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【Objective】The present paper aimed to clarify the effects of different degradation films on the growth of pumpkin and the characteristics of the changes in the degradation performance and mechanical properties of the films.【Method】We investigated the trends of mechanical indexes such as film elongation and breaking force values of black PE film (CK), white degradable film (T1), black degradable film (T2) and black carbon dioxide-based degradable film (T3) and their effects on the growth of pumpkin plants during the reproductive period of pumpkin through the field mulching test.【Result】With the increase of coating time, it was found that the mechanical properties of different membranes showed a decreasing trend through the mechanical properties testing and degradation degree analysis during the important fertility period, and the values of the mechanical indexes of the three degradable membranes showed the most obvious decreasing magnitude. Among them, the initial values of all mechanical indexes of T1 treated membranes were higher than those of T2 and T3, and the degradation degree was weaker than that of T2 and T3 during the reproductive period of pumpkin; the values of all mechanical characteristics of T2 and T3 were relatively similar, and the degradation degree of the membranes was of the same grade. Through correlation analysis, it was concluded that the mechanical characteristics of the degraded film were negatively correlated with the degree of degradation, and the degree of degradation increased with the decrease of the mechanical characteristic values; the SPAD value, chlorophyll a and b contents of the leaves of CK mulching treated plants were higher than those of the three degraded films, and they had stronger photosynthetic capacity, so the growth and development in the number of leaves, area and length of the vine showed better performance. Black degradation film (T2) and black carbon dioxide-based degradation film (T3) treated pumpkins had increased soluble solids and Vc contents, which had an enhancement effect on the overall quality of pumpkin, and the pumpkin yields of the two converged and were not significantly different from those of CK. 【Conclusion】 Degradation of the mechanical properties of the degradable film will accelerate the rate of degradation and affect the performance of film-assisted production, covering the black degradable film and black carbon dioxide-based degradable film can be made to improve the quality of pumpkin quality, and pumpkin yield is not significantly different from the covering of black PE film. In view of the environmentally friendly nature of degradable films in agricultural production, it is feasible to replace ordinary PE films in crop and vegetable production. [ABSTRACT FROM AUTHOR]

Microplastics are high molecular-weight polymers with micro- or nano-meter size, which have become a major global environmental issue in recent decades due to their ubiquity in the environment, bioavailability and potential toxicity. New analytical methods for the characterization of microplastics and nanoplastics are quickly emerging, such as particle size measurement, component identification and quantification. Many techniques have been developed and applied for the characterization of microplastics, such as Fourier-transform infrared spectroscopy, Raman spectroscopy and mass spectrometry (MS), etc. In recent years, the continuous development of MS technology has drawn more and more attention to the characterization and the environmental impact of microplastics. This paper mainly reviewed the state-of-the-art development and application of MS in microplastics analysis during the past decade. The principles and characteristics of various MS techniques used in the qualitative and quantitative analysis of microplastics were described, including thermal analysis coupled with MS-based techniques, elemental analytical MS, MALDI-ToF MS, LC-MS and ToF-SIMS. MS can provide chemical structure, molecular weight, degree of polymerization, additives, main functional groups and other information about the polymers, so it can be widely applied for chemical characterization, particle size determination and semi-quantitative/quantitative analysis of microplastics of small size. It has the advantages of replicable, fast real-time in situ analysis and high throughput detection, which can not only detect microplastics in the environment but also in biological tissues or cells in situ, showing great application potential in the research on the source, migration, transformation and interaction with biological organisms. The microplastics have been detected in the ocean, atmosphere, soil, consumer products, organisms and even human tissue, including polyethylene, polyamide, polyvinyl chloride, polypropylene, polystyrene, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, etc. The health risks of ingestion of microplastics deserve further exploration, especially nano plastics. The continuous development of MS technique and its combination with other separation/characterization methods will greatly promote the analysis of microplastics, and MS will become a more and more powerful tool in this research field and provide important scientific basis for the control of microplastic pollution. [ABSTRACT FROM AUTHOR]

This review provides an overview of the application of lignin in 3D printing and discusses related research progress.As a biopolymer composed of various phenylpropane units linked by different bonds, lignin is rich in hydroxyl, carbonyl and ether groups.Hence it can be used as a renewable bio-based material in 3D printing, including degradable plastic composites for biomedical applications, lignin-based hydrogel, lignin-based thermoplastic materials, etc.The structural characteristics of lignin obtained by different extraction methods and its application to various 3D printing technology methods by compounding with various materials are highlighted.In addition, the advantages and disadvantages of using lignin in 3D printing material applications are analyzed.Furthermore, modification of lignin structure using enzymes and chemicals is proposed to overcome its limitations due to its structural recalcitrance.Finally, the opportunities of lignin in 3D printing are described. [ABSTRACT FROM AUTHOR]

