Preparation Of The Modified Kaolin And Its Application In Polymers

Kaolin is the kind of important chemical raw materials, which is abundant in our country,and it distributes a wide range of areas. Its application in polymer as a functional filler, it not only reduce the cost of materials but also expected to improve mechanical properties,thermal stability,flame resistance. However surface properties of the kaolin are different from the polarity of polymer chain, the compatibility is poor, so that kaolin appeared agglomeration in the polymer matrix. So it is necessary to have an organic modification for kaolin, make it well dispersed in the polymer matrix.In the second chapter, the calcined kaolin was modified by amino silane coupling agent (KH550), isophorone diisocyanate (IPDI), octadecylamine (ODA). Di(dioctylpyrophosphato) ethylene titanate makes washed kaolin surface properties from the hydrophobe to hydrophilic. The structure of modified kaolin Was characterized by FT-IR. The suspending rate of kaolin in the water is studied. The results showed:the organic matter was successfully grafted to the surface of the calcined kaolin. Three Dry Process Modification has greatly changed the surface feature of the calcined kaolin from hydrophilic to oleophilic, the activation index was 100%. The modified washed kaolin well dispersed in the water, the suspending rate was 85%.In the third chapter, waterborne polyurethane/calcined Kaolin-K composite latex was synthesized with calcined Kaolin-K and polyurethane prepolymers end capped by isocyanato. The structure of the modified kaolin was characterized by Fourier transform infrared spectrometer (FTIR). The morphology, mechanical properties and heat resistance of composite material (WPU-K) have been observed through scanning electron microscope (SEM), tensile tests and thermogravimetry (TG).The results indicated that, When the mass fraction of calcined Kaolin-K was 8%, the temperature for the maximal thermal mass-loss was increased 28 ℃ than the polyurethane, the tensile strength of the composites increased 22.64% and Shore A hardness increased from 53 to 82. Additionally, water absorption for the sample was reduced 277%. calcined Kaolin-K improved mechanical properties and the thermal stability of the films obviously.In the fourth chapter,. A series of hydrophilic modified kaolin(washed Kaolin-T)/ waterborne polyurethane dispersions were prepared successfully by mechanical blending. The morphology, mechanical properties and heat resistance of composite material have been studied. The results indicated that the tensile strength of the composites was 24.4MPa with the content of washed Kaolin-T was 2.0%, which increasing 53.1% than the polyurethane, and the elongation at break up to 492%, increasing 9.6%. The composites were achieved the effect of enhancing and toughening because of the adding of washed Kaolin-T. Furthermore, the thermal stability was improved.In the fifth chapter,the PP/calcined Kaolin-O composites were prepared by a melt blending technique with PP and calcined Kaolin-O. The morphology of the composites (PP/calcined Kaolin-O) was characterized by TEM, SEM.The crystallization behavior and the thermal stability of composites was studied by XRD、 DSC and TG. The mechanical properties of PP/ calcined Kaolin-O composites were also discussed by tensile testing machine. The results showed:when the content of calcined Kaolin-O is lower than 5%, calcined Kaolin-O layers are uniformly dispersed in PP matrix.In addition, calcined Kaolin-O filled in PP matrix promoted β crystallization nucleation, improved crystallization rate and thermal stability of PP. When the content of the calcined Kaolin-O was 3phr, the tensile strength, the percentage of breaking-elongation, increased by 37%,18%, respectively.