Novel polypropene materials derived from vinylidene-terminated oligopropenes

Metallocene-based homogeneous Ziegler–Natta catalysts produce mono-olefin-terminated oligopropenes with narrow molecular weight distributions, controlled stereoregularities, and molecular weights ranging from 100 to 30,000 g/mole in high yield slurry and solution processes. Steric and molecular weight control are influenced by metallocene structures, and by polymerization conditions such as temperature and propene concentration. Predominantly mono-vinylidene-terminated oligopropenes are attractive intermediates, and feedstock for the synthesis of a variety of polypropylene materials, including blends, block and graft copolymers. The key step is the chain end functionalization of the vinylideneterminated oligopropenes via double bond conversion reactions, followed by the controlled synthesis of polypropylene block and graft copolymers. In melt and solution processes the olefinic end groups have been converted into a variety of polar functional groups, e.g. hydroxy, carboxy, succinic anhydride, thiol and acrylic groups. The thiol-terminated oligopropenes are chain transfer agents in radical methylmethacrylate polymerization with chain transfer constant measured to be 0.2. Acrylic monomers and styrene are grown onto the thiol end group via a chain transfer reaction, thus producing a family of block copolymers, e.g. poly(propene-b-methylmethacrylate) and poly(propene-b-styrene). As demonstrated by SEM fracture surface analysis, the poly(propene-b-styrene) block copolymers are efficient dispersing agents for compatibilizing polystyrene/polypropene (70/30) blends. Homo- and copolymerization of acrylic oligopropene macromonomers yield novel classes of graft copolymers with pendant isotactic or atactic oligopropene chains. Hydroxy-terminated oligopropenes are useful initiators in caprolactone polymerization to form poly(propene-b-caprolactone) block copolymers. IR spectroscopic studies demonstrate that succinic anhydride-terminated oligopropenes, obtained by ene-type addition of maleic anhydride to the olefinic oligopropene end group, react with oligomeric diamine-terminated polyamide-6,6 in the melt to yield polypropene-b-polyamide-6,6-b-polypropene triblock copolymers.     

Morphology development of immiscible polymer blends during melt blending: Effects of interfacial agents on the liquid-solid interfacial heat transfer

This article reports on a new phenomenon: The presence of a compatibilizer accelerates the melting/plastification of an immiscible polymer blend during melt blending. The increase in the rate of melting as a result of the addition of a compatibilizer is believed to be one of the important factors responsible for the fact that the morphology of compatibilized blends develops much faster than that of their uncompatibilized counterparts. To substantiate the above statement, blends based on polypropylene (PP) and polyamide 6 (PA6) were used as model systems. The compatibilizer was a graft copolymer (PP-g-PA6) with PP as the backbone and PA6 as grafts. Its presence in a PP/PA6 blend accelerated the rate of melting of the PA6. This effect was observed only when the compatibilizer itself was molten and migrated to the interfacial layer between the PA6 and PP phases. It is likely that the presence of the compatibilizer increased the chain entanglements at the PP and PA6 interface and consequently reduced the thermal resistance of the interfacial layer. Detailed mechanisms are discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 3368–3384, 1999     

Atomic force microscopy study on blend morphology and clay dispersion in polyamide‐6/polypropylene/organoclay systems

The phase structure and clay dispersion in polyamide‐6(PA6)/polypropylene(PP)/organoclay (70/30/4) systems with and without an additional 5 parts of maleated polypropylene (MAH‐g‐PP) as a compatibilizer were studied with atomic force microscopy (AFM). AFM scans were taken from the polished surface of specimens that were chemically and physically etched with formic acid and argon ion bombardment, respectively. The latter technique proved to be very sensitive to the blend morphology, as PP was far more resistant to ion bombardment than PA6. In the absence of the MAH‐g‐PP compatibilizer, the organoclay is located in the PA6 phase; this finding is in line with transmission electron microscopic results. Further, the PP is coarsely dispersed in PA6 and the adhesion between PA6 and PP is poor. The addition of MAH‐g‐PP resulted in a markedly finer PP dispersion and good interfacial bonding between PA6 and PP. In this blend, the organoclay was likely dispersed in the PA6‐grafted PP phase. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43:1198–1204, 2005     

