【作者】 蒋涛；

【导师】 范志强； 程时远；

【作者基本信息】 浙江大学 ， 高分子化学与物理， 2005， 博士

【摘要】 论文采用层状共混吹塑工艺制备了高密度聚乙烯(HDPE)/尼龙6(PA6)高阻隔性塑料瓶,在重点研究高阻隔性积层材料制备工艺的基础上,考察了阻隔性能与工艺、相态以及高密度聚乙烯/尼龙6共混物相容性之间的关系,同时系统的研究了尼龙6/蒙脱土纳米复合材料的阻隔机理,探讨了高密度聚乙烯/尼龙54以及高密度聚乙烯/尼龙54/蒙脱土(MMT)积层材料的阻隔性能。 采用动态力学测试(DMTA)结合原子力显微分析(AFM),比较了两种增容剂Zn-n-EAA(CPa)和EAA(CPb)的增容效果,通过测定高密度聚乙烯/改性尼龙(HDPE/MPA)共混物中两相的玻璃化转变温度的变化,观察共混物的两相界面,证明CPa的增容效果优于CPb。 将增容剂和尼龙在双螺杆挤出机中反应挤出,研究螺杆转速以及原料配比对改性尼龙阻隔性和熔体粘度的影响。结果表明,当螺杆转速为300rpm、增容剂含量为15phr时,改性尼龙具有最高的熔体粘度和最高的阻隔性能,其抗乙醇渗透性能比纯尼龙提高4.5倍。 系统研究了中空成型工艺以及原料配比对形态结构和容器阻隔性能的影响,确定了最佳工艺和配方。结果表明,HDPE/MPA瓶阻隔性明显好于纯HDPE瓶,且随着CPa改性尼龙(MPAa)中CPa含量的增加,HDPE/MPAa瓶的阻隔性也相应提高,逐渐达到一最佳值。在最佳条件下制备的中空瓶对甲苯的阻渗性能比纯聚乙烯瓶提高300多倍,对比HDPE/MPAa和HDPE/MPAb系列中空瓶阻隔性能,发现HDPE/MPAa瓶普遍好于HDPE/MPAb瓶。随后通过SEM观察中空瓶瓶壁断面,发现在HDPE/MPAa内部形成了较连续而清晰的层状结构,而HDPE/MPAb内部则是很短的取向片段。 为了更进一步改善尼龙阻隔层的阻隔性,探索了尼龙/蒙脱土共混物的制备工艺和阻隔机理。研究发现,蒙脱土的添加量对材料的阻隔性有显著影响。当蒙脱土含量为0.1%时,阻隔性能达到最大值,在合适的工艺条件下,共混物对甲苯和乙醇的阻隔性能比纯尼龙分别提高了3倍和4倍。随后的研究表明,尼龙的结品性能对小分子在其内部的吸收和扩散都有较大的影响。XRD、AFM、DSC和PLM研究证明,蒙脱土的加入,使尼龙6结晶度提高,球品尺寸明显减小,另一方面,蒙脱土的加入,能促使尼龙形成γ品型。由于γ晶型的晶面间距小于更多还原

