| Polymer / Clay nanocomposites is a newly rapid developed cross-subject in recent 10 years. Their unique structures lead that they have better properties in mechanical, thermal and gas / liquid barrier than their conventional counterparts. Today Polymer / Clay nanocomposites have showed their important significance and applied future.As the development of this field is not long enough and the research is rather plain both in extension and in depth no matter in home and abroad . The published paper are mainly focused on the preparation of materials, the character of the microstructure and the mechanical properties. The current trend of development goes along the two directions: industrialization of the manufacturing of the new materials, and exploitation of the technology of products made of the new materials. The molding process is the key step that makes the material into products with superior properties. During the processing of the crystalline polymer / Clay nanocomposites, the distribution of clay nanomer layers in the polymer matrix and the interaction between the matrix and the layers must influence the crystallization behavior of the matrix, and put some effect on the properties of the final products. The systemic research for the crystallization behavior of Polymer / Clay nanocomposites can provide strong theoretic foundation for the development of the molding equipment and the process conditions.The crystallization behavior of Polymer / Clay nanocomposites, especially the PET/ Clay nanocomposite, Nylon / Clay nanocomposite was studied by means of DSC2920 in this paper.(1) The DSC behavior of the three origin samples, the quenched samples of PET, PET / Clay nanocomposite and viscous PET / Clay nanocomposite during heating and the DSC behavior of them during cooling from melted state have been studied. The relation between the clay nanomer layers and the crystal perfection has been analyzed, the effect of the clay nanomer layers and the increasing viscosity on the mechanism of the change of the melting temperature are studied.It is found from the experiment results that the temperature of the crystallizationpeaks of PET / Clay nanocomposite from glassy state and the melting temperature are both lower than those of PET. But the melting temperature of the viscous PET / Clay nanocomposite is between the last two materials. The order of the span of supercooling(tm- t'c ) from low to high is PET / Clay nanocomposite, viscous PET / Claynanocomposite, PET. The order of temperature range for crystallization has the opposite sequence.It is indicated from the experiment analysis that the presence of the clay nanomer layers makes crystallization easier, increases the crystallization rate faster, decreases the molding temperature and expands its application of this material in the molding products. During heating, in the PET / Clay nanocomposite. the clay nanomer layers dispersed in the PET matrix make the crystalloids less perfect and a slight reduction in crystalloid size, the melting point is slightly lower than PET. Yet in the viscous PET / Clay nanocomposite, there are obvious effect on the crystalloid perfection of the clay nanomer layers and on increasing viscosity during heating. The increasing viscosity makes the motion of the chain segment more difficult, and the melting temperature higher, so the melting temperature of PET matrix in the viscous PET / Clay nanocomposite depends on the synthetical actions from the two sides and in the middle of the last two samples. So the melting point order of these three samples from low to high is PET / Clay nanocomposite, viscous PET / Clay nanocomposite, PET.(2) The DSC behaviors during heating from the room temperature of the three annealed samples, PET, PET / Clay nanocomposites and viscous PET / Clay nanocomposites are studied. These annealed samples are from the quenched samples that anneal for certain minutes at some temperature below than Tm after quenching from melting state. On this base, the relation of the melting tempera... |
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