PP-g-Si对PP/GF的增容效果研究

制备了硅烷接枝聚丙烯(PP-g-Si),研究了PP-g-Si作为PP/GF体系的界面相容剂对界面结合和力学性能的影响,并与马来酸酐接枝聚丙烯(PP-g-MAH)的增容效果进行了比较。结果表明,PP-g-Si对PP/GF体系有增容作用,PP-g-Si不仅可以改善PP/GF复合体系的拉伸强度,而且可以改善PP/GF复合体系的韧性;PP-g-Si的增容效果优于PP-g-MAH。     

长玻纤增强聚丙烯复合材料性能研究

采用熔体浸渍包覆长玻璃纤维装置制备了长玻纤增强聚丙烯(PP/LFT)复合材料,通过双螺杆挤出机制备了同等配比的短玻纤增强聚丙烯(PP/SFT)复合材料。研究了增容剂含量、预浸料颗粒长度以及加工工艺对玻纤增强聚丙烯(PP/GF)复合材料力学性能的影响。结果表明:PP/LFT复合材料的力学性能明显优于PP/SFT复合材料,其拉伸强度及缺口冲击强度分别可达115.0 MPa和42.4 kJ/m~2;增容剂马来酸酐接枝聚丙烯(PP-g-MAH)的加入明显改善了GF与PP间的界面黏结强度,进一步提升了复合材料的力学性能,相比之下,增容剂对PP/SFT复合材料的性能提升效果更为明显;提高预浸料颗粒长度有利于复合材料纤维保留长度和力学性能的提升;适度提高加工温度,可进一步提高浸渍效果和复合材料的力学性能。     

高韧性高强度聚丙烯复合材料的研究

研究了自制的马来酸酐接枝聚丙烯(PP-g-MAH)和马来酸酐、苯乙烯接枝聚丙烯(PP-g-MAH-g-St)2种增容剂对聚丙烯/聚烯烃弹性体/玻璃纤维(PP/POE/GF)复合材料力学性能的影响,利用扫描电子显微镜观察了试样断口形貌。结果表明,2种增容剂均显著改善了GF与PP基体的界面粘结强度,从而提高了复合材料的力学性能;就2种增容剂的效果而言,PP-g-MAH-g-St的增容效果远优于PP-g-MAH。当PP-g-MAH-g-St的质量分数为8%时,PP/POE/GF/PP-g-MAH-g-St复合材料的综合性能已接近常用工程塑料的性能。     

聚丙烯/芦苇纤维复合材料力学及热性能的研究

以聚丙烯接枝马来酸酐(PP-g-MAH)为增容剂,制备了聚丙烯(PP)/芦苇纤维复合材料。采用万能拉力试验机、扫描电子显微镜(SEM)和热重分析仪(TGA)对复合材料的力学性能、断面形态以及热性能进行了表征。研究结果表明:添加增容剂可以改善芦苇纤维与PP基体的界面结合性,从而提高了PP/芦苇纤维复合材料的拉伸性能、弯曲性能以及热稳定性。     

高强高韧GF／PP复合材料的研究

通过在短玻(GF)增强聚丙烯(PP)中添加聚烯烃弹性体(POE),并用马来酸酐对PP进行接枝交联的方法, 制备了高冲击韧性GF／PP复合材料。在该材料中,短切玻璃纤维的加入大幅度提高了材料的拉伸、弯曲强度,而POE 则通过产生形变等方式,提高了材料的冲击韧性;在其中加入马来酸酐接枝聚丙烯增加界面结合力,可使GF／PP／POE 复合体系表现出良好的综合力学性能,其拉伸强度为51．9 MPa,弯曲强度为68．1MPa,冲击韧性为44．2 kJ／m2。     

高性能NBR/PP热塑性硫化胶的制备与研究

研究了马来酸酐接枝聚丙烯(MP)、氯化聚丙烯(CPP)以及端胺基液体丁腈橡胶(ATBN)和马来酸酐接枝聚丙烯复合增容剂对NBR／PP共混体系的增容效果。采用溴化树脂体系、酚醛树脂体系和DCP体系。分别对共混体系的动态硫化效果进行了讨论。研究了DOP和聚酯对共混体系的增塑效果及耐油效果的影响。对TPV的相态结构、力学性能和耐热油性能研究表明：用ATBN／MP增容的共混体系经酚醛树脂动态硫化后，可以获得相态结构精细、性能优异的TPV；聚酯增塑剂是NBR／PP共混体系的一种比较理想的增塑剂。     