A questionnaire survey was conducted in different crop-planting areas, and typical sample points were analyzed according to the present situation of plastic film and the residue in soil in the Hetao irrigation area. The results showed that the level of plastic film pollution was moderate, and that the residual amount of plastic film in farmland was 18.20-418.60 kg∙hm-2, with an average value of 131.11 kg∙ hm-2. The residual amount of plastic film was affected by the age of the plastic film mulching, crop type, recovery, soil texture, and other factors, among which the contribution rate of plastic film mulching age was the highest. With the increasing age of plastic film mulching, the residual amount of plastic film increased significantly, and the residual amount of plastic film in plots covered for more than 20 years was significantly higher than that in plots covered for less than 20 years (P<0.05) . The residual amount of plastic film in maize planting areas (132.77 kg∙hm-2) was higher than that in sunflower planting areas (127.88 kg∙hm-2) . Awareness of plastic film recovery was an important factor affecting the residual amount of plastic film in Hetao irrigation area. Recovery methods mainly include manual picking or raking out of farmland. The recovery rate of plastic film in the study area was only 38.10%, and the residual amount of plastic film recycled plots (108.28 kg∙hm-2) was significantly lower than that of non-recycled plots (145.03 kg∙hm-2) . Under the same conditions, the amount of residual film in sandy loam soil with different texture was the highest (153.84 kg∙hm-2) . The investigation results show that Hetao irrigation area can adjust planting structure, strengthen recycling awareness and recycling methods, popularize biodegradable plastic film to reduce plastic film pollution. [ABSTRACT FROM AUTHOR]

This experiment was conducted to screen the suitable mulching type of plastic film for Rosa roxburghii orchard, according to explore the effects of different color plastic film mulching on soil, shoot growth, flowering and fruit setting. Four different colors (colorless was marked as T1, red was T2, green was T3 and black was T4) of plastic film with PE material were selected in this study. The natural grass with no plastic film covering was taken as the control. The differences of soil physical properties, microbial carbon content, shoot growth, flowering, fruit setting and yield performance under different treatments were compared. The results showed that plastic film mulching could increase soil temperature in different degrees, and lead to an earlier phenological period, in which the flowering time of black and red plastic film mulching treatments was 4-5 days earlier than that of the control. Soil physical parameters such as salinity, volume water content, total dissolved solids, electrical conductivity and dielectric constant under the treatment of black plastic film were higher than those under the control, while other plastic films had no such effects but the soil physical properties were more stable. Covering with black and red plastic film could significantly inhibit the growth of weeds, and the biomass of weeds in the covered area was reduced by 88.36% and 89.5% respectively, which was significantly lower than that of other treatments and the control. All plastic film mulching treatments could increase the chlorophyll content of leaves, and green plastic film was the most beneficial to promote the growth of new shoots of R. roxburghii. The colorless and black plastic film mulching could significantly promote the flowering of R. roxburghii, and the fruit-bearing capacity in the early stage increased about 43.8% and 37% respectively compared with the control. Finally, the treatment with colorless plastic film had the most prominent effect of increasing the yield, which was 52.55% higher than that of the control. While the black plastic film lead to more fruit dropping during the fruit development, so that the final yield was only increased by 14.39% compared with the control. The results of this research showed that different color plastic films had their own advantages in improving or stabilizing soil physical parameters, promoting tree growth, inhibiting weeds and increasing yield, and could be used as needed in production. Among them, the colorless plastic film was particularly effective in increasing fruit yield, and could be suggested as the preferred plastic film type for cultivation of R. roxburghii. [ABSTRACT FROM AUTHOR]

