Acidic and basic hydrolysis of poly(N‐vinylformamide)

Poly(N‐vinylformamide) (PNVF) was synthesized and hydrolyzed to poly(vinylamine) (PVAm) in both HCl and NaOH solutions. The hydrolysis kinetics and the equilibrium hydrolysis were examined experimentally at different temperatures, polymer concentrations, and acid‐ or base‐to‐amide molar ratios. The hydrolysis kinetics strongly depended on temperature, polymer, and HCl or NaOH concentrations, but showed little dependence on PNVF molecular weight. The acid hydrolysis of PNVF exhibited limited conversions because of the electrostatic repulsion among the cationic amine groups generated during hydrolysis and proton hydrates. In the basic hydrolysis, complete amide conversions were observed when the NaOH/amide molar ratios were greater than unity. The effects of temperature and PNVF concentration on the equilibrium amide conversion appeared to be negligible in both acidic and basic hydrolysis. The equilibrium conversions of base hydrolysis were higher than those of acidic hydrolysis under the same reaction conditions. At NaOH/amide ratios of less than unity, the equilibrium hydrolysis experiments revealed that one base molecule could induce the hydrolysis of more than one amide group. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3412–3419, 2002     

ENHANCING ENZYMATIC HYDROLYSIS OF RICE STRAW BY MICROWAVE PRETREATMENT

In an attempt to elucidate the effect of microwave pretreatment (MP) on enzymatic hydrolysis of rice straw (RS), three distinct MP procedures, microwave treatment (MT) alone, MT and alkali treatment (AT) together, and MT after AT, were investigated and compared with conventional alkali pretreatment (AP) by measurement of reducing sugar during its enzymatic hydrolysis. The combination of MT and AT could significantly accelerate the hydrolysis rate whereas the hydrolysis yield stayed unchanged. The effect of miwcrowave irradiation power and treatment time on the hydrolysis was also studied, and the optimal hydrolysis conditions were determined by an orthogonal experiment.     

ENHANCING ENZYMATIC HYDROLYSIS OF RICE STRAW BY MICROWAVE PRETREATMENT

In an attempt to elucidate the effect of microwave pretreatment (MP) on enzymatic hydrolysis of rice straw (RS), three distinct MP procedures, microwave treatment (MT) alone, MT and alkali treatment (AT) together, and MT after AT, were investigated and compared with conventional alkali pretreatment (AP) by measurement of reducing sugar during its enzymatic hydrolysis. The combination of MT and AT could significantly accelerate the hydrolysis rate whereas the hydrolysis yield stayed unchanged. The effect of miwcrowave irradiation power and treatment time on the hydrolysis was also studied, and the optimal hydrolysis conditions were determined by an orthogonal experiment.     

丙烯酰胺-苯乙烯共聚物乳液的水解反应

本文以丙烯酰胺(AM)、苯乙烯(ST)为主要原料,采用无皂乳液聚合技术合成了一系列丙烯酰胺-苯乙烯共聚物乳液,并对其进行水解反应研究。采用胶体滴定法跟踪水解反应过程中水解度的变化;探讨了反应条件对产物的表面电荷和乳胶粒径的影响等。研究结果表明,温度对水解反应速率和转化率的影响较大;水解反应可有效提高乳胶粒子表面的电荷量;水解度随着碱的用量的增加而上升;AM:ST 的摩尔比对水解度的影响不大。     

Hydrolytic stability of sulfonated poly(butylene terephthalate)

The hydrolysis of sulfonated poly(butylene terephthalate) copolymers was studied. Sulfonated poly(butylene terephthalate) copolymers, referred to as PBT-ionomers (PBTIs), were shown to hydrolyze faster than poly(butylene terephthalate) (PBT). An experiment designed to isolate the effect of the sulfonated isophthalate (SIP) moieties on hydrolysis rate showed that the SIP moieties were responsible for the faster hydrolysis. Experiments aimed at identifying the mechanism of influence of the SIP moieties on hydrolytic stability indicated that hydrolysis was enhanced by the presence of ionic multiplets which increase amorphous content, imbibe water, and perhaps exert a medium effect on the hydrolysis of esters associated with the ionic groups.     

