ZIF-67掺杂纸基锂离子电池隔膜的制备及其性能研究

本研究将二甲基咪唑钴（ZIF-67）添加到剑麻浆料中,抽滤后制备ZIF-67掺杂纸基锂离子电池隔膜。结果表明,随着ZIF-67掺杂量由0增加至30%,纸基锂离子电池隔膜的孔隙率由74.5%降至45.5%,亲液性增加,离子电导率由0.29 mS/cm提高至2.58 mS/cm,界面电阻由467 Ω减小至210 Ω,电化学稳定窗口由4.6 V增加至5.2 V。当ZIF-67掺杂量为30%时,组装的锂离子电池在循环50次后容量保持率高达90%。剑麻纤维经羧甲基化改性后,纸基锂离子电池隔膜的孔隙率增加,各项电化学性能也有所提高,但由于其机械强度较差,导致其电池容量快速衰减。     

Influence of carboxymethylation on the gelling capacity,rheological properties,and antioxidant activity of feruloylated arabinoxylans from different sources

Feruloylated arabinoxylans (FAX) are gelling polysaccharides presenting antioxidant activity (AC) and potential application as delivery systems. The influence of carboxymethylation on the gelling capacity, rheological properties, and AC of FAX from wheat flour (FAX1) and maize distillers grains (FAX2) was analyzed. The degree of substitution of carboxymethyl groups was 0.27 and 1.77 for carboxymethylated FAX1 (CFAX1) and FAX2 (CFAX2), which presented a change in M _n from 446 to 362 kDa and from 120 to 180 kDa, and a loss in FA content from 1.05 to traces and from 10.13 to 0.12, respectively, after carboxymethylation. G′ value at the end of rheological tests for FAX1 (71 Pa) and FAX2 (726 Pa) was higher than the corresponding G″ value. In contrast, G″ value for CFAX1 (0.35 Pa) and CFAX2 (0.03 Pa) was higher than the respective G′ value, indicating that they do no form gels. The AC increased in CFAX1 in relation to FAX1 from 4.49 to 8.30 mmol Trolox equivalent antioxidant capacity (TEAC) kg⁻¹, respectively, while it decreased in CFAX2 with regard to FAX2 from 11.31 to 9.43 mmol TEAC kg⁻¹, respectively. Carboxymethylation could be a path to design FAX derivatives offering alternative potential applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48325.     

响应面分析优化菊粉的羧甲基改性工艺

研究菊粉的羧甲基改性工艺条件,以碱化时间、醚化温度、醚化时间、碱用量以及氯乙酸用量为影响因素,以羧甲基的取代度为考察指标,运用Plackett-Burman设计筛选出3个对菊粉羧甲基取代度影响显著因素,即碱化时间、醚化温度和氯乙酸用量,采用响应面分析试验优化菊粉的羧甲基改性工艺。菊粉的羧甲基改性最优工艺条件为菊粉用量6.8g、碱化时间30min、醚化温度81℃、氯乙酸用量2.96g,此时菊粉的羧甲基取代度为0.66±0.000167。     

壳聚糖的化学改性方法及其应用

介绍了壳聚糖的化学改性方法及改性机理,并简述了壳聚糖及其改性物在造纸工业中的主要应用.     

羧甲基葛根淀粉的制备及其流变特性的研究

研究了葛根淀粉羧甲基化改性的最佳条件以及羧甲基化改性对葛根淀粉流变学特性的影响。结果表明，在淀粉乳浓度为12％，一氯乙酸与淀粉的摩尔比为0．7，氢氧化钠与淀粉的摩尔比为1．4，温度为45℃，醚化反应时间为1．5h时，羧甲基化取代程度最大，取代度为1．42。对羧甲基淀粉流变学特性的研究表明，随淀粉溶液浓度的增加，溶液粘度也随之增加，添加蔗糖对溶液粘度影响不大，而添加氯化钠对溶液粘度有显著影响；在强酸强碱性条件下，溶液的粘度较低，而在中性条件下溶液粘度保持在高水平上；随溶液温度的升高，粘度以指数形式迅速减小。     

