【作者】 贺卫卫；

【导师】 李玉平；

【作者基本信息】 湖南大学 ， 材料学， 2006， 硕士

【摘要】 本文研究了在常压低温下以一步湿化学方法制备纳米ZnO晶须较佳的工艺路线,分析了复配改性剂对所制备的纳米ZnO晶须的修饰改性效果,并将此ZnO晶须应用到聚丙烯酸酯乳液制备复合涂料,初步探讨了纳米ZnO晶须对复合涂层的增强以及其他基础性能的影响。纳米ZnO晶须制备工艺的研究中,经依次改变不同合成因素的水平制备产物,并以TG-DSC,XRD,TEM,FT-IR等检测手段对合成产物进行表征和分析,其结果表明,在55℃恒温水浴环境下,将初始浓度为1.2mol·L^-1的ZnSO₄溶液滴入到低速搅拌的3mol·L^-1 NaOH溶液中,同时滴入适量0.01mol·L^-1的DBS有机助剂,在pH酸度计的测定下,通过控制ZnSO₄的加入量控制反应混合液的滴定终点的pH值大于9,待ZnSO₄及DBS全部滴入后降低搅拌速度并保温2h,让反应进行完全并让产物充分结晶。保温结束,将反应混合液进行减压洗滤分离,无水乙醇脱水,最后经80℃真空干燥4h就可制得直径为20⁵0nm,长度达到400nm,形貌为针状或棒状的ZnO晶须。本文所采用一步湿化学法制备工艺无需高温煅烧,在液相体系中就可直接生成ZnO,XRD表征显示该ZnO为六方晶相纤锌矿结构,其晶格参数a_o、c_o计算值分别为0.325nm和0.521nm,无其它杂质相存在,晶型单一。XRD图谱中衍射峰尖锐,结晶性良好。HRTEM照片显示相邻晶格条纹间距为0.26nm,与ZnO晶体（002）晶面的面间距相当,纳米ZnO晶须是沿（002）晶面取向生长。对纳米ZnO晶须进行修饰改性时,采用含DBS为30%（质量比）的DBS/PEG400为复配改性修饰剂,控制改性体系中复配改性剂浓度为400mg?L^-1,以适当搅拌速度搅拌60min,纳米ZnO晶须就得到较好的修饰改性效果。改性后ZnO晶须悬浮体系的吸光度较改性前明显增大,而且随着沉降时间的延长变化很小。这证明改性后的悬浮体系中纳米粒子分散性及稳定性更好。将该纳米ZnO晶须经修饰改性后引入到聚丙烯酸酯类涂料体系后,复合涂层硬度增大,涂层增强,而且涂层的耐沾污性、耐擦洗性得到明显提高。此外复合纳米ZnO晶须的涂料的触变性及储存稳定性也有相应的改善,这些性能基本上是随的纳米ZnO晶须的应用量的增加而提高。综合各项性能指标显示,纳米ZnO晶须在涂料体系中的质量百分含量达到6%时所制备的涂料试样性能最优。更多还原

【Abstract】 The suitbale technological parameters of synthesizing nano-ZnO whiskers by a one-step wet chemical method with low-temperature in normal pressure were investigated in this paper, and the modification effects of as-prepared nano-ZnO whiskers by built surfactant in different dispersion condition were also studied. The polyacrylate nanocomposite coatings were parepared by the dispersion of nano-ZnO whskers in polyacrylate, the hardness and other basis performance of nanocomposite film were evaluated.Through changing the different synthetic parameters in turn to prepare final products, and characterizing as-prepared products with DSC-TG, XRD, TEM,FT-IR, the best technological parameters of synthesizing nano-ZnO whiskers were attained. 1.2 mg·L^-1 ZnSO₄ was added drop-wise into 3.0 mg·L^-1 NaOH under stirring in baker that was heated at a temperature of 55°C in thermostat water bath, following that, 0.01 mg·L^-1 C₁₈H₂₉NaO₃S （DBS） was introduced into the aforementioned solution. In the monitoring of pH meter, the pH value of reaction mixture was adjusted to above 9 though controlling the amount of ZnSO₄ added. 2 hours later, the precursor was harvested by filtering under vacuum and washing 3 to 5 times with distilled water and absolute ethanol, finally, the naonsized ZnO whiskers was attain after the precursor was dried in a vacuum oven 4h at 80°C. Depending on the synthetic conditions used, ZnO can be formed directly in aqueous solution without calcination. Transmission electron microscope （TEM） observation reveales that nano-ZnO whiskers are needle-like or rod-like morphology, they have diameters ranging from 30 to 50 nm and lengths up to 400nm. The nano-ZnO whiskers show high crystalline pattern, and all the diffraction peaks can be well assigned to the hexagonal-phase ZnO reported in the literature （Wurtzite-type, space group P63mc）, the calculated cell parameters of a₀ and c₀ are 3.25 and 5.21·, respectively. None other phases can be observed in the patter, verifying that the sample is phase-pure. The HRTEM image shows the lattice spacing of 0.26nm, corresponding to a lattice constant of the （002） plane of wurtzite structured ZnO, and implies the preferred growth orientation of ZnO nanorods along the （002） plane.In modification of nano-ZnO whiskers experiments, using DBS / PEG400 which containing 30% DBS as built modifying agent, controlling the concentration of DBS / PEG400 is 400mg·L^-1, and agitating for 60min, the best effects of modification can be gotten. The absorbance of modified nano-ZnO whiskers dispersion is higher than that of unmodified, dispersion and stability in system is also better.The polyacrylate nanocomposite coatings were parepared through dispersing the nano-ZnO whiskers into polyacrylate, After detected some basic performance of the composite coating, we attained the conclusion that, the composite coatings with 6% nano-ZnO whiskers contained have the best comprehensive performance, not only film hardness is strengthened, stain-resisting and scrub resistance of the coating are much increased, but also the coating’s thixotropy and storage stability are clear improved.更多还原