Montmorillonite as support for peroxide in the melt grafting of maleic anhydride onto polypropylene

Grafting of maleic anhydride onto polypropylene was performed in a Haake torque rheometer, in the presence of organically modified montmorillonite, MMT (used as support for the peroxide), according to a 2³ factorial design, where the maleic anhydride concentration (C_MA), peroxide concentration (C_per) and reaction time (t_r) were varied. For comparison, the reaction in the absence of MMT was also conducted. Polypropylene degradation was assessed by parallel plate rheometry and size exclusion chromatography (SEC) and percentage of reacted maleic anhydride (%MA_g) was obtained by titration and FTIR spectroscopy. The results showed differences in both systems, conventional and in the presence of MMT. The structure of polypropylene grafted with maleic anhydride, PP‐g‐MA, indicates longer branches are formed in the presence of MMT compared to in its absence, demonstrated by FTIR analysis. As in conventional reaction systems, an increase in C_per caused an increase in %MA_g and a reduction in molar mass. The variable C_MA showed to be not significant in the grafting reaction in the presence of MMT, even at high DCP levels, at a 5% significance level. On the other hand, increase in C_MA resulted in significant increase in viscosity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44134.     

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     

马来酸酐接枝聚丙烯的方法及其发展

介绍了马来酸酐(MAH)接枝聚丙烯(PP)的方法,主要有熔融接枝、溶液接枝、固相接枝、悬浮接枝等。指出了每种接枝方法的优缺点及研究进展。提出了工业放大、接枝机理的研究以及接枝过程中应考虑经济环保等是接枝技术的发展方向。     

马来酸酐固相接枝聚丙烯纤维

了提高非极性聚丙烯纤维(PP)的相容性,采用固相法以马来酸酐(MAH)对聚丙烯纤维进行接枝改性,研究了反应条件对接枝率的影响。结果表明,马来酸酐成功接枝到聚丙烯上,当反应温度为80℃,PP用量为0.5 g,MAH用量为0.2 g,BPO用量为0.05 g,回流时间为2.5 h时,最大接枝率可达到7.51%;BPO的用量、MAH单体的用量以及反应温度对PP纤维的接枝率影响较大。而测定PP纤维接枝率时回流时间对其接枝率的影响不大;接枝聚丙烯纤维的分解温度明显高于纯聚丙烯纤维。     

苯乙烯对马来酸酐熔融接枝聚丙烯的影响

用双螺杆挤出机分别制备了马来酸酐(MAH)和MAH-苯乙烯(St)共单体接枝共聚聚丙烯(PP)。红外光谱分析表明:MAH单体被接枝到PP大分子链上;引入St后,产物熔体流动速率从16.42 g/10min降为0.60 g/10 min;吸光度比从0.021升高到0.778,但St含量过高时,PP基体发生交联,影响接枝共聚物的加工性能。探讨了共单体St的作用机理以及交联机理。     

马来酸酐熔融接枝二元乙丙橡胶的研究

在转矩流变仪中,以过氧化二异丙苯(DCP)为引发剂,采用多单体熔融接枝技术,研究了二元乙丙橡胶(EPM)熔融接枝马来酸酐(MAH),考察了MAH含量、DCP用量、反应温度、反应时间、转子转速以及第二单体苯乙烯(St)的用量对接枝反应的影响,并用红外光谱(FTIR)对接枝产物进行了表征.研究结果表明:对于EPM-g-MAH体系,MAH和DCP最佳用量分别为3.0 phr和0.22 phr,最佳反应温度为170℃,反应时间8 min,转子转速60 r/min,此时接枝率最高达到0.46％;加入第二单体St后,当n(St) /n(MAH)为1/1时,EPM-g-(MAH-co-St)的接枝率为0.64％,接枝率明显提高.     

Peroxide‐catalyzed swell grafting of maleic anhydride onto polypropylene

A new grafting method was developed to incorporate maleic anhydride directly onto solid‐state polypropylene powders. Maleic anhydride grafts altered the nonpolar characteristics of polypropylene so that much better mixing was achieved in blends and composites of polypropylene with many other polymers and fillers. Maleic anhydride was grafted onto polypropylene by the peroxide‐catalyzed swell grafting method, with a maximum extent of grafting of 4.60%. Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, tensile testing, and impact testing were used to characterize the isotactic polypropylene (iPP), maleic anhydride grafted polypropylene (MAH‐g‐iPP), and (isotactic polypropylene)/(calcium carbonate) composites (iPP/CaCO₃). The crystallinity and heat of fusion of the MAH‐g‐iPP decreased as the extent of grafting increased. The mechanical properties of the CaCO₃ filled polypropylene were improved by adding MAH‐g‐iPP as a compatibilizing agent. The dispersion of the fillers in the polymer matrix and the adhesion between the CaCO₃ particles and the polymer matrix were improved by adding the compatibilizer.     

