原位固相接枝改性碳酸钙/聚丙烯复合材料的制备

用马来酸酐（MAH）在碳酸钙（CaCO3）表面引入双键,通过原位固相接枝法将聚丙烯蜡（PPW）化学键合在CaCO3表面,制得3种接枝率的CaCO3-MAH-PPW。 将这3种改性CaCO3填充聚丙烯（PP）制备复合材料,研究了PP/CaCO3界面作用对复合材料强度的影响。 结果表明,CaCO3表面经PPW接枝改性后在PP中的分散性提高,与PP相容性变好;随着改性CaCO3表面PPW接枝率的提高,CaCO3与PP之间界面作用逐渐增强。 当PPW接枝率为4.48 mg PPW/g CaCO3时,CaCO3与PP之间的界面作用最强,复合材料拉伸强度下降最小,杨氏模量提升最大,当m(PP)∶m(CaCO3)=100∶50时,杨氏模量达0.86 GPa,是纯PP的1.63倍;而PPW化学接枝率为2.49 mg PPW/g CaCO3时,CaCO3与PP之间的界面作用适中,复合材料缺口冲击强度提升最大,且当m(PP)∶m(CaCO3)=100∶10时,缺口冲击强度达3.91 kJ/m2,是纯PP的1.35倍。     

不同改性剂对聚丙烯/碳酸钙复合材料性能的影响

以马来酸酐(MAH)、聚丙烯蜡(PPW)为主要原料,采用原位固相接枝改性法制得PP/CaCO3-MAH-PPW复合材料,并与添加相容剂聚丙烯接枝马来酸酐(PP-g-MAH)所制得的PP/PP-g-MAH/CaCO3复合材料进行比较。结果表明,CaCO3良好的分散性及其与PP基体适宜的界面粘接是复合材料具有较好韧性的关键因素。与PP/PP-g-MAH/CaCO3复合材料相比,PP/CaCO3-MAH-PPW复合材料表现出更佳的冲击、弯曲和加工性能,当m(PP)∶m(CaCO3)=100∶20时,材料缺口冲击强度达到最大值,是基体树脂的1.19倍。     

PP/EPDM/CaCO3三元复合材料的相结构及力学性能研究

采用以化学键合方式在CaCO3表面包覆上聚丙烯蜡和将改性后的CaCO3先与EPDM复合、再与PP复合的工艺,制备PP/EPDM/CaCO3三元复合材料,以期在PP基体材料中得到EPDM包裹CaCO3的相结构.通过测量三元复合体系中各组分的表面张力,计算各可能组分对之间的界面张力和黏结功,分析三元复合体系中可能的相结构.热力学计算结果表明,三元复合体系中既存在以EPDM为壳、CaCO3为核的"核壳结构",又存在CaCO3与EPDM各自独立分散在PP基体中的结构.电镜照片进一步揭示,在PP/EPDM/改性CaCO3三元复合体系与PP/EPDM/未改性CaCO3三元复合体系中,这两种相结构的比例是不同的,在前者中以核壳结构为主.CaCO3表面性质的不同是产生这一差别的原因.由于这一结构差别的存在,PP/EPDM/改性CaCO3三元复合体系比PP/EPDM/未改性CaCO3三元复合体系具有更好的力学性能.当EPDM用量为8 phr、改性CaCO3用量为15 phr时,三元复合体系的冲击强度达14.25 kJ/m2,是纯PP的3.17倍.     

MMA接枝改性PVC/CaCO3纳米复合材料的力学性能

采用熔融共混法制备PMMA接枝改性纳米CaCO3增韧PVC（PVC/CaCO3）复合材料,并研究了复合材料的力学性能.结果表明,通过表面PMMA的接枝改性,可以显著提高纳米CaCO3增韧聚氯乙烯复合材料的拉伸强度和拉伸模量,在纳米CaCO3颗粒表面PMMA包覆层厚度为2nm时,复合材料的拉伸强度和拉伸模量达到极大值.对比于未处理纳米CaCO3和钛酸酯偶联剂处理纳米CaCO3,PMMA接枝改性纳米CaCO3增韧PVC复合材料的拉伸强度得到较大幅度提高.SEM显示,经过PMMA接枝改性后的碳酸钙在PVC基体中分散均匀,与基体界面结合良好.     

