2010届硕士毕业生
发布人： 发布时间: 2014-02-27 作者: admin 访问次数: 107

 

论文题目：共混方式对尼龙6/EVA/纳米蒙脱土复合材料性能影响的研究
毕业学生：陈川
指导老师：吴唯
中文摘要：
       通过改变共混加料顺序，并使用极性有机化蒙脱土，制备了尼龙/EVA-g—MAH/蒙脱土共混材料。研究了蒙脱土种类、乙烯一醋酸乙烯共聚物(EVA)接枝状况以及共混加料顺序对尼龙6/EVA/蒙脱土共混材料力学性能和热学性能的影响。结果表明，尼龙6中加入极性较强的有机化蒙脱土，并使用EVA接枝马来酸酐(MAH)，对尼龙6冲击韧性的改性效果明显。采用母料法制备PA6/EVA-g-MAH/有机化蒙脱土材料，可使蒙脱土有效分散到尼龙6相或EVA相中时，增韧效果最好，拉伸和弯曲强度的损失最小。
Abstract:
      Through changing the feeding order of blending and use the organic montmorillonite, nylon 6/ EVA-g-MAH/montmorillonite composites was prepared. The effects of the types of the montmorillonite, EVA grafted conditions and the blend feeding order on the mechanical property and thermal properties of nylon 6/ EVA/MMT composites were studied. The results showed that the notched Izod impact strength of the nanocomposite exhibited a great reinforcement by adding the hydrophilic organoclay and EVA-g-MAH. The composites was prepared by masterbatch process, the MMT could be dispersed into nylon 6 phase or EVA phase better, and got the best toughness effect, also reduced the loss of the tensile and flexure strength to the minimum.

 

 

论文题目：聚碳酸酯弹性体复合增韧尼龙纳米复合物的制备与性能研究

毕业学生：陈军

指导老师：吴唯 

中文摘要：

       本文主要研究聚碳酸酯弹性体在尼龙纳米复合物中的复合增韧机制。根据聚碳酸酯在尼龙基体中的分散状态，从分相层面、微结构层面到分子层面逐级递进建立三种复合增韧模型。并对纳米蒙脱土与复合增韧体系的关系进行了研究。

