PP固相接枝改性研究进展

聚丙烯(PP)是一种具有优异性能且价格低廉的通用高分子材料,但由于聚丙烯为非极性聚合物,其染色性、亲水性、粘结性等均较差,且与其它材料的相容性也很差,这些缺点限制了聚丙烯的应用。通过固相接枝法改性聚丙烯,不仅可以在保持聚丙烯原有优异性能的情况下引入极性官能团,而且具有低温、低压、低成本、较高的接枝率和无需溶剂回收等优点。本文简要介绍了PP固相接枝反应机理,从接枝单体角度综述了近几年PP固相接枝改性的研究进展,并讨论了反应工艺对接枝产物的接枝率、接枝效率和性能的影响。     

聚丙烯与马来酸酐在超临界CO2中的接枝聚合

聚丙烯(PP)以其强度高、耐热性好、密度小、易加工和价廉等特点成为重要的通用塑料。但由于非极性的分子结构,其亲水性、染色性、抗静电性、粘接性和印刷性并不理想,难以与极性聚合物和填料共混、复合。PP通过接枝引入极性基团是最常用的化学改性方法。常用的接枝单体有马来     

聚丙烯粉料固相光接枝马来酸酐的研究

聚丙烯（ＰＰ）由于其优越的性能价格比而具有广泛的用途，但ＰＰ的非极性、易氧化等缺点使其在一些重要领域中的应用受到限制，因此需采用涂层法、等离子体处理、接枝法等方法对ＰＰ改性．其中ＰＰ表面接枝共聚法可使其脱去主链氢原子，引入极性基团，改善染色性和亲水性...     

在超临界CO_2中进行的PP固相接枝改性研究进展

由于性价比高,聚丙烯(PP)成为增长最快的通用塑料,在汽车工业、家用电器和管材方面得到了广泛地应用。然而由于聚丙烯自身的非极性限制了其在某些领域的应用,向聚丙烯主链上接枝极性单体是改善其极性的有效方法。常用的接枝改性方法有:溶液接枝、熔融接枝、等离子体处理、表面可控活性聚合以及超临界CO2状态下接枝等。其中超临界CO2由于溶解单体能力强,对聚合物基体也有很好的溶胀能力,且阻燃性好、无毒以及价格相对低廉,克服了传统接枝方法存在的操作工艺复杂,溶剂不易回收等缺点,得到了广泛研究。本文从超临界CO2协助固相接枝改性机理、接枝单体的选择、影响过程的因素以及超临界CO2协助固相接枝的应用等方面出发,系统阐述了超临界CO2协助PP固相接枝改性近些年来的研究概况。     

聚丙烯熔融接枝中共单体的作用机理

聚丙烯树脂是当今最具发展前途的热塑性高分子材料之一,在聚烯烃与工程塑料,如与聚酰胺或聚酯的共混合金中,聚丙烯接枝共聚物则广泛地被用为相容剂．此外,聚丙烯接枝共聚物还广泛应用于极性添加物等,用于改善制品的表面喷涂性能．聚丙烯接枝共聚物是通过自由基熔融接...     

不饱和非极性合成橡胶接枝共聚改性研究进展

不饱和非极性合成橡胶本身具有优良的电绝缘性、高弹性、粘弹性,应用非常广泛.但其与基体的相容性差,耐油、有机溶剂性差,不耐热.含硅/不饱和非极性橡胶共聚物不仅兼备了含硅聚合物的诸多优良性能,而且能有效地提高与基体的相容性并提高橡胶的应用范围.本文以接枝共聚方法为主线,对接枝共聚机理进行了初步讨论,按接枝共聚引发方式对橡胶接枝改性进行了分类,同时介绍了接枝共聚产物的性能及应用,并对非极性不饱和橡胶接枝改性前景作简要展望.     

