聚乙烯醇的阳离子化改性研究

以三甲胺(TMA)和环氧氯丙烷(EPIC)为原料合成了活性中间体失水甘油基三甲基氯化铵(GTA),用该中间体在碱性条件下对聚乙烯醇进行改性,可制得季铵盐型阳离子聚乙烯醇膜材料。通过实验确定GTA最优合成工艺条件为n(TMA)∶n(EPIC)=2∶1,反应温度20℃,反应时间4 h;季铵盐型阳离子聚乙烯醇最优合成工艺条件为n(Na OH)∶n(GTA)∶n(PVA)=4∶2∶1,反应温度60~70℃,反应时间5 h,终产物收率达80.01%。     

环氧丙基三乙基氯化铵的合成与表征

环氧丙基三乙基氯化铵(GTA)为新型高效活性醚化剂,可用于改性含活泼氢的有机物合成阳离子化产物,用途广泛。以环氧氯丙烷(EPIC)与三乙胺(TEM)反应合成GTA,实验得出GTA的最佳合成条件为:磁力搅拌下,n(TEM)∶n(EPIC)=1∶3,反应时间为2.5 h,反应温度为25℃,GTA的收率为97.36%,熔点为139.6℃。通过元素分析和IR对产品进行了表征。     

高效活性醚化剂失水甘油基三甲基氯化铵的合成与表征

失水甘油基三甲基氯化铵(GTMAC)有高反应活性的醚键,可用于有机合成和作为接枝改性剂。以环氧氯丙烷(EPIC)与三甲胺(TMA)反应水法合成GTMAC,实验得出GTMAC的最佳合成条件为:n(TMA)∶n(EPIC)为0.3,反应时间6.5 h,反应温度20℃,最佳溶剂为EPIC,GTMAC的收率为92.5%,测定其熔点为137~139℃。并对产物的环氧值、吸湿性进行了测试,通过IR对产品进行了表征。     

聚乙烯醇改性研究进展

综述了聚乙烯醇(PVA)在醋酸乙烯共聚前后改性的方法和原理,前期改性是选用带有酰胺基、羧 基、环氧基、磺酸基的不饱和化合物与醋酸乙烯共聚;后期改性是通过PVA上醇羟基的缩醛化酯化、醚化等 化学反应以及Michael加成反应等实现。指出应注重高低聚合度,低醇解度PVA和改性PVA产品的开发。     

聚乙烯醇醚化改性及影响因素研究

选用环氧氯丙烷为醚化剂,以10%的氢氧化钠溶液或0.5%的硫酸溶液为催化剂对聚乙烯醇(PVA)进行醚化。对PVA与环氧氯丙烷的物质的量比、反应时间和反应温度等三个因素进行研究。实验结果表明,醚化最佳条件为:所选溶剂为二甲基亚砜,PVA和环氧氯丙烷的物质的量比为1.5∶1.0,醚化温度为65℃,反应时间为6 h。在最佳醚化条件下,PVA的最大醚化度可达50%。     

脂肪醇醚化接枝聚乙烯醇合成高耐水性树脂

采用聚乙烯醇(PVA)与脂肪醇进行醚化接枝反应,通过红外光谱分析和对接枝聚合物耐水性能测试研究了从不同的脂肪醇,反应温度、反应时间及反应物配比对产物的影响。通过正交实验方法确定了最佳反应条件:以浓H2SO4为催化剂,二甲亚砜为醚化溶剂、正辛醇为醚化剂,醚化反应温度120℃、反应时间2h、PVA与正辛醇物质的量比为1∶1.2。在此反应条件下合成的接枝聚合物耐水性能最好,蒸馏水抽提后的余重高达98.03%,属高耐水性树脂。     

甲苯二异氰酸酯和硼砂交联改性聚乙烯醇胶水的研究

探讨了硼砂和甲苯二异氰酸酯 ( TDI)对聚乙稀醇 ( PVA)胶水进行交联改性。采用正交实验法研究硼砂和 TDI的加入量对 PVA粘合剂的耐水性能和剥离强度的影响。利用硼砂、TDI与 PVA反应产物的水不溶性判断该交联反应的进程。研究结果表明 ,少量硼砂和 TDI能较大程度地提高 PVA胶水的耐水性能和粘结性能     

