官能化聚烯烃的进展和应用

官能化聚烯烃是由聚烯烃改性后得到的产物,一般通过交联改性、共聚改性、固相力化学改性和接枝改性等方法制备,可应用于黏附、能源和封装等多重领域。基于聚烯烃高通量低成本的优势,聚烯烃接枝改性利用自由基反应直接向聚烯烃链上引入极性单体,较为经济便捷。聚烯烃接枝改性按反应条件的不同,又可分为溶液接枝、熔融接枝、辐射接枝、固相接枝和悬浮接枝。在接枝改性过程中,接枝率和接枝效率受多种因素影响,如聚烯烃型号、接枝单体、引发剂、共单体和反应条件等。本文综述了聚烯烃接枝改性不同接枝方法的研究进展,分析了各种接枝方法的优势和短板,并将接枝改性过程中的影响因素进行了总结。文章依据聚烯烃的可控自由基接枝改性和金属催化改性以及官能化聚烯烃的应用,展望了聚烯烃可控改性和官能化聚烯烃规模化生产。     

聚烯烃熔融接枝改性

熔融接枝技术是聚烯烃改性的一个重要手段,尤其是聚烯烃的挤出熔融接枝技术。本文介绍了聚烯烃熔融接枝的反应机理和动力学模型,以及接枝聚烯烃的定性定量分析测试方法,并探讨了工艺条件、引发剂与接枝单体用量等对聚烯烃接枝率的影响及接枝对聚烯烃结构与性能的影响。     

反应挤出制备GMA接枝聚烯烃研究进展

介绍了化学滴定法和红外光谱分析2种表征甲基丙烯酸缩水甘油酯(GMA)接枝聚烯烃接枝率的方法,分析了GMA熔融接枝聚烯烃的反应机理,从反应挤出接枝物的影响因素、性能变化及其应用等方面介绍了反应挤出制备GMA接枝聚烯烃的最新进展。     

熔融接枝反应改进聚烯烃粘结性的研究

选用丙烯酸（AA）和马来酸酐（MAH）等为接枝改性单体，以DCP（过氧化二异丙苯），DTBP（二叔丁基过氧化物）为引发剂，研究了不同工艺条件下聚烯烃树脂接枝改性后与极性材料（如金属铝箔，尼龙等）的粘结性能以及加入其他树脂稀释后对其性能的影响。研究结果表明，对不同类型的聚烯烃树脂，选用合适的接枝改性单体，引发剂和工艺条件，可以制备出与极性材料粘结性能良好的改性树脂；通过适当的稀释，在提高（对PP类）或不明显降低（对PE类）粘结性能的情况下，可以匀化改性树脂，调整改性树脂的流动性能，此类改性树脂可用作挤出涂覆或共挤出复合的粘结剂，聚烯烃与极性聚合物合金的相容剂或聚烯烃与无机填料共混物的分散剂。     

聚烯烃接枝的研究进展

介绍了以过氧化物为中间产物的聚烯烃本体接枝、链转移反应、多单体熔融接枝的进展情况,重点阐述了表面接枝中的化学方法、利用辐照和光照技术对聚烯烃的表面改性、等离子体工艺及相关的聚丙烯表面改性剂。聚烯烃接枝是制备功能性聚烯烃的主要方法,也是高分子与工程材料领域最活跃的研究热点之一。     

甲基丙烯酸缩水甘油酯接枝聚烯烃及在塑料改性中的应用进展

简单介绍了甲基丙烯酸缩水甘油酯熔融接枝聚烯烃的第二单体、引发剂、反应温度和反应时间等因素对接枝反应的影响,探讨了接枝率的测定方法及接枝聚烯烃在塑料改性中的应用等。     

GMA接枝聚烯烃及在塑料改性中的应用进展

简单介绍了甲基丙烯酸缩水甘油酯(GMA)熔融接枝聚烯烃的第二单体、引发剂、反应温度和反应时间等因素对接枝反应的影响,接枝率的测定方法及接枝聚烯烃在塑料改性中的应用等。     

