Novel Wood Plastic Composites Prepared From Recycled Paper/Plastic/Aluminum Composite Packaging Materials

In recent years, many governments and Tetrapak are all in focus and vigorously promote the recovery of paper/plastic/aluminum composite packaging and have achieved some success. Some enterprises devoting themselves on the separation of such packaging materials are also founded in China. However, the benefits they gained do not fit they hoped, due to a comprehensive system of waste separation and recovery has not been established in our country, which results in low recovery rate of the packaging, high energy cunsuption and high cost of scondary pollution treatment. In this study, recovered paper/plastic/aluminum composite packaging (r-PPA) was employed without any separation process as raw materials to prepare a novel wood plastic composites via blending modification technology. The process shows significant advantages of environmental protection and energy conservation.Firstly r-PPA filled HDPE or recyled PE composites were prepared, the properties of these two composites were compared and the better matrix were selected. The results show that the melt viscosity of HDPE/r-PPA and r-PE/r-PPA composites increases with the content of r-PPA, but is still within the range of extrusion processability. The tensile strength respectively reaches the maximum 25.01 MPa for HDPE/r-PPA and 18.95 MPa for r-PE/r-PPA when 40% r-PPA was filled. The bending properties of the composites significantly increase, whereas the notched impact strength decrease with the addition of r-PPA. In addition, the 24 hours water adsorption capacity of the composites increases with the presence of r-PPA.Secondly, the content of r-PPA was fixed at 50 wt% of the HDPE/r-PPA composites. Three different compatibilizers were used to improve the compatibility between HDPE and paper fibers. The results show that PE-g-MAH, POE-g-MAH and POE-g-GMA are all effective compatibilizers to HDPE/r-PPA composites. The tensile strength of the composite reaches a maximun value of 33.01MPa when 6 phr POE-g-GMA added. The phenomenon of agglomeration and 24 hour water adsorption reduces in the presence of compatibilizers, which decreases by 54.2% when 10 phr PE-g-MAH presents. In the third, the comprehensive properties of the composites in the presence or absence of the aluminum were discussed by simulating the composition of r-PPA. The results show that aluminum gives no effect on the tensile or notched impact strength, but enhances the matrix in a certain degree when dispersed by a uniform in the system. The mechanical properties of the sample decline after soaked in water for 10 days. Moreover, the aluminum powder exposures on the surface could promote water infiltration. Some microcracks appeare in the internal of composites. The interfaces of fibers and matrix were damaged resulting in the decrease of mechanical properties.Finally, the impact of the mechanical properties of CaO content and CaO treated with coupling reagents were discussed. It is clear that the tensile strength of composites decreases gradually, while flexual strength inceases, and little gap between the impact stength. The tensile strength reduces by water immersion for 10 days, but notched impact strength keeps steady even abnormally rises. The bending stength of the composites also incease when the content of CaO is more than 15%. The CaO modified by silane coupling agent KH560 has the lowest water adsorption among the various composites, whose isothermal adsorption process has been found to meet the Fickian law.