       第一部分主要研究以尼龙6为复合物基体的聚碳酸酯、聚(苯乙烯-丙烯酰胺)/有机蒙脱土核壳结构复合增韧机制。用自制的以蒙脱土为核、聚苯乙烯为次外层、聚丙烯酰胺为外层的新型聚(苯乙烯-丙烯酰胺)/有机蒙脱土核壳结构，通过熔融共混法制备了聚碳酸酯、核壳结构复合增韧尼龙6复合物。研究了尼龙6复合物的力学性能、加工流动性能、结晶性能和热稳定性能。结果表明，聚碳酸酯、核壳结构复合增韧尼龙6具有明显的弯曲力学性能改性效果；核壳结构对PA6的结晶有成核作用，其结晶温度提高了8.5 ℃，结晶度提高了3.3%；聚碳酸酯、核壳结构复合增韧尼龙6与纯尼龙6具有基本一致的热稳定行为；核壳结构还能有效提高尼龙6的加工流动性，其熔体流动速率是纯尼龙6的2.18倍。
       第二部分首先通过介绍PA66/PC/硅橡胶复合物的形态和性能来系统性地研究聚碳酸酯硅橡胶的复合增韧机制。以硅橡胶作为增韧剂，尼龙66复合物通过动态硫化制备而得。硅橡胶在PA66/PC基体中交联形成类似semi-IPN的拟网状结构，这有利于增强尼龙66基体和聚碳酸酯之间的相互作用，并且使得聚碳酸酯颗粒紧密镶嵌在尼龙66基体中。这种新型复合物具有良好的力学性能和加工性能，因而硅橡胶和聚碳酸酯复合增韧是一种具有协同效应的理想增韧体系。此外，PA66/PC/硅橡胶/OMMT复合物在其他力学性能不减弱的情况下具有更好的弯曲强度和弯曲弹性模量。
        本文接着对尼龙66/聚碳酸酯/硅橡胶复合物的热性能进行系统研究。在热处理后该尼龙66/聚碳酸酯/硅橡胶复合物表现出非常稳定的冲击强度和更高的硬度。该复合物的平均降解温度和软化点温度要高于其他普通的工程塑料，这主要归功于引入了动态硫化硅橡胶和在尼龙66与聚碳酸酯之间形成了半互穿网络结构。另外蒙脱土的引入进一步提高了复合物的硬度和降解温度。
第三部分主要研究扩链剂对聚碳酸酯弹性体复合增韧体系的增容效应。以尼龙6（PA6）为主要原料，在聚碳酸酯(PC)和聚烯烃弹性体（POE）复合增韧的基础上，加入扩链剂(HDI)，经由反应挤出制备了具有超韧性的新型尼龙6工程塑料。这种新型增韧合金拥有非常出色的机械性能。本文探讨了合金的增韧机理，并且对性能与多重网络结构的关系进行了深入分析。另外蒙脱土的引入显著提高了合金的弯曲性能。另外本文还探讨了不同HDI含量对复合物力学性能的影响，并对相关热性能和流变性能做了比较研究。结果发现HDI的加入能够显著提高尼龙6和聚碳酸酯之间的相容性，同时复合物的粘度显著提高，结晶度有所降低。
        第四部分主要研究尼龙66纳米复合物中的蒙脱土添加方式，弹性体和纳米填料的协同增强效应，力求开发强度和韧性平衡性良好的弹性体增强尼龙合金纳米复合物。首先用熔融共混法制备尼龙6纳米蒙脱土母料，再与尼龙66、弹性体共混，得到尼龙合金纳米材料。由于采用二次加工法，纳米蒙脱土得到很好的剥离分散。蒙脱土纳米硅层同尼龙6的引入改变了橡胶相的形态，缩小了弹性体颗粒尺寸，并且导致合金中γ晶型的出现，限制基体分子链的移动进而阻碍α晶型的结构精致化。POE-g-MA 弹性体的添加引起冲击强度值的显著增大。同时拉伸强度随弹性体的添加而降低，随纳米蒙脱土的添加而增大。与PA66/POE-g-MA相比较，添加1%的纳米蒙脱土即显著改善材料的拉伸性能，纳米合金不仅韧性好，而且强度高。可见弹性体和剥离好的纳米蒙脱土的同时添加对于材料的拉伸性能具有互补效应。
Abstract：
The research mainly focused on the combine toughening system of polycarbonate and elastomer in nylon nanocomposites.Three different kinds of combine toughening systems were developing step by step from phase, micro-structure, to molecular angle according to the dispersion state of PC in the nylon matrix. The relationship of nano-montmorillonite and the combine toughening systems was also investigated.
The first part mainly focused on the combine toughening mechanism of polycarbonate and the (polystyrene-polyacrylamide)/organic montmorillonite core–shell structures for nylon 6 composites. In this experimentation the P(St-AM)/OMMT core–shell structures were synthesized through emulsion polymerization. Core–shell structure particles and PC were used to combine toughen Nylon 6 and their influence on mechanical properties, processability, crystallization behavior and thermal stability of the PA6 composites was also investigated. The results showed that the inducing of core–shell structures and PC has improved the flexile properties of PA6. The core–shell structures acted as nucleating agent can improve the crystallinity of the PA6 composites(the melting temperature increased by 8.5oC and the crystallinity increased by 3.3%) and  the PA6 composites also show a good thermal stability and processability(the MFR valve increased by 118%).
In the second part the combine toughening system of polycarbonate and silicone rubber was studied through the introduction of the morphology and properties of the PA66/PC/silicone rubber composites. By adding silicone rubber as a toughener, thecomposites were prepared via dynamic vulcanization. The crosslinking of silicone rubber in the PA66/PC matrix formed the netlike structure like semi-IPN which is propitious to enhance the interaction between PA66 matrix and PC and in further makesthe PC particles embed in PA66 matrix closely. Novel composites are gained with outstanding mechanical properties and high-temperature-resistance, so the combine toughening by silicone rubber and PC is an ideal toughening system because of the synergistic effect. In addition, The PA66/PC/silicone rubber/OMMT composite exhibits better flexile strength and flexile modulus without the weakening of other mechanical properties.
The thermal properties of PA66/PC/silicone rubber composites prepared by dynamic vulcanization were also investigated systematically. The PA66/PC/silicone rubber composites show very good retention of impact strength and higher hardness even after heat aging. The average degradation and softening temperatures of the composites are higher than that of other common engineering plastics which we mainly attribute to the introduction of the dynamically vulcanized silicone rubber and the forming of a netlike structure in the PA66/PC matrix. Of the fillers studied, the introduction of montmorillonite even improved the hardness and the degradation temperature of the composites.
In the third part the compatiblizing effect of chain extender on the combine toughening system of polycarbonate and elastomer was studied. This part focused on a new kind of super-tough PA6 engineering plastic. Based on the combine toughening by polycarbonate(PC) and polyolefin elastomer(POE), the PA6/PC/POE/HDI composites were prepared via reactive extrusion by adding of chain extender (HDI). Novel toughening alloy is gained with outstanding mechanical properties. Toughening mechanism was studied and the relationship between properties and the multi-network structure was analyzed. The influence of different loading of HDI on mechanical properties of the composites was also studied. The results showed that the compatibility between PA6 and PC can be improved by adding the chain extender (HDI), the viscosity of the composites increased sharply andthe crystallization degree decreased in some degree with the adding of HDI. In addition, the adding of montmorillonite(OMMT)improve the flexile property of the composite remarkably.
In the fourth part the synergistic effect of elastomer and nano-filler were studied. The elastomer toughening of PA66/PA6 nanocomposites prepared from the organic modified montmorillonite (OMMT) was examined as a means of balancing stiffness/strength versus toughness/ductility. Several different formulations varying in OMMT content were made by mixing of PA6 and OMMT as a master-batch and then blending it with PA66 and different elastomers in a twin screw extruder. In this sequence, the OMMT layers were well exfoliated in the nylon alloy matrix. The introduction of silicate layers with PA6 induced the appearance of the γ crystal phase in the nanocomposites which is unstable and seldom appears in PA66 at room temperature and in further affected the morphology and dispersion of rubber phase resulting in much smaller rubber particles. The incorporation of POE-g-MA particles toughened the nanocomposites markedly, but the tensile modulus and strength were both reduced. Conversely, the use of OMMT increased the modulus but decreased the fracture toughness. The nanocomposites exhibited balanced stiffness and toughness.