Optimization of Enzymatic Production of Oligopeptides from Apricot Almonds Meal with Neutrase and N120P

Neutrase 0.8L and N120P proteases were used for oligopeptide production from apricot almonds meal, and response surface design was carried out to optimize the effect of hydrolysis conditions on hydrolysis degree (DH) and oligopeptide yield rate. Four independent variables were used to optimize the hydrolysis process: hydrolysis temperature (X(1)), enzyme-to substrate ratio (E/S) (X(2)), substrate concentration (X(3)) and reaction time (X(4)). Statistical analysis indicated that the four variables, quadratic terms of X(1), X(3), and X(4), and the interaction terms with X(1) had a significant (p < 0.05) effect on DH. The yield rate was also significantly affected by the four variables and quadratic terms of X(1), X(2) and X(4). Two mathematical models with high determination coefficient were obtained and could be employed to optimize protein hydrolysis. The optimal hydrolysis conditions were determined as follows: hydrolysis temperature 52.5 °C; enzyme-to-substrate ratio (E/S) 7200 U/g; substrate concentration 2%; reaction time 173 min. The initial pH 6.5 and Neutrase-to-N120P dosage ratio 2:1 were fixed in this study according to the preliminary research. Under these conditions, the experimental DH and yield rate were 34.10 ± 5.25% and 72.42 ± 2.27%, respectively.     

L-(-)-二对甲氧基苯甲酰酒石酸的合成

以对甲氧基苯甲酸、二氯亚砜、L-酒石为原料,经过生成酰氯、酯化、酐化和水解反应得到L-(-)-二对甲氧基苯甲酰酒石酸。研究了对甲氧基苯甲酰氯的用量、反应时间和酸酐水解体系、水解时间等因素对产率的影响。确定了最佳工艺条件。结果表明,L-酒石酸与对甲氧基苯甲酰氯的摩尔比为1∶2.4,反应时间4 h及酸酐水解体系为丙酮-水(V/V=1∶1),水解时间3 h,目标产物的产率为88.0%。     

加压微波辅助水解甘草酸粗品制备甘草次酸(英文)

A pressured microwave-assisted hydrolysis(PMAH) technique has been developed for hydrolyzing the crude glycyrrhizic acid(GA) extracted from licorice root to prepare glycyrrhetinic acid(GRA).In order to optimize the efficiency of PMAH,several experimental parameters were investigated,including liquid-solid ratio,hydrolysis time,sulfuric acid concentration and hydrolysis temperature.The optimized hydrolysis conditions were as follows:pressured microwave-assisted hydrolysis of crude GA for 21 min(taking 15 min to reach 150 oC,and holding it for 6 min) at 150 oC(at a radiation power of 450 W) in 3%-5% sulfuric acid solution with the liquid-solid(ml?g?1 crude GA) ratio of 25︰1.As a result of the considerable saving in time and higher product yields(up to 90%),PMAH was proved more effective than conventional methods.     

杨木废弃物稀酸水解预处理条件的响应面优化

以聚糖类转化率为考核指标,探讨了杨木废弃物稀酸水解预处理物料的适宜颗粒尺寸范围,并用响应面实验设计优化了稀酸水解条件.结果表明,稀酸水解预处理物料的适宜颗粒尺寸为0.075~0.096 mm,稀硫酸水解的优化工艺条件为:固液比1:10,温度158 ℃,时间5 min,硫酸质量分数2.5%.在此优化条件下,聚糖类转化率为59.23%.稀酸水解液的高效液相色谱分析表明,水解液主要成分为木糖(29.897 g/L),占总糖量的64.8%,其次为葡萄糖(8.748 g/L),占总糖量的18.9%,稀酸水解单糖继续降解较少.SEM形貌和XRD分析表明,水解残渣的纤维结构破坏明显,其结晶度由原料的57.45%降低到47.37%,该稀酸水解残渣存在通过酶解和发酵制备生物乙醇的可能性.     

