反应性挤出聚丙烯接枝偶联马来酸酯的研究

在过氧化物的存在下,聚丙烯(PP)易于降解,因而进行反应性挤出接枝是很困难的。选用偶联马来酸酯(CMAE)为单体,通过反应性挤出加工使PP分子链接枝上极性官能团,从而防止了PP的降解。其产物接枝率较高,外观光滑、无气泡,具有广泛的应用价值。     

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。     

聚酰胺6/黏土/聚乙二醇共混调温纤维的制备与性能

通过熔融纺丝法制备了系列聚酰胺6/黏土/聚乙二醇(PTFs)共混调温纤维,并采用傅里叶红外光谱仪、差示扫描量热仪、热红外成像仪、热失重分析仪和复丝强力仪测试了纤维的结构、热性能、调温性能和力学性能。研究显示,PTFs调温纤维的结晶温度为33℃,结晶焓值达到8.46 J/g,且在100次升降温热循环后调温纤维仍保持良好的热性能。通过模拟冷热环境交替下纤维的温度—时间响应行为发现,在热环境(90℃)和冷环境(10℃)下,调温纤维体现出明显的温度滞后响应,与纯PA6纤维相比温差达到3℃。黏土/聚乙二醇在纤维中的最大质量分数为15%,在牵伸4倍时,纤维的拉伸断裂强度达到3.15 cN/dtex。     

聚酰胺6蓄热调温纤维的制备与表征

以聚乙二醇为储能调温介质,通过多孔纳米材料吸附制备了形态稳定的相变材料(PCMS),然后以聚酰胺6(PA6)为基体,采用熔融共混纺丝制备了蓄热调温PA6纤维。通过场发射扫描电子显微镜、差示扫描量热仪、热重分析仪、粉末X射线衍射仪表征了纤维的结构和性能。研究表明:熔纺PA6/PCMs纤维储能调温焓值达到19.01 J/g,预期可在航空服、军用作战服和民用服装等领域获得很好的应用。     

反应性挤出聚乙烯接枝低偶联马来酸酯

将低密度聚乙烯(LDPE)、过氧化二异丙苯(DCP)、低偶联马来酸酯(LCME)均匀混合后,在单螺杆挤出机中进行反应性挤出,得到聚乙烯接枝低偶联马来酸酯(PE-LCME)产品。红外光谱分析确证有部分LCME接枝到PE分子链上。示差扫描量热法(DSC)测定揭示了反应性挤出过程中化学反应的起始温度、峰温和终止温度,以及在静态下反应所需的时间。并且从不同升温速度的DSC曲线可以初步确定挤出温度及分布。反应性挤出得到PE—LCME的接枝率(G)随PE的型号、不同DCP的浓度而呈规律性变化。     

聚丙烯纤维与丙烯酸接枝共聚反应的研究

用高锰酸钾 /硫酸作为引发体系 ,聚丙烯纤维与丙烯酸进行接枝共聚反应。研究聚丙烯纤维接枝率与硫酸浓度、丙烯酸浓度、高锰酸钾浓度、高锰酸钾预处理纤维时间、预引发时间、聚合温度和反应时间的关系。结果表明 :硫酸浓度为 0 .2 mol/ L,高锰酸钾浓度为 5× 10 - 3mol/ L,丙烯酸浓度为 0 .8mol/ L,高锰酸钾预处理时间为 30 min,预引发时间为 32 min,反应温度为 80℃ ,反应时间为 3.5h时 ,接枝率较高。     

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%.     

CPCM/PP蓄热调温纤维的制备及表征

采用熔融复合纺丝法,通过自制的复合纺丝组件,以聚丙烯(PP)为皮层,由脂肪酸酯类和高级酯肪族醇类组成的复合相变材料(CPCM)为芯层,制备了具有皮芯结构的CPCM/PP蓄热调温纤维,并对纤维的结构与性能进行表征。结果表明:CPCM/PP初生纤维呈皮芯结构,其直径约为100μm;当CPCM/PP质量比为55∶45时,其初生纤维在70℃下5倍拉伸后,得到的CPCM/PP蓄热调温纤维中CPCM的质量分数为53.63%,熔融相变温度与结晶相变温度分别为32.65~48.02℃和20.96~39.02℃,熔融焓和结晶焓分别为90.04,81.01 J/g,纤维线密度为10.3 dtex,断裂强度为2.59 cN/dtex,断裂伸长率为41.38%。     