多组分单体熔融接枝聚丙烯及其性能研究

利用单螺杆挤出机研究聚丙烯的多组分极性单体熔融接枝，从而改善和提高聚丙烯的极性。红外和熔体流动速率的结果表明，对于单组分接枝体系，在适当的反应条件下，甲基丙烯酸缩水甘油酯、甲基丙烯酸羟乙酯等极性单体均可以接枝在聚丙烯上，但同时也伴随着较严重的聚丙烯降解。而采用多组分单体接枝体系，通过加入甲基丙烯酸缩水甘油酯和苯乙烯单体，或甲基丙烯酸羟乙酯和苯乙烯单体，能够有效地控制聚丙烯的降解，大幅度提高接枝率，     

聚丙烯微孔膜的等离子体接枝聚合改性

利用拉伸时的晶型转变致孔特性,从β晶相聚丙烯经单向或双向拉伸制得了新型聚丙烯微孔膜、用等离子体接枝聚合技术接上了亲水性聚合物如聚丙烯酸、聚丙烯腈等。研究了等离子体处理时间、单体性质对得到的亲水膜的亲水性、离子/溶质渗透性的影响。发现接枝聚丙烯酸的双向拉伸膜对Na~+、Mg~(++),尿素有较大的渗透性,并具有优良的形状稳定性。     

GMA熔融接枝EPDM的研究

以甲基丙烯酸缩水甘油酯（ＧＭＡ）为接枝单体，过氧化二异丙苯（ＤＣＰ）为引发剂，对三元乙丙胶（ＥＰＤＭ）进行了熔融接枝，在烃链上引入极性基团，以改善ＥＰＤＭ与极性聚合物的相容性。用差示扫描量热计（ＤＳＣ）研究了ＧＭＡ的聚合温度，用富里叶红外（ＦＴ－ＩＲ）、凝胶渗透色谱（ＧＰＣ）对接枝产物进行了表征。实验结果表明，产物的接枝率和凝胶量可以通过反应条件（温度、时间、反应物组成及加料方式）来控制。     

聚丙烯熔融接枝马来酸酐反应机理的研究

改变聚丙烯（PP）熔融接枝马来酸酐（MAH）反应中的单体和引发剂的浓度以及添加适当助剂,考察了接枝产物的接枝率和恒定剪切应力（600kPa)及温度（210℃）下的剪切粘度,验证了作先前所提出的PP熔融接枝MAH的反应机理。即：在PP熔融接枝MAH的过程中,过氧化物自由基在熔融接枝过程中直接引发MAH单体及MAH单体在聚丙烯的大分子链段发生β断裂前直接被其引发而产生的接枝反应是影响产物的接枝率和分子量的关键。在不改变单体和引发剂浓度的情况下,降低过氧化物自由基在熔融接枝过程中直接引发MAH单体反应的程度而提高聚丙烯的大分子自由基直接引发MAH单体的反应趋势,是提高接枝产物接枝率和分子量的有效途径。     

双单体固相共聚改性聚丙烯技术及其机理研究

在马来酸酐(MAH)固相接枝改性聚丙烯(PP)的过程中加入合适比例的异氰脲酸三烯丙酯(TAIC)作为共聚单体,可以大大提高MAH在PP上的接枝率,同时可以有效抑制在普通固相接枝过程中PP的严重降解,得到了性能较好的高极性PP.与普通固相接枝法与熔体接枝法对比,双单体固相共聚接枝改性PP是一种得到高极性PP的有效方法.本文同时对双单体在固相接枝反应中的作用机理进行了探讨.     

马来酸酐-苯乙烯熔融接枝聚丙烯的影响因素及其性能研究

用单螺杆挤出机制备了马来酸酐 (MAH) 苯乙烯 (St)对聚丙烯 (PP)的多组分单体自由基熔融接枝体系 .研究证实了当两种单体物质的量比约为 1∶1时 ,接枝物的接枝率最高 ,而熔体流动速率 (MFR)最大 .对反应体系影响因素的研究表明单体用量和引发剂用量对不同单体用量比的系列接枝物的接枝率会产生不同的影响 ;另外 ,单体用量增加 ,接枝物的MFR减小 ,过氧化二异丙苯 (DCP)用量增加 ,接枝物的MFR增加 .对多单体熔融接枝聚丙烯PP g (MAH co St)的力学性能研究发现 ,选用合适的单体用量比、单体用量和DCP用量时 ,所制备的接枝物可具有与纯PP相当或更佳的力学性能     