NaOH-Fenton试剂预处理桑木的纤维素酶分段酶水解研究

采用分段酶水解木质纤维原料的方法,以NaOH-Fenton试剂预处理桑木为原料,通过在反应过程中及时移除葡萄糖和纤维二糖,减轻产物的抑制作用,最终达到提高酶水解得率和缩短酶解反应时间的目的。实验结果表明：纤维素酶用量为15FPIU/g（以纤维素计,下同）时,在三段（8+8+8h）水解过程中,经第一段水解,纤维素酶反应速率从1.25g/（L·h）提高到2.21g/（L·h）,第二段水解后,酶反应速率为1.54g/（L·h）,比未分段水解的酶反应速率提高了73%;当纤维素酶用量为40FPIU/g时,三段（8+8+8h）水解得率增至88.08%;三段（8+8+8h）水解充分利用了酶解残渣上的结合酶进行后续水解。对纤维素酶在预处理桑木上的吸附情况进行研究,发现桑木经NaOH-Fenton试剂预处理后,对纤维素酶的最大吸附量为8.08mg/g,预处理增加了纤维素酶与桑木间的吸附位点。     

Thermoplastic polyurethane hydrolysis stability

This paper reviews several types of thermoplastic polyurethane elastomers, and the unique properties these polymers have. In discussing the hydrolysis stability of thermoplastic polyurethane elastomers the suitability of these polymers for such study was pointed out. A relationship between poly(ester-urethane) composition in terms of methylene group concentration, hardness and chain stiffness, and hydrolysis stability was shown. The dominant role of polyurethane acid number in thermoplastic poly(ester-urethane) hydrolysis stability was demonstrated and the origin of this unexpected acid number was discussed. The pronounced stabilizing action of added poly(carbodiimide) in thermoplastic poly(ester-urethane) hydrolysis was shown, as well as the severe destabilizing action of a carboxylic acid, stearic acid. The hydrolysis stabilities of thermoplastic poly(ester-urethane) elastomers based on poly(?-caprolactone) glycol and on poly(hexamethylene carbonate) glycol were also described.     

Tunable fluorescent and antimicrobial properties of poly(vinyl amine) affected by the acidic or basic hydrolysis of poly(N-vinylformamide)

Synthesis of poly(N-vinylformamide) (PNVF) and its subsequent hydrolysis to convert it to poly(vinyl amine) (PVAm) were performed. Kinetics of acidic and basic hydrolysis of poly(N-vinylformamide) (PNVF), and products of hydrolysis were investigated by using Fourier transform infrared, size exclusion chromatography, ¹H NMR, and ¹³C NMR spectroscopies, and thermogravimetric analysis. It was observed that amide groups did not completely transform into amine groups by acidic hydrolysis of PNVF while the conversion of amides into amine groups via basic hydrolysis of PNVF was complete in 12 h, as confirmed by spectroscopic measurements. Results of extensive characterization revealed significant structural and conformational differences between acidic and basic hydrolysis products. Fluorescence spectroscopy was used for the first time to follow the conversion of amide groups into amine groups. The fluorescence intensity of PVAm obtained from basic hydrolysis of PVNF showed significant increase with amide/amine conversion. Finally, PVAm obtained from acidic hydrolysis of PNVF demonstrated potent antimicrobial activity, 10–20 times more, against common pathogens for example, C. albicans as fungal strain and E. coli, S. aureus, B. subtilis, and P. aeruginosa as bacterial strains as compared to PVAm obtained from basic hydrolysis.     