微波辅助法由豆渣制备羧甲基纤维素

以豆渣为原料用超声波清洗除杂后,经微波辅助碱化、醚化制备羧甲基纤维素。通过正交试验和单因素考察优化得到的碱化最佳条件是:m豆渣粉∶mNaOH=1∶1~1.5、m豆渣粉∶m95%乙醇=1∶1.6~2.2、微波辐照下在30~35℃时碱化5~10min;醚化的最佳条件是:m豆渣粉∶m氯乙酸(氯乙酸∶碳酸氢钠=1∶0.5~0.6)=1∶1~1.5、m豆渣粉∶m95%乙醇=1∶1.8~2.6,微波辐照下在50~60℃时醚化10~20min后,羧化中水质量分数为30%~40%,可制得高纯度的豆渣CMC。经测定,在最佳制备条件下制得的豆渣CMC产品的取代度和黏度分别达到了1.096 5、596 MPa.s,较无微波辅助时的取代度0.745 2和黏度467MPa.s分别提高了47.1%、27.6%。所制备的CMC达到了GB 1904—1989食品添加剂的性能要求。     

魔芋葡甘聚糖羧甲基化食品增稠剂的制备及分析

以魔芋葡甘聚糖（konjac glucomannan,KGM）为原料,将其羧甲基化制备了一种食品增稠剂。傅里叶变换红外光谱结果表明,羧甲基基团己被引入到KGM分子上;扫描电子显微镜结果显示,羧甲基化KGM（carboxymethyl konjac glucomannan,CMKGM）表面有很多凹痕;热重分析结果表明,CMKGM热稳定性较KGM
增强。此外,CMKGM在水溶液中的黏度测试表明：随着剪切速率和温度的增加,其表观黏度减小;随着CMKGM质量分数的增加,其表观黏度增大;随着溶液pH值的升高,其表观黏度先增大后减小。     

汽爆玉米秸秆羧甲基纤维素的制备

秸秆是自然界中资源丰富的天然木质纤维素原料, 本研究以秸秆为反应原料,采用无污染蒸汽爆破技术活化预处理,然后进行羧甲基化反应,通过反应产物理化性质的不同实现秸秆的组分分离并制备出高附加值的羧甲基纤维素。实验结果表明：制备羧甲基纤维素的最优条件为液固比（ml∶g）18∶1,氢氧化钠∶氯乙酸钠(摩尔比)为4∶3,H₂O/底物（ml∶g）为1∶2,75℃反应2 h。在优化的反应条件下,从羧甲基化产物中可分离得到40.70%的羧甲基纤维素,其取代度可达0.91, 而且具有低黏的性质,并利用红外图谱和¹H NMR进行了分析表征;同时,还可从羧甲基化产物中分离出木质素组分,可进一步拓展其在工业方面的用途。相对于目前工业上普遍采用的α-纤维素含量较高的棉浆和木浆等反应原料,不仅原料和预处理成本大为下降, 工艺流程更为简单,而且还实现了秸秆的组分分离与全利用。     

A study on the sorption of NO3− and F− on the carboxymethylated starch‐based hydrogels loaded with Fe2+ ions

Using the principle of geochemistry of fluoride, green and cost effective anion adsorbents were developed for the removal of F^? from water systems. The scheme was further applied for the removal of NO₃^? also. Carboxymethylated starch functionalized through network formation with acrylamide was used as adsorbent, and the resultant hydrogels were loaded with Fe²⁺ ions to generate anchorage for the anions. Sorption of Fe²⁺ was studied as a function of different factors such as time, temperature, pH, and ion strength. The network having the highest Fe²⁺ uptake was loaded with the Fe²⁺ ions under optimum conditions and used for the sorption of F^? and NO₃^?. High efficiency has been observed for F^?, as even up to 100% uptake has been observed within just 10 minutes. The support shows high selectivity for NO₃^?, which was used as anion reference. Thermodynamics of sorption confirms low order and low energy processes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

羧甲基蔗渣木聚糖的合成与表征

以蔗渣木聚糖和一氯乙酸为主要原料,乙醇水溶液为溶剂,冠醚为催化剂,经碱活化、醚化反应两步合成了羧甲基蔗渣木聚糖。考察了物料摩尔比、反应时间、反应温度和溶剂中水含量等因素对合成工艺的影响,确定的较佳工艺条件:n(蔗渣木聚糖结构单元)∶n(氢氧化钠)∶n(一氯乙酸)=1∶3.25∶1.25,溶剂V(乙醇)∶V(水)=4∶1,45℃碱化2 h,70℃醚化3 h,所得羧甲基化产物的取代度可达0.59。用FTIR与SEM对原料和产物的结构进行了表征。热分析表明,反应后蔗渣木聚糖在234~312℃内分解量由总质量的46.27%降至30.58%。质量浓度为12 g/L的产物水溶液的表面张力为63.6 mN/m。