单环氧化合物接枝改性PA6材料的制备及其性能研究

利用反应挤出法制备了聚酰胺6（PA6）接枝新癸酸缩水甘油酯（GND）改性材料,通过红外光谱分析对改性产物的分子结构进行了测试,并对改性材料的结晶性能、流变性能和力学性能等进行了研究。结果表明,单环氧化合物能够在挤出过程中与PA6发生接枝反应,生成支化PA6产物;接枝链降低了PA6的结晶速率和结晶度,在宏观上相应地表现出材料力学性能的变化;GND最佳用量范围为1~3份,当其用量为1份时,相对于纯PA6,支化PA6的拉伸强度降低了8 %,断裂伸长率和缺口冲击强度分别提高了161 %和35 %。     

反应挤出制备接枝聚丙烯研究

以过氧化二异丙苯(DCP)为引发剂,利用反应挤出技术将马来酸酐(MAH)接枝到聚丙烯(PP)分子链上。详细考查了接枝产物的结构;MAH/DCP配比及反应挤出条件对接枝率的影响;接枝产物的流变性能。结果表明:在适宜的加工条件下,当PP/MAH/DCP的质量比为100∶3.5∶0.3时,可获得较高的接枝率。并且接枝产物的流变性能与PP一样为假塑性流体。     

反应型流滴剂接枝线性低密度聚乙烯的制备、表征及性能

对含有羟基、酯基和双键的反应型流滴剂(D)的结构进行了表征,采用预辐照和反应挤出接枝技术将D接枝到了线性低密度聚乙烯(LLDPE)分子链上,应用FTIR对纯化接枝物的结构进行了表征.研究了单体浓度和反应温度对接枝率的影响,对接枝产物膜的力学性能、透光性能及高温加速流滴性能进行了表征.在60℃时,接枝产物膜的流滴持效期为52天.     

Graft polymerization of N‐tert‐butylacrylamide onto polypropylene during melt extrusion and biocidal properties of its products

Functionalization of polypropylene (PP) by radical graft polymerization with N‐tert‐butylacrylamide (NTBA) was successfully conducted during melt extrusion, and the grafted products were employed as precursors of biocidal N‐halamine polymers. Graft polymerization conditions, including monomer and initiator concentrations, addition of a comonomer styrene (St), were studied. Fourier transformed spectroscopy (FTIR) results and nitrogen analysis confirmed the graft polymerization on PP backbone during the reactive extrusion. The results also indicated that increase in initiator concentration led to more PP chain scission and reduction in mixing torque or polymer chain length. As the monomer concentration rose, grafted monomer content in the products improved, revealing increased grafting copolymerization in the system. Addition of St as a comonomer adversely affected grafting of NTBA, but significantly prevented polymer chain scission. This may be due to lower tendency of NTBA for copolymerization. The halogenated products exhibited potent antimicrobial properties against Escherichia coli, and the antimicrobial properties were durable and regenerable. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

反应加工制备接枝聚合物的研究进展

综述了利用哈克转矩流变仪及采用反应挤出法制备接枝聚合物的特点及接枝体系的选择。另外，以马来酸酐为例，阐述了接枝反应的机理，同时总结了几类可通过反应挤出进行接枝改性的聚合物，并对接枝聚合物的应用进行概括。关于接枝物的表征，主要从纯化方法、接枝的确定、接枝率的测定方法等方面进行了概述。     

反应性挤出原理及应用研究进展

综述了国内外聚合物反应挤出方面的研究进展。从反应挤出的原理和特点、螺杆反应挤出机、反应挤出的应用等方面分别进行了介绍。     

反应性挤出接枝概述

对反应性挤出接枝方法，反应机理，设备及产物表征作一概述。     

Free Radical Graft Polymerization

Abstract

A critical review of the development of free radical graft copolymerization is presented. This is done in the context of a broader review of free radical polymerization. We consider in particular (1) free radical polymerization and copolymerization of two monomers, (2) grafting onto natural rubber primarily to improve its oil resistance and mechanochemical phenomenon in natural rubber, (3) grafting onto polystyrene to improve its mechanical toughness, (4) reactive extrusion to improve properties of polyolefins and make reactive polymers, (5) kinetics of graft polymerization, and (6) grafting of multiple monomers.     

