Techniques to Reduce Hydrolytic Degradation in Polylactic Acid Packaging

A biodegradable packaging material with improved durability and barrier properties, comprising a paper substrate coated with a composition of polyhydroxyalkanoate (PHA) and two or more types of polylactic acid (PLA) with different melting indices. The PHA provides thermal stability and the PLA enhances barrier properties, while the combination of both enables the material to meet both industrial and household composting standards.

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Biaxially stretched film comprising polylactic acid with a tear strength of 50-100 N/mm, enabling both punching processability and heat resistance. The film is suitable for applications such as protective films for electronic devices, where it provides a balance of mechanical strength, thermal stability, and ease of processing.

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Resin composition comprising a β-methyl-δ-valerolactone copolymer and a polylactic acid polymer, where the copolymer has a specific molecular structure that enhances the plasticity and elongation of the polylactic acid polymer. The composition can be molded into various shapes and used as a modifier for polylactic acid-based polymers.

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Biodegradable barrier film for packaging applications that has improved oxygen barrier properties and transparency compared to existing biodegradable films. The film is made by alternately laminating layers of an aliphatic polyester like polylactic acid and a polyvinyl alcohol. This structure provides both oxygen barrier and transparency. The layers are melt extruded, alternated, and then biaxially stretched and heat set to form the film.

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Degradable plastic bottle for pesticides that can meet the storage requirements of pesticide products. The bottle is made by melt extrusion of a resin blend containing polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polymethyl ethylene carbonate (PMEC), polyglycolic acid (PGA), and calcium carbonate. The resin mixture is extruded into a preform, which is then blown into the final bottle shape. The PMEC and PGA nucleate PLA crystallization, improving its crystallinity without decreasing barrier properties compared to PLA blends without these additives. The calcium carbonate reinforces the bottle. The degradable bottle can be recycled and degrades under biodegradation conditions.

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Biodegradable and bio-based polymers, including polyhydroxyalkanoate (PHA), polylactic acid (PLA), and poly(butylene succinate-

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Lime essential oil (LEO) has the potential to be incorporated into a film. Biodegradable polylactic acid (PLA) has shown potential in packaging applications. In this study, Lime extraction was carried out using a simple distillation method, and solvent casting methods were used to form the films. FT-IR result shows that the PLA primary functional group was visible at the frequency region of 495-560 cm-1 and 1740-1750 cm-1. With the addition of polyethylene glycol (PEG) and lime essential oil, the composite shows improvement in thermal stability. Even after being heated to 500 C, none of the three samples completely disintegrated after being given lime essential oil as an additive.

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Biaxially oriented film for environmentally friendly packaging with improved properties like flexibility, noise reduction, and biodegradability. The film contains a specific range of polylactic acid (PLA) and polyhydroxyalkanoate (PHA) copolymer. The film has a low loop stiffness (LS) value of 20 or less, indicating flexibility. It also has a biodegradability of 90% or more. The copolymer composition is 0-30 wt% PHA based on total film weight. This provides balanced properties for packaging applications. The film can be made by coextrusion and biaxial stretching.

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A biodegradable plastic composition with improved processability and mechanical properties, comprising a blend of polylactic acid (PLA) and suberin or suberin-based compounds extracted from plant sources, such as cork and potato periderm. The composition exhibits enhanced plasticity and biodegradability compared to conventional PLA-based bioplastics, making it suitable for various applications including disposable products, packaging, and agricultural materials.

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Polylactic acid (PLA) is a biodegradable thermoplastic made from lactic acid monomers obtained through fermented glucose in crops like wheat and corn. PLA has numerous applications, including industrial packaging, biomedical equipment, and membranes, due to its low toxicity, biodegradability, and recycling potential. However, little is known about the short-term aging effects of particulate reinforced PLA composites in complex environments. This study investigates the chemical endurance of various PLA composites before and after exposure to different chemicals and hygrothermal conditions. The results reveal that the fabrication processing method greatly affects the degradation rate. The PLA/Carbon Fiber Powder (CFP) samples had the highest chemical resistance towards degradation in 1% HNO followed by 2% NaOH with a maximum mass increase of 2.8% and 3.9% respectively. The PLA/CFP samples showed lowest chemical resistance under a combination of water and aging temperature, with an average maximum weight gain of 9.64% throughout the three CFP loadings. Continuous test for 15wt% CFP sam... Read More

