Biodegradable Composites Developed from PBAT/PLA Binary Blends and Silk Powder: Compatibilization and Performance Evaluation

Development of antifouling antibacterial polylactic acid (PLA) -based packaging and application for chicken meat preservation

Microbial contamination is the leading cause of food spoilage and food-borne disease. Here, we developed a multifunctional surface based on polylactic acid (PLA) bioplastic with antifouling and antibacterial properties via a facile dual-coating approach. The surface was designed with hierarchical micro/nano-scale roughness and low surface energy. Bactericidal agent polyhexamethylene guanidine hydrochloride (PHMG) was incorporated to endow the film with bactericidal activity. The film had good superhydrophobic, antifouling and antibacterial performance, with a water contact angle of 154.3°, antibacterial efficiency against E. coli and S. aureus of 99.9 % and 99.6 %, respectively, and biofilm inhibition against E. coli and S. aureus of 63.5 % and 68.9 %, respectively. Synergistic effects of antibacterial adhesion and contact killing of bacteria contributed to the significant antibacterial performance of the film. The biobased biodegradable film was highly effective in preventing microbial growth when applied as antibacterial food packaging for poultry product, extending the shelf life of fresh chicken breast up to eight days.

The improvement of flame retardancy and compatibility of PBAT/PLLA via a hybrid polyurethane

Poly (butylene adipate-co-terephthalate)/poly (L-lactic acid) (PBAT/PLLA) is one of the most important biodegradable polymer combinations; however, they are flammable with heavy melt dripping and incompatible. To achieve the objective of flame retardation and compatibility, a hybrid polyurethane (PU) with multiple flame retardation elements is synthesized via a new ring-opening polymerization (ROP) method and integrated into PBAT/PLLA film. The PU not only dissolves in different organic solvents at mild temperature but also improves the compatibility of PBAT/PLLA. As PU with respect to PBAT/PLLA is 20 wt%, the limiting oxygen index (LOI) and UL-94 reach 25.5 % and V-0 rating, respectively. In cone calorimeter test, the peak heat release rate (pHRR) of PU/PBAT/PLLA is ahead of PBAT/PLLA, and the total heat release (THR) decreases to 25.85 MJ/m2. The fire safety is achieved successfully. The initial pyrolysis of PU promotes the formation of a seed carbon layer; it continuously breaks down into a series of phosphorus‑oxygen radicals and generates different inert gases, while the pyrolytic solid products accelerate the carbonization to form the carbon/silicon composite layer. Then the polymeric combustion is braked completely. Besides, the PU can also tune the mechanical properties of PBAT/PLLA film and enhance its hydrophobicity. This work opens a new window for developing multifunctional flame retardant and paves the way for the richening engineering application of PBAT/PLLA.

Advancing sustainable agriculture: Evaluation of Poly (lactic acid) (PLA) based mulch films and identification of biodegrading microorganisms among soil microbiota

Non-biodegradable polyolefin based plastic mulch residues in agricultural fields after the end of a crop cycle have raised several concerns as an environmental pollutant in recent years. This study explores the potential of Poly (lactic acid) (PLA) and Poly (butylene adipate-co-terephthalate) (PBAT) based compostable films reactively blended with compatibilizers and chain extenders as a promising solution to environmental challenges associated with traditional plastic mulch films. Epoxidized soybean oil (ESO) and Epoxy-functionalized styrene acrylic copolymer (ESA) have been used as reactive compatibilizers and chain extenders respectively. In-depth analysis of the mechanical, thermal, and barrier properties of the developed films, revealed that the PLA/PBAT blend films at 75:25 weight ratio in the presence of 5 phr ESO and 0.5 phr ESA exhibit improved performance characteristics for application as mulch films. Furthermore, the films were subjected to 360-h UV exposure to gauge their stability under prolonged exposure, specifically investigating changes in the carbonyl index. Additionally, a rigorous real-time field trial of the mulch films spanning eight months with various crops was carried out to understand their performance in practical agricultural settings. The study also involved the identification of microorganisms responsible for the degradation of the developed mulch films employing 16S rRNA sequencing.

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.