Study on grafting maleic anhydride onto polypropylene in microcolloid systems by coirradiation

Grafting of maleic anhydride (MAH) onto polypropylene (PP) performed in microcolloid systems by coirradiation was studied in this paper. First, the microcolloid of PP and MAH in xylene was prepared and its dynamic light scattering (DLS) shows particle size distributions of microcolloid system in 4–6 μm. Second, the effect of irradiation dose and monomer concentration on the amount of grafted MAH was investigated. The results show that the coirradiation in microcolloid systems can obviously cause an increase of the amount of grafted MAH. The percentage of grafting of the product amounts to 5.24%. The molecular structures of grafted MAH prepared were characterized by Fourier-transform infrared spectroscopy. Differential scanning calorimetry and wide-angle X-ray diffraction were used to determine the degree of crystallinity and crystalline structure. POLYM. ENG. SCI., 47:1703–1707, 2007. © 2007 Society of Plastics Engineers     

Styrene‐assisted grafting of maleic anhydride onto polypropylene by reactive processing

The grafting of maleic anhydride (MA) onto polypropylene (PP) was performed in the presence of the electron‐donating monomer styrene (ST) according to a central composite experimental design, in which the initial MA and ST concentrations were varied. The grafting of MA onto PP in the absence of ST was also performed. All reactions were carried out in the molten state in a Haake rheometer. The amount of reacted MA and the extent of degradation in PP were determined by means of Fourier transform infrared spectroscopy and melt flow index (MFI) measurements, respectively. The results showed that the presence of ST in the reactive processing caused a reduction in MFI and an increase in the level of reacted MA when the initial MA concentration equaled the initial ST concentration. An increase in the initial MA concentration presented distinct behavior that depended on the ST content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

C5石油树脂熔融接枝马来酸酐的研究

采用熔融法制备C5石油树脂接枝马来酸酐（C5-g-MAH）,研究了过氧化二异丙苯（DCP）、马来酸酐（MAH）用量和第三组分（助交联剂）品种对C5-g-MAH接枝率的影响。研究结果表明,DCP用量为0.2份,MAH用量为4份时接枝率最大,为1.28%;第三组分品种对C5-g-MAH接枝率的影响从大到小依次为：腰果壳油、三烯丙基异三聚氰酸酯（TAIC）、1,2-聚丁二烯（1,2-PBd）,均比空白样有所提高。此外,傅立叶红外光谱（FT-IR）分析证实发生了MAH熔融接枝C5石油树脂的接枝反应。     

Nano‐reactors for controlling the selectivity of the free radical grafting of maleic anhydride onto polypropylene in the melt

This paper reports on a successful application of the concept of nanoreactors to effectively controlling the selectivity of the free radical grafting of maleic anhydride (MAH) onto polypropylene (PP) in the melt, an industrially relevant process. More specifically, a free radical initiator of type ROOR was first confined into (or encapsulated by) the galleries of an organically modified montmorillonite (o‐MMT) whose interdistance was 2.4 nm. Primary free radicals (RO ·) formed inside the o‐MMT galleries had to diffuse out before they could react with the PP backbone. The controlled release of the primary free radicals significantly increased the grafting degree of MAH onto PP and greatly reduced the level of the chain scission of the latter. Those results were better understood by electron spin resonance studies on model systems and by Monte Carlo simulations. POLYM. ENG. SCI. 46:1443–1454, 2006. © 2006 Society of Plastics Engineers.     