Influence of maleic anhydride grafted polypropylene on the miscibility of polypropylene/polyamide-6 blends using ATR-FTIR mapping

In this work we describe an approach to study the influence of the compatibilizer, maleic anhydride grafted polypropylene (PP-g-MAH), on the miscibility of polypropylene/polyamide-6 blends (PP/PA6) using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopic mapping. In measurement, the image area for each blend was 100 μm × 100 μm. Different amounts of PP-g-MAH were introduced into the polymer blends, and the miscibility was characterized by the spatial distribution of PA6 in the image based on the corrected absorbance at 1640 cm^?1. It was found that small quantities of the compatibilizer could significantly improve the miscibility of the two immiscible polymers. Furthermore, our results proved that blend with 6 parts of PP-g-MAH by weight exhibited an optimal miscibility behavior. This paper demonstrates that ATR-FTIR mapping is a direct method to visualize the miscibility of polymer blends.     

Mathematical modeling of the graft reaction between polystyrene and polyethylene

Polystyrene (PS) and polyethylene (PE) are two major components of household plastic waste whose blends are immiscible. Recycling them together is an attractive option that requires a compatibilization process to improve the blend mechanical properties. If a PE/PS copolymer is added or formed in situ, it may act as compatibilizer. The structure and molecular properties of this copolymer are key factors to assure its effectivity as a compatibilizer. In this work, we study the graft copolymerization reaction between polystyrene and polyethylene using the catalytic system composed of AlCl₃ and styrene. We develop a model of this process which considers that PE/PS grafting and PS degradation occur simultaneously. We propose a kinetic mechanism for the whole process and apply the method of moments to solve the mass balance equations. The model is able to calculate average molecular weights as well as the amount of grafted PS. It accurately describes the available experimental data, constituting a valuable tool for simulation and optimization purposes.     

Maleic Anhydride Polyethylene Octene Elastomer Toughened Polyamide 6/Polypropylene Nanocomposites: Mechanical and Morphological Properties

A series of polyamide 6/polypropylene (PA6/PP) blends and nanocomposites containing 4 wt% of organophilic modified montmorillonite (MMT) were designed and prepared by melt compounding followed by injection molding. Maleic anhydride polyethylene octene elastomer (POEgMAH) was used as impact modifier as well as compatibilizer in the blend system. Three weight ratios of PA6/PP blends were prepared i.e. 80:20, 70:30, and 60:40. The mechanical properties of PA6/PP blends and nanocomposite were studied through flexural and impact properties. Scanning electron microscopy (SEM) was used to study the microstructure. The incorporation of 10 wt% POEgMAH into PA6/PP blends significantly increased the toughness with a corresponding reduction in strength and stiffness. However, on further addition of 4 wt% organoclay, the strength and modulus increased but with a sacrifice in impact strength. It was also found that the mechanical properties are a function of blend ratio with 70:30 PA6/PP having the highest impact strength, both for blends and nanocomposites. The morphological study revealed that within the blend ratio studied, the higher the PA6 content, the finer were the POEgMAH particles.     

The effect of compatibilization on the dynamic properties of polypropylene/nylon‐6 blends studied by broad band dielectric spectroscopy

Polypropylene (PP) and polyamide‐6 (Ny‐6) blends with a 70/30 composition have been studied by broadband dielectric spectroscopy. The unmodified blends are immiscible, and 10% of PP functionalized with maleic anhydride was added as a compatibilizer. The influence of the compatibilizer on the water sorption and on the molecular dynamics of the Ny‐6 phase is followed by the changes induced in the dielectric loss spectra of these blends in both wet and dry states. The shortest range motions are unaffected by the compatibilizer in the dry state, but a higher water sorption is observed in the unmodified blend. Higher activation energies are found for the β relaxation in the dry blends than for the Ny‐6 homopolymer, showing the existence of constraints on these longer scale motions. During increasing temperature experiments, two segmental modes are recorded, the lower temperature mode corresponding to the plasticized material; as the temperature is raised, a second cooperative mode is found, originating in the dry Ny‐6 amorphous phase, rigidized by the loss of moisture. The comparison of the dielectric strengths of the modes shows that the unmodified blend absorbs more water than the compatibilized blend. The segmental dynamics are unaffected by compatibilization. At high temperatures, the high temperature tail of the segmental mode is much higher in the absence of the compatibilizer. The contribution of a peak due to interfacial polarization is lowered by the presence of the compatibilizer, which makes the interface more diffuse and the trapping of free carriers less effective. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1408–1420, 2005     