The Role of Interchain Force and/or Chain Entanglement in the Melt Strength and Ductility of PLA-Based Materials

As an eco-friendly material, PLA was a desirable alternative to polyethylene and polypropylene films due to its biodegradability. The preferable melt strength of PLA-based materials was a key factor in ensuring its processing using extrusion blow. This paper focuses on the influence of interchain force and/or chain entanglement on the melt strength and ductility of PLA-based materials in recent years. In addition, the preparation of PLA-based materials via physical blending or reactive processing was also summarized. The blending of PLA with a flexible heteropolymer, driven by the interchain force and/or chain entanglements, were characterized as a practicable method for toughening PLA-based materials. Also, the restructuring of PLA chains, by branching based on chain entanglement, was suitable for increasing chain entanglements in PLA matrix, yielding satisfactory melt strength and ductility. This review aims to elucidate the relationship between interchain forces and/or entanglement with the melt strength and ductility of PLA-based materials. An essential and systematic understanding of the tailoring melt strength and rheological properties of PLA by interchain forces and/or entanglement was apt to improve and perfect the processing technology of the extrusion blow, and consequently improve the tensile strength and toughness of PLA films.

A Review of Biodegradable Plastics: Chemistry, Applications, Properties, and Future Research Needs

Environmental concerns over waste plastics' effect on the environment are leading to the creation of biodegradable plastics. Biodegradable plastics may serve as a promising approach to manage the issue of environmental accumulation of plastic waste in the ocean and soil. Biodegradable plastics are the type of polymers that can be degraded by microorganisms into small molecules (e.g., H2O, CO2, and CH4). However, there are misconceptions surrounding biodegradable plastics. For example, the term "biodegradable" on product labeling can be misconstrued by the public to imply that the product will degrade under any environmental conditions. Such misleading information leads to consumer encouragement of excessive consumption of certain goods and increased littering of products labeled as "biodegradable". This review not only provides a comprehensive overview of the state-of-the-art biodegradable plastics but also clarifies the definitions and various terms associated with biodegradable plastics, including oxo-degradable plastics, enzyme-mediated plastics, and biodegradation agents. Analytical techniques and standard test methods to evaluate the biodegradability of polymeric materials in alignment with international standards are summarized. The review summarizes the properties and industrial applications of previously developed biodegradable plastics and then discusses how biomass-derived monomers can create new types of biodegradable polymers by utilizing their unique chemical properties from oxygen-containing functional groups. The terminology and methodologies covered in the paper provide a perspective on directions for the design of new biodegradable polymers that possess not only advanced performance for practical applications but also environmental benefits.

Elucidation of Non-Intentionally Added Substances from Plant Fiber/Plastic Composites by UPLC-QTOF/MS

Plant fiber/plastic composites (PPCs) have been widely used in food contact materials (FCMs) for many benefits, such as their claimed better environmental footprint compared to conventional plastics. However, their safety is still not fully understood and must be comprehensively evaluated. Non-volatiles extracted from six PPCs with different plant fibers and polymer matrices were characterized by employing ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry in combination with various spectral libraries and manual elucidation, taking into account spectral similarity and characteristic product ions. A total of 115 compounds were tentatively identified, 50 of which were oligomers or their derivatives from the sample with polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT) as the polymer matrix, and some of them were Cramer rules class III substances based on the threshold of toxicological concern (TTC). Seven reaction products between PLA and PBAT monomers, as well as four derivatives of melamine, were elucidated and well detailed for the first time. In addition, bisphenol S was detected in all samples even though its origin remains to be further explored. Isoprothiolane, as an insecticide and fungicide used to control a range of rice pests, was identified in the sample with rice husk as fillers, experimentally confirming the presence of agrochemicals in samples containing plant fibers.

