Testing And Characterization Of Degradation Properties For Three Biodegradable Mulches

The research on full-biodegradable mulches is vital to solve the white pollution in agriculture. The aim is to study the change of physical and chemical properties of the three full-biodegradable mulches based on PBAT through the field trials, exposure test, soil burial test and the constant temperature test in the laboratory and provide the foundation basis for developing new full-biodegradable mulches.The field trials studied the degradation process of three kinds of full-biodegradable films in garlic field under natural conditions. Tensile test explored the changes of mechanical strength. The structure changes of three mulches were analyzed by Fourier transform infrared spectroscopy(FT-IR) and Scanning electron microscopy(SEM) during degradation process.The thermo properties were studied by Thermogravimetric analysis(TGA) and Differential scanning calorimetry(DSC). Light transmittance and haze test reflected the changes of the optical properties. The acid value and cross-linking test reflected the changes of hydrolysis and cross-linking.The results of mechanical property test showed the mechanical property dropped dramatically within 60 d and lost mechanical property after 120 d. The mechanical property of No.8 film was poor compared with others. The results of SEM images showed the change of membrane surface in the degradation process was smooth-rough-uneven thickness-penetrating holes. The full-degradable films degrade too quickly. The results of optical property test showed that the light transmittance gradually declined with time. Haze had shown a gradual increase with time. The results of FT-IR test showed no components changed in degradation process. The results of TGA showed that the change of thermodynamic temperature was instability. The results of DSC showed melting temperature and crystallization temperature of PBAT was decreased. The main reason was that the crystallinity and intermolecular forces had decreased. The results of cross-linking showed that the degree of cross-linking rose at beginning and then declined with the time. The results of acid value test showed that the cross-linking lead to the decrease of –COOH. The results of Gel permeation chromatog-raphy(GPC) test showed that the molecular weight increased at beginning and then declined with the time in the process of degradation.The results of soil buried experiment showed that the full-biodegradable mulches could be degraded completely and could not affect the crop on next season. The results of exposure experiment indicated that the light and temperature had great influence to the mechanical properties of full-biodegradable mulches.By the tensile and cross-linking test on the constant temperature experiment in the laboratory, the results showed that temperature could reduce the mechanical properties of fullbiodegradable mulches, but could not cause cross-linking.The three full-degradable mulches possess excellent degradability, but one problem is that the full-degradable mulches degrade too quickly. There are many complex factors in the degradation process.