【Abstract】 In this paper, high density polyethylene (HDPE)/modified polyamide(MPA) laminar materials have been prepared by laminar-blend blow-molding process to improve permeation resistance of HDPE. The relationship between the barrier properties, processing technology and morphology were studied. The research was focused on solvent resistant property of HDPE)/ MPA6 blends, HDPE/MPA54 and HDPE/MPA54/MMT series.First of all two types of compatibilizer precursors (CPs), Zinc-neutralized ethylene/acrylic copolymer (CPa) and non-neutralized ethylene/acrylic copolymer (CPb), were selected to modify polyamide 6 (PA6). The compatibility effect of CPs were studied by dynamic mechanical thermal analysis (DMTA) and atomic force microscope (AFM). The results show that CPa has stronger compatibility effect than CPb in HDPE/PA blend.Compatibilizer modified polyamid(MPA) were prepared in twin screw extruder and the reacting extrution processing were studied in detail. The barrier property of MPAa series are better than MPAbs. As the content of CPa was 15phr and the rotation speed was 300rpm, the melting index of MPAa was lowest, and the barrier property was best. Under these conditions the ethanol permeation resistance of MPAa were 4.5 times better than pure PA.Bottles of HDPE/MPA were produced by a laminar-blend blow-molding process. The effects of preparation temperature, screw speed, and compositions were investigated systematically, and optimal preparation parameters were obtained. The results showed that the HDPE/MPA blends exhibit significantly better barrier properties than those blow-molded from pure HDPE. The barrier resistance of HDPE / MPAa blends are improved gradually with increasing CP content in MPAa and the lowest toluene permeability is obtained. The barrier improvement of the best sample is 308 times better than pure HDPE. The barrier properties of HDPE/MPAa bottles are better than that of HDPE/MPAb. The further investigation on the morphology showedthat MPAa exhibits strong interfacial adhesion with a HDPE matrix and forms a multi-lamina morphology, but MPAb only formed the "broken" and "discontinuous" orientation structure.In order to further improve the barrier property of PA, Nylon6/clay nanocomposite was prepared by mixing organically montmorillonite(MMT) with nylon6 in HAAKE mixer, and solvent permeation resistance of nanocomposite is measured. The nanocomposite shows the resistance against solvent permeation superior to that of pure nylon6.The maximum improvement in barrier properties of nylon6/clay composite was found when the content of clay was about 0.1%. Using proper composites and under suitable processing conditions, the permeation rate of toluene and ethanol in nylon6/clay nanocomposite is about 3 and 4 times slower than that in purenylon6at 50"C.Our studies indicated that the crystalline property of nylon6 has a strong impact on the sorption and diffusion of small molecules in the polymer. The improvement in solvent barrier properties of nylon6/clay nanocomposite is attributed to incorporation of an impermeable phase such as layered silicate, improvement in crystallinity and the decrease of crystalline dimention, which are evidenced by XRD, AFM, DSC and polarized optical micrographs (POM). In PA6/ MMT nanocomposites, the addition of MMT favors the formation of the y crystalline phase was investigated by XRD. The result showed that d-spacing of y crystalline phase is smaller than that of a crystalline phase, and the crystallinity is higher in nanocomposites as compared with neat PA6. POM analyses show that spherulites of nylon6 are fairly big and perfectly grown with the maltese cross, but nylon6/ MMT nanocomposite has fine and uniform spherulite. This result implies that MMT reduces the size of nylon6 crystallites.Non-isothermal crystallization experiments involving differential scanning calorimetry (DSC) were conducted to understand the nucleat effect of MMT, The result shows that the addition of MMT increased the rate of crystallization and decreased the time of crystallization. The nucleating activity of MMT(<j>) is about 0.56.The transparency of nanocomposite was investigated by ultraviolet-visiblespectrometer. Although the degree of crystallinity of the nanocomposite is higher than that of the pure nylon6, interestingly the nanocomposite prepared under suitable cooling conditions shows better transparence than pure PA6. This can be attributed to the smaller sizes of spherulites in nanocomposites. In addition, the rheological properties of nanocomposite were studied. It shows that the addition of MMT increased the melt viscosity at lower shear rate but decreased the melt viscosity at higher shear rate.Finally, the bottles of HDPE/MPA54 and HDPE/MPA54/MMT were prepared by laminar-blend blow-molding process, and their barrier property and morphology were studied, the investigations indicate that the best processing temperature of HDPE/MPA54 and HDPE/MPA54/MMT are about 40°C lower than HDPE/MPA6 blend. Clearly defined laminas were observed on the fracture surfaces of the PE/MPA54 bottles. The toluene permeation resistance of HDPE/MPA54 were improved more than 80 times compared with pure HDPE.更多还原