钛酸钾晶须增强聚丙烯研究

采用钛酸钾晶须(K2Ti6O3)对聚丙烯(PP)进行填充，对几种不同的表面处理剂的偶联作用效果进行了比较。实验结果表明：钛酸钾晶须对聚丙烯有较好的增强增韧效果，可以普遍提高材料的力学性能，最佳用量为25％～35％。硅烷偶联剂KH-550对材料的界面结合有较好的促进作用，马来酸酐接枝改性的聚丙烯(PP-g-MAH)可以作为复合体系的有效增容剂。     

PP-g-MAH和SMAH增容PP/PA11的研究

分别用马来酸酐接枝聚丙烯(PP-g-MAH)和(苯乙烯/顺丁烯二酸酐)无规共聚物(SMAH)作增容剂,对聚丙烯(PP)／尼龙11(PA11)共混体系的拉伸性能、缺口冲击性能进行了研究。傅立叶转换红外光谱表明,SMAH的增容机理与PP-g-MAH不同。比较了两种增容体系的差示扫描量热曲线,PP-g-MAH增容体系中PP的熔融温度向更高温度移动。     

PP-g-MAH和PE-g-MAH对玻纤增强废旧聚丙烯复合材料性能的影响

采用熔融挤出的方法制备了玻璃纤维增强废旧聚丙烯(RPP/GF)复合材料,分析了不同含量的PP接枝马来酸酐(PP-g-MAH)和PE接枝马来酸酐(PE-g-MAH)相容剂对复合材料力学性能的影响。结果表明:添加PP-gMAH能改善玻纤与RPP界面结合强度,随着相容剂PP-g-MAH含量的增加,RPP/GF复合材料的弯曲强度逐渐提高,当PP-g-MAH的含量为7 phr时,能有效提高复合材料的弯曲强度。由于RPP中含有PE成分,添加少量PE-g-MAH能增加玻纤与RPP基体中PE的界面结合强度,从而继续提升复合材料的弯曲强度,复合材料的缺口冲击强度也得到提升。     

PP/EVOH共混物结构与性能研究

采用丙烯酸接枝聚丙烯（PP-g-AA）、衣康酸接枝聚丙烯 (PP-g-ITA)、马来酸酐接枝聚丙烯 (PP-g-MAH)3种相容剂增容聚丙烯（PP）/乙烯-乙烯醇共聚物(EVOH)共混体系,研究了共混体系的相容性、热性能、力学性能和阻隔性能。红外光谱分析表明,相容性的改善源于相容剂与EVOH之间形成的酯键和氢键。扫描电镜显示,PP-g-AA、PP-g-ITA、PP-g-MAH的增容作用依次增强,共混体系中相容剂增容作用越强,分散相尺寸越小,界面结合越牢固。差示扫描量热分析发现,PP/EVOH增容共混体系中EVOH组分的结晶温度低于不含相容剂的共混体系EVOH组分的结晶温度,PP组分的结晶温度变化则相反。增容共混体系与不含相容剂的共混体系相比,拉伸强度提高了10 MPa,吸油率降幅达0.8 %。     

A reactive extrusion process for the free radical grafting of silanes onto polypropylene: Effects of processing conditions and properties of water cross‐linked silane‐grafted polypropylene

Silane grafting and water cross‐linking of polypropylene (PP) are a recent method to modify its properties, such as melt strength, heat, and chemical resistance. This work aims at grafting silanes onto PP by reactive extrusion. The occurrence of the grafting of silane onto PP was confirmed by Fourier transform infrared (FTIR) and a method based on FTIR was developed to quantify the amount of polymerized silane and that of silane grafted onto PP. The molar mass of the silane‐grafted PP and its melt viscosity were also measured. A multiobjective optimization strategy was used to study the effects of processing conditions on the quality of the silane‐modified PP. It was concluded that to maximize the amount of silane grafted on PP and minimize the amount of polymerized silane and the decrease in PP chain scission, screw speed and barrel temperature should be low and feed rate high. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers     