相变调温纤维的制备技术研究进展

介绍了相变材料的分类及各自的性能特点,综述了目前相变微胶囊及相变调温纤维的制备方法,并指出了不同制备方法存在的优缺点及应用范围。目前,适用于纺织领域的相变材料主要为有机相变材料石蜡;相变微胶囊的制备主要采用化学法,该方法在纺织领域应用较多,关键技术是乳化工艺;相变调温纤维的制备多采用复合纺丝法和后整理法,但存在相变微胶囊的制备工艺较复杂、加入相变材料损伤纤维机械性能、相变调温纤维经过纺纱及织造等流程后调温能力减弱等问题。指出相变微胶囊的制备技术、相变调温纤维的制备工艺、相变材料的保持率及温度调节能力的稳定性等是相变调温纤维未来发展的重点研究方向。     

Preparation of polypropylene‐graft‐cardanol by reactive extrusion and its composite material with bamboo powder

The polypropylene‐graft‐cardanol was prepared by reactive extrusion, which is solvent‐free melt process, continuous processing, and controllable over residence time. The effect of monomer and initiator concentration on grafting ratio, grafting efficiency, and melt flow index (MFI) was also studied. The yield was quantified by UV–vis spectrometer. The chemical structure was investigated by infrared spectroscopy and gel ratio. A possible mechanism was supposed. The particular structure of cardanol can retain the MFI value of matrix resins and prevent polypropylene (PP) from being decomposed. The grafting ratio could be easily obtained from an experimental formula deduced from the linearity relationship between grafting ratio and MFI. The effect of cardanol grafted onto PP on the compatibility of PP and bamboo powder was studied by contact angle measurements, scanning electron microscopy, and tensile properties test. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

POE/PP体系的反应挤出接枝马来酸酐研究

通过研究辛烯-乙烯共聚物/聚丙烯（POE/PP）比例。第二反应单体的选择，马来酸酐（MAH）单体和过氧化二异丙苯（DCP）用量变化以及反应温度，螺杆转速，真空度对接枝产品性能的影响情况，找出了适合于工业生产的最佳配方和工艺条件，即POE/PP为60：40，MAH为1.5%，DCP为0.04%，提纯苯乙烯为1.5%。螺杆转速为45r/min，真空度为-0.10MPa，螺筒各段温度为160，190（反应段），190（除杂段），150（机头）℃。     

利用反应挤出的聚丙烯熔融接枝改性

系统简介了聚丙烯熔融接枝体系的组成、机理及实现熔融接枝的反应挤出技术。介绍了聚丙烯接枝物的表征和应用状况，并指出了熔融接枝体系中存在的问题。     

Comparison of maleic anhydride grafting onto powder and granular polypropylene in the melt by reactive extrusion

The grafting of powder and granular polypropylene (PP) with maleic anhydride (MA) was investigated in a reactive extrusion process with dicumyl peroxide (DCP) as an initiator. The effects of the MA and DCP contents in the feed on grafting were investigated. Under the experimental conditions applied in this study, the grafted monomer unit content was varied from 0.023 to 0.5%. The MA grafting efficiency of powder PP was higher than that obtained for the granular form of PP. In general, the grafting degree first increased with the MA or DCP content in the feed, then reached a maximum value, and finally decreased because of several possible alternative reactions during the grafting. The grafting of powder PP was more successful because of better initial mixing and less diffusional resistance during the grafting. An increase in the MA content in the feed caused significant reductions in the melt‐flow index of the graft copolymers. The results obtained with Fourier transform infrared, differential scanning calorimetry, and X‐ray powder diffraction analyses indicated that the structure, macrotacticity, crystallinity, crystallization, and thermal behavior of PP changed with grafting and depended on the grafting degree. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3675–3684, 2004     

