纳米碳酸钙微粒填充改性聚丙烯复合材料的力学性能和结晶行为研究

研究了两种不同粒径的纳米碳酸钙(Nano-CaCO3)熔融共混改性均聚聚丙烯(PP)材料的力学性能和结晶行为，结果表明，两种纳米CaCO3填料对PP的B晶形成均有不同程度的诱导作用，并可提高基体结晶温度和结晶速率，从而提高材料的冲击韧性．     

改性纳米碳酸钙-聚丙烯复合材料的结构与性能研究

制备了硬脂酸钙包覆的纳米碳酸钙( CaSt-nano-CaCO3),并采用熔融共混的方法制备出iPP/CaStnano-CaCO3和iPP/nano-CaCO3复合材料.与纯iPP相比,复合材料的弯曲强度和弯曲模量随着CaCO3粒子含量的增加而提高,冲击性能也得到改善.相对于iPP/nano-CaCO3,iPP/CaS...     

KH550改性纳米SiO_2的制备及其界面相互作用研究

采用KH550为硅烷偶联剂对纳米SiO2进行改性,对改性前后的纳米SiO2采用XRD、TEM、FTIR、NMR等表征手段研究样品的微观结构、表面羟基含量、有机/无机界面相互作用等问题。实验结果表明,纳米SiO2经过KH550的改性,亲水性减弱、亲油性增强,表面质子运动活性也随之增加,并且KH550与SiO2有相互作用存在。29Si核的NMR谱表明,由于KH550与纳米SiO2表面的偶极相互作用,分子运动变慢,使得纳米SiO2改性后的29Si弛豫时间比改性前明显增加。     

超细CaCO_3的粒子尺寸对PP结晶行为的影响

The effects of CaCO3 on the crystallization behavior of polypropylene (PP) were studied by means of DSC and WAXD.The average sizes of the CaCO3 powders used were 0.1μm (UC) and 0.5μm (GC),respectively.The PP/CaCO3 composites at compositions of 1phr and 10 phr were investigated.The results showed that the addition of CaCO3 reduced the supercooling,the rate of nucleation and the overall rate of crystallization (except for the 10phr UC/PP sample).The crystallinity of PP was increased and the size distribution of the crystallites of α-PP was broadened.On the other hand,the crystallization rate of 10phr UC/PP is 1.5 times higher than that of neat PP.It has an overall rate of crystallization 2 times as much as that of the neat PP and has the maximum crystallinity.The sizes of crystallites and the unit cell parameters of α-PP were varied by the addition of CaCO3.β-PP was formed by addition of GC and was not detected by addition of UC.The differences of crystallization behaviors of PP might be attributed to the combined effects of the content and size of CaCO3 filled.     

固体高分辨核磁共振研究聚氧乙烯/纳米二氧化硅复合物的界面相互作用

采用固体高分辨核磁共振碳谱对聚氧乙烯(PEO)/纳米二氧化硅(Nano-SiO₂)复合物体系的相态结构、分子间相互作用和分子运动进行了研究,发现随着复合物中SiO₂含量增加,PEO结晶度明显降低,且PEO非晶区的分子运动受到明显约束,基于对PEO非晶区及SiO₂颗粒表面羟基质子的自旋-自旋弛豫行为的分析,提出了复合物的界面模型以及SiO₂与PEO之间的界面相互作用机制.     

具有包藏结构的三元聚丙烯纳米复合材料结构与性能关系的研究

制备了一种新型聚丙烯 丁苯橡胶 纳米碳酸钙三元纳米复合材料 .研究结果显示 ,复合材料中的大多数纳米碳酸钙粒子被包藏在丁苯橡胶中 ,并与之共同形成分散于聚丙烯树脂中的分散相 ,这种聚丙烯纳米复合材料具有高刚性、高韧性、高耐热性和高的结晶速率 .系统研究了成核剂苯甲酸钠的加入和纳米碳酸钙的用量对该类纳米复合材料相态结构、结晶形态和结晶动力学的影响 ,以及具有包藏结构的分散相粒径和PP中β晶含量对材料性能的影响 .结果表明 ,苯甲酸钠的加入和纳米碳酸钙用量的提高均可使体系中分散相粒径减小 ,结晶速率加快 ,进而使材料的韧性、刚性和耐热性提高 .     

