Low density polyethylene/zinc peroxide composite and nanocomposite prepared by cast solution: Thermal, mechanical and morphological characterization

Hanebal Mousa Issa Mansour
هنبال موسى عيسى منصور
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Al-Quds University
Polymer composite and nanocomposite materials with inorganic filler like metal oxides such as zinc oxide, magnesium oxide and zinc peroxide are motive fields of research due to the innovative combination of properties between the polymer and filler, arising from the application of inorganic filler and nanofiller within polymer matrix. The present study investigated the influence of different concentration of zinc peroxide (ZnO2) particles and nanoparticles on the thermal, mechanical, morphological, and antibacterial properties of low-density polyethylene (LDPE)/ZnO2 composite and nanocomposite. Different compositions of LDPE/ZnO2 and LDPE/nano ZnO2 composites were prepared by solution cast technique with ZnO2 concentration of (1wt%, 3wt % and 5wt%) for composite and (0.5wt%, 1wt%, 1.5wt%, 3wt% and 5wt %) for nanocomposite. Firstly, ZnO2 nanoparticles were synthesized using three different methods, the first one reflux reaction method used polyethyleneimine (PEI) as capping agent and the second one reflux reaction method without capping agent and the last one sol-gel method. Reflux reaction method without capping agent was chosen for preparing nanocomposite, because it has the good reaction percentage yield compared to the other methods. The synthesized ZnO2 nanoparticles were characterized by X-Ray Diffraction (XRD), Scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR) and Differential scanning calorimetry (DSC). Highly crystalline cubic-ZnO2 nanoparticles grown in a near- spherical shape were obtained with average size about 82 nm ,48 nm and 55 nm for reflux without PEI, reflux with PEI and sol-gel respectively, based on SEM and XRD analysis. It was found by DSC that the synthesized ZnO2 samples decomposes into zinc oxide (ZnO) at about 230-238 oC. The observed vibrational modes by FTIR in the ZnO2 nano-powder are discussed and compared with previous reports and suggest the purity of the ZnO2 particles that synthesized from the reactants. The results of the morphological analyses of composite shows a distribution of ZnO2 in the LDPE matrix with little signs of agglomerates and the particles were embedded in the matrices of the composite but they don't appear well on the surface of composite. For the nanocomposite, The SEM micrographs show that the nanoparticles are well distribution within the whole polymer matrix. The micrograph of the nanocomposite with ZnO2 nanoparticles filler showed a distinct dispersion behavior as that of the composite containing the ZnO2 filler. The addition of ZnO2 filler in the composite and nanocomposite imparted slight variations in the melting temperature of different concentration of composite and nanocomposite samples and gave significant improvements in the degree of crystallinity since the filler could act as a nucleating agent. The results of mechanical characterization showed that the tensile properties of LDPE/ZnO2 nanocomposites are higher than those of LDPE/ZnO2 composites except yield strength which mean that the composite can withstand high stress without a permanent plastic deformation as compared to nanocomposite. It was found that LDPE without any filler achieved a tensile strength of 4.94 MPa and the tensile strength of ZnO2 /LDPE nanocomposites increased with increasing ZnO2 nanoparticles concentration until reaching the highest value of tensile strength 5.28 MPa at 5wt% of nanoparticles, while the tensile strengths of the composites decreased with increased concentration of ZnO2 powder and dropped to 4.35 MPa at 5wt% ZnO2 particles. The elastic modulus of ZnO2 /LDPE composite and nanocomposite was found to increase progressively with ZnO2 concentration, the highest set of values was obtained for 5 % concentration of ZnO2 for nanocomposite with the modulus value 0.124 GPa compared to pure LDPE with modulus value 0.103 GPa. As well the fracture strength increased as the nanofiller size decreased to nano sized as compare to composite, so the nanocomposite has higher ability to resist failure than composite. Moreover, the elongation at fracture decreased steadily with increasing in ZnO2 concentration for the composite from 36 % to 29 % and for nanocomposite from 48 % to 42 %. Unfortunately, the antibacterial characterization of composite and nanocomposite did not show any zone of inhibition on agar plates for composites and nanocomposite against aerobic and anaerobic bacterias.