Grafting of maleic anhydride onto polypropylene by reactive extrusion

Maleic anhydride grafting onto polypropylene was conducted in a twin‐screw extruder according to an experimental design in which the maleic anhydride and peroxide concentrations were varied. The modified polypropylene was characterized by FTIR spectroscopy, melt‐flow index measurements, size‐exclusion chromatography, differential scanning calorimetry, and nuclear magnetic resonance. The results showed that only the independent variable peroxide concentration influenced the amount of reacted maleic anhydride, whereas the two variables studied influenced the molecular weight of the grafted polypropylene. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2706–2717, 2002     

Polypropylene degradation control during reactive extrusion

In this work, a proportional‐integral‐derivative (PID) control scheme with two different tuning methods to control the degree of degradation of polypropylene (PP) during reactive extrusion is proposed. The concentration of dicumyl peroxide is taken as the manipulated variable. The molten viscosity of PP under processing is taken as the controlled variable. The degree of degradation is determined by a viscosity function derived by an off‐line identification. A first‐order‐plus‐time‐delay empirical model is identified to simulate the system plant. Both Ziegler–Nichols tuned PID and internal model control (IMC)‐based PID controllers are implemented on the system. Better performances in settling time and precision can be achieved using the IMC‐based PID controller. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 280–289, 2005     

反应挤出制备高熔体强度PP

采用反应挤出方法制备高熔体强度聚丙烯,通过凝胶渗透色谱仪、差示扫描量热仪、偏光显微镜等研究了改性产品的结构与性能,并进行挤出发泡应用实验。结果表明：采用特殊的过氧化物引发剂和支化促进剂,与聚丙烯基础树脂共混后通过双螺杆挤出机熔融连续反应挤出,可以直接制备具有长链支化结构的聚丙烯,熔体强度提高300％;挤出发泡试样泡孔均匀,发泡倍率达到50倍,具有较好的可发性能。     

反应挤出马来酸酐接枝聚丙烯的结构与性能

选择最佳的配方和工艺条件,制备了每100g试样总酐基含量为8．1mmol的马来酸酐接枝聚丙烯(PP-g-MAH)产品、通过化学分离和红外光谱分析,发现PP-g-MAH产品的纯度很高,几乎没有游离态的MAH。广角X射线衍射实验发现,PP经过接枝处理后,晶型没有改变,但040晶面明显增大;晶胞在a和c轴上变化不大．在b轴上减小;结品度略有上升：通过分析接枝物的流变性能,发现接枝物与PP一样．仍属于非牛顿型假塑性流体。实验证明,PP-g-MAH产品具有良好的可注塑性。     

Rheological properties of high melt strength poly(ethylene terephthalate) formed by reactive extrusion

A reactive extrusion process was developed improving the rheological properties of PET via the coaddition of a dianhydride and polyol. Specifically, the coaddition of pyromellitic dianhydride (PMDA) with pentaerythritol resulted in a gel‐free polyester with superior melt strengths and viscosities compared to the addition of PMDA alone. The enhancement in rheological properties were dependent on the relative amounts of dianhydride and polyol with the resultant polyester structurally stable in the melt. These results are consistent with the formation of a hyperbranched polyester with long chain branches. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3646–3652, 2006     

Chain extension of poly(butylene terephthalate) by reactive extrusion

The chain extension reaction in poly(butylene terephthalate) (PBT) melt was studied in detail. A high‐reactivity diepoxy, diglycidyl tetrahydrophthalate, was used as a chain extender that can react with the hydroxyl and carboxyl end groups of PBT at a very fast reaction rate and a relatively high temperature. A Haake mixer 600 was used to record the torque during the chain extension reaction. The data show that this chain extension reaction could be completed within 2 to 3 min at temperatures above 250°C, and the reaction time decreased very fast with an increase in the temperature. Shear rate also had some effects on the reaction rate. The effect of the diepoxy chain extender on the flowability, thermal stability, and mechanical properties of PBT were investigated. The melt flow index (MFI) of the chain‐extended PBT dramatically decreased as the diepoxy was added to PBT. In addition, the notched Izod impact strength and elongation‐at‐break of the chain‐extended PBT also increased. The chain‐extended PBT is more stable thermally. Compared with the conventional solid post‐polycondensation method, this approach is simpler and cheaper to obtain high‐molecular‐weight PBT resins. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1827–1834, 1999