Effect of the Addition of Different Natural Waxes on the Mechanical and Rheological Behavior of PLA-A Comparative Study

In this study, poly(lactic acid) (PLA) blended with different natural waxes (beeswax, candelilla, carnauba, and cocoa) was investigated. Different wax amounts, 3, 5, 10, and 15 wt%, were incorporated into the PLA using a Brabender internal mixer. The blends were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), rotational rheometer (RR), dynamic mechanical analysis (DMA), and contact angle to observe the effect of the different waxes on the PLA physicochemical, rheological, mechanical behavior, and wetting properties. The complex viscosity of the blends was studied by employing a RR. The effect of the addition of the waxes on the mechanical properties of PLA was evaluated by DMA in the tension modality. A slight decrease in the thermal stability of PLA was observed with the addition of the waxes. However, in the case of the mechanical properties, the cocoa wax showed a considerable effect, especially in the elongation at break of PLA. Likewise, waxes had an essential impact on the water affinity of PLA. Specifically, with the addition of cocoa, the PLA became more hydrophilic, while the rest of the waxes increased the hydrophobic character.

Processing Polymer Blends of Mater-Bi® and Poly-L-(Lactic Acid) for Blown Film Application with Enhanced Mechanical Strength

Mater-Bi^® is one of the most commercialized starch-based blends used in biodegradable flexible packaging. However, the high ductility and low stiffness of Mater-Bi^® might limit its application and developing a solution to tailor the stiffness and mechanical strength is highly desirable. In the present work, blends based on Mater-Bi^® and poly-L-(lactic acid) (PLLA) at a different ratio from 70/30 to 50/50 wt% were prepared via melt-extrusion and the effect of the PLLA content and Joncryl ADR^® as a reactive compatibilizing agent, on the mechanical properties, melts rheology, morphology and disintegration aptitude were investigated. The inclusion of PLLA in Mater-Bi^® has a marked beneficial effect on the tensile strength and stiffness of the blend while maintaining acceptable ductility. The addition of the reactive compatibilizing agent contributed to improving the strength and elongation at the break of the blend. The melt rheology of the blend was also affected by the ratio of the two components, mostly when the Joncryl ADR^® was present. The disintegration by biodegradation of the blend was preserved in the presence of PLLA, and it takes less than 30 days for the films to completely decompose and disintegrate under controlled composting conditions. Interestingly, a thin film from Mater-Bi^®/PLLA 60/40 was successfully prepared by blown film extrusion, demonstrating a good balance between stretchability (elongation at break exceeding 100%) and stiffness (1.8 GPa). This work opened to broadening the use of starch-based biodegradable plastic toward more demanding applications such as mulching films.

Bioinspired Electropun Fibrous Materials Based on Poly-3-Hydroxybutyrate and Hemin: Preparation, Physicochemical Properties, and Weathering

The development of innovative fibrous materials with valuable multifunctional properties based on biodegradable polymers and modifying additives presents a challenging direction for modern materials science and environmental safety. In this work, high-performance composite fibrous materials based on semicrystalline biodegradable poly-3-hydroxybutyrate (PHB) and natural iron-containing porphyrin, hemin (Hmi) were prepared by electrospinning. The addition of Hmi to the feed PHB mixture (at concentrations above 3 wt.%) is shown to facilitate the electrospinning process and improve the quality of the electrospun PHB/Hmi materials: the fibers become uniform, their average diameter decreases down to 1.77 µm, and porosity increases to 94%. Structural morphology, phase composition, and physicochemical properties of the Hmi/PHB fibrous materials were studied by diverse physicochemical methods, including electronic paramagnetic resonance, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, elemental analysis, differential scanning calorimetry, Fourier-transformed infrared spectroscopy, mechanical analysis, etc. The proposed nonwoven Hmi/PHB composites with high porosity, good mechanical properties, and retarded biodegradation due to high antibacterial potential can be used as high-performance and robust materials for biomedical applications, including breathable materials for wound disinfection and accelerated healing, scaffolds for regenerative medicine and tissue engineering.

