Preparation And Characterization Of Copolymer PA66/PACM12and PACM12Nanocompo Sites

Copolymerization modification and in situ polymerization are kinds of method to improve the properties of materials. As for PACM12which is a new type of polyamide has unique miicrocrystalline structure and excellent optical performance but lack of mechanical strength. We can copolymerize PACM12with PA66to change the microstructure of PACM12, as a result, the mechanical property, crystallization behavior, thermal behavior and optical property is different. In this paper we prepared a set of copolymers with different proportion of PACM12and PA66, and through testing the performance of these materials, we discussed the relationship betweenmicrostructure and properties of them. In another section of this paper, we also prepared PACM12nanocomposites with different content of nano silica or nano claythrough in situ polymerization and the influences of nano silica or nanoclay to the materials was studied.The main results are summarized as follows:1. XRD test show that the crystallization behavior of copolymers changes obviously with different proportion of PACM12and PA66.When the content of PACM12is less than20wt%, the crystallization behavior of materials is similar to the PA66, then more amounts of PACM12makes the diffraction maximum of materials shifts to the position with lower angle; when the content of PACM12is more than40wt%, the crystallization behavior of materials is similar to the PACM12. Especially the crystal size of the copolymers turns to smaller when more PACM12is added. The results of IR tests showed that the position of stretching vibration peak of N-H moves to the position has higher wave number when more amounts of PACM12is added, but the hydrogen bonding interaction between molecular chains is weaken, which verify the results of the XRD test. As to the nanocomposites the addition of nano silica or nano clay both impede the the crystallization process of materials.2. The thermal stability of materials were measured by TGA testing. It turns out that the initial decomposition temperature of materials gets higher with increasing the content of PACM12and arrives to its maximum(469℃) at34wt%. Besides, the addition of nanoclay can amazingly improve the thermal stability of materials compared with pure PACM12, and the initial decomposition temperature gets to its maximum at471℃, when the content of nanoclay reaches to2wt%.3. Through DSC testing, the thermal behavior of materials is examined. As we can see, the Tg of copolymers first declines when the content of PACM12is no more than34wt%and then increases with the increase of PACM12. Especially, at24wt%,28wt%,and34wt%content of PACM, there exit cold crystallization transition in the copolymers. Because of the imperfect crystallization process of PACM12, when the addition amounts of PACM is higher than40wt%we can no longer find the melting transition in the second temperature curve of DSC testing, but actually we know that melting point of PACM12is about190℃according to the first temperature curve of DSC testing. In terms of PACM12nanocomposites, both nanoclay and nano silica can improve the Tg of materials, But the melting peak of PACM12in the first temperature curve of DSC testing gets wider and wider with increase of nanoclay and nano silica.4. According to the DMA testing, the Tg of the materials is first decline and then increase coupled with the more addition of PACM12; which depends on both molecular chain structure and the degree of crystallization. When the content of the PACM12is less than34wt%in copolymer, the molecular chain structure is similar to PA66. Then there exists a obviously phase separation in materials when40wt%and75wt%is added. Besides, when the amount of PA66and PACM12is equal, the products is completely amorphous. As to the PACM12nanocomposites, the nano clay play the part of the wild phase to the polymer matrix, and improve the Tg of polymer matrix. Conversely, the addition of nano silica makes the storage modulus of the composites less than pure PACM12.5. The influence of the content of PACM12to the mechanical property of copolymers is complicated. In general the tensile strength of copolymer is lower than pure PA66but higher than pure PACM12and the impact strength is higher when the amounts of PACM12is higher. It is strange that at28wt%and34wt%content of PACM12the copolymers turn out outstanding mechanical property compared with other materials, which might be the result of grain refinement of materials. As to the PA PACM12nanocomposites, the effect on the mechanical property of materials is different between nano clay and nano silica. The addition of nano clay improves the tensile strength of PACM12but lowers the impact strength of PACM12when its content is less than4wt%. Unfortunately, the addition of nanosilica makes the mechanical property of PACM12get worse, because the nanosilica is not compatible with PACM12.6. The light transmittance and refractive indices are very important performances of optical materials. The testing results show that if materials get higherrefractive indices, its light transmittance will be loseto some extent. The light transmittance of copolymers is more than90%when the content of PACM12is higher than40wt%. At the28wt%to34wt%content of PACM12, althoughthe light transmittance of copolymersis declined, they are still better than PA66which is completely opaque.The addition ofnanoclay can increase the refractive indices from1.53(pure PACM) to1.71(8wt%nano clay composites) at cost of light transmittance, but it can maintain its light transmittance at75%even the addition of nanoclay is very high.On the contrary, when we add lwt%nanosilica to PACM12, the composite is no longer transparent.