A series of dimer acid-based polyamides were synthesized by melt-polycondensation of dimer acid and various aromatic diamines, and were characterized by Fourier transform infrared spectrum （FT-IR） and nuclear magnet...A series of dimer acid-based polyamides were synthesized by melt-polycondensation of dimer acid and various aromatic diamines, and were characterized by Fourier transform infrared spectrum （FT-IR） and nuclear magnetic resonance （^1H NMR）. The physical properties of the polyamides, such as glass transition temperature, melting temperature, decomposition temperature and mechanical properties were also investigated. The polyamides＇ intrinsic viscosity ranges from 1.8 dL·g^-1 to 2.2 dL·g^-1, and the melting temperature ranges from 140 ℃ to 181 ℃. The glass transition temperatures, observed from dynamic mechanical analysis, fall in the range of 34.8-48.2 ℃. The physical and mechanical properties of the resultant polyamides are similar to those of the PA1212. The heat resistance and mechanical properties of poly （4, 4′-diphenylsulfone dimeramide） （PSD） and poly（4, 4′-di pb enyl dimeramide） （PPDI） are comparable to those of PA 1212.展开更多
The employment of sustainable chemicals, such as citric acid, represents a possibility for the development of textile dyeing processes. This study aimed to analyze the possibility of replacement of acetic acid (common...The employment of sustainable chemicals, such as citric acid, represents a possibility for the development of textile dyeing processes. This study aimed to analyze the possibility of replacement of acetic acid (commonly used in textile processing) by citric acid in polyester and polyamide 6 dyeing processes. The utilization of citric acid as leveling agent for disperse dyestuffs was also investigated. Dyeing processes in turquoise color for these fabrics were performed employing citric and acetic acid. Color differences between dyeing processes and color fastness to water were evaluated. All the color dyeing differences were not significant and there was no transference in color fastness tests (grade 5). Otherwise, the differences among polyamide dyeing processes could be related to the efficiency of citric acid solution as sequestering agent. Notwithstanding citric acid to be more expensive than acetic acid and the need of previous dissolution by stirring, it could be advantageous for some formulations.展开更多
[Objective] The paper was to evaluate effects of peracetic acid （PAA） combined with calcium treatments on storage quality of Ioquat fruits, so as to pro- vide practical techniques to solve the problems of postharves...[Objective] The paper was to evaluate effects of peracetic acid （PAA） combined with calcium treatments on storage quality of Ioquat fruits, so as to pro- vide practical techniques to solve the problems of postharvest rot and quality deteri- oration for Ioquat fruits. [Method] With Ioquat fruits of Qingzhong variety as materi- als, 0.2%, 0.4% and 0.8% PAA combined with 0.8% CaCI2 was used to soak Ioquat fruits for 4 min, 0.8% CaCl2 and water treatments were set as two controls; the fruits were dried and packaged by 0.02 mm PE bags, then stored under non-chilling low temperature of （7±1） ℃. The indicators related to storage quality of Ioquat fruits were randomly tested once every 3 d, and their variation situations were analyzed. [Result] Compared with two control treatments and 0.2% PAA, 0.8% PAA combined with calcium treatments, the treatment of 0.4% PAA combined with 0.8% CaCl2 could significantly inhibit rot index, weight loss rate, firmness and cell membrane permeability of Ioquat fruits during storage period, which could also effectively delay the reduction of titratable acid, vitamin C, soluble solid content and juice yield, and maintain respiration intensity of fruits at a low level; the appearance and flavor qual- ity of fruits were good after stored for 25 d. [Conclusion] 0.4% PAA combined with 0.8% CaCl2 treatment is an efficient, safe and economical practice technology in an- ti-corrosion and quality preservation for postharvest Ioquat fruits .展开更多
A new multifunctional mPEG-b-PAA-grafted chitosan copolymer possessing amino and carboxyl groups,mPEG-b-PAA-g-CHI(compound 6) ,was designed for a potential application in gene/drug delivery and synthesized by the meth...A new multifunctional mPEG-b-PAA-grafted chitosan copolymer possessing amino and carboxyl groups,mPEG-b-PAA-g-CHI(compound 6) ,was designed for a potential application in gene/drug delivery and synthesized by the methods of reversible addition-fragmentation chain transfer(RAFT) polymerization of acrylic acid(AA) and grafting reaction of a biodegradable chitosan(CHI) derivative.Completion of the reactions and characterization of the resulting compounds were demonstrated by 1 H NMR,FTIR and gel permeation chtomatography(GPC) studies.The results show that the molar ratio of amino groups to carboxyl groups in the copolymer(compound 6) is 0.41-0.59.展开更多