The properties of 3D printed poly (lactic acid) (PLA)/poly (butylene-adipate-terephthalate) (PBAT) blend and oil palm empty fruit bunch (EFB) reinforced PLA/PBAT composites used in fused deposition modelling (FDM) 3D printing

Poly (lactic acid) (PLA) is amongst the preferable materials used in 3D printing (3DP), especially in fused deposition modelling (FDM) technique because of its unique properties such as good appearance, higher transparency, less toxicity, and low thermal expansion that help reduce the internal stresses caused during cooling. However, PLA is brittle and has low toughness and thermal resistance that affect its printability and restricts its industrial applications. Therefore, PLA was blended with various content of polybutylene adipate terephthalate (PBAT) at 20, 50 and 80 wt% via twin-screw extruder to improve the ductility and impact properties of PLA. The addition of PBAT increased the elongation at break of PLA with a linear increasing amount of PBAT. However, 20 wt% PBAT was selected as the most promising and balance properties of PLA/PBAT because although it has a slight increment in its elongation at break but it exhibits higher impact strength than that of PLA. The tensile strength and tensile modulus of sample with 20 wt% PBAT is greater than 50 and 80 wt% PBAT. Then, PLA/PBAT (80/20, 50/50 and 20/80) and PLA/PBAT/EFB (80/20/10) were printed using FDM machine and were characterized in tensile, impact and morphological properties. The tensile result indicated that the addition of PBAT decreased the tensile strength and tensile modulus of PLA/PBAT-3DP. The terephthalate group in the PBAT affects the mechanical properties of PLA/PBAT-3DP, resulting in high elongation at break but relatively low tensile strength. Besides, the tensile strength and tensile modulus of PLA/PBAT/EFB-3DP decreased and lower than PLA-3DP and PLA/PBAT-3DP. The impact test resulted in high impact strength in PLA/PBAT-3DP, where 50/50-3DP and 20/80-3DP are unbreakable. The impact strength of PLA/PBAT/EFB-3DP is also increased from PLA-3DP but lower than PLA/PBAT-3DP. The scanning electron microscopy (SEM) results revealed that the filament layering on 80/20-3DP was oriented than 50/50-3DP and 20/80-3DP. Besides, the SEM images of PLA/PBAT/EFB-3DP revealed the inhomogeneous and large agglomeration of EFB particle in PLA/PBAT matrix. Therefore, in the future, the polymer blend and polymer blend composite from PLA, PBAT and EFB can be developed where the properties will be based on the study and this study also shed light on the importance of extrusion settings during the manufacture of filament for 3D printing.

Enhancement of the Mechanical Properties of Poly(lactic acid)/Epoxidized Soybean Oil Blends by the Addition of 3-Aminophenylboronic Acid

Here, the high-strength, high-ductility blends of poly(lactic acid) (PLA) with epoxidized soybean oil (ESO) and 3-aminophenylboronic acid (APBA) were successfully prepared via a melt-bending method. The effects of APBA addition on the mechanical and thermal properties, morphologies, and crystallization behavior of the blends were investigated. The results showed that the addition of APBA endowed the PLA/ESO/APBA blends with a good balance of strength and toughness. The yield strength of the PLA/ESO/APBA (90:10:3) blend was 70 MPa, which was 25% higher than that of the corresponding PLA/ESO blend without APBA (56 MPa), while its elongation at break reached 160%, which is greatly superior to that of pure PLA (6.5%). Scanning electron microscopy images showed that the incorporation of APBA significantly improved the compatibility between PLA and ESO, while gel permeation chromatography and rheological analysis suggested the occurrence of complex reactions between the three constituents, which improved the compatibility between PLA and ESO and enhanced the mechanical properties of the blends. Hence, the PLA/ESO/APBA blends possess great potential for application in the manufacture of environmentally friendly degradable plastics.

Novel Poly(butylene adipate-co-terephthalate)-degrading Bacillus sp. JY35 from wastewater sludge and its broad degradation of various bioplastics