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To use polylactic acid in demanding technical applications, sufficient long-term thermal stability is required. In this work, the thermal aging of polylactic acid (PLA) in the solid phase at 100 C and 150 C is investigated. PLA has only limited aging stability without the addition of stabilizers. Therefore, the degradation mechanism in thermal aging was subsequently investigated in more detail to identify a suitable stabilization strategy. Investigations using nuclear magnetic resonance spectroscopy showed that, contrary to expectations, even under thermal aging conditions, hydrolytic degradation rather than oxidative degradation is the primary degradation mechanism. This was further confirmed by the investigation of suitable stabilizers. While the addition of phenols, phosphites and thioethers as antioxidants leads only to a limited improvement in aging stability, the addition of an additive composition to provide hydrolytic stabilization results in extended durability. Efficient compositions consist of an aziridine-based hydrolysis inhibitor and a hydrotalcite co-stabilizer. At a... Read More

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The hydrolytic degradation of polyhydroxyalkanoates, polylactide and their mixtures in vitro in physiological solution and phosphate-salt buffer as well was researched. The hydrolysis intensity of biopolymers was evaluated via the mass loss, change in molecular weight as well as the water absorption applying the methods of infrared spectroscopy and complex thermal analysis. It was determined that films based on the researched biodegradable polymers thermostated in a phosphate-salt buffer have been degrading faster than in physiological solution.

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A multiblock copolymer for toughening polylactic acid (PLA) comprises a polyamide 11 (PA11) block and a PLA block, where the PA11 block is covalently linked to the PLA block through a urethane bond. The copolymer is prepared by first synthesizing a diamine-terminated PA11, then ring-opening polymerizing lactide to form a hydroxyl-telechelic PLA-PA11-PLA triblock, and finally reacting the triblock with a diisocyanate to form the multiblock copolymer. The resulting copolymer exhibits improved toughness and ductility compared to pure PLA, while maintaining its initial modulus and strain-hardening behavior.

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Blends of polylactic acid (PLA) with amorphous polyhydroxyalkanoate (aPHA) are less brittle than neat PLA, thus enabling their use as biodegradable packaging. This work investigated the impact of recycling on the properties of neat PLA and PLA/aPHA blends with 90 and 75 wt. % PLA. After the materials were subjected to five heat histories in a single-screw extruder, the mechanical, rheological, and thermal properties were measured. All recycled compounds with 100% PLA and 75% PLA had similar decomposition behavior, whereas the decomposition temperatures for the blends with 90% PLA decreased with each additional heat cycle. The glass transition and melting temperatures were not impacted by reprocessing, but the crystallinity increased with more heat cycles. The complex viscosity of the reprocessed PLA and PLA/aPHA blends was much lower than for the neat PLA and increasing the number of heat cycles produced smaller reductions in the complex viscosity of 100% PLA and the blend with 90% PLA; no change in complex viscosity was observed for blends with 75% PLA exposed to 2 to 5 heat cycles.... Read More

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Nowadays, increased food safety and decreased food waste are two of the major global interests. Self-healable active packaging materials are an attractive option to achieve such targets. This property is critical for the hygiene and the consumption appropriateness of the food. Polylactic acid is a very promising polymeric matrix that potentially could replace the widely used low-density polyethylene due to its biobased origin and its easy biodegradable nature. The main drawback of this polymeric matrix is its brittle, fragile nature. On the other hand, tetraethyl citrate is a biobased approved food additive which became an attractive option as a plasticizer for industries seeking alternative materials to replace the traditional petrochemically derived compounds. A novel biobased film exhibiting self-healing behavior suitable for food-active packaging was developed during this study. Polylactic acids brittleness was reduced drastically by incorporating tetraethyl citrate, and a random cut on the original self-repairing film was fully healed after 120 s. The optimum concentration of t... Read More

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Polylactic Acid (PLA) is a biodegradable and bioactive polyester derived from renewable sources such as corn and sugar cane. Because PLA is eco-friendly, researchers have recently tried to make PLA replace other polymers that cause greenhouse gases and other pollution. However, for many industries, PLA has limitations of unsatisfactory toughness, heat resistance, etc. In this case, it is necessary to invest in the modification of PLA, which can offer PLA desired traits to adapt to different situations. This review focuses on the recent modifications that successfully improve PLA to fit the aims, as well as the advantages and disadvantages of each method that is used for modification. There is no doubt that these methods provide a path to expand the use of PLA in different fields, such as packaging, medicine, agriculture, and textiles. The paper concludes by emphasizing the need for continued research and technological development to fully release PLA's potential in promoting a sustainable and eco-friendly future.

