Study On Aging Performance Of Ldpe With The Presence Of Ferriferrous Oxide

In this thesis, the Fe3O4/LDPE composites had been prepared by blending method. The composites were characterized by XRD, FT-IR, TGA and tensile test. Moreover, the carbonyl index, viscosity average molecular weight, crystallinity, tensile strength and elongation at break of the composites were also performed by light aging test in artificial accelerated aging test box. Some main conclusions were summarized as follows:1. X-ray diffraction was performed to clarify the structure of Fe3O4, showing that the Fe3O4had a spinel structure, which was consistent with the spectrum in the standard card. The grain size analysis results showed that the Fe3O4had a relatively uniform distribution ranging from2to8μm, the average particle size of Fe3O4powder was3.69μm.2. With the adding of the content of the Fe3O4, the crystallinity, tensile strength and elongation at break of the composites were lower, but the degree of branching was higher. The thermal stability and thermal degradation mechanism of the Fe3O4/LDPE composites were further studied by TGA. The results showed that the thermal decomposition of composites was only one stage, indicating that the above degradation was a stair reaction. Moreover, the activation energy of the thermal degradation increased with increase of Fe3O4 content. The thermal decomposition temperature of the LDPE rose with the presence of the Fe3O4, it meant that the Fe3O4had a stable effect on the thermal decomposition of LDPE, but the thermal decomposition mechanism had not changed.3. The tensile strength, elongation at break and viscosity average molecular weight of LDPE were lower with the prolonging of the UV irradiation time. The reduction rate was higher than pure LDPE while the content of Fe3O4were0.05%,0.1%,0.3%,0.5%and1%respectively. However the reduction rate was lower than pure LDPE while the content of Fe3O4was2.0%. The value of positron annihilation lifetime(τ) after the UV irradiation had decreased, meaning that the structure of composites had changed. The carbonyl index of LDPE was higher along with the prolonging of the UV irradiation time, accordance with the lower rates of the viscosity average molecular weight and the mechanical strength. These results demonstrated that the structures and properties of the LDPE especially the photo-degradation performance had changed in the presence of ferriferrous oxide. The degradation rate of LDPE was higher while the content of Fe3O4was at a lower-level, but was lower while the content of Fe3O4was over that level. It clearly showed that the ferriferrous oxide could be widely used in the degradable LDPE composites, the degradation rate and aging resistance could be controlled by adjusting the content of Fe3O4.