Metalization of polypropylene. I. Synthesis and melt free‐radical grafting of novel maleimides and methacrylates containing chelating moieties

Several chelating monomers with methacrylate and maleimide residues as polymerizable groups and diketone and aspartic acid residues as metal‐bonding groups were synthesized. A long‐chain aliphatic spacer was introduced to increase the solubility of the monomers in the polymer melt and to enhance the compatibility of grafted side chains and homopolymers with polypropylene (PP). PP was functionalized by melt free‐radical grafting, and some properties of the modified polymer were investigated. The grafting of a chelating methacrylic ester by injection molding afforded grafting yields of 30–50%. A comparison with products obtained by the grafting of commercially available acetoacetoxy methyl methacrylate showed the beneficial effect of the aliphatic spacer with respect to the grafting yield as well as the tensile strength and flexural modulus. The grafting of an aspartic acid based maleimide in an extruder afforded grafting yields of 80–95% and a significant increase in the surface wettability, as shown by contact‐angle measurements. A comparative study using samples obtained by the grafting of maleimidobenzoic acid indicated that the homogeneity‐increasing effect of the spacer was neutralized by the detrimental effect of the dicarboxylic chelating group. Nevertheless, the results showed that the maleimides were well suited for grafting by reactive extrusion because of their low susceptibility to homopolymerization under melt‐processing conditions. Preliminary metalization experiments showed the feasibility of plating without the use of corrosive etchants. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3400–3413, 2003     

1,6-己二醇二丙烯酸酯和苯乙烯多单体熔融接枝制备长支链聚丙烯研究

采用哈克转矩流变仪制备了1,6-己二醇二丙烯酸酯(HDDA)和苯乙烯(St)多单体熔融接枝聚丙烯(PP)体系.红外测试结果表明St的加入能够促进HDDA接枝到PP主链,提高接枝率.动态流变行为研究结果也表明采用多单体熔融接枝PP更有利于体系在熔融接枝中生成长支链(LCB).随着St单体添加量的增加,HDDA的接枝率增大...     

Influence of different functionality degree grafting monomers on polypropylene melt radical branching reaction and their structure

Long‐chain–branched polypropylene (LCBPP) is one of polypropylenes (PPs) with high melt strength and good melt elasticity. Recently, due to its outstanding properties, LCBPP have been attracted increasingly attention in the field of development and characterization by the researchers all over the world. In this study, LCBPP was prepared by the melt radical branching reaction in a torque rheometer. The influences of various acrylate monomers with different functionality degrees on the structure and melt performance of PP products were investigated. The results indicated that grafting monomers with different functionality degrees made diverse influences on the branching density and branching chain length of branching PP products. With the increase of the functionality degree of grafting monomers, the branching level of PP products increased gradually and the “multiplicity” of branches became increasingly obvious. Besides, a higher reactivity of pentaerythritol triacrylate with hydroxyl than the similar molecular structured pentaerythritol tetraacrylate was confirmed. Furthermore, due to the high reactivity of dipentaerythritol penta(hexa)acrylate, branching and crosslinking reaction occurred simultaneously during the reaction process. As a result, the gel content increased and finally formed highly star branching structures with a shape of “dense and short.”     

多官能团单体对马来酸酐接枝聚丙烯流变行为的影响

研究了多官能团辅助单体偏苯三酸三丙烯酯(TATM)对马来酸酐接枝聚丙烯的熔体流动速率(MFR)和流变行为的影响.当以不含抗氧剂的聚丙烯粉料为原料时,TATM的加入对稳定接枝产物MFR的效果并不理想.但将聚丙烯粉料添加抗氧剂并造粒后,TATM的加入则可有效稳定体系的MFR,各种流变曲线显示出接枝产物的熔体弹性明显提高,说明有枝化或交联结构出现.针对PP粉料和粒料间接枝产物流变行为存在的重大差异,结合熔体自由基接枝反应的机理进行了解释.TATM能够起到稳定MFR的效果是由于其提高了接枝物的熔体弹性,从而抵消了聚丙烯熔体接枝反应中所不可避免的β断链所造成的剪切黏度下降.聚丙烯粉料和粒料中抗氧剂的差异对聚丙烯的加工降解有严重影响,造成了TATM在不同聚丙烯体系中效果的差异.     