Synthesis and characterization of polyethylene‐g‐polystyrene as the compatibilizer for polypropylene/ Polystyrene blends

Polyethylene‐g‐polystyrene (PE‐g‐PS) was synthesized as a compatibilizer for polypropylene/polystyrene­(PP/PS) blends by the living radical polymerization of styrene with polyethylene‐co‐glycidylmethacrylate (PE‐co‐GMA). The compatibilizer effect of PE‐g‐PS on the morphology and thermal properties of PP/PS blends was investigated. The crystalline temperature of PP in PP/PS blends decreased with increasing PE‐g‐PS contents. Morphologies of PP/PE‐g‐PS/PS blends showed much better dispersion of each domain for higher PE‐g‐PS contents. The molecular weight of PS segment in PP/PE‐g‐PS/PS blend was increased by addition of styrene monomer during the post melt blending process where post living radical polymerization reaction proceeded. Copyright © 2003 John Wiley & Sons, Ltd.     

The early stage of the morphology development of immiscible polymer blends during melt blending: Compatibilized vs. uncompatibilized blends

The early stage of the morphology development has been studied for the blending of two immiscible polymers. Controlled experiments were carried out in a batch mixer in such a way that the rate of melting was low enough to follow up the morphology development of dilute and concentrated systems. For a dilute or semidilute polypropylene and polyamide 6 (PP/PA6) blend with 0.5, 5, or 10 wt % PA6, particles formed in the very early stage of melt blending were very small, of the order of 0.25 to 0.3 μm in radius. They immediately began to grow in size when no compatibilizer was added, indicative of coalescence even in the very early stage of melt blending and/or in very dilute systems (0.5 wt % PA6). Further growth of the particles was eliminated with the introduction of a graft copolymer compatibilizer providing evidence of the stabilizing effect of the copolymer from the very beginning of melting blending. However, the behavior of the morphology development of a concentrated PP/PA6 (80/20) system was similar to that reported in the literature. The average radius of the particles of the uncompatibilized blend decreased with increasing mixing time, whereas that of the compatibilized blend remained almost constant during mixing. The most favorable conditions to obtain a fine morphology seems to be the following: rate of melting/plastification of pellets < rate of dispersion (deformation + breakup) of the polymer melt to small particles < rate of stabilization (with an adequate copolymer). © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 601–610, 2001     

多单体接枝聚丙烯对PBT/PP共混体系的形态结构及力学性能影响研究

研究了甲基丙烯酸缩水甘油酯 (GMA)和苯乙烯 (St)多单体熔融接枝聚丙烯 (PP g (GMA co St) )对聚对苯二甲酸丁二酯 (PBT) 聚丙烯 (PP)共混物的形态结构和力学性能的影响 .利用双螺杆挤出机对PBT PP合金进行共混挤出 ,使用DSC、FT IR和SEM、TEM等手段对共混物进行了分析和相形态观察 ,并测试了力学性能 .实验证明 ,熔融共混过程中PP g (GMA co St)的环氧基团可以与PBT的端羧基发生化学反应 ,就地生成了PBT g PP共聚物 ,该共聚物可对PBT PP合金起到良好的增容剂作用 ,使共混物的相区尺寸显著减小 ,共混物的拉伸强度和冲击强度等力学性能同时得到明显改善 ,达到了弹性体系或小分子增容所难以达到的力学性能平衡的效果 .此外 ,TEM的研究还在PBT PP g (GMA co St)共混物中发现了特殊的微相分离结构     