Reactive extrusion vs. batch preparation of starch–g–polyacrylonitrile

Acrylonitrile (AN) was graft polymerized onto unmodified cornstarch by a continuous reactive extrusion process and, for comparison, by a typical batch reaction process. The effect of AN/starch weight ratios, level of ceric ammonium nitrate (CAN) initiator, starch in water concentration, reaction temperature, reaction time, and extruder screw speed in the reactive extrusion process was studied. Add-on, reaction efficiency, grafting frequency, weight average molecular weight (MW) and MW distribution of polyacrylonitrile (PAN), and water absorbency of the saponified copolymers were determined. Processing times in the twin-screw extruder (ZSK) were 2–3 min, and total reaction time was about 7 min before reaction of the extruded material was terminated, compared to a reaction time of 2 h used in the typical batch procedure. The continuous reactive extrusion process was found to be a rapid and efficient means of preparing St-g-PAN with high add-on (% PAN of the grafted product). For example, 42% add-on was achieved within the 7-min reaction period using an AN/starch weight ratio of 1.0 (3.5% CAN, starch weight basis), as compared to 38–49% for the 2-h batch process (0.75–1.5 AN/starch ratio). Percentages of homopolymer of the copolymers were low for both extrusion and batch processes. Grafting frequencies were substantially higher while MWs were significantly lower for grafts from the extrusion process. Water absorbency of the saponified St–g–PAN products was somewhat greater for the products prepared by the batch process.     

双螺杆挤出过程数值模拟研究进展

在聚合物的双螺杆挤出过程的研究中，采用数值模拟的方法可以克服传统实验方法的局限，可为挤出机的设计加工提供参考。回顾了近年来国内外对双螺杆挤出过程数值模拟的研究成果，介绍了一维数学模型和三维数学模型对挤出过程进行数学描述的优缺点，从双螺杆挤出机内部的流场特性、瞬态混合性能、停留时间分布以及反应挤出等方面综述了相关研究进展，并对双螺杆挤出过程数值模拟的今后发展方向进行了展望。     

反应挤出聚丙烯接枝马来酸二丁酯的研究

以马来酸二丁酯(DBM)为单体,反应挤出聚丙烯(PP)接枝DBM(PP-g-DBM).研究了口模温度、螺杆转速、单体用量、引发剂过氧化二异丙苯(DCP)对接枝率和熔体流动速率的影响,并用红外光谱(IR)、差示扫描量热等测试方法对接枝物进行了表征与分析.结果表明,DBM是用于反应挤出加工的良好接枝单体;IR表征DBM接枝到PP分子链上,且接枝产物中DBM残留量较少;PP、DBM、DCP接枝的最佳温度为190～200℃,螺杆转速不宜过高,DCP的适宜质量分数为0.04%～0.10%.     

Amylose graft polymers made by 60Co gamma-irradiation

Model products were needed to elucidate structure–property relationships in a starch graft polymer research program. Simultaneous irradiation of amylose and acrylamide in oxygen-free, dilute aqueous solutions gave graft polymers with maximum add-on of about 16%. The graft polymers were separated from homopolymer and subfractionated by incremental additions of nonsolvent (methyl or ethyl alcohol) to irradiated aqueous reaction media. The graft polymers were fairly homogeneous in graft content. Effects were determined of ratios of monomer to substrate, dose rate, and total dose on yield, graft content, intrinsic viscosity, and homopolymer characteristics. Under some conditions, crosslinks probably formed between graft side chains. Large differences in solution properties of a synthetic mixture of separately irradiated amylose and acrylamide and an irradiated solution of amylose and acrylamide indicated that grafting had occurred. Further evidence for true grafting was based on the action of a selective precipitant, n-butyl alcohol, on graft polymer solutions.     

反应挤出技术在高聚物本体聚合中的应用进展

反应挤出技术是高聚物加工的一种新技术，是目前国际上竞相投资的热点。在高聚物本体聚合中反应挤出技术具有广阔的发展前景。重点介绍了反应挤出技术的特点，阐述了用反应挤出技术进行本体聚合制备高聚物的优点，综述了国内外近十年来反应挤出技术在高聚物本体聚合中的应用进展。