用PAANa掺杂的纳米CaCO_3的合成及其产品表征

在反应物经超声波预处理和聚丙烯酸钠PAANa分散剂的掺杂下运用化学沉淀方法制备出窄粒径纳米碳酸钙。将所获纳米粒子运用现代分析测试手段进行结构、晶形、组成等的表征。结果表明纳米级超细碳酸钙在红外区有蓝移40cm-1和峰形窄化现象纳米粒子的高表面能及CO32-存在的共轭体系CaO键的相互作用以及表面配位的不饱和性和晶体生长的人为终止是存在表面效应的主要原因。     

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.     

大分子相容剂改性Mg(OH)2/PP阻燃材料的性能

用双螺杆挤出机熔融挤出法制备了相容剂改性氢氧化镁/聚丙烯[Mg(OH)2/PP]阻燃材料。研究了马来酸酐接枝聚丙烯(PP-g-MA),马来酸酐接枝(乙烯/辛烯)共聚物(POE-g-MA)和马来酸酐接枝聚醋酸乙烯酯(EVA-g-MA)3种大分子相容剂对阻燃材料的熔体流动性、结晶行为、力学性能和断口形态的影响。结果表明:相容剂PP-g-MA和POE-g-MA的加入使阻燃材料的熔体流动速率降低,PP结晶温度提高,EVA-g-MA的加入使阻燃材料熔体流动速率数提高;Mg(OH)2对PP结晶存在异相成核作用,Mg(OH)2的加入使PP的冲击强度、拉伸强度和断裂伸长率降低,杨氏模量提高;相容剂改性后Mg(OH)2/PP阻燃材料的拉伸强度提高,其中以PP-g-MA最为明显,而POE-g-MA则提高了阻燃材料的冲击强度。     

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     

纳米级CaCO_3粒子与弹性体CPE微粒同时增韧PVC的研究

研究了平均粒径为 30nm的超细级纳米CaCO3 与氯化聚乙烯 (CPE)对聚氯乙烯 (PVC)共混体系二元协同增韧效应及机制 .结果表明 ,当共混体系中有一定量的CPE时 ,纳米CaCO3 的加入可以明显地提高共混物的韧性 ,而不降低共混物的强度和刚性 .纳米CaCO3 在PVC基体中达到了纳米级的分散 .当纳米CaCO3 的用量为 8份 (质量 )时 ,PVC CPE 纳米CaCO3 共混物的冲击断面产生了大量的有规则的网丝状结构 ,共混物的缺口冲击强度达到 81 1kJ m2 ,比不加纳米CaCO3 的共混体系高 7 3倍 .CPE的加入对共混体系的加工流动性能无影响 ,纳米CaCO3 的加入使共混体系的加工流动性能变差     

纳米碳酸钙及其表面处理对等规聚丙烯结晶行为的影响

应用差示扫描量热方法研究了不同表面改性碳酸钙纳米粒子对聚丙烯 (PP)等温与非等温结晶动力学的影响 ,并研究了上述各聚丙烯结晶样品的熔融行为和晶型 .研究发现纳米碳酸钙具有明显的成核效应 ,并具有较强的诱导 β 型结晶的能力 ,而且与粒子的表面处理密切相关 .     

碳纤维-尼龙1010界面形态的研究

通过偏光显微镜,研究了碳纤维-尼龙1010的界面形态,发现石墨、高模量碳纤维(M40)诱发尼龙1010形成横晶的能力大于高强度、中强度碳纤维;界面横晶形态强烈地依赖于结晶温度。     

界面作用对HDPE/POEg/CaCO_3三元复合材料韧性的影响

通过界面改性,制备了以CaCO3为核,马来酸酐接枝乙烯-辛烯共聚物弹性体(POEg)为壳的高密度聚乙烯(HDPEg)/弹性体(POE)/CaCO3的三元复合材料.由于“核-壳”结构的形成,弹性体和CaCO3表现出协同的增韧作用.同未经表面处理的CaCO3复合材料相比,在相同的CaCO3含量的情况下,表面处理的CaCO3由于与弹性体形成更强的界面粘结,使得三元复合材料的“脆-韧”转变发生在较低的弹性体含量.     