Molecular modeling study of the resistance of PLA to hydrolysis based on the blending of PLLA and PDLA

Molecular modeling has been used to explain how the blending of poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) affects the resistance of poly(lactide) (PLA) to hydrolysis. Amorphous PLLA/PDLA blends were created using molecular modeling, and the minimum potential energy of the blends before and after hydrolysis were obtained. The 50/50 blend has the greatest resistance to hydrolysis, which agrees with past experiments and is due to its having stronger hydrogen-bonding and dipole-dipole interactions than pure PLLA or PDLA. This is based on the 50/50 blend having more of these interactions and shorter average lengths for the hydrogen-bonds and dipole-dipole interactions compared to pure PLLA and PDLA. Hydrogen-bonding possibly has a greater effect than the dipole-dipole interactions on the resistance to hydrolysis. The change in potential energy for hydrolysis decreases linearly with increasing % PLLA or % PDLA from 0 to 50%.     

分子筛催化葡萄糖水解的宏观动力学

分别采用硅铝比为20~25和30的两种ZRP-5分子筛催化剂研究不同温度下葡萄糖水解动力学。研究结果表明,葡萄糖水解属于一级反应,反应温度显著地影响葡萄糖的转化。在相同反应温度下,前者作用下葡萄糖水解的表观反应速率常数大于后者。前者作用下葡萄糖水解的表观活化能为99.24 kJ/mol,后者作用下葡萄糖水解的表观活化能为108.99 kJ/mol。该反应动力学方程的葡萄糖水解转化率计算值与实验值吻合较好。     

Kinetics of continuous hydrolysis of tallow in a multi-layered flat-plate immobilized-lipase reactor

To investigate the feasibility of industrial hydrolysis of tallow in an immobilized-lipase bioreactor, a pilot plant was operated continuously at one gram/min for more than one year. A new thin-layer chromatography (TLC) method was employed for analysis of the composition of the product. Data were reduced by averaging, categorizing, and averaging again. The reduced data were used to calculate rates of the three individual reactions: hydrolysis of triacylglycerol (TG) to diacylglycerol (DG) and free fatty acid (FFA), hydrolysis of DG to monoacylglycerol (MG) and FFA, and hydrolysis of MG to glycerol and FFA. It was concluded that separation of mono- and diacylglycerol from FFA and triacylglycerol would be required to achieve a high concentration of FFA in the product.     

Study of biodegradability of poly(δ-valerolactone-co-L-lactide)s

The biodegradability of poly(δ-valerolactone-co-L -lactide)s was studied both with enzymatic (lipase from Rhizopus arrhizus) and nonenzymatic hydrolyses. The hydrolyzability was evaluated by recording the amount of the hydrolyzed water-soluble products. The enzymatic hydrolysis was considerably affected by copolymer composition. The copolyester, the most susceptible to enzymatic hydrolysis, was the one containing a 90 mol % δ-valerolactone unit. The copolymers were also nonenzymatically hydrolyzed at 70°C. The results were similar to those of enzymatic hydrolysis, confirming the influence of copolymer composition on the hydrolyzability. However, the L -lactide rich copolymers were more susceptible to hydrolysis. These results suggest that poly(δ-valerolactone) is easily degraded by lipase, whereas poly(L -lactide) is degraded through simple hydrolysis. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 741–748, 1997     

秸秆中木质素对其超低酸水解过程的影响

以湖北稻草秸秆为研究对象,研究了超低酸水解木质纤维素的适宜条件,测定了适宜条件下的超低酸法水解15种不同种类秸秆的纤维素及半纤维素的转化率、还原糖得率及结晶度的变化。实验结果表明:秸秆投料量3 g、硫酸投料量45 mL(硫酸质量分数0.05%)、搅拌转速500 r/min、反应温度210 ℃、反应时间10 min为适宜的水解条件。对15种不同种类秸秆的水解结果统计得到,随着秸秆中木质素含量的增大,纤维素和半纤维素的转化率都逐渐降低,还原糖得率逐渐降低;通过SEM和X衍射分析水解前后的木质纤维素结构,得到了木质素影响水解过程的方式:1)木质素含量越大,纤维素的结晶度越大,纤维素的非晶化越困难,从而影响了纤维素的水解;2)原木质素不溶于反应体系且在酸性条件下相对稳定,富木质素层的木质素阻碍反应物与产物扩散,使富木质素层内的纤维素、半纤维素水解速率降低;3)木质素含量越高,木质纤维素的富木质素层越厚、强度越大,水解时难以从颗粒表面脱落,进一步降低水解速率。     

