1.52 °C. Other properties such as tensile strength, tear strength, grain cracking load, and distention at grain cracking were comparable to conventional vegetable- tanned leather. The cross-sectional morphology of the tanned leathers was also characterized by scanning electron microscopy (SEM) which revealed a compact structure of the leather fibers. In light of the findings from the study, X. granatum bark tannin could be a well alternative to chromium and a new source of vegetable tannin for the leather industry.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The radical polymerization of maleic anhydride（MA）,styrene（ST）with the vinyl groups introduced onto the surface of the nano-sized silica via solution polymerization method was developed.The methacryloxypropyl nano-sized silica（MPNS）was used as macromonomer and polymerized with maleic anhydride and styrene by initiating with BPO in toluene.The structure and properties of MPNS/SMA nano-composite were characterized by FT-IR spectra and TEM.Meanwhile,it was applied as tanning agent compared with the traditional styrene-maleic anhydride copolymer in leather.It was found that the applied leather had better quality characteristics with the addition of the nano-sized silica.
文摘Traditional chrome tanning technology is still widely used today. In this technology, chrome shaving as well as chrome contained effluent in tanning and retanning processes is a big issue in the industry. Wet white tanning technology has been gaining in importance in recent years, but in general, the comprehensive performance of chrome-free tanned leather is not comparable with that of chrome tanned leather. In the present work, chrome-free tanning and chrome tanning are combined in a reversed procedure, which produces leather with chrome tanned leather quality without chrome tanned leather waste problems. In this procedure, a special amphoteric organic compound, no pickle, no salt chrome-free tanning agent TWT was used to tan delimed hides （no pickle） making wet white with shrinking temperature at 80-85 ~C. Then, new method called reversed tanning further process the wet white into chrome-tanned crust. In this reversed method, retanning, fatliquoring and coloring processes were carried out before chrome tanning. This technology eliminates chrome waste issue in tanning, shaving, post tanning processes. The chrome contained effluent is only concentrated in the last chrome tanning process. The leather made with this technology has complete conventional chrome-tanned leather quality. In this way, chrome leather quality without chrome waste problems was achieved. So, it is a new clean tanning technology.
基金financially supported by the National Natural Science Foundation of China(21506129).
文摘A promising and practical chrome-free tanning system has been developed based on a novel Al–Zr bimetal complex tanning agent.However,to achieve satisfactory resultant leather,the retanning process that is compatible with this emerging tannage needs to be investigated systematically.This paper aims to explore the interaction between the bimetal complex tanned wet white and retanning agents.The isoelectric point(pI)of wet white was 7.2,which was nearly the same as wet blue.The electropositivity of wet white was even higher than that of wet blue during post-tanning processes,resulting in higher uptake rate of retanning agents.The distribution of various retanning agents in wet white was analyzed by pI measurement of layered leather and fluorescent tracing technique.The retanning agents were unevenly distributed throughout the cross-section,which might be an important restriction factor in obtaining satisfactory organoleptic properties of the crust leather.This fact is mainly due to the strong electrostatic interaction between anionic retanning agents and wet white.Applying a high dosage of multiple retanning agents in a proper sequence of addition benefited the full penetration of retanning agents in leather matrix and thus improved the organoleptic properties of crust leather.This work provides guidance for optimizing retanning process of the wet white leather.
基金funded by the Ministry of Science and Technology,Bangladesh by the National Science and Technology(NST)fellowship(Group:Physical Science,Reg.No:317).
文摘The use of vegetable tanning materials in leather processing has drawn attention as an alternative to basic chromium sulphate for its natural abundance and environmental aspects.In this work,an attempt has been made to extract vegetable tannins from Xylocarpus granatum bark using different solvents(e.g.,water,methanol,ethanol,and chloroform)and compare with conventional vegetable tanning agents such as mimosa and quebracho.The highest extraction efficiency was observed 31.22%by methanol.The presence of tannin content and polyphenolic compounds,e.g.(-)epicatechin(503 mg/100 g dry extract),catechin hydrate(218 mg/100 g dry extract),catechol(29 mg/100 g dry extract)were ensured by UV-Vis,FT-IR spectroscopy and HPLC.Again,condensed tannins,moisture content,and pH of the methanol extracted tannin were found 47.80%,5.82%,and 3.97 respectively.The leather tanned by Xylocarpus granatum tannin showed a shrinkage temperature of 86.34±1.52℃.Other properties such as tensile strength,tear strength,grain cracking load,and distention at grain cracking were comparable to conventional vegetable-tanned leather.The cross-sectional morphology of the tanned leathers was also characterized by scanning electron microscopy(SEM)which revealed a compact structure of the leather fibers.In light of the findings from the study,X.granatum bark tannin could be a well alternative to chromium and a new source of vegetable tannin for the leather industry.
基金the Ministry of Science and Technology,Bangladesh by the National Science and Technology(NST)fellowship(Group:Physical Science,Reg.No:317).
文摘The use of vegetable tanning materials in leather processing has drawn attention as an alternative to basic chromium sulphate for its natural abundance and environmental aspects. In this work, an attempt has been made to extract veg-etable tannins from Xylocarpus granatum bark using different solvents (e.g., water, methanol, ethanol, and chloroform) and compare with conventional vegetable tanning agents such as mimosa and quebracho. The highest extraction efficiency was observed 31.22% by methanol. The presence of tannin content and polyphenolic compounds, e.g. (-)epicatechin (503 mg/100 g dry extract), catechin hydrate (218 mg/100 g dry extract), catechol (29 mg/100 g dry extract) were ensured by UV-Vis, FT-IR spectroscopy and HPLC. Again, condensed tannins, moisture content, and pH of the methanol extracted tannin were found 47.80%, 5.82%, and 3.97 respectively. The leather tanned by Xylocar-pus granatum tannin showed a shrinkage temperature of 86.34 ± 1.52 °C. Other properties such as tensile strength, tear strength, grain cracking load, and distention at grain cracking were comparable to conventional vegetable- tanned leather. The cross-sectional morphology of the tanned leathers was also characterized by scanning electron microscopy (SEM) which revealed a compact structure of the leather fibers. In light of the findings from the study, X. granatum bark tannin could be a well alternative to chromium and a new source of vegetable tannin for the leather industry.
