The problem of white pollution caused by waste agricultural mulch film (WAMF) has a long history and has brought great damage to the soil and ecological environment. The recycled WAMF has no processing performance because it is doped with a large amount of cotton straw and soil inorganic particles. In this study, it was reported for the first time that high-quality and efficient recovery of WAMF was carried out by means of solid-state shear milling ((SM)-M-3) technology. After the pretreatment of (SM)-M-3, the recycled WAMF is transformed into an active composite powder with a particle size of microns, which regains certain processing performance. Then we prepared a composite material similar to WPC (wood-plastic composite) by using the composite powder. It was found that under the action of strong three-dimensional shear force, the phase domain size of the composite decreased significantly, and the compatibility of each component improved. The macroscopic performance was that the tensile strength was increased by 65% and the bending strength was increased by 74%, reaching 8.30 and 17 MPa, respectively. The 24-h water absorption of this composite decreased by 13%. More importantly, the thermal stability was not significantly reduced during the milling process. This process does not require sorting, cleaning, or other operations, which can greatly simplify the process flow and improve recovery efficiency. It provides an effective solution to the problem of white pollution caused by WAMF.

In the present work, we report the effect of low-temperature plasma treatment on thermal, mechanical, and biodegradable properties of polymer composite blown films prepared from carp fish scale powder (CFSP) and linear low-density polyethylene (LLDPE). The CFSP was melt compounded with LLDPE using a filament extruder to prepare 1, 2, and 3 wt.% of CFSP in LLDPE polymer composite filaments. These filaments were further pelletized and extruded into blown films. The blown films extruded with 1, 2, and 3 wt.% of CFSP in LLDPE were tested for thermal and mechanical properties. It was observed that the tensile strength decreased with the increased loading content of CFSP, and 1% CFSP/LLDPE exhibited the highest tensile strength. To study the effect of low-temperature plasma treatment, 1% CFSP/LLDP polymer composite with high tensile strength was plasma treated with O2 and SF6 gas before blow film extrusion. The 1% CFSP/LLDPE/SF6-extruded blown films showed increased thermal decomposition, crystallinity, tensile strength, and modulus. This may be due to the effect of crosslinking by the plasma treatment. The maximum thermal decomposition rate, crystallinity %, tensile strength, and modulus obtained for 1% CFSP/LLDPE/SF6 film were 500.02 degrees C, 35.79, 6.32 MPa, and 0.023 GPa, respectively. Furthermore, the biodegradability study on CFSP/LLDPE films buried in natural soil for 90 days was analyzed using x-ray fluorescence. The study showed an increase in phosphorus and calcium mass percent in the soil. This is due to the decomposition of the hydroxyapatite present in the CFSP/LLDPE biocomposite. Schematic diagram of polymer film fabrication process. image

Changes in water content have a significant impact on the consolidation of peat soil. Through the water content test and thermogravimetric analysis test, the water content, and the free water, weakly bonded water and strongly bonded water content of peat soil with different organic content in Yunnan Province (China) at different load levels and consolidation times were studied. The results show that the free water in peat soil samples was discharged when the temperature was less than 60 degrees C; the weakly bound water was released at 60 - 110 degrees C; and the strongly bound water was dehydrated at 110 - 200 degrees C. During the consolidation of peat soil, the water content in different states changed significantly. In the primary consolidation stage, the proportion of free water in the peat soil samples decreased by approximately 20%, while the proportion of weakly bound water increased slightly. In the secondary consolidation stage, the proportion of water in different states did not change considerably. In the third consolidation stage, the proportion of free water increased, and the proportion of weakly bonded water causing creep decreased by approximately 11%. For the undisturbed and deformed peat soil, the contents of free water and bound water increased with increasing total water content, but the ratio of free water to bound water remained relatively stable at approximately 1:2.