Production of high melt strength polypropylene by gamma irradiation

High melt strength polypropylene (HMS-PP) has been recently developed and introduced in the market by the major international producers of polypropylene. Therefore, BRASKEM, the leading Brazilian PP producer, together with EMBRARAD, the leading Brazilian gamma irradiator, and the IPEN (Institute of Nuclear Energy and Research) worked to develop a national technology for the production of HMS-PP. One of the effective approaches to improve melt strength and extensibility is to add chain branches onto polypropylene backbone using gamma radiation. Branching and grafting result from the radical combinations during irradiation process. Crosslinking and main chain scission in the polymer structure are also obtained during this process. In this work, gamma irradiation technique was used to induce chemical changes in commercial polypropylene with two different monomers, Tri-allyl-isocyanurate (TAIC) and Tri-methylolpropane-trimethacrylate (TMPTMA), with concentration ranging from 1.5 to 5.0 mmol/100 g of polypropylene. These samples were irradiated with a ⁶⁰Co source at dose of 20 kGy. It used two different methods of HMS-PP processing. The crosslinking of modified polymers was studied by measuring gel content melt flow rate and rheological properties like melt strength and drawability. It was observed that the reaction method and the monomer type have influenced the properties. However, the concentration variation of monomer has no effect.     

Development of continuous process enabling nanofibrillation of pulp and melt compounding

Microfibrillated cellulose (MFC), a mechanically fibrillated pulp mostly consisting of nanofibrils, is a very attractive material because of its high elastic modulus and strength. Although much research has been done on composites of MFC and polypropylene (PP), it has been difficult to produce such composites at an industrial level because of the difficulties in using MFC in such composites are not only connected to the polarity (that can be improved with compatibilizers), but also with the challenge to make a homogeneous blend of the components, and also the low temperature stability of cellulose that could cause problems during processing. We developed a new processing method which enables continuous microfibrillation of pulp and its melt compounding with PP. Never-dried kraft pulp and powdered PP were used as raw materials to obtain MFC by kneading via a twin-screw extruder. Scanning electron microscopy showed nano to submicron wide fibers entangled in the powdered PP. MFC did not aggregate during the melt compounding process, during which the water content was evaporated. Maleic anhydride polypropylene (MAPP) was used as a compatibilizer to reinforce interfacial adhesion between the polar hydroxyl groups of MFC and non-polar PP. We investigated the effect of MAPP content on the mechanical properties of the composite, which were drastically improved by MAPP addition. Needle-leaf unbleached kraft pulp (NUKP)-derived MFC composites had better mechanical properties than needle-leaf bleached kraft pulp (NBKP)-derived MFC composites. Injection molded NUKP-derived MFC composites had good mechanical and thermal properties. The tensile modulus of 50 wt% MFC composite was two times, and the tensile strength 1.5 times higher than that of neat PP. The heat distortion temperature of 50 wt% MFC content composite under 1.82 MPa flexural load was increased by 53 °C, from 69 to 122 °C. This newly developed continuous process using powder resin has the potential for application at an industrial level.     

固相共聚接枝合成功能化聚丙烯及机理研究

通过马来酸酐 (MAH)和乙酸乙烯酯 (VAc)固相共聚接枝聚丙烯 (PP) ,在二者的投料摩尔比接近 1:1时 ,得到了高接枝率的多官能团功能化的PP .反应的机理是两单体摩尔比接近 1:1时容易形成较为稳定的过渡态 ,从而两者的共聚活性大大增加 ,接枝率大大提高 ,同时抑制了接枝产品熔体流动指数的增加 .这种含有多种官能团 (酸酐官能团和酯基官能团 )的极性PP对于拓展PP的应用范围 ,促进PP本身及其共混合金材料的功能化和高性能化有着重要的意义     

聚烯烃的化学接枝改性

综述了化学接枝改性聚烯烃的三种方法，即溶液法，熔融法及固定相法，并讨论了接枝单体的选择，接枝机理和接枝物的性能表征。