Long Mao,Yuejun Liu,Huiqing Wu,Jianhong Chen,Jin Yao
Inspired by the versatile adhesion capability of marine adhesive proteins, core-shell structured polydopamine-coated layered double hydroxide (LDH@PDA) were prepared successfully by in-situ growing PDA on the surface of MgAl-LDH with a high aspect ratio . LDH@PDA/poly(ε-caprolactone) (PCL) nanocomposites were prepared by blending LDH@PDA and pure PCL via solution casting method to obtain homogeneous films. The results of thermal analysis confirmed that LDH@PDA can act as a nucleating agent . And thermal stability of nanocomposites was improved due to core-shell structured LDH@PDA. With incorporation of as low as 1 wt% of LDH@PDA, a 20% increase in tensile strength (41.1 MPa), 26% increase in elongation at break (772%) and 26% reduction in the oxygen relative permeability were achieved. The improvement in the mechanical and gas barrier properties of nanocomposites at low filler loading was attributed to the strong interfacial interaction of LDH@PDA wtih the PCL matrix.
Siyuan Dong,Yingqi Jia,Xiaozhi Xu,Jianeng Luo,Jingbin Han,Xiaoli Sun
Poly(ethylene terephthalate) (PET) generally suffers from low crystallization rate and long molding duration, which as a result limit its application as engineering plastics. To overcome these drawbacks, series of PET/layered double hydroxide (LDH) nanocomposites were prepared by a solution blending process. The effect of metal composition (MgAl and CaAl) and organo-modification (stearic acid intercalated) for LDH fillers on the crystallization behavior of the nanocomposites was investigated. It was revealed that, compared with PET/CaAl-LDH, the PET/MgAl-LDH nanocomposite exhibits a higher crystallization temperature and faster crystallization rate, which is associated with the superior nucleation ability of MgAl-LDH. The nucleation mechanism of PET induced by LDHs was explored by means of Avrami equation and theory of Hoffman-Lauritzen, pointing out that the incorporation of LDHs reduce the free energy of nucleation and the fold surface free energy of PET. In order to improve the compatibility between LDH and PET, stearic acid (SA) intercalated MgAl-LDH was prepared and filled into PET matrix. The resultant PET/MgAl-LDH-SA shows a further enhanced crystallization temperature and accelerated crystallization rate, in comparison with PET/MgAl-LDH nanocomposites. In addition, the thermal stability, gas barrier and mechanical properties of PET/LDH composites were improved upon incorporation of LDH fillers.
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