Preparation Of Polymeric Graphitic Carbon Nitride Nanocomposites And Its Thermal Stability Properties

As a large-scale applications and daily life essential]:olymers,polyviny alcohol(PVA)and polystyrene(PS)are widely used in construction,textiles and electronic products.However,their thermal properties are not always sufficient for specific applications.It is demonstrated that graphitic carbon nitride(GPPCN)can be potentially applied in the flame-retardant field of PVA and PS.Nevertheless,there are two important problems for further investigation:(1)GPPCN is poorly dispersed in PVA and PS host;(2)GPPCN does not provide enough flame-retardant efficiency to meet requirement for practical applications when incorporated into PS matrix.Therefore,this dissertation primarily focuses on improving dispersion of GPPCN and enhancing thermal stability and flame retardancy of GPPCN/PVA and GPPCN/PS composites.Herein,we report the design and synthesis of composites based on GPPCN,and the application in enhancing their thermal stabitiy.The thesis includes the following two sections:1.The light yellow bulk GPPCN with large surface area was synthesized by thermal condensation of urea.GPPCN/PVA nanocomposites were obtained by simply mixing GPPCN and polyvinyl alcohol(PVA).By scanning electron microscope(SEM),Fourier transform infrared spectroscopy(FT-IR),ultraviolet-visible(UV-vis)absorption spectra,X-ray diffraction(XRD),and thermo gravimetric analyzer(TGA)methods,the physicochernical properties of the compositewere were characterized.The results showed that the initial pyrolysis temperature of sample increased,i.e.,the thermal decomposition temperature of sample increased by 11.8%,and the carbon residue of sample was higher than that of control sample.This indicated that the proper addition of GPPCN can effectively improve the thermal stability of PVA.2.GPPCN was incorporated into PS by electrostatic interaction,and the thermal stability of polystyrene was improved by the high thermal stability and interface effect of GPPCN and PS.By SEM,FT-IR,UV-vis spectra,XRD and TGA,the physico-chemical properties of the compositewere were characterized.It showed although the interaction between GPPCN and PS was not very strong,the thermal decomposition temperature of the sample was still greatly improved.The carbon residue of the sample was higher than that of the control sample.This indicated that the incorporation of appropriate GPPCN can effectively improve the thermal stability of PS.