CRYSTALLIZATION AND MECHANICAL PROPERTIES OF POLYPROPYLENE FILLED WITH SiO2 NANOPARTICLES

Oleic acid （OA）-modified SiO2 （OA-m-SiO2） nanoparticles were prepared using surface modification method. Infrared spectroscopy （IR） was used to investigate the structure of the OA-m-SiO2 nanoparticles, and the result showed that OA attached onto the surface of SiO2 nanoparticles through esterification. Effect of OA concentration on the dispersion stability of OA-m-SiO2 in heptane was also studied, and the result indicated that OA-m-SiO2 nanoparticles were dispersed in heptane more stably than the unmodified ones. OA-m-SiO2 nanoparticles can also be dispersed in polypropylene （PP） matrix in nano-scale. The effect of OA-m-SiO2 on crystallization of PP was studied by means of DSC. It was found that the introduction of OA-m-SiO2 resulted in significant increase in the crystallization temperature, crystallization degree and crystallization rate of PP, and OA-m-SiO2 could effectively induce the formation of β-crystal PP. Effect of OA-m-SiO2 content on mechanical properties of PP/OA-m-SiO2 nanocomposites was also studied. The results show that OA-m-SiO2 can significantly improve the mechanical properties of PP.     

增容剂对聚丙烯/粘土纳米复合材料热分解动力学的影响

采用三单体固相接枝聚丙烯作为增容剂制备了聚丙烯粘土纳米复合材料.通过XRD和TEM表征了其纳米结构.利用动态TGA方法研究了聚丙烯和纳米复合材料的热稳定性.分别采用Flynn Wall Ozawa和Kissinger法研究了聚丙烯及其纳米复合材料的热分解动力学.结果都表明,蒙脱土的加入明显提高了聚丙烯的起始热分解温度,纳米复合材料热失重10%时的温度比聚丙烯提高40K左右;纳米复合材料的热分解温度区间明显比聚丙烯的窄;纳米复合材料热分解表观活化能明显增大,与聚丙烯相比提高50%以上.     

SPATIAL HIERARCHY AND INTERFACIAL STRUCTURE IN INJECTIONMOLDED BARS OF POLYPROPYLENE-BASED BLENDS AND COMPOSITES

The hierarchical structure and interfacial morphology of injection-molded bars of polypropylene （PP） based blends and composites have been investigated in detail from the skin to the core. For preparation of injection-molded bars with high-level orientation and good interfacial adhesion, a dynamic packing injection molding technology was applied to exert oscillatory shear on the melts during solidification stage. Depending on incorporated component, interfacial adhesion and processing conditions, various oriented structure and morphology could be obtained. First, we will elucidate the epitaxial behavior between PP and high-density polyethylene occurring in practical molded processing. Then, the shear-induced transcrystalline structure will be the main focus for PP/fiber composites. At last, various oriented clay structures have been ascertained unambiguously in PP/organoclay nanocomposites along the thickness of molded bars.     

STUDIES ON THE MECHANICAL PROPERTIES AND CRYSTALLIZATION BEHAVIOR OF POLYETHYLENE COMPOSITES

The effects of inter facial modifier on the mechanical, dynamic mechanical properties andcrystallization behavior of the polyethylene composites were investigated in the present paper.It was found that the interfacial modifer significantly improved the mechanical properties,influenced the dynamic mechanical spectra and slightly changed the crystallization behavior.The results showed that the interfacial modifier changed the dispersion state of dispersedphase of the composites, resulting in different phase structure, which was the major reasonIeading to different mechanical and crystallization properties.