| Recently,much attention were paid for the aging and fire risk of wood-plastic composites(WPC)application in construction and decoration materials.But traditional light stabilizers and flame retardant can hardly adapt to the development of modern science and hardly meet the people’ demand of high qulity products due to their drawbacks.In this paper,rutile nano-TiO2 were used to improving the weathering resistance of WPC due to its ultraviolet radiation shielding and ultraviolet absorption properties,and TiO2 nanotubes(TNTs)were prepared to enhancing the inflaming retardancy of WPC,and their mechanism were systematically analysed.The main contents and results as follows:The rutile nano-TiO2 were added in bamboo fiber/HDPE composites.When the content of nano-TiO2 was lower than 6 wt%,nano-TiO2 can well dispersed in WPC and enhanced the compatibility between bamboo fiber and HDPE.When the contents was up to 8 wt%,it would reunited.The results of X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)indicted that Ti atoms on the surfaces of TNTs interacted with the bamboo fiber and HDPE,and formed intermolecular interactions between the two polymers and crosslinking network structur;By adding 6 wt%nano-TiO2,the bending strength,bending modulus and of BH composites increased from 14.2 MPa and 1424MPa to 16.6MPa and 1765MPa while dimensional shrinkage under heat of BH composites dropped from 1.71%to 1.21%,respectively.The results of X-Ray Diffraction(XRD)indicated that The addition of 2 wt%nano-TiO2 promoted the crystallization,which caused the increase of the crystallization rate and crystallinity degree,as well as the micronization of the crystalline grain.When the content of nano-TiO2 was continually increased,the inhibitory effect of the crystallization was gradually enhanced,which resulted in a decrease in the crystallization rate and crystallinity degree of the composites.The results of accelerated weathering test showed that a series of performance reduction containing color fading,surface cracking,structural transformations and loss of mechanical properties appeared on the composites during the accelerated weathering process.Compared to anatase nano-TiO2,rutile nano-TiO2 mainly acted as light screening agent and ultraviolet absorbent,which retarded the photo-oxidative of the composites.Titanate nanotubes(TNTs)were prepared through hydrothermal synthesis method and dispersed in the composites.The TEM observation shows that TiO2 particles transformed into TNTs by hydrothermal treatment at 120 °C for 12 h in 8 M sodium hydroxide solution.Average length and diameterof these tubes was about～200 and～7-8 nm.The results of XRD demonstrated that the ingredient of TNTs are Na2Ti3O7 and some other titanate.After pickling,Na+ was removed and Na2Ti3O7 translated in H2Ti2O5·H2O with the same morphology and size.The results of XRD demonstrated that H2Ti2O5·H2O would resolve into TiO2 at high temperature.TNTs were used to improving the inflaming retardancy of bamboo fiber/HDPE composites.The SEM graphs indicated that TNTs can deposited and well dispersed in the BH matrix,and contributed to improving the compatibility between the HDPE and bamboo fiber.Then Cone Calorimeter and Limiting Oxygen Index Chamber were used to evaluating the effects of TNTs on the flame retardancy of BH composites.The results demonstrated that,by adding 6 wt%TNTs,the TTI,FPI,pSEA and LOI of BH composites increased from 29 s,0.004 m2·s/kW,588.0 m2/kg,and 18.7%to 36 s,0.071 m2·s/kW,519.7 m2/kg and 19.7%while pHRR,av-HRR,pTHR and pSEA of BH composites dropped from 658.6 kW/m2,222.7 kW/m2 and 55.8 MJ/m2 and 588.0 m2/kg to 503.0 kW/m2,158.0 kW/m2,39.6 MJ/m2and 519.7 m2/kg,respectively.Ce ions were adulterated to TNTs.XRD and XPS results indicated that,instead of dispersed into TNTs,Ce ions were adulterated to the crystal lattice of TNTs and resulted more lattice imperfection;The structure of TNTs remained the same and the average length was～200 nm and the average diameter was～7-8 nm;The results of TMA demonstrated that Ti atoms on the surfaces of TNTs and Ce-TNTs interacted with the bamboo fiber and HDPE,and formed intermolecular interactions between the two polymers and crosslinking network structur,and the adulteration of Ce ions into TNTs had no impact on it;The results of SEM,Cone Calorimeter and Limiting Oxygen Index Chamber demonstrated that the adulteration of Ce ions into TNTs resulted more lattice imperfection and increased the superficial area,and then improved the flame retardancy of BH composites by absorb decomposition products produced during combustion due to its giant specific area and tubular structure... |
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