Degradation performance experiment of paper and straw-based seedling pot

Abstract: Most of the articles about the degradation performance of biodegradable nursery pots were focused on degradation morphology, strength of pot body, changes of soil, effect of raising seedings and so on. However, it rarely study on degradation rate, molecular structure of degradation process and changes of crystallinity. In order to study the degradation performance of biodegradable nursery pots, three types containing paper pot, undecomposed straw pot and decomposed straw pot were used to carry out the experiment in this paper. The degradation rate, molecular structure and crystallinity were evaluated and analyzed through the experiments of degradation test in soil, Fourier infrared scanning and x-ray diffraction. It is necessary to have a further research on degradation performance of biodegradable nursery containers and mechanism of degradation. The results showed that the degradation rate of paper pot with the best degradation property was growing at a rate of about 2 times. The maximum degradation rate was up to 85%. The undecomposed straw pot has always maintained a stable and increasing degradation rate. The undecomposed straw pot with degradation rate of 78% in the eighth week was higher than that of decomposed straw pot. The changes of mass loss and degradation rate were likely to be affect by a variety of microbial community structure. On the one hand, due to partial degradation of cellulose and semicellulose, the remaining part kept stable performance. On the other hand, the changes of microbial structure and activity affected the degradation performance. By comparison, FTIR absorption strength of the biodegradable nursery pots was decreased in different degree due to the changes of molecular structure during biodegradation. The absorption strength of paper pot decreased in the location of 3340 cm-1 and 2920 cm-1 indicated that the degradation of cellulose and hemicellulose. In addition, the relative peak of 1640 cm-1 and 1460 cm-1 decreased with the further degradation, showing that lignin was degraded in the biological reaction. The peak strength of CH stretch band was enhanced obviously at 892 cm-1. It showed that the substitution reaction of aromatic ring was an important part of the degradation process of lignin. The main group structure of undecomposed straw pot and decomposed straw pot were basically the same. The absorption peaks strength decreased at 3340 cm-1 and 1010 cm-1 might be due to the oxidative decomposition of benzene methanol unit. The peak strength of CH stretch band decreased at 2920 cm-1 probably because of the decomposition of carbohydrates and the fracture of partial fatty chain. The degradation of lignin resulted in the decrease of peak strength of 1650 cm-1. The x-ray diffraction peak intensity of paper pot with the best degradation property decreased obviously after 8 weeks test. The diffraction peak disappeared at 2 θ=15.6°. At the same time, The intensity of diffraction peak decreased at 2 θ=22.5°. In addition, it appeared new diffraction peaks at 2 θ=27° of undecomposed straw pot and decomposed straw pot. This might be due to the changes of crystalline which caused by the degradation of straw. The biodegradable nursery containers with excellent degradation property could improve the problem of environmental pollution effectively.