Surface modification on a polytetrafluoroethylene （PTFE） panel was performed with sequential nitrogen plasma treatments and surface-initiated polymerization. By introducing COO- groups to the surface of the PTFE pan...Surface modification on a polytetrafluoroethylene （PTFE） panel was performed with sequential nitrogen plasma treatments and surface-initiated polymerization. By introducing COO- groups to the surface of the PTFE panel through grafting polymerization of acrylic acid （AA）, a transparent poly （acrylic acid） （PAA） membrane was achieved from acrylic acid solution. Grafting polymerization initiating from the active group5 was achieved on the PTFE panel surface after the nitrogen plasma treatment. Utilizing the acrylic acid as monomers, with COO- groups as cross link sites to form reticulation structure, a transparent poly （acrylic acid） membrane with arborescent macromolecular structure was formed on the PTFE panel surface. Analysis meth- ods, such as fourier transform infrared spectroscopy （FTIR）, microscopy and X-ray photoelectron spectroscopy （XPS）, were utilized to characterize the structures of the macromolecule membrane on the PTFE panel surface. A contact angle measurement was performed to characterize the modified PTFE panels. The surface hydrophilicities of modified PTFE panels were significantly enhanced after the plasma treatment. It was shown that the grafting rate is related to the treating time and the power of plasma.展开更多
This paper has studied processing conditions and the influence of every variable to the pulp when the fluorescence in cotton linter pulp is eliminated with peracetic acid. The suitable variables of the elimination of ...This paper has studied processing conditions and the influence of every variable to the pulp when the fluorescence in cotton linter pulp is eliminated with peracetic acid. The suitable variables of the elimination of fluorescence. are found.展开更多
Bacterial cellulose/polyacrylic acid (BC/PAA) pH-responsive hydrogels were prepared by free-radical polymerization (in situ) using BC as the raw material and AA as the monomer. The hydrogels were loaded with curcumin ...Bacterial cellulose/polyacrylic acid (BC/PAA) pH-responsive hydrogels were prepared by free-radical polymerization (in situ) using BC as the raw material and AA as the monomer. The hydrogels were loaded with curcumin (Cur) to prepare pH-responsive intelligent medical dressings. The preparation process of the hydrogels was optimized by a single factor and response surface experiment using their swelling degree as an index. The structures of BC/PAA pH-responsive hydrogels were characterized by scanning electron microscope (SEM), Fourier Transform Infrared spectrometer (FTIR), X-ray diffraction (XRD), and tensile tester, and the swelling properties, mechanical properties, bacteriostatic properties, and drug release behavior were investigated. The results showed that the BC/PAA pH-responsive hydrogel has a three-dimensional network structure with the swelling rate up to 1600 g/g, compressive strength of up to 8 KPa, and good mechanical properties, and the drug release behavior was in line with the logistic dynamics model, and it has good inhibitory effects on common pathogens of wound infection: E. coli, S. aureus, and P. aeruginosa.展开更多
文摘A series of dimer acid-based polyamides were synthesized by melt-polycondensation of dimer acid and various aromatic diamines, and were characterized by Fourier transform infrared spectrum （FT-IR） and nuclear magnetic resonance （^1H NMR）. The physical properties of the polyamides, such as glass transition temperature, melting temperature, decomposition temperature and mechanical properties were also investigated. The polyamides＇ intrinsic viscosity ranges from 1.8 dL·g^-1 to 2.2 dL·g^-1, and the melting temperature ranges from 140 ℃ to 181 ℃. The glass transition temperatures, observed from dynamic mechanical analysis, fall in the range of 34.8-48.2 ℃. The physical and mechanical properties of the resultant polyamides are similar to those of the PA1212. The heat resistance and mechanical properties of poly （4, 4′-diphenylsulfone dimeramide） （PSD） and poly（4, 4′-di pb enyl dimeramide） （PPDI） are comparable to those of PA 1212.
文摘The employment of sustainable chemicals, such as citric acid, represents a possibility for the development of textile dyeing processes. This study aimed to analyze the possibility of replacement of acetic acid (commonly used in textile processing) by citric acid in polyester and polyamide 6 dyeing processes. The utilization of citric acid as leveling agent for disperse dyestuffs was also investigated. Dyeing processes in turquoise color for these fabrics were performed employing citric and acetic acid. Color differences between dyeing processes and color fastness to water were evaluated. All the color dyeing differences were not significant and there was no transference in color fastness tests (grade 5). Otherwise, the differences among polyamide dyeing processes could be related to the efficiency of citric acid solution as sequestering agent. Notwithstanding citric acid to be more expensive than acetic acid and the need of previous dissolution by stirring, it could be advantageous for some formulations.