Thermal and crystallization behavior of silane‐crosslinked polypropylene

Silane‐crosslinked polypropylene (PP) has been prepared first by the grafting of silane onto the backbone of PP in a melt process and then by crosslinking in warm water. The effects of type and concentration of silane and peroxide on the silane grafting on PP were investigated. The thermal behavior of the silane‐crosslinked PP was studied by thermogravimetric (TG) and differential scanning calorimetry (DSC) methods. TG results show that PP prepared via silane crosslinking increases its thermal stability greatly. It has been found from DSC measurements that the crystallization temperatures, ie the onset temperature and peak temperature of the exotherm of the silane‐crosslinked PP, increase compared with those of the pure PP. The silane crosslinking hardly changes the crystallinity degree of PP. The crystallization behavior of the silane‐crosslinked PP was also studied by wide‐angle X‐ray diffraction analysis. Copyright © 2004 Society of Chemical Industry     

Influence of grafting formulations and extrusion conditions on properties of silane‐grafted polypropylenes

The melt grafting of unsaturated silanes onto powdered polypropylene (PP) in a Haake TW100 twin‐screw extruder and curing in hot water were studied. The influence of grafting formulations and extrusion conditions on the melt flow rates of grafted PP and the gel percentages of crosslinked PP was investigated. The gel percentages of methacryloylpropyltrimethoxysilane (VMMS)‐grafted PP were markedly higher than those of vinyltriethoxysilane (VTES)‐ and vinyltrimethoxysilane (VTMS)‐grafted PP, while significantly less degradation of PP during grafting was observed for VMMS‐grafted PP. When benzoyl peroxide (BPO) was used as an initiator, no degradation of PP during grafting was observed, and the melt flow rates of grafted PP decreased with increasing BPO concentration. In contrast, use of dicumyl peroxide (DCP) as an initiator resulted in severe degradation of PP, and the melt flow rates of grafted PP increased gradually with increasing DCP concentration. BPO resulted in higher gel percentages than those of DCP at a fixed initiator concentration. Introduction of styrene into the grafting system greatly improved the gel percentage of crosslinked PP and reduced the degradation of PP during grafting. The optimum molar ratio of styrene to monomer is at about 1.5:1. Relatively low processing temperatures and high screw speeds are favorable. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1233–1238, 2000     

聚丙烯的接枝改性及其进展

介绍了聚丙烯（PP）接枝改性的几种常用方法，研究进展和接枝PP在增韧增强PP中的应用，并报道了PP／接枝PP／粘土插层纳米复合材料。     

Crosslinkable polypropylene composites made by the introduction of silane moieties

Silane‐crosslinkable polypropylene (PP) composites containing calcium carbonate (CaCO₃) as a filler have been investigated. The melt grafting of vinyl trimethoxysilane to PP with dicumyl peroxide (DCP) as a radical initiator is demonstrated. The thermal and mechanical properties of the crosslinkable products are also discussed. The results show that two reactions, that is, silane grafting and PP degradation, take place in parallel. The extents of silane grafting and PP degradation strongly depend on the reaction temperature, grafting formulation, and amount of the filler in the systems. Increasing the DCP concentration (up to 0.05 wt %) leads to an increase in the grafting degree. However, when the concentration of radicals is over a certain degree, the dominant reaction is PP chain scission. This results in a drastic decrease in the polymer viscosity. In systems containing both silane and CaCO₃, the viscosity of the polymer is higher than that of a grafted sample without CaCO₃ addition; in other words, the effect of the filler on the polymer viscosity compensates for the effect caused by PP degradation. Differential scanning calorimetry results show that the crystallization starts earlier for grafted samples. The percentage of the crystallinity of grafted PP is higher than that of the pure polymer. The incorporated silane does not have a strong effect on the mobility of the PP chains, as revealed by dynamic mechanical analysis. In comparison with ungrafted composites, the silane‐crosslinkable products show higher tensile stress and modulus. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1476–1483, 2005     

