Development of indium-doped zinc oxide nanoparticles for use as an ultraviolet and infrared attenuated additive in polyethylene greenhouse film

In this study, a nanocomposite film having high visible transmission, low ultraviolet (UV), and low near-infrared radiation (NIR) transmission was developed for a greenhouse cover application in tropical regions. Indium zinc oxide (IZO) nanoparticles were used as blocking of UV and NIR additives to mix with low-density polyethylene (LDPE) polymer matrix for fabricating greenhouse cover film. The thesis is divided into two parts; the first part focuses on the synthesis and characterizations of IZO nanoparticles. The second part focuses on the compounding and characterizations of LDPE/IZO nanocomposites. In the first part, the IZO nanoparticles were synthesized by a solvothermal reaction in a microwave reactor. The effectiveness of UV and NIR blocking properties of IZO was investigated by varying the In/Zn ratios. The result showed that increasing indium concentration in IZO up to 6 wt% leads to an increase in the NIR absorption but a decrease in the UV absorption.In the second part, the preparation of IZO/LDPE nanocomposite film was developed by investigating the effects of the blending methods, the concentration of the IZO additives, and the indium content in the IZO particles to obtain optimal mechanical and optical (200-2500 nm) properties of IZO/LDPE films. Results show that using xylene solvent for preparing the composite films with a 1 wt% of IZO containing 3 wt% indium was found to have the optimum properties for greenhouse application. The transmission of the composite film in the UV region (200-400 nm) and NIR region (700-2500 nm) presenting less than 11% and 70%, which lower than the neat LDPE film consisting about 65% and 83%, respectively, while the transmission remained high in the visible region (400-700 nm) of over 80% with high haze diffusion about 52% higher than the neat LDPE (23%). The composite films showed good mechanical properties similar to those of the neat LDPE film with 16-18 MPa of tensile strength, 768-835% of elongation at break, and 124-136 MPa of modulus. Degradation of the film's test under UV-A irradiation for 30 days shows the transmission of irradiated polymer films decrease slightly in the whole region (200-2500 nm) with a slight increase value of haze diffusion. The mechanical properties of irradiated polymer films present the decrease of tensile strength in a range of 13-14 MPa and elongation at break of 689-764% with increasing of modulus to 131-164 MPa. However, the irradiated neat LDPE exhibited more decrease of elongation value (689%) than the composite films if compared to its initial value (825%), which indicated that the resistance efficiency of the composite films to UV irradiation is better than the neat LDPE.