Novel approach toward poly(butylene succinate)/single-walled carbon nanotubes nanocomposites with interfacial-induced crystallization behaviors and mechanical strength

Biodegradable poly(butylene succinate) (PBS)/single-walled carbon nanotube (SWCNT) nanocomposites were successfully prepared through silication and physical blend between PBS and acyl aminopropyltriethoxysilane functionalized single-walled carbon nanotube (SWCNT-APTES), which was obtained from acylate between 3-aminopropyltriethoxysilane and acyl chloride functionalized single-walled carbon nanotube. Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) observations revealed that the PBS chains were covalently attached to the SWCNT-APTES by hydrolysis. PBS/SWCNT-APTES nanocomposites after hydrolysis exhibited strong interfacial interaction between SWCNT-APTES and PBS matrix, leading to a less agglomeration. However, the PBS/SWCNT-APTES nanocomposite prepared by only physical blend without hydrolysis exhibited severe reagglomeration of SWCNT in the PBS. The addition of SWCNT-APTES enhanced the crystallization of the PBS in the nanocomposites for both approaches of hydrolysis and physical blend due to the heterogeneous nucleation effect while the crystal structure of PBS remained. Especially, a more significant increase of crystallization rate for physical blend was present as comparison to PBS/SWCNT-APTES after hydrolysis due to the higher diffusion constant, which is attributed to the change of surface properties of nanotubes. Furthermore, the incorporation of SWCNT-APTES improved the storage modulus of the nanocomposites compared with that of neat PBS. The PBS/SWCNT-APTES nanocomposites after hydrolysis showed of higher tensile strength than PBS/SWCNT-APTES nanocomposite without hydrolysis.     

环氧/氢氧化铝复合材料性能研究

采用水解的KH-560处理微米级Al(OH)3粉末,改善其与树脂基体的表面相容性。通过FTIR对处理后的Al(OH)3进行了表征。优化了偶联剂水解条件及用量,并对不同Al(OH)3填充量的环氧/氢氧化铝复合材料分别采用热常数分析仪及电子万能试验机测试了其热导率和力学性能。结果表明,最佳水解条件为8%的KH-560在pH=4.5溶液中室温水解40 min。当KH-560的质量分数为Al(OH)3的10%左右时,效果最优。材料的热导率随着Al(OH)3填充量的增加而增高。填充量为6%时,力学性能达到最优。     

Enzymatic hydrolysis and detection of 3-monochloropropane-1,2-diol esters

There are more and more studies on the detection method of 3-chloro-1,2-propanediol fatty acid esters (3-MCPD esters) at present, by comparing these methods for the determination of 3-MCPD esters. Indirect methods, which determine total amount of 3-MCPD after hydrolysis of the esters, have an advantage over direct methods. The existing indirect methods, however, may yield unreliable results or require long hours of alkaline methanolysis. In contrast, the indirect enzymatic hydrolysis method has mild conditions and more accurate results. In this study, we developed a reliable and rapid indirect method for determination of 3-MCPD esters. 3-MCPD esters were enzymolysis to 3-MCPD by indirect enzymatic hydrolysis method, and the conditions of enzymatic hydrolysis were optimized, the content of 3-MCPD after enzymatic hydrolysis was detected by gas chromatography–mass spectrometry (GC–MS) and the yield was calculated. Finally, the optimum conditions for enzymatic hydrolysis of 3-MCPD esters were determined. According to the optimal enzymatic hydrolysis condition, the contents of 3-MCPD esters in four food oils were determined. The method is simple and sensitive and can meet the requirement of 3-MCPD esters detection in general oils.