The Study On The Organoclay Prepared By Solid State Method And Its Application In Polymers

In recent years, polymer-clay nanocomposites have attracted great interests from researchers since they frequently exhibit unexpected hybrid properties synergistically derived from the two components. In most cases, the new and improved properties are derived when the dimensions of dispersion clay is less than 100nm and many techniques have been attempted for the ultrafine dispersion of clay into the polymer matrix. This is due, in great part, to the recent developments of new functionalization of smectic clays, especially Na+-montmorillonite. Nowadays many polymers have been used to prepare polymer/clay nanocomposites successfully. In general, polymer/clay nanocomposites were successfully prepared through intercalation. In most cases, in order to provide a better physical and chemical environment for the polymer, clay is organically modified through an ion exchange reaction between organic cations and inorganic cations to change the clay from hydrophilic to organophilic and to increases interlayer spacing of clay. The commonly used organic modification agents are long carbon-chain alkyl amine or ammonium salts. However, the processes of organically modified clay which mainly operate in the solvent (e.g. water or ethanol) are costly and inefficient. In addition, the processes cost much time and may bring environmental pollution on environment.In this paper, the organically modified clay (organoclay) was prepared by treating Na- montmorillonite with modified agent (alkyl ammonium ions and self-made surface-active cation) through solid state method without solvent. The Solid State Method has some advantages, such as simple process, cheap and harmless to environment. X-ray diffraction(XRD) and Fourier transform infrared(FTIR) spectroscopy indicated that modified agent could intercalate into the interlayer of the clay.The organoclay was applied to polypropylene(PP), poly (vinyl chloride)(PVC) and nature rubber(NR). The results from XRD and transmission electron microscopy(TEM) showed that the molecular chains of PP, PVC and NR had intercalated into the gallery of organoclay. The structure and properties of the polymer/organoclay nanocomposites were investigated by XRD, FTIR, diferential scanning calorimeter (DSC), thermogravimetric analysis (TGA), TEM, rubber processing analyzer (RPA), dynamic mechanical analyzer(DMA) and Mechanical properties testing.The organoclay which was modified by alkyl ammonium ions did not change the crystal structure of PP(α-PP). On the other hand, The organoclay which was modified by phosphonium cation did bring on theγcrystal structure of PP(10%).The nonisothermal crystalline process was described by the the modified theory of Avrami by Jeziorny, Ozawa and Mo methods. The results show that both Jeziorny and Mo methods could describe this system very well, but Ozawa analysis failed. The crystallization temperature of the composites was higher than that of the neat PP and crystallization speed of the composites was faster than that of the neat PP. Clay could increase the index of crystallization n of PP and had hardly effect on the constant of crystallization Zc of PP. The addition of organoclay decreased the activation energy of crystallization of the PP, which was used as nucleating agent during nonisothermal crystallization process of polymer. The thermal degradation temperature of PP increased evidently in the presence of the silicate layers. The organoclay could lead to depress apparent shear viscosity and improve processing properties. The mechanical properties of PP/organoclay nanocomposites were better than those of neat PP. In addition, organoclay could lightly lower peak heat release ratio(pHRR) of PP.Mechanical properties testing indicated that the PVC/organoclay nanocomposites were better than neat PVC. Silane coupling agent could lead reinforcement effect to PVC/organoclay nanocomposites and reinforcement effect of coupling agent KH-550 was much better than that of coupling agent KH-560. The glass transition temperatures(Tg) of PVC/organoclay nanocomposites were appreciably higher than that of neat PVC and silane coupling agent had hardly effect on the Tg. Silane coupling agent could increase the thermal degradation temperature of PVC and slower speed of thermal degradation of PVC. The addtion of organoclay decreased the activation energy of thermal degradation of PVC.Some of chains of NR could intercalate into interlayer of the organoclay when NR and organoclay were blended. During vulcanizing, The interlayer distance of the organoclay was expanded with increasing vulcanization time. Na- montmorillonite had hardly effect on the vulcanization properties of NR and the organoclay could obviously decrease vulcanization time of NR. The organoclay decreased the thermal degradation apparent activation energy of NR but silane coupling agent could increase the thermal degradation apparent activation energy of NR. The rolling resistance and anti wet-slide properties of NR/organoclay nanocomposites were lower than that of neat NR. In a general way, the addition of organoclay improved mechanical properties and silane coupling agent could lead reinforcement effect to NR/organoclay nanocomposites. After aging at 100℃for 72h, the mechanical properties of NR/organoclay keep better than those of NR.