【作者】 吴香发；

【导师】 何杰；

【作者基本信息】 安徽理工大学 ， 应用化学， 2006， 硕士

【摘要】 重钙是一种常用无机材料,因来源广、价格便宜等,广泛应用于橡胶、塑料、涂料等领域。但超细重钙表面亲水疏油、比表面积大、表面能高、颗粒间极易团聚,当直接或大量填充时,不但在PVC等有机基体中难以均匀地分散,且与基体的结合力很弱,导致两相界面缺陷、复合材料的某些性能下降。因此,填充至高聚物前必须对重钙表面进行改性,使其表面亲油疏水,增强与有机基体的相容性,提高在有机基体中的分散性,改善和提高复合材料的性能。 实验采用硬脂酸、钛酸酯偶联剂NDZ-311以及两者的复配等三种改性剂,分别在搅拌和超声条件下对重钙进行表面改性。将改性前后重钙粉体辅以适当的加工助剂与PVC树脂进行熔融混炼而制得PVC/CaC03复合材料。 采用活化指数、分散相体积、粘度等物性参数以及DSC、IR、XPS等表征方法对改性重钙的性能进行考察。结果表明:无论是搅拌改性还是超声改性工艺,改性后重钙粉体的活化指数较未改性前增大,分散相体积得到有效提高即改性重钙在液体石蜡中的分散稳定性得到改善;表面改性对重钙分散体系具有很强的降粘性能。改性前后重钙颗粒尺寸稍有变小;改性剂分子与重钙表面发生了较强的化学键合作用;超声和搅拌工艺达到最佳改性条件是改性剂用量分别为2.5wt%、3.0wt%的复配改性剂,而超声改性方法显示了比搅拌改性方法具有更好的效果,复合改性剂显示了比单一改性剂更好的性能。 采用拉伸强度、断裂伸出率、简支梁缺口冲击强度、维卡软化温度等热物理和力学参数对PVC/CaCO₃复合材料进行评价,并结合SEM、TG-DSC联用等方法对复合材料进行表征,结果表明:重钙在PVC基料中的最佳填充量为20wt%,此时,PVC/超声改性重钙体系显示了比未填充重钙体系具有更好的冲击强度和热稳定性等性能。更多还原

【Abstract】 Ground calcium carbonate （GCC） is one kind of ordinary non-metallic mineral materials. It is widely applied to many industrial areas such as rubber, plastics, coating and so on. Because it has the nature of large specific surface area and high surface energy, it is easy to become agglomerate among particles. When GCC is filled in organic basic body directly or with high quantity, it is difficult to disperse uniformly which results in descent of some properties of composites because of their poor interfacial interaction. Therefore, the surface of GCC must be modified to adjust its polarity, descend surface energy and reinforce its compatibility with organic basic body. The dispersibility of GCC into organic basic body and the properties of composites would be improved.In order to get better PVC/CaCO₃ composites, stearic acid, titanate coupling agent NDZ-311 and the two formers’ compounded agent were used to modify GCC under the conditions of stirring and ultrasonic. After that, modified and unmodified GCC putting into some process additives and PVC were put together respectively to obtain PVC/CaCO₃ composites with the method of melt co-mixing.To get the optimal modification craft, activation index, volume of dispersion phase, viscosity and Infrared spectrum（IR）, differential scanning calorimetry（DSC）, X-ray photoelectron spectroscopy （XPS）, etc. were used to evaluate and characterize successively. The results show that regardless of the type of modification craft, activation index, volume of dispersion phase and viscosity were to increase or improve after modification of GCC, chemical reaction between the surface of GCC particles and the molecular of modifiers has existed obviously. The optimal dosage of stirring modification and ultrasonic modification are 3.0% and 2.5% respectively. So, the ultrasonic craft is better than the stirring one.In order to get optimal fill percentage of GCC into PVC, many property parameters were characterized, such as tensile strength, elongation at break, notched charpy impact strength and vicat softening temperature. After the analysis of scanning electron microscope （SEM）, thermogravimetry（TG）, TG-DSC of PVC-based composites, results show that the optimal fill percentage of GCC in PVC is 20wt%. Meanwhile, the system of ultrasonic modified GCC/PVC composite has better impactstrength and higher vicat softening temperature than stirring one and no filled one. Moreover, the conclusion that ultrasonic craft was superior to stirring craft was proved once again.更多还原