Large amounts of plastic film residues in soil have posed a negative impact on the crops and environment. Alternatively, the sugarcane bagasse has widely been used as inexpensive, abundant, easily available, and sustainable raw material. In this study, a biodegradable film was developed to treat the sugarcane bagasse, in order to reduce the pollution of plastic film and the seasonal drought in the spring in Yunnan-Guizhou Plateau of South China. A Box-Behnken experiment was designed, where the sizing agent components of sodium silicate, soluble starch, and silicone oil content were chosen as the independent variables, whereas, the response values were the degradation rate, tensile strength, soil temperature, and soil moisture. Field experiments were conducted in the School of Modern Agricultural Engineering, Kunming University of Science and Technology, China from September to November 2017, where ten mulching times (10, 19, 27, 34, 40, 45, 49, 52, 62, and 72 d) were designed. Taking the no film mulching as a control (CK), the influence of the film was determined on the degradation rate, tensile strength of two mulching modes, as well as soil temperature and moisture. Scanning Electron Microscopy (SEM) was used to characterize the fiber structure of biodegradation film under two mulching modes during the test period. A bagasse biodegradable film was verified to regulate the degradation cycle for the high soil temperature and moisture, particularly for the better soil environment of sowing in spring. The results showed that the degradation rate and the intensity of the underground film were higher than that of the surface film after 72 days of mulching, where the mass-loss rates of the two mulching modes were 86.41% and 70.44%, respectively. Under the surface biodegradable film mulching, the average degradation rate in test group 1 was the lowest during the entire degradation period, which was 20.1%. The tensile strength in the surface test groups decreased to 9.77-21.97 N/m after 72 days of degradation, whereas, the mechanical properties in the underground tests group were close to 0 N/m after 49 days. The fiber of the mulch film was outstandingly dispersed, where the short fibers were appeared in the SEM images, indicating an excellent consistence with the biodegradable film holes and the gradual decline in the quality during degradation. There was no significant difference in the daily accumulated temperature of the soil in the two mulching modes (P>0.05), compared with the CK, but the significant differences in the accumulated temperature of the soil in the morning, noon, and evening. In the case of ground surface mulching, the thermal preservation performance in test group 1 was the best, where the accumulated temperature in the morning and evening was higher by 6.1% and 5.4%, respectively, and that lower by 7.9% at noon, compared with the CK. The soil moisture content in each test group was significantly higher than that of the CK (P<0.05) during the entire experimental period. In addition, the water retention capacity in test group 1 was the highest. It infers that the capacity of water retention decreased with the degradation of biodegradable film. However, the soil water content in test group 1 was 11.36%, which was significantly higher by 158.77% than CK. To sum up, considering soil moisture, soil temperature, degradation rate of biodegradable film and tensile strength comprehensively, the sizing agent of test group 1 had the best performance among all test groups, and the contents of which were: sodium silicate 10%, soluble starch 20%, and silicone oil 15%. Therefore, the sugarcane bagasse biodegradable mulching film was feasible to increase the soil temperature and moisture, providing for promising application prospects in agricultural production. [ABSTRACT FROM AUTHOR]

Plastic pollution has posed a serious threat to the environment in the world. Biodegradable plastics can be widely expected to effectively mitigate plastic pollution. The subsequent industrial composting can also be treated to reduce the growing demand for landfills. In this research, the microorganisms responded to the biodegradation mechanism was proposed for the PBAT-PLA biodegradable packaging under the controlled industrial aerobic composting, according to the national standard (GB/T 19277.1-2011). Microcrystalline cellulose was used as reference material. The compost samples were taken on day 140 when the degradation was in the active period. The initial compost (before degradation), compost without any biodegradable material, compost with microcrystalline cellulose, and compost with PBAT-PLA packaging materials were then labeled as compost A, B, C, and D, respectively. The bacterial/fungal community was analyzed during degradation, including the species diversity, speciation, and species difference. A sample comparison was made through 16S/18S high-throughput sequencing of microorganisms in compost. The microscopic morphologies of PBAT-PLA packaging materials and microcrystalline cellulose were characterized by a Scanning Electron Microscope (SEM), in order to explore the intrinsic microbial response to the degradation mechanism. The results showed that the bacterial diversity of compost B under the industrial composting at 58 ± 2 ℃ was significantly lower than that of initial compost A since only some thermophilic bacteria survived. The bacterial diversities in compost C and D were significantly higher than that of compost B, due to the addition of cellulose or biodegradable packaging materials which provided carbon sources. There was no significant change in the fungal diversity, due to unsuitable for most fungi to survive at high temperatures. The fungal abundance changed, due to the temperature and carbon source in the compost, where the compost B (blank sample) showed the lowest fungal abundance. The dominant bacteria in the compost C and D were Sphaerobacter, Longispora, norank_f_norank_o_Actinomarinales, and Rubrobacter, which belonged to Actinomycete. The student’s T-test was used to compare the composition of bacteria and fungi in the compost C and D with those in the compost B. The significant growing bacteria in the compost C and D, including norank_f_Euzebyaceae, unclassified_c_Actinobacteria, and Actinobacteria, belonged to Actinomycetes. Therefore, there were similar degrading microorganisms of PBAT-PLA membrane bag and microcrystalline cellulose at (58±2) ℃. The SEM images showed that the surface of PBAT-PLA packaging after degradation was covered with a layer of biofilm. The biofilm was mainly composed of the clusters of ellipsoid bacteria, which were inferred to be Sphaerobacter. Actinomycetes presented a positive effect on the depolymerization of polyester and the degradation of cellulose under industrial composting conditions. The complete biodegradation of polyester and cellulose depended on the microbial synergy, rather than a single strain. Therefore, the dominant bacteria and significant growth bacteria of biodegradable materials under industrial composting conditions can be expected to serve as a theoretical basis for screening key biodegradation bacteria in the future. It can also greatly contribute to breaking through the technical barriers of the long detection cycle with the current biodegradation for higher efficiency and speed. The identification of microbial communities can be an important indicator to evaluate the impact of the compost produced by biodegradable plastics on crops growth, and agricultural ecological environment. Consequently, a theoretical foundation can be made to optimize the industrial composting and biodegradable plastic testing standards. The finding can also provide a scientific basis for the large-scale promotion of biodegradable plastic films and the application of the compost produced from biodegradable plastics in advanced (or modern) agriculture. [ABSTRACT FROM AUTHOR]