累托石/聚丙烯插层纳米复合材料的制备与性能

采用熔融共混法制备了有机改性累托石 (OREC)粘土 均聚聚丙烯 (PP)纳米复合材料 ,以X 射线衍射分析 (XRD)及透射电子显微镜分析 (TEM)观察了复合材料的相貌结构 ,研究了复合材料的力学性能及热性能 .结果表明 ,OREC在添加份数较少时可与均聚聚丙烯熔融插层形成插层型聚丙烯纳米复合材料 ,该复合材料与纯PP相比 ,具有较高的拉伸强度、断裂伸长率及冲击强度 .在有机粘土添加 2 %时 ,复合材料的拉伸强度、断裂伸长率、冲击强度最高 ,与纯PP相比 ,2 %添加量的聚丙烯纳米复合材料拉伸强度提高 6 5 7% ,断裂伸长率提高 2 89 3% ,冲击强度提高 14 1% ,10 %失重率时对应的热分解温度提高 50K .     

PP-g-(MAH/St)和PP-g-MAH对聚丙烯/木粉复合材料性能的影响

在转矩流变仪中用熔融接枝法制备马来酸酐(MAH)和苯乙烯(St)接枝聚丙烯（PP）-PP-g-(MAH/St)和PP-g-MAH,将其作为聚丙烯/木粉复合材料的相容剂。 FTIR证实MAH和St单体与PP发生接枝反应。 用SEM和DSC等手段考察两种相容剂对PP/木粉复合材料微观形貌和结晶性能的影响,探索了各种PP/木粉复合材料加工和力学性能不同的内在原因。 SEM显示,PP-g-(MAH/St)改性木粉比PP-g-MAH改性木粉在PP基体中分散性更佳,木粉与PP的界面更加模糊,相容性进一步改善。 DSC结果表明,PP-g-(MAH/St)改性体系可增强木粉对PP的异相成核作用,提高结晶温度和结晶度。 复合材料的加工和力学性能测试结果表明,PP-g-(MAH/St)改性效果明显优于PP-g-MAH。 复合材料的熔体质量流动速率随相容剂用量的增加而逐步下降,PP-g-(MAH/St)改性体系拉伸强度和弯曲强度却逐步上升,并在相容剂用量为4.8 g/100 g PP时达到极值。 此时其拉伸强度达40.62 MPa,分别是未改性体系和PP-g-MAH改性体系的1.29和1.17倍;其弯曲强度达45.72 MPa,分别是未改性体系和PP-g-MAH改性体系的1.23和1.59倍;而无缺口冲击强度却在相容剂用量为3.6 g/100 g PP时达到极值13.35 kJ/m2,分别是未改性体系和PP-g-MAH改性体系的1.62倍和1.42倍。     

聚丙烯/硫酸钡复合体系的界面相互作用与流变性质和结晶行为的关系

制备了一系列具有不同界面状态的聚丙烯 (PP) 硫酸钡 (BaSO4)复合体 .PP BaSO4的界面分别用硅烷、硬脂酸、马来酸酐接枝聚丙烯 (PP g MAH)改性 .研究表明 ,填充体系的熔体粘度和熔体弹性均高于基体 .以硅烷和PP g MAH进行界面改性后 ,PP BaSO4的界面相互作用加强 ,导致复合体系中的熔体粘度和熔体弹性进一步提高 ,同时BaSO4对PP的成核活性提高 .填料用硬脂酸处理后 ,硬脂酸能够在填料粒子表面上形成一个包覆层 ,使粒子与PP的亲和性改善 .同时该包覆层具有润滑作用 ,使得复合体系的熔体粘度和熔体弹性下降 ,并使得该体系中BaSO4的成核活性低于硅烷和处理的体系 .本文探讨了由复合体系的熔体粘度定量比较填充复合体系中聚合物 填料界面相互作用的方法 ,讨论了界面改性对复合体系流变性质和结晶行为影响的机理     