PP-g-(MAH-St)对PP/木粉复合材料力学性能的影响

在聚丙烯中(PP)中添加马来酸酐(MAH)和共单体苯乙烯(St),通过熔融挤出法制备了高接枝率的PP-g-(MAH-St),红外光谱分析证明了St和MAH成功接枝到PP主链上。研究了PP-g-(MAH-St)对PP/木粉复合材料力学性能的影响,并用扫描电镜观察了复合材料冲击断面的微观形貌。结果表明,与现有PP-g-MAH相比,只要添加少量PP-g-(MAH-St)就能有效改善PP/木粉复合材料的界面相容性,从而提高材料的力学性能;PP-g-(MAH-St)中MAH的接枝率对复合材料力学性能影响显著,当MAH接枝率为2.8 %时,能使木塑复合材料力学性能达到最佳。     

m-异丙烯基-α, α-二甲基苄基异氰酸酯熔融接枝聚丙烯的研究

在苯乙烯(St)存在下,将含不饱和键和异氰酸酯双官能团的单体m-异丙烯基-α, α-二甲基苄基-异氰酸酯(m-TMI)熔融接枝到聚丙烯(PP)上,分别采用无水滴定法、红外光谱、热重分析和差示扫描量热法对接枝产物进行测试。结果表明,m-TMI、St均与PP发生接枝反应,并且St的存在能够有效抑制PP在接枝过程中的降解,提高m-TMI与PP的接枝产物的热稳定性。在保持St用量不变的条件下,m-TMI的接枝率和接枝效率随其用量的增加先增大后减小;在保持m-TMI用量不变的条件下,m-TMI的接枝率在St与m-TMI的摩尔比为1.6时达到最大值。     

高熔体强度聚丙烯的研究进展

综述了国内外采用接枝与交联改性法制备高熔体强度聚丙烯(HMSPP)的研究进展。分析了目前采用接枝与交联改性PP所存在的问题,指出硅烷接枝交联改性技术的成本适中,产品质量好,是获得HMSPP的最有希望的改性技术。     

Enhancement of graft yield and control of degradation during polypropylene maleation in the presence of polyfunctional monomer

Free‐radical initiated grafting of maleic anhydride (MAH)/polyfunctional acrylate (PFA) multimonomer system onto polypropylene (PP) via reactive extrusion was studied. The effects of PFA and initiator concentration on the grafting reaction were investigated. It was shown that PFA as a comonomer could greatly enhance MAH grafting degree, which increased monotonically as the molar ratio of PFA to MAH increased. The rheology test demonstrated that the viscosity of grafted PP was also promoted as more PFA was used. The formation of branched structure during the grafting process was proved by oscillatory shear rheological analysis. The mechanism of grafting in the presence of PFA was discussed, suggesting PFA had higher reactivity with PP macroradicals than MAH and therefore forming stabilized macroradicals, thus resulting in depression of β‐scission and favoring the formation of branched structure. Higher initiator concentration gave higher MAH grafting degree but more severe degradation. The mechanical properties of the grafted PP were comparable with those of unmodified PP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Study of multi‐monomer melt‐grafting onto polypropylene in an extruder

Free‐radical melt‐grafting of the dual‐monomer systems glycidyl methacrylate–styrene (GMA‐St) and hydroxyethyl methacrylate–styrene (HEMA‐St) onto polypropylene (PP) has been studied using a single‐screw extruder. For single monomer grafting systems, degradation of PP was unavoidable and deterioration of the mechanical properties of the grafted PP subsequently occurred because of β‐scission of PP chains during the free‐radical melt‐grafting process. However, for the dual‐monomer systems, it is shown that the addition of styrene as a comonomer can significantly enhance the GMA or HEMA grafting levels on PP and reduce the extent of β‐scission of PP backbone. It has been found that the grafting degree of dual‐monomer melt‐grafted PP, such as PP‐g‐(GMA‐co‐St) or PP‐g‐(HEMA‐co‐St), is about quadruple that of single‐monomer grafted PP for the same monomer and dicumyl peroxide concentrations. Moreover, the melt flow rate of the dual‐monomer grafted PP is smaller than that of the unmodified PP. Hence, PP not only was endowed with higher polarity, but also kept its good mechanical properties. © 2000 Society of Chemical Industry