Degradability and Properties of PBAT-Based Biodegradable Mulch Films in Field and Their Effects on Cotton Planting

A study on the performance, structure, composition, and release behavior changes of polybutylene adipate terephthalic acid (PBAT) film during food contact

Polybutylene adipate terephthalic acid (PBAT) is an emerging biodegradable material in food packaging. However, concerns have been raised regarding the potential hazards it could pose to food safety. In this study, the changes of PBAT films during food contact and the release of small molecules were inestigated by a multiscale approach. On a macro-scale, the surface roughness of the films increased with the reduction in the concentration of food simulants and the increase in contact temperatures, especially after immersion in acidic food environments. On a micro-scale, the crystallinity (Xc) and degradation indexes (DI) of the films increased by 5.7-61.2% and 7.8-48.6%, respectively, which led to a decrease in thermal stability. On a scale approaching the molecular level, 2,4-di-tert-butylphenol (2,4-DTBP) was detected by gas chromatography-mass spectrometry (GC-MS/MS) with the highest migration content, and the release behavior of 2,4-DTBP was further investigated by migration kinetics. In addition, terephthalic acid (TPA), a hydrolysis product of PBAT, was detected in acidic food environments by liquid chromatography-mass spectrometry (LC-MS/MS). The results of this study could provide practical guidance and assistance to promote sustainable development in the field of food packaging.

Poly(butylene oxalate-co-terephthalate): A PBAT-like but rapid hydrolytic degradation plastic

Concerns over worldwide plastic pollution have led to the development of biodegradable polyester materials with excellent physical and chemical properties through the copolymerization of poly(butylene oxalate) (PBOx). As a result, poly(butylene oxalate-co-terephthalate)s (PBOTs) with varying compositions, were prepared by incorporating aromatic units. Studies have indicated that PBOT-47 (with a 47% molar terephthalate), exhibits exceptional mechanical properties. With an elongation at break of 1160% and a tensile strength that remains above 30 MPa, similar to or even better than those of the commercial biodegradable plastic poly(butylene adipate-co-terephthalate) PBAT-47 (47% molar terephthalate). Moreover, the permeability coefficients of PBAT-47 for H2O, CO2 and O2 were 5.8, 50.6 and 5.6 times higher than that of PBOT-47, revealing the superior barrier properties of PBOT. Through experimental research and theoretical simulation, the mechanism of the copolymer hydrolysis was elucidated. The readily hydrolytic nature of the oxalate unit endows it with the capacity for rapid degradation, possessing the potential to be a short-term degradable material with physical properties similar to PBAT.

Recent progress in PBAT-based films and food packaging applications: A mini-review

Bioplastics are a promising alternative to non-biodegradable plastics. One of these bioplastics, PBAT (polybutylene adipate co-terephthalate), is a polyester-based bioplastic commonly used to manufacture flexible packaging films. PBAT-based films have high flexibility but relatively low strength compared to other bioplastics. The strength of PBAT films can be improved by blending them with other fillers/polymers. Additionally, the functionality of PBAT films can be enhanced by incorporating bioactive functional fillers. The physical and functional properties of PBAT films produced by adding active ingredients provide functionality and are a good alternative to non-degradable petrochemical-based plastics. The PBAT-based functional films protect food and improve packaged foods' quality and life span. Thus, this review provides recent advances in PBAT-based films and their use in active food packaging applications. After briefly describing the different fabrication methods of PBAT films, various important physical and functional properties and biodegradability are comprehensively discussed. PBAT-based active packaging film in real-time food packaging is also briefly covered. Through this review, more attention is expected to be focused on research on PBAT-based biodegradable active food packaging.

Lignocellulose based biofiller reinforced biopolymer composites from fruit peel wastes as natural pigment

In this study, the utilization of mangosteen and durian peel wastes as bio-filler and natural pigment in biopolymer of polybutyrate adipate terephthalate (PBAT) were examined. The related research work of hybridization of both mangosteen and durian peels reinforced in biopolymer as cellulose-based bio fillers and natural pigment is rarely studied. The content variation of mangosteen powder and durian powder ranged from 0 to 30 wt% with an increment of 10. The influence of mangosteen and durian powders reinforced in PBAT on color change, morphological, chemical composition, mechanical, thermal, and rheological properties were determined. Mangosteen peel and durian peel provided dark appearance for the green composites without pre-burn of these fruit peels. It can be concluded that mangosteen peel and durian peel can be used as bio pigment and natural reinforcement material in biopolymer matrix which can reduce massive waste of mangosteen and durian peel and add value to these wastes. These black biopolymer composites can be used in applications of eco-friendly food packaging and medicine zipper packaging. The overall mechanical properties, thermal stability, and dark color of mangosteen/PBAT composites were greater than those of durian/PBAT composites. However, durian/PBAT composites presented greater thermal and rheological properties than mangosteen/PBAT composites.

