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Polybutylene adipate terephthalate (PBAT) has emerged as a potential biodegradable mulching film in recent years. Taking the tomato cultivation as the research object, three treatments were selected for the biodegradation characteristics, including the ordinary PE mulching film (T1), PBAT/ straw-based biodegradable mulching film (T2), and non-mulching film (T3) in Jiangsu Province of China. The microstructure, morphology, and mechanical strength of the film were characterized during degradation. Meanwhile, the effects of mulching film on the tomato plant height, stem diameter, and yield were clarified to determine the comprehensive benefits of biodegradable mulching film. The results show that there were a series of changes in the physical and chemical properties of the PBAT/straw-based biodegradable mulching film during the 120 d mulching period. The Fourier infrared spectrum showed that the molecular chain of the degradable mulching film was broken under the action of soil microorganisms, light, and water. The X-ray diffraction pattern exhibited that the crystalline area of degradable mulch was destroyed gradually, whereas, the amorphous area increased relatively. Thermogravimetric analysis indicated that there were a few Tmax changes, T0 increase, and a decrease in the carbon residue rate, indicating the thermal properties of the degraded mulching film. The water contact angle confirmed that the degradable mulching film was degraded in the field. Scanning electron microscopy (SEM) images illustrated that there was an uneven degradation of mulching film. The tensile strength and elongation decreased gradually at the break of the degradable film, as the film covering time increased. The mechanical property test verified that the PBAT/ straw-based biodegradable mulching film was degraded gradually in the field with a slow degradation rate after 120 days. Moreover, there was a better effect of degradable mulching film on the tomato growth, compared with the conventional PE and non-mulching film group, in terms of the plant height and stem diameter of tomato plants. The yield of tomato fruit in the degradable and the PE mulching group was equivalent to 667 m2 , which was 13.5% and 15.0% higher than that in the non-mulching film group, respectively. The excellent ecological benefits and the higher recovery cost-saving were achieved for the PBAT/straw-based fully biodegradable mulching film, although the product cost was relatively high. In general, the PBAT/ straw-based fully biodegradable mulching film can be widely expected to serve a remarkable effect on tomato cultivation in the greenhouse. The degradation cycle can be further explored to accelerate the spread the promotion of the degradable mulching. [ABSTRACT FROM AUTHOR]

In order to develop a safe and efficient antibacterial material, the PHMB antibacterial film was prepared by preparing a polyhexamethylene biguanide hydrochloride (PHMB) antibacterial masterbatch and adding the antibacterial masterbatch to a polyethylene substrate. The effects of the amount of PHMB masterbatch (0~7%) on the antibacterial and physical properties of the film were compared, and the antibacterial film preservation experiment was carried out. The results showed that the antibacterial property of the film increased with the increase of the amount of PHMB masterbatch added. The antibacterial film has good physical properties and preservation effect. In the inhibition of Escherichia coli, when the amount of PHMB masterbatch added amount was 3%, the number of plaques after bacterial suspension was significantly reduced after contact with the film for 24 hours, and the antibacterial rate was 85.2%. When the amount of PHMB masterbatch addition was 4%, only 3 colonies eluted from the film, and the antibacterial rate was 99.1%. Moreover, the antibacterial rate data has a small variance, and the antibacterial film has a relatively stable and strong antibacterial effect. In the inhibition of Staphylococcus aureus, when the amount of PHMB masterbatch addition was 2%, 3%, the plaque eluted from the antibacterial membrane was significantly reduced compared with the CK membrane, and the antibacterial rate was 60.3%, 72.6%. When the amount of PHMB masterbatch addition was 4%, only 2 colonies were cultured on the plate and the antibacterial rate increased to 99.2%. The antibacterial film had strong antibacterial activity against Staphylococcus aureus. The antibacterial rate of PHMB (4%) antibacterial film against Shanghai green-loaded colonies was 83.4%, and the antibacterial rate of PHMB (6%) antibacterial film against Shanghai Qing loaded colonies was more than 90%. Shanghai Qing does not have any treatment, and various microorganisms in the field accompany it. The microbial species in the flora are diversified, and the antibacterial effect of the PHMB antibacterial membrane is still significant. This shows that PHMB antibacterial film has the characteristics of broad-spectrum antibacterial and strong antibacterial. After 6 months of storage of PHMB (4%) antibacterial film, the antibacterial rates against Escherichia coli and Staphylococcus aureus were 97.5% and 96.9%, respectively. The antibacterial rate of the film decreased slightly, but it still maintained strong antibacterial properties. It shows that PHMB antibacterial film has antibacterial long-term effect. After the addition of the PHMB masterbatch, the transmittance of the film began to increase gradually, followed by a slight decrease. At 560 nm wavelength, the transmittance of the control film was 86.9%, and the transmittance of the antibacterial film of PHMB (5%) was the highest, reaching 89.1%. In general, the transmittance of the antibacterial film did not change much and was not affected at all. After the addition of PHMB masterbatch, the water vapor transmission rate of the film showed an increasing trend, but the increase was not obvious. As the amount of PHMB masterbatch addition increased from 0 to 3%, the water vapor transmission rate of the antibacterial film increased from 28.86 to 35.25 g/(m2·d), and then tended to be steady. After the addition of the PHMB masterbatch, the moisture permeability of the film does not change much, and the moisture permeability is still maintained, which is beneficial to the storage and preservation of the food. With the increase of the amount of PHMB masterbatch added, the mechanical properties of the antibacterial film increased first and then decreased. The mechanical strength is the highest when the amount of the masterbatch is 4%, and the mechanical properties of the antibacterial film which added PHMB masterbatch is superior to those of the CK film. The PHMB (4%) antibacterial membrane is effective in inhibiting the growth of total colonies, Escherichia coli and Staphylococcus aureus in dried salmon samples. Samples packaged in PHMB antibacterial film can reduce the irradiation dose and save energy in the subsequent irradiation sterilization process. Therefore, it is determined that the optimal amount of PHMB masterbatch in the antibacterial film is 4%. The film has good processability, mechanical strength, and long-lasting antibacterial properties, while achieving non-toxic, odor-free, environmentally friendly requirements. The subsequent application of PHMB antibacterial film in various food storage and preservation can be further explored. This study provides a reference for the development of antimicrobial materials. [ABSTRACT FROM AUTHOR]