稀土偶联剂对Mg(OH)_2的改性作用及其在PP/Mg(OH)_2体系中的应用

研究了稀土偶联剂 (ReC)对Mg(OH) 2 的表面改性作用及PP/Mg(OH) 2 体系的燃烧性能、流动性能、力学性能及老化性能。稀土偶联剂可显著改善Mg(OH) 2 在非极性介质中的分散性 ;PP/Mg(OH) 2 体系当Mg(OH) 2 填充量超过 5 0 %时 ,氧指数 (OI)≥ 2 8.5 ,但这时冲击强度不足纯PP的 30 % ,熔体流动速率 (MFR)低于 0 .6g/1 0min ;而填料用 2 .5 % (质量 )ReC处理后 ,填充量为 5 0 %的体系冲击强度接近纯PP ,MFR达 2 .8g/1 0min ;Mg(OH) 2对体系光氧老化过程有加速作用 ,而对热氧老化过程有阻滞作用 ;稀土偶联剂对体系光氧老化过程有轻微的促进作用 ,而对热氧老化过程无明显影响     

十六烷基膦酸表面修饰纳米镍粉及其复合材料的制备和性能

以十六烷基膦酸作为修饰剂, 对纳米镍粉进行表面改性处理, 通过溶液共混的方法制备改性镍粉与聚丙烯的聚合物基复合材料. 利用X射线光电子能谱(XPS)、 X射线衍射(XRD)及透射电子显微镜(TEM)等测试手段研究改性镍粉的表面形态; 利用扫描电子显微镜(SEM)研究复合材料断面形貌; 利用介电频谱分析系统对复合材料的介电常数和介电损耗等进行了测试. 结果表明, 纳米镍粉表面形成厚度为2~4 nm的十六烷基膦酸包覆层, 使纳米镍粉由亲水性变为亲油性; 聚丙烯基复合材料中, 改性镍粉均匀分散; 复合材料的介电常数在镍填充量为40%时, 可以达到纯聚丙烯的近10倍.     

稀土偶联剂对Mg(OH)2的改性作用及其在PP/Mg(OH)2体系中的应用

研究了稀土偶联剂(ReC)对Mg(OH)2的表面改性作用及PP/Mg(OH)2体系的燃烧性能、流动性能、力学性能及老化性能.稀土偶联剂可显著改善Mg(OH)2在非极性介质中的分散性;PP/Mg(OH)2体系当Mg(OH)2填充量超过50%时,氧指数(OI)≥28.5,但这时冲击强度不足纯PP的30%,熔体流动速率(MFR)低于0.6g/10min;而填科用2.59%(质量)ReC处理后,填充量为50%的体系冲击强度接近纯PP,MFR达2.8g/10min;Mg(OH)2对体系光氧老化过程有加速作用,而对热氧老化过程有阻滞作用;稀土偶联剂对体系光氧老化过程有轻微的促进作用,而对热氧老化过程无明显影响.     

二步法聚丙烯/丙烯酸表面接枝聚合研究

研究了二步法聚丙烯膜表面的丙烯酸接枝反应 .实验发现 ,以醋酐为溶剂的反应体系所得接枝率明显好于以水为溶剂的体系 ;接枝率随光敏剂浓度、单体浓度增大而增加 ;提高反应温度 ,可使接枝率明显增大 ;接枝后的聚丙烯膜表面亲水性可明显改善 .并用红外光谱证实了丙烯酸在聚丙烯膜表面的接枝 .     

PP熔融接枝改性研究进展

聚丙烯作为一种非极性聚合物,其亲水性、染色性、粘结性及与其它极性聚合物和无机填料的相容性都很差,这大大限制了它的应用。因此,往往采用官能化的方法赋予聚丙烯以极性、反应活性和功能性。通过熔融接枝的方法,在聚丙烯链段上接枝极性单体,可以显著提高聚丙烯的极性,改善表面亲水性及染色性等。本文简要介绍了聚丙烯熔融接枝改性及其影响因素,并按接枝单体分类,综述了熔融接枝聚丙烯的研究进展、性能与应用,展望了其发展趋势。     

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.     