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Polylactic acid (PLA) has garnered significant attention due to its advantages of excellent biodegradability, biocompatibility, and renewable raw materials. This article begins by briefly introducing the research progress in the synthesis and modification of PLA, as well as its specific applications such as medical sutures and textiles, and the pros and cons of PLA itself. It then provides a detailed overview of the direct polymerization methods of PLA, including melt condensation and solution polymerization, and ring-opening polymerization methods such as cationic, anionic, and coordination. The process mechanisms, advantages, and disadvantages of each method are discussed, along with their suitability for practical industrial production and current limitations. Several specific modification methods of PLA are also discussed, such as low-temperature plasma modification and blending modification, highlighting the advantages, disadvantages, and specific research examples. These modifications aim to improve the deficiencies of PLA in areas such as mechanical strength or biological acti... Read More

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Polylactic acid (PLA) possesses characteristics such as biodegradability, ease of processing, and environmental friendliness, making it an ideal alternative to petroleum-based polymers. However, PLA has drawbacks such as susceptibility to hydrolysis and sensitivity to ultraviolet (UV) light, limiting its application in certain areas. In this study, poly(carbazole diimide) (PCDI) and the epoxy chain extender Joncryl ADR4468 (CE) were employed as a synergistic anti-hydrolysis agent for PLA, and tannic acid (TA) was used as a UV-resistant agent. A melt-blending process was employed to prepare PLA composite materials with enhanced resistance to both hydrolysis and UV radiation. The results indicate that the addition of PCDI-TA-CE significantly improved the performance of PLA. After 8 h of hydrolysis at 80 C, the tensile strength of PLA increased from 38.31 MPa for pure PLA to 77.69 MPa with the incorporation of PCDI-TA-CE. The elongation at break increased from 0.6% to 1.5%, and the Ultraviolet Protection Factor (UPF) value elevated from 3.19 for pure PLA to 503.46.This demonstrates tha... Read More

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Biodegradable poly(L-lactic acid) (PLLA) has seldom used for dairy packaging due to medium permeability and brittleness. Novel PLLA copolymers, poly (L-lactic acid-co-butylene itaconate-co-glycolic acid) (PLBIGA), were developed by integrating glycolic acid (GA) and poly(butylene itaconate) (PBI) into PLLA's structure using low molecular weight PLLA as a key initiator. Then, packaging materials with better barrier and mechanical properties were obtained by blended PLBIGA with PLLA. Both PLLA/PLBIGA films and polyethylene nylon composite film (PE/NY) were used for stirred yogurt packaging and storage at 4 C for 25 days. Results revealed that yogurt packed by PLLA/PLBIGA films maintained stabler water-holding capacity, color, and viscosity over the storage period. Moreover, the integrity of the gel structure and the total viable count of lactic acid bacteria in yogurt packaged in PLLA/40-PLBIGA8 were also found to be superior to those in PE/NY packages, highlighting its eco-friendly advantages in dairy packaging.

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Polylactic acid (PLA) is a biobased and biodegradable thermoplastic polyester with great potential to replace petroleum-based plastics. However, its poor toughness and slow biodegradation rate affect broad applications of PLA in many areas. In this study, a glycerol triester existing in natural butter, glycerol tributyrate, was creatively explored and compared with previously investigated triacetin and tributyl citrate, as potential plasticizers of PLA for achieving improved mechanical and biodegradation performances. The compatibilities of these agents with PLA were assessed quantitively via the Hansen solubility parameter (HSP) and measured by using different testing methods. The incorporation of these compounds with varied contents ranging from 1 to 30 % in PLA altered thermal, mechanical, and biodegradation properties consistently, and the relationship and impacts of chemical structures and properties of these agents were systematically investigated. The results demonstrated that glycerol tributyrate is a novel excellent plasticizer for PLA and the addition of this triester not o... Read More

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