醚化改性麦糟吸附材料的制备及其对亚甲基蓝的吸附

以麦糟(RSG)为基材,氯乙酸为醚化剂,NaOH为催化剂,制备了醚化改性麦糟(MSG),研究了MSG对亚甲基蓝(MB)的吸附性能.考察了改性条件对MB吸附效果的影响.结果表明,在固液比1:50(g:mL)、n(NaOH):n(ClCH2COOH)=1.25:1.0、醚化温度为75℃、醚化时间为2.5 h的条件下,制得的MSG对MB吸附效果最好,吸附量达到201.20 mg/g.采用SEM、N2吸附-脱附、FTIR、XPS和零电荷点技术对改性前后麦糟的外观形貌、比表面积和孔径分布、表面性质等进行了表征.Langmuir方程和拟二级动力学方程可很好地描述MSG吸附MB的过程,化学吸附为其主要吸附方式.     

一种新型季铵盐松香表面活性剂的合成与表征

改性松香可以合成一系列性能优良的表面活性剂。以松香、三乙胺(TEA)和环氧氯丙烷(EPIC)为主要原料,合成了新型季铵盐松香阳离子表面活性剂(3-松香酰氧-2-羟丙基-N,N,N-三乙基氯化铵),并采用红外光谱(FT-IR)和元素分析对该表面活性剂的结构进行了表征。研究结果表明:超声条件下合成该表面活性剂的最佳工艺条件是n(松香)∶n(TEA)∶n(EPIC)=1.5∶1.0∶1.3、p H为8~9、反应温度为85℃和反应时间为1.5 h,此时该表面活性剂的产率达到93.72%且性能良好。     

改进的Williamson醚化法合成葡萄糖衍生物

以葡萄糖衍生物、碱金属氢氧化物、氯化苄为原料,以正辛烷为带水剂,经Williamson醚化反应合成了3个苄醚化葡萄糖衍生物。考察了带水剂、碱、苄醚化试剂及投料比对反应的影响,得到优化的反应条件为:n(底物羟基)∶n(氢氧化钾或氢氧化钠)∶n(氯化苄)=1.00∶(1.10~1.15)∶(1.10~1.15),正辛烷为带水剂,125~130℃保温回流脱水反应4 h,在该条件下产物产率为96.8%~98.2%。产物结构经FTIR、UPLC-MASS、1HNMR确证。     

我国聚乙烯醇改性技术进展

综述了国内聚乙烯醇改性技术的进展情况.改性方法包括:共聚、共混和聚合物后反应(涉及醚化、醇化、缩醛化、交联、降解及表面改性等)三大类.较为详细地介绍了聚乙烯醇纤维的改性.并对我国聚乙烯醇工业的发展进行了展望.     

聚乙烯醇胶的改性及性能测试

以丁二酸为交联剂,对聚乙烯醇（PVA）胶进行改性;并对改性PVA胶的粘度、硬度、附着力、抗冲击力、固化程度和红外光谱进行测试。确定最佳改性条件如下：PVA胶质量浓度7%、反应温度85℃、PVA胶与丁二酸质量比5.6∶1,在此条件下,可得到性能优良的改性PVA胶。     

Etherification of hemicelluloses from sugarcane bagasse

Conditions for the preparation of etherified hemicelluloses from sugarcane bagasse with 2, 3‐epoxypropyltrimethylammonium chloride (ETA) using sodium hydroxide as a catalyst in aqueous solution were studied comparatively. The extent of the etherification was measured by yield percentage and degree of substitution. The effects of reaction time of 3–7 h, reaction temperature of 50–80°C, temperature of alkaline activation of 30–60°C, and time of alkaline activation of 0–60 min on the reaction yield and degree of substitution were investigated in detail. The overall yield and degree of substitution were varied from 35.2 to 41.9% and from 0.14 to 0.33, respectively, by changing the reaction temperature and duration as well as time and temperature of alkaline activation. The new materials were characterized by FT‐IR and 13C NMR spectroscopy, thermal analysis as well as GPC. It was found that the thermal stability of the hemicellulosic ethers decreased after chemical modification, and the molecular weights of the etherified hemicelluloses were lower than those of the native hemicelluloses. ¹³C NMR spectra gave the evidence for etherification reaction and the quaternization of hemicelluloses occurred mainly at C‐3 position. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

