| Incorporating layered silicate into polymers for preparing polymer-clay hybrids hasattracted extensive interesting on polymer modification and advanced matrials in therecent years. There are many reports on PET layered silicate composites, However,most of reports are focus on montmorillonite (MMT), there are very few reports onPET/vermiculite (VMT) composites. VMT is a kind of layer silicate with the widedistribution and the low price; therefore, having an in-depth study on the preparationand characterization of PET/VMT composites will be helpful to promote the actualapplication of VMT used in PET composites.Firstly, we prepared three different quaternary phosphonium salts (Butyl triphenylphosphorane phosphorus chloride BTP, Tetraphenyl phosphorane phosphorus chlorideFP, Benzyl triphenyl phosphorane phosphorus chloride BPTP) to modified vermiculite.Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) resultsshowed quaternary phosphonium salts modified vermiculite was successfullyprepared, and the interlayer space was increased with the increasing of the alkyl thatbelong to quaternary phosphonium salts. The result of thermogravimetric analysis(TG) showed phosphorus vermiculite had good thermostability, the modification rateof vermiculite varies directly as the size of alkyl group of quaternary phosphoniumsalts. Particle size analysis showed the size of modified vermiculite increased with theend group of quaternary phosphonium salts and trended to uniformity. Electronmicrograph showed the agglomeration of clay was related to it’s size and uniformity.Secondly, a series of PET with different kinds and contents of modified vermiculitecomposites were prepared by the melt-mixing and injection moulds method.Ultraviolet spectrometry (UV), XRD, scanning electronic microscope (SEM),transmission electron microscope (TEM) and dynamic mechanical analysis (DMA)were used to characterize the PET composites, and the mechanical properties ofcomposites was studied. with the addtion of modified vermiculite increasing, thetensile strength of the composite first increases, then declining, but the elongation at break and impact strength presented a reduced situation; PET modified withBTP-VMT (OVMT) was better than the others, the toughness of PET composites wasthe best when1wt%OVMT contained and had the maximum tensile stress when3wt%contained; when the addition of OVMT was less than5wt%, these vermiculitethat intercalate by quaternary phosphonium salts showed fully exfoliation in PETcomposites, the diffraction intensity peaks of composites reduced after tensile test.When the content of OVMT was3wt%, PET composites showed flocculent stuctureafter tensile test, the OVMT that contained in PET composites showed the best scatter,what’s more, the storage modulus and Tan δ were the best. During the stretchingprocess, the orientation of OVMT that followed by the motion of PET chains wouldmake the distribution of clay better.Finally, through the thermol degradation and barrier properties of PET compositesstudy found that: The addition and dispersive degree of OVMT had significantinfluence on the char of PET under the air atmosphere; PET composite with moreresidual and higher decomposition temperature when the addition of OVMT was3wt%; the amount of OVMT could increase the Tg of PET, but would hinder thecrystallinity behaviors of PET during TG analysis; Quaternary phosphonium salts hadno effect on the degradation of PET during melting process; When the addition ofOVMT was less than5wt%, the oxygen-permeability coefficient of PET compositesreduced dramatically; Compared pristine PET, a reduction of up to15.09%in theoxygen-permeability coefficient was observed when the addition of OVMT was3%.On the basis of obtained results showed that: PET with3wt%OVMT balanced themechanical properties wonderfully. |
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