Poly(butylene adipate-co-terephthalate) (PBAT), a bioplastic consisting of aliphatic hydrocarbons and aromatic hydrocarbons, was developed to overcome the shortcomings of aliphatic and aromatic polyesters. Many studies report the use of PBAT as a blending material for improving properties of other bioplastics. However, there are few studies on microorganisms that degrade PBAT. We found six kinds of PBAT-degrading microorganisms from various soils. Among these, Bacillus sp. JY35 showed superior PBAT degradability and robustness to temperature. We monitored the degradation of PBAT films by Bacillus sp. JY35 using scanning electron microscopy, field emission scanning electron microscopy, Fourier-transform infrared spectroscopy, and gel permeation chromatography. GC-MS was used to measure the PBAT film degradation rate at different temperatures and with additional NaCl and carbon sources. Certain additional carbon sources improve the growth of Bacillus sp. JY35. However, this did not increase PBAT film degradation. Time-dependent PBAT film degradation rates were measured during three weeks of cultivation, after which the strain achieved almost 50% degradation. Additionally, various bioplastics were applied to solid cultures to confirm the biodegradation range of Bacillus sp. JY35, which can degrade not only PBAT but also PBS, PCL, PLA, PHB, P(3HB-co-4HB), P(3HB-co-3HV), P(3HB-co-3HHx), and P(3HB-co-3HV-co-3HHx), suggesting its usability as a superior bioplastic degrader.

Essential Work of Fracture and Evaluation of the Interfacial Adhesion of Plasticized PLA/PBSA Blends with the Addition of Wheat Bran By-Product

In this work biocomposites based on plasticized poly(lactic acid) (PLA)-poly(butylene succinate-co-adipate) (PBSA) matrix containing wheat bran fiber (a low value by-product of food industry) were investigated. The effect of the bran addition on the mechanical properties is strictly correlated to the fiber-matrix adhesion and several analytical models, based on static and dynamic tests, were applied in order to estimate the interfacial shear strength of the biocomposites. Finally, the essential work of fracture approach was carried out to investigate the effect of the bran addition on composite fracture toughness.

Preparation of effective ultraviolet shielding poly (lactic acid)/poly (butylene adipate-co-terephthalate) degradable composite film using co-precipitation and hot-pressing method

Biodegradable poly (lactide) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT) composite films were made by a co-precipitation and hot-pressing method. The property of composite films like the chemical interaction, phase morphology, mechanical properties, and thermal properties were studied. The Fourier transform infrared spectroscopy (FTIR) test manifested that there was a small amount of the transesterifications between the PBAT and PLA during hot pressing, which could improve the compatibility of the two phases. The tensile strength of the film only reduced by 7.4%, while the elongation at break was increased by 119.1% compared with PLA after adding 4%wt PBAT. The composite films showed a high Ultraviolet-visible (UV) light barrier property. The UV blocking rate of the composite after adding 4%wt PBAT was 6.95 times higher than that of pure PLA at 380 nm. The PLA/PBAT composite films with excellent thermal stability, satisfactory mechanical properties and UV-light barrier have high a possibility for an UV screening packaging application.

Effect of the Hemin Molecular Complexes on the Structure and Properties of the Composite Electrospun Materials Based on Poly(3-hydroxybutyrate)

The creation of innovative fibrous materials based on biodegradable semicrystalline polymers and modifying additives is an urgent scientific problem. In particular, the development of biomedical materials based on molecular complexes and biopolymers with controlled properties is of great interest. The paper suggests an approach to modifying the structure and properties of the composite materials based on poly(3-hydroxybutyrate) (PHB) obtained by the electrospinning method using molecular complexes of hemin. The introduction of 1-5 wt. % of hemin has a significant effect on the supramolecular structure, morphology and properties of PHB-based fibers. Changes in the supramolecular structure intensified with the increasing hemin concentration. On the one hand, a decrease in the fraction of the crystalline phase by 8-10% was observed. At the same time, there is a decrease in the density of the amorphous phase by 15-70%. Moreover, the addition of hemin leads to an improvement in the strength characteristics of the material: the elongation at break increased by 1.5 times, and in the tensile strength, it increased by 3 times. The antimicrobial activity of the hemin-containing composite materials against Escherichia coli and Staphylococcus aureus was confirmed. The obtained materials are proposed to be used in the creation of composite systems for regenerative medicine.