聚乙烯醇缩乙醛酸树脂的研制

聚乙烯醇缩醛型胶粘剂可通过聚乙烯醇(PVA)与醛类缩合而得,其性质取决于原料PVA的结构、水解程度、醛类的化学结构和缩醛化程度等。将PVA与乙醛酸(无毒、无味和不挥发)进行缩醛化反应,可制备出一种安全环保型聚乙烯醇缩乙醛酸树脂(PVGa)胶粘剂。以n(乙醛酸)∶n(PVA中-OH基)比例、反应时间、反应温度和PVA水溶液浓度为试验因素,缩醛度为衡量指标,采用正交试验法优选出制备PVGa的最适宜工艺条件。结果表明:当反应温度为80℃、PVA水溶液浓度为15%、n(乙醛酸)∶n(PVA中-OH基)=1∶5和反应时间为40min时,PVGa的缩醛度为39.85%;PVGa的吸湿性能比PVA高4～6倍,PVGa的力学性能优于PVA,两者的热失重情况基本相似。     

Synthesis and characterization of isocyanate-functionalized PVA-based polymers with applications as new additives in lubricant formulations

This work deals with the incorporation of reactive isocyanate groups into polymer additives, which could be potentially used to modify the rheological properties of lubricating greases by reinforcing the role of traditional thickening agents. Thus, a batch of partially protected poly(vinylalcohol) (PVA) copolymers was successfully synthesized. Some of their  OH groups were blocked as tetrahydropyranyl (THP) ethers (PVA–THP), while the spare hydroxyl groups were further functionalized with  NCO pendant groups by reaction with 1,6-hexamethylene diisocyanate, leading to several isocyanate-functionalized PVA-based polymers (PVA–THP–NCO), which were tested as rheology modifiers of lithium lubricating greases. The highest protection degree of hydroxyl groups achieved as THP-ether was 58.5% and the recovered polymers were isolated with excellent yields (close to 90% in most cases). NCO-functionalized PVA-based polymers (PVA–THP–NCO) exerted a significant rheological modification in lithium 12-hydroxystearate lubricating greases, increasing the values of the linear viscoelastic functions. The influence of the degree of protection and later functionalization of PVA on the rheological properties of PVA–THP–NCO-additivated lubricating greases is discussed. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Crosslinking reaction of poly(vinyl alcohol) with poly(acrylic acid) (PAA) by heat treatment: Effect of neutralization of PAA

The crosslinking reaction of poly(vinyl alcohol) (PVA) by esterification using poly(acrylic acid) (PAA) as a crosslinking reagent was investigated to obtain highly insoluble PVA materials. Blend films of PVA and PAA (PVA/PAA = 8/2) were prepared to examine the effect of degree of neutralization (DN) in PAA and heat‐treatment conditions on the degree of crosslinking reaction. The degree of crosslinking reaction varied significantly when the DN of PAA changed. The optimum DN for the crosslinking reaction was in the range of 5 to 10 mol %. In the case of unneutralized PAA, the degree of crosslinking reaction was at most 15 mol % by heat treatment for 20 min at 200°C. Applying partially neutralized PAA (DN = 10 mol %) raised the degree to about 40 mol % under the same heat‐treatment conditions. FTIR analysis revealed that the hydroxyl group of PVA in the film blended with unneutralized PAA was degraded to a greater degree than that with partially neutralized PAA as a result of heat treatment. It was found that heat treatment at a low pH condition enhances the degradation of the hydroxyl group of PVA, resulting in a decrease of the number of crosslinking sites by esterification. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2420–2427, 2003