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     

Covalently attached graft polymer monolayer on organic polymeric substrate via confined surface inhibition reaction

A grafting technique was proposed for the preparation of polymer monolayer on polymeric substrate. On the basis of our recent work on polymer‐supported inhibitor (PSI), hydroquinone (HQ) was first implanted onto polypropylene (PP) surface through UV‐initiated grafting. The resulting immobilized HQ was used as PSI for the thermal‐induced free radical polymerization (FRP) of acrylic acid (AA). The inhibition mechanism was similar to that of free HQ molecule, that is, polymer chain‐carrying radical or peroxy radical could be deactivated by abstracting hydrogen atom from hydroxyl group of immobilized HQ, and the resulting oxyradical (semiquinone radical) combined with another active chain free radical. According to this mechanism, a devised redox initiator consisting of sodium hydrogen sulfite and ammonium persulfate was used to initiate FRP of AA in water at low temperature (50 °C). High crystalline biaxial oriented PP film with HQ immobilized was deliberately laid in this system as a radical trap to capture poly(acrylic acid) (PAA) short chain radical. Through X‐ray photoelectron spectra (XPS) analysis it was found that the atom ratio of C_HQ (carbon in HQ) to C_COOH (carbon in COOH) decreased with prolonging polymerization time and became stable after about 30 min. The formed PAA short chain on the surface showed a distribution of monolayer, and the saturated thickness was calculated as 5–7 Å. The degree of polymerization of graft chain in PAA monolayer was estimated as 15–20 through three different models. Relating to surface coverage being 100% in ideal densely packed PAA monolayer, real monolayer surface coverage in such reaction system was estimated as 12.3–18.5%. This method was expected to give us a general approach for constructing kinds of graft polymer monolayer on polymeric substrate, because the involved chemistry was only common inhibition reaction between immobilized inhibitor (HQ) and FRP system in solution (herein redox initiating system of AA). We named this grafting chemistry as confined surface inhibition reaction. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 745–755, 2007     

Surface modification of polyolefins by photografting of acrylic monomers

High-speed surface modification of polypropylene (PP) and polyethylene (PE) films has been achieved by liquid phase photograft polymerisation of acrylic acid (AA) and hydroxypropyl acrylate (HPA). Benzophenone was used as photoinitiator to generate polymer radicals at the surface of the polyolefin film. The grafting reaction was carried out in aqueous solution or with the neat monomer, which was laminated between two PP films, in the presence of air. Under the intense illumination of a UV-curing line, acrylic acid was grafted within seconds to polypropylene films or fabrics, which were thus made hydrophilic. Direct evidence of surface grafting was obtained through infrared spectroscopy analysis and surface energy measurements. This continuous photografting process proved to be very efficient to improve the adhesion of UV-cured acrylate coatings on polyolefin-made materials.     

Fabrication of shape-controllable polyaniline micro/nanostructures on organic polymer surfaces: obtaining spherical particles, wires, and ribbons

A novel strategy was developed in order to prepare various micro/nanostructured polyanilines (PANI) on polymer substrates. The strategy involved two main steps, i.e., a grafting polymerization of acrylate acid (AA) onto the surface of a polypropylene (PP) film and subsequently an oxidative polymerization of aniline on the grafted surface. By tuning the conformation of the surface-grafted poly acrylate acid (PAA) brushes, as well as the ratio of AA to aniline, the shape of the PANIs fixated onto the surfaces of the polymer substrate could be controlled to go from spherical particles to nanowires and eventually to nanoribbons. In these structures, the PAA brushes not only acted as templates but also as dopants of PANI, and thereby, the nanostructured PANIs could be strongly bonded with the substrate. In addition, the surface of the PP films grafted with polyaniline nanowires and nanoribbons displayed superhydrophobicity with contact angles for water of approxiamtely 145 and 151 degrees , respectively.     

Sulfonated polystyrene grafted polypropylene composite electrolyte membranes for direct methanol fuel cells

Polypropylene (PP)-g-sulfonated polystyrene (SPS) composite membranes were prepared by grafting polystyrene (PS) on microporous polypropylene membranes via plasma-induced polymerization. Grafting of polystyrene was established not only inside the pores but also on the surface of PP membranes, followed by the sulfonation reaction. The chemical and physical structure of PS-g-PP membranes was investigated using FTIR and SEM. The thickness and weight of the composite membrane increased with increasing grafting time. Ion exchange capacity (IEC), ion conductivity, and methanol permeability coefficient were measured and analyzed according to grafting reaction and sulfonation time. While both the ion conductivity and methanol permeability coefficient increased with grafting amount, the characteristic factor was comparable to that of Nafion^®.