Novel elastomeric polyurethane fibers modified with polypropylene microfibers

Extrusion of immiscible polymer biphasic blends to form in situ microfibers of the minor component in the matrix of the major component is an elegant way to create composites with new properties. The process was used to obtain thermoplastic polyurethane elastomers modified with polypropylene microfibers. The effect of phase interaction on blend morphology and properties was studied by running a series of blends with and without a maleated polypropylene compatibilizer. Six different blends were prepared: three with compatibilizer and three without the compatibilizer. All blends contained polypropylene as a minor component (80/20; 90/10 and 95/5). Extrusion spinning of polyurethane/polypropylene blends with and without compatibilizer resulted in polyurethane fibers modified with highly-oriented polypropylene microfibrils at all component ratios. Increasing polypropylene concentration in the thermoplastic polyurethane matrix increased hardness and modulus, but did not affect tensile strength and lowered elastic recovery.     

超细聚酰胺6粒子增韧聚丙烯体系的研究

采用磨盘形力化学反应器室温下制备了聚丙烯 (PP) /聚酰胺 6 (PA6 )超细粉体 ,研究了其粒度、粒度分布及PA6超细粒子填充对PP力学性能的影响 .结果表明 ,磨盘形力化学反应器可有效实现PP/PA6的粉碎 ,所得粉体平均粒径达微米级 ,初级粒子尺寸甚至可达纳米级 ,粒度分布呈双峰分布状态 .在PA6和PP熔点之间的温度下加工可制得PA6超细粒于填充的PP/PA6共混体系 ,其力学性能明显好于PP/PA6简单共混体系 ,30 %PA6用量下 ,拉伸强度由 2 3 .2MPa提高至 2 9 3MPa ,Izod缺口冲击强度由 4.6 2kJ/m2 提高到6 .34kJ/m2 .形貌分析结果表明 ,由于基本保持了PA6超细粉体的原始尺寸 ,填充体系中PA6相区尺寸小、分布均匀 ,与使用增容剂得到的相区结构类似 .     

Rheology,morphology and tensile properties of thermotropic liquid crystalline polymer/polypropylene in‐situ composites

Blends of various grades of polypropylene (PP) with a thermotropic liquid crystalline polymer (TLCP), namely a copolymer of p‐benzoic acid and ethylene terephthalate (60/40 mole ratio) were prepared as extruded films. A thermoplastic elastomer styrene (ethylene‐butylene) styrene (SEBS) was used as a compatibilizer. Melt viscosities of all specimens were measured using a plate‐and‐plate rheometer with oscillating mode in the shear rate region of 1 ‐ 200 rad/s. Addition of SEBS compatibilizer resulted in an increase of the blend viscosity. Observation of the blend morphology revealed an improvement of TLCP dispersion. The TLCP fiber aspect ratio (length to diameter) in the extruded film also increased after addition of SEBS. As a result, the film modulus in extrusion direction was enhanced. The tensile strength of the film specimen was also increased due to an improvement of interfacial adhesion.     

Weld line morphology and strength of polystyrene/polyamide-6/poly(styrene-co-maleic anhydride) blends

The effect of weld line on the morphology and mechanical properties of 70/30 polystyrene and polyamide-6 blends with various amounts of poly(styrene-co-maleic anhydride) (SMA) as compatibilizer was investigated. For blends without or with low content of SMA, the dispersed domains near the weld line were elongated parallel to the weld line; and the dispersed domains in weld line were spherical. But for blend with high content of SMA, the isotropic morphology was observed. And the difference of morphology at weld line caused the distinction of fracture mechanism. The tensile strength of the blend is greatly influenced by the morphology of dispersed domains at weld line. While the morphology has only slight effect on impact strength of the blends.     

阴离子聚合制备聚乙烯-g-聚氧化乙烯接枝共聚物

聚烯烃 (聚乙烯 ,聚丙烯等 )的化学改性一直是科学研究和实际生产的一个热点 ,改性过的聚烯烃可以广泛应用到高分子共混物和复合材料中 .在众多聚烯烃中 ,聚乙烯产量最大 ,但因其惰性也最难于化学改性 .我们采取的改性方法是在聚合物中引入反应性基团 ,可以在温和条件下进行有选择的而且高效的化学改性 .由于两亲性共聚物可用作乳液聚合和悬浮聚合中的表面活性剂及稳定剂 ,塑料的表面改良剂和聚合物的共混相容剂等[1,2 ] ,因此人们对该共聚物的研究越来越多 .过去 ,多数两亲性共聚物的研究局限于聚苯乙烯 (ＰＳ)和聚氧化乙烯 (ＰＥＯ)接枝共…     