Recent progress on biodegradable polylactic acid based blends and their biocomposites: A comprehensive review

Being less dependent on non-renewable resources as well as protecting the environment from waste streams have become two critical primers for a global movement toward replacing conventional plastics with renewable and biodegradable polymers. Despite all these efforts, only a few biodegradable polymers have paved their way successfully into the market. Polylactic acid is one of these biodegradable polymers that has been investigated thoroughly by researchers as well as manufactured on a large industrial scale. It is synthesized from lactic acid obtained mainly from the biological fermentation of carbohydrates, which makes this material a renewable polymer. Besides its renewability, it benefits from some attractive mechanical performances including high strength and stiffness, though brittleness is a major drawback of this biopolymer. Accordingly, the development of blends and biocomposites based on polylactic acid with highly flexible biodegradable polymers, specifically poly(butylene adipate co terephthalate) has been the objective of many investigations recently. This paper focuses on the blends and biocomposites based on these two biopolymers, specifically their mechanical, rheological, and biodegradation, the main characteristics that are crucial for being considered as a biodegradable substitution for conventional non-biodegradable polymers.

Composite Polymer Granules Based on Poly-ε-Caprolactone and Montmorillonite Prepared by Solution-Casting and Melt Extrusion

Eco-friendly polymer composites in the form of granules based on biodegradable polycaprolactone (PCL) with the inclusion of montmorillonite (MMT) from 5 to 50 wt% were prepared by solution-casting and melt extrusion. The physicochemical properties of the composite granules were studied using FTIR spectroscopy, XRDA, DSC, and TGA methods. The paper presents comparative values of crystallinity of composite granules which depend on the method of measuring (XRDA, DSC). It was shown that the crystallinity of PCL/MMT granules was affected by the preparation method and by the MMT content, and that with increase in MMT content, crystallinity increased by up to 61-67%. The change in crystallinity of the granules also affected its biodegradation in soil. At the end of exposure in soil, the mass loss for the granules prepared by solution-casting was more than 90%, whereas for the composite granules prepared by extrusion it was less than 60%. Applying melt extrusion enabled obtaining intercalated composites with predictable features, whereas only mixed-structure microcomposites could be prepared by solution-casting.

Detection of Water Changes in Plant Stems In Situ by the Primary Echo of Ultrasound RF with an Improved AIC Algorithm

The detection of water changes in plant stems by non-destructive online methods has become a hot spot in studying the physiological activity of plant water. In this paper, the ultrasonic radio-frequency echo (RFID) technique was used to detect water changes in stems. An algorithm (improved hybrid differential Akaike's Information Criterion (AIC)) was proposed to automatically compute the position of the primary ultrasonic echo of stems, which is the key parameter of water changes in stems. This method overcame the inaccurate location of the primary echo, which was caused by the anisotropic ultrasound propagation and heterogeneous stems. First of all, the improved algorithm was analyzed and its accuracy was verified by a set of simulated signals. Then, a set of cutting samples from stems were taken for ultrasonic detection in the process of water absorption. The correlation between the moisture content of stems and ultrasonic velocities was computed with the algorithm. It was found that the average correlation coefficient of the two parameters reached about 0.98. Finally, living sunflowers with different soil moistures were subjected to ultrasonic detection from 9:00 to 18:00 in situ. The results showed that the soil moisture and the primary ultrasonic echo position had a positive correlation, especially from 12:00 to 18:00; the average coefficient was 0.92. Meanwhile, our results showed that the ultrasonic detection of sunflower stems with different soil moistures was significantly distinct. Therefore, the improved AIC algorithm provided a method to effectively compute the primary echo position of limbs to help detect water changes in stems in situ.

Biodegradable Mulching Films Based on Polycaprolactone and Its Porous Structure Construction

Polycaprolactone (PCL) is one of the promising linear aliphatic polyesters which can be used as mulching film. Although it has suitable glass transition temperature and good biodegradability, further practical applications are restricted by the limited temperature-increasing and moisturizing properties. The rational design of the PCL structure is a good strategy to enhance the related properties. In this study, thermally-induced phase separation (TIPS) was introduced to fabricate a PCL nanoporous thin film. The introduction of a nanoporous structure on the PCL surface (np-PCL) exhibited enhanced temperature-increasing and moisturizing properties when used as mulch film. In detail, the average soil temperature of np-PCL was increased to 17.81 °C, when compared with common PCL of 17.42 °C and PBAT of 17.50 °C, and approaches to PE of 18.02 °C. In terms of water vapor transmission rate, the value for np-PCL is 637 gm^-2day^-1, which was much less than the common PCL of 786 and PBAT of 890 gm^-2day^-1. As a result, the weed biomass under the np-PCL was suppressed to be 0.35 kg m^-2, almost half of the common PCL and PBAT. In addition, the np-PCL shows good thermal stability with an onset decomposition temperature of 295 °C. The degradation mechanism and rate of the np-PCL in different pH environments were also studied to explore the influence of nanoporous structure. This work highlights the importance of the nanoporous structure in PCL to enhance the temperature-increasing and moisturizing properties of PCL-based biodegradable mulching film.