基金Supported by Special Fund for Agro-scientific Research in the Public Interest "Tec-hnology Research and Experimental Demonstration of Loquat Industry"(201003073)~~
文摘[Objective] The paper was to evaluate effects of peracetic acid （PAA） combined with calcium treatments on storage quality of Ioquat fruits, so as to pro- vide practical techniques to solve the problems of postharvest rot and quality deteri- oration for Ioquat fruits. [Method] With Ioquat fruits of Qingzhong variety as materi- als, 0.2%, 0.4% and 0.8% PAA combined with 0.8% CaCI2 was used to soak Ioquat fruits for 4 min, 0.8% CaCl2 and water treatments were set as two controls; the fruits were dried and packaged by 0.02 mm PE bags, then stored under non-chilling low temperature of （7±1） ℃. The indicators related to storage quality of Ioquat fruits were randomly tested once every 3 d, and their variation situations were analyzed. [Result] Compared with two control treatments and 0.2% PAA, 0.8% PAA combined with calcium treatments, the treatment of 0.4% PAA combined with 0.8% CaCl2 could significantly inhibit rot index, weight loss rate, firmness and cell membrane permeability of Ioquat fruits during storage period, which could also effectively delay the reduction of titratable acid, vitamin C, soluble solid content and juice yield, and maintain respiration intensity of fruits at a low level; the appearance and flavor qual- ity of fruits were good after stored for 25 d. [Conclusion] 0.4% PAA combined with 0.8% CaCl2 treatment is an efficient, safe and economical practice technology in an- ti-corrosion and quality preservation for postharvest Ioquat fruits .
基金Project(20704011) supported by the National Natural Science Foundation of ChinaProject(09JJ3027) supported by the Natural Science Foundation of Hunan Province,ChinaProject(50725825) supported by the National Science Foundation for Distinguished Young Scholars
文摘A new multifunctional mPEG-b-PAA-grafted chitosan copolymer possessing amino and carboxyl groups,mPEG-b-PAA-g-CHI(compound 6) ,was designed for a potential application in gene/drug delivery and synthesized by the methods of reversible addition-fragmentation chain transfer(RAFT) polymerization of acrylic acid(AA) and grafting reaction of a biodegradable chitosan(CHI) derivative.Completion of the reactions and characterization of the resulting compounds were demonstrated by 1 H NMR,FTIR and gel permeation chtomatography(GPC) studies.The results show that the molar ratio of amino groups to carboxyl groups in the copolymer(compound 6) is 0.41-0.59.
基金supported by National Natural Science Foundation of China (No. 10975162)Knowledge Innovation Project of Young Talent, Hefei Institutes of Physical Science, CAS (Nos. 075FCQ0126, Y05FCQ0127)
文摘Surface modification on a polytetrafluoroethylene （PTFE） panel was performed with sequential nitrogen plasma treatments and surface-initiated polymerization. By introducing COO- groups to the surface of the PTFE panel through grafting polymerization of acrylic acid （AA）, a transparent poly （acrylic acid） （PAA） membrane was achieved from acrylic acid solution. Grafting polymerization initiating from the active group5 was achieved on the PTFE panel surface after the nitrogen plasma treatment. Utilizing the acrylic acid as monomers, with COO- groups as cross link sites to form reticulation structure, a transparent poly （acrylic acid） membrane with arborescent macromolecular structure was formed on the PTFE panel surface. Analysis meth- ods, such as fourier transform infrared spectroscopy （FTIR）, microscopy and X-ray photoelectron spectroscopy （XPS）, were utilized to characterize the structures of the macromolecule membrane on the PTFE panel surface. A contact angle measurement was performed to characterize the modified PTFE panels. The surface hydrophilicities of modified PTFE panels were significantly enhanced after the plasma treatment. It was shown that the grafting rate is related to the treating time and the power of plasma.
文摘This paper has studied processing conditions and the influence of every variable to the pulp when the fluorescence in cotton linter pulp is eliminated with peracetic acid. The suitable variables of the elimination of fluorescence. are found.
文摘Bacterial cellulose/polyacrylic acid (BC/PAA) pH-responsive hydrogels were prepared by free-radical polymerization (in situ) using BC as the raw material and AA as the monomer. The hydrogels were loaded with curcumin (Cur) to prepare pH-responsive intelligent medical dressings. The preparation process of the hydrogels was optimized by a single factor and response surface experiment using their swelling degree as an index. The structures of BC/PAA pH-responsive hydrogels were characterized by scanning electron microscope (SEM), Fourier Transform Infrared spectrometer (FTIR), X-ray diffraction (XRD), and tensile tester, and the swelling properties, mechanical properties, bacteriostatic properties, and drug release behavior were investigated. The results showed that the BC/PAA pH-responsive hydrogel has a three-dimensional network structure with the swelling rate up to 1600 g/g, compressive strength of up to 8 KPa, and good mechanical properties, and the drug release behavior was in line with the logistic dynamics model, and it has good inhibitory effects on common pathogens of wound infection: E. coli, S. aureus, and P. aeruginosa.