PP-EPR二嵌段共聚物作PP/EPT共混增容剂的探讨

对以实验室合成的PP-EPR二嵌段共聚物作为PP/EPT二元共混物的增容剂进行了探讨。共混物在增容前后的物理力学性能的变化说明PP-EPR对PP/EPT共混物具有优良的增容效果;同时又有克服通常因橡胶增韧塑料而强度下降的优点。形态结构的表征结果说明共混物为两相结构,阐明了PP-EPR的作用以及低温冲击强度大幅度提高和在增容后抗张强度损失减少的原因。     

PP/PP-g-MAH/PA6共混物结构与可纺性研究

运用DSC、SEM、纺丝成形等手段研究了增容剂聚丙烯接枝马来酸酐 (PP g MAH)对聚丙烯 聚酰胺 6(PP PA6 )共混物结构和性能的影响 .结果表明 ,共混物呈典型海岛型两相结构 ;增容剂PP g MAH与PA6之间的在位反应改善了PP PA6共混体系的相容性 ,使共混物中PA6的热结晶峰消失 ,PP的结晶生长速率和成核速率降低 ,可纺性提高     

Facile synthesis and applications of polypropylene/polydimethylsiloxane graft copolymer

It is of great significance to synthesize polyolefin/polysiloxane hybrid materials due to their unique combination of crystalline polyolefin segments and semiorganic polysiloxane segments. Herein, we report the syntheses of a novel polypropylene/polydimethylsiloxane (PP‐g‐PDMS) graft copolymer via the coupling reactions between maleic anhydride‐grafted PP and monoaminopropyl‐terminated PDMS. The chemical structures of PP‐g‐PDMS have been characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC). The correlation between reaction conditions and the structural parameters of PP‐g‐PDMS has been established. Consequently, the potential applications of resultant PP‐g‐PDMS were investigated, and the results showed that PP‐g‐PDMS can serve as an efficient compatibilizer in heterogeneous PP/PDMS blend system and also as an ideal processing aid for high‐viscosity PP.     

用苯乙烯-丙烯腈无规共聚物作增容剂改善聚碳酸酯/聚甲基丙烯酸甲酯相容性的研究

对聚碳酸酯（ＰＣ）／苯乙烯 丙烯腈无规共聚物（ＰＳＡＮ）／聚甲基丙烯酸甲酯（ＰＭＭＡ）三元共混物，运用平均场理论，通过二元链段相互作用参数χｉｊ计算了其中三个二元对共混组成的相互作用参数χｂｌｅｎｄ，并计算了三元共混体系的ｓｐｉｎｏｄａｌ曲线．由此预测了三元共混物相容的条件，讨论了ＰＳＡＮ组成，各聚合物分子量对体系相容性的影响，并进行了实验验证．结果表明通过适当控制共聚组成和分子量，ＰＳＡＮ可以作为ＰＣ和ＰＭＭＡ共混物的增容剂，并可以通过仅改变ＰＳＡＮ在共混物中的比例来改善体系的相容性，直至得到完全均相的三元共混物．     

HIPS-g-GMA相容剂对PC/HIPS共混物相容性的影响*

将两种或两种以上聚合物进行共混是获得性能优异合金材料的简单而有效的途径[1,2 ] .但是大多数聚合物共混时 ,由于混合焓ΔＨ >0且混合熵ΔＳ非常小 ,导致混合自由能大于零 ,故大多数共混体系是不相容的 .而对于不相容的共混 ,由于两相间的界面张力大 ,两相间形成锐形界面 ,两相之间的界面粘结力低 ,导致材料性能很差 .为了改善两相间的相容性 ,需要加入相容剂[3 ,4 ] .绝大多数增容剂是嵌段或接枝共聚物 .这类增容剂分子量较大 ,在加工条件下 ,由于其粘度较大往往难于迁移到两相的界面处 ,起不到应有的增容作用 .聚合物反应加工技术是近 2…