马来酸酐固相接枝ABS树脂

采用固相接枝法制备了马来酸酐(MAH)接枝丙烯腈-丁二烯-苯乙烯三元共聚物(ABS)(ABS-g- MAH),研究了反应温度、反应时间及单体和引发剂用量对接枝率的影响。确定最佳接枝条件为:反应温度70℃,反应时间5～6 h,引发剂质量分数8％,单体质量分数10％,此时可得到接枝率为1．4％的ABS-g-MAH。对ABS的组分分离证明,接枝发生在ABS的丁二烯部分。     

Solid-state grafting of maleic anhydride onto polypropylene: The influence of morphology of polypropylene on heterogeneous reaction

Polypropylene (PP) was modified with maleic anhydride (MAH) via heterogeneous solid-state radical grafting performed in a fluidized polymerization reactor. The effect of PP morphology and different concentration of initiator (dibenzoyl peroxide, DBP) on the course of the reaction and grafting efficiency was evaluated with using infrared spectroscopy, scanning electron microscopy (SEM) and particle surface analysis (BET method). With respect to obtained results, the reaction course can be strongly affected by the reaction conditions and PP morphology. Unlike the reactive modification in melt, heterogeneous reaction exhibits lower extent of β-scission albeit the reaction conversion is lower. Solid-state grafting can be used as an alternative method for the surface modification of nonpolar surfaces with polar monomers under mild conditions.     

Concept of nano-reactor for the control of the selectivity of the free radical grafting of maleic anhydride onto polypropylene in the melt

The aim of this work was to apply the concept of nano-reactors to the reactive extrusion process of the free radical grafting of maleic anhydride onto polypropylene (PP), an important process in the polymer industry. Pre-confinement of dicumyl peroxide in the lamellar structures of organically modified montmorillonite allowed slowing down the release of primary radicals and consequently to significantly improve the selectivity of the grafting of maleic anhydride onto PP and decrease the selectivity of PP chain scission. To the authors’ knowledge, this is the first time that a non-chemical method is found to solving the inherent problem facing this complicated process: increasing the grafting degree is always concomitant to increasing PP chain scission.     

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     

马来酸酐溶液法接枝聚丙烯的探讨

采用溶液法制备了马来酸酐接枝聚丙烯。采用单因素及正交实验方法研究了单体、引发剂用量、反应温度、反应时间、溶剂用量及引发剂加入工艺等因素对产物接枝率的影响。结果表明,各因素对聚丙烯接枝率都有一定的影响,马来酸酐及二甲苯的用量对聚丙烯接枝率影响最大,当马来酸酐、二甲苯与聚丙烯之间比例为0.1/2/1时,聚丙烯的接枝率最大,接枝率可达4.36%。     

Grafting of maleic anhydride onto polypropylene: Synthesis and characterization

Isotactic polypropylene was grafted with maleic anhydride using benzoyl peroxide as an initiator and toluene as a solvent. Effects of various parameters such as monomer and initiator concentration, reaction time, and reaction temperature on percentage grafting were studied. Effect of various solvents on extent of grafting was also studied. The maximum extent of grafting achieved was 5.3%. The graft copolymers were characterized by i.r., thermal, viscometric, and contact angle studies. Improved thermal stability and decreased intrinsic viscosity and critical surface tension were observed for graft copolymers. © 1994 John Wiley & Sons, Inc.     

氯化聚丙烯接枝马来酸酐接枝率的测定

考查了马来酸酐接枝氯化聚丙烯反应中马来酸酐不同接枝率时红外特征峰的大小变化规律，通过特征峰比值和化学法接枝率的测定值线性回归，建立了相应的经验方程式，提出可以用红外法测定马来酸酐接枝率。该方法简便实用。     

马来酸酐和苯乙烯接枝改性对天然橡胶/聚丙烯共混物物理机械性能的影响

用动态硫化法制备了天然橡胶(NR)/聚丙烯(PP)热塑性弹性体(TPV)。研究了马来酸酐/苯乙烯/过氧化二异丙苯(MAH/St/DCP)多单体熔融接枝交联改性及纳米二氧化硅用量对NR/PP TPV物理机械性能的影响,讨论了NR/PP TPV的重复加工性能。结果表明,当MAH/St/DCP用量为3.750/1.875/0.375质量份、纳米二氧化硅用量为3质量份时,NR/PP TPV的物理机械性能最好,达到了国内外有关通用橡胶/PP TPV的水平,并且具有较好的重复加工性能。     

加入助剂的马来酸酐熔融接枝聚丙烯研究

用双螺杆挤出机研究了马来酸酐 (MAH)对聚丙烯 (PP)的自由基熔融接枝。采用正交试验优化了熔融接枝条件 ,系统研究了引发剂过氧化二异丙苯 (DCP)、单体MAH、助剂ABX用量对马来酸酐接枝率的影响 ,并对其影响因素作了分析。研究表明ABX助剂能降低PP降解 ,同时也提高了马来酸酐的接枝率。确定了较佳的原料配比为m(PP)∶m(MAH)∶m(DCP)∶m(ABX)=1 0 0∶4∶0 4∶0 35。