Chain Extension of Poly(Lactic Acid) (PLA)-Based Blends and Composites Containing Bran with Biobased Compounds for Controlling Their Processability and Recyclability

The present work focused on the research, design, and study of innovative chain extender systems of renewable origin for PLA-based biocomposites, reinforced with wheat bran as filler. The majority of employed chain extender compounds belongs to fossil world, affecting the biodegradability property which characterizes biopolymers. The aim of this work was thus to find promising biobased and sustainable alternatives to provide the same enhancements. According to this objective, epoxidized soybean oil (ESO) was chosen as principal component of the chain extender systems, together with a dicarboxylic acid, malic acid (MA), or succinic acid (SA). The reactivity of the modifier systems was previously studied through thermogravimetric analysis (TGA) and IR spectroscopy, to hypothesize the reaction mechanism in bran-filled blends. Hence, small-scale extrusion was carried out to investigate the effects of ESO/MA and ESO/SA on formulations of different composition (both pure PLA blends and composites). The variation of melt fluidity parameters was analyzed to define the optimized concentration of modifier systems. A comparison between the effects on blends of designed biobased systems and the action of fossil-based Joncryl was performed, to understand if the developed green solutions could represent competitive and efficient substitutes. The modified composites were characterized in terms of mechanical tests, degradation and thermal studies (TGA and DSC), and morphological analysis (SEM), to figure out their main features and to understand their potential in possible industrial applications.

Application of Quaternary Ammonium Compounds as Compatibilizers for Polymer Blends and Polymer Composites—A Concise Review

A wide variety of quaternary ammonium compounds (QACs) have escalated the attraction of researchers to explore the application of QACs. The compounds have frequently been synthesized through alkylation or quaternization of tertiary amines with alkyl halides. Recently, QACs have been applied to compatibilize polymer blends and polymer composites in improving their thermo-mechanical properties. This concise review concentrates on the application of two types of QACs as compatibilizers for polymer blends and polymer composites. The types of QACs that were effectively applied in the blends and composites are quaternary ammonium surfactants (QASs) and quaternary ammonium ionic liquids (QAILs). They have been chosen for the discussion because of their unique chemical structure which can interact with the polymer blend and composite components. The influence of QASs and QAILs on the thermo-mechanical properties of the polymer blends and polymer composites is also described. This review could be helpful for the polymer blend and polymer composite researchers and induce more novel ideas in this research area.

Development of Toughened Flax Fiber Reinforced Composites. Modification of Poly(lactic acid)/Poly(butylene adipate-co-terephthalate) Blends by Reactive Extrusion Process

The presented study focuses on the development of flax fiber (FF) reinforced composites prepared with the use of poly(lactic acid)/poly(butylene adipate-co-terephthalate)-PLA/PBAT blend system. This type of modification was aimed to increase impact properties of PLA-based composites, which are usually characterized by high brittleness. The PLA/PBAT blends preparation was carried out using melt blending technique, while part of the samples was prepared by reactive extrusion process with the addition of chain extender (CE) in the form of epoxy-functionalized oligomer. The properties of unreinforced blends was evaluated using injection molded samples. The composite samples were prepared by compression molding technique, while flax fibers reinforcement was in the form of plain fabric. The properties of the laminated sheets were investigated during mechanical test measurements (tensile, flexural, impact). Differential scanning calorimetry (DSC) analysis was used to determine the thermal properties, while dynamic mechanical thermal analysis (DMTA) and heat deflection temperature (HDT) measurements were conducted in order to measure the thermomechanical properties. Research procedure was supplemented with structure evaluation using scanning electron microscopy (SEM) analysis. The comparative study reveals that the properties of PLA/PBAT-based composites were more favorable, especially in the context of impact resistance improvement. However, for CE modified samples also the modulus and strength was improved. Structural observations after the impact tests confirmed the presence of the plastic deformation of PLA/PBAT matrix, which confirmed the favorable properties of the developed materials. The use of PBAT phase as the impact modifier strongly reduced the PLA brittleness, while the reactive extrusion process improves the fiber-matrix interactions leading to higher stiffness and strength.

Improvement of Interlayer Adhesion and Heat Resistance of Biodegradable Ternary Blend Composite 3D Printing

Poly(lactic acid) (PLA) filaments have been the most used in fused deposition modeling (FDM) 3D printing. The filaments, based on PLA, are continuing to be developed to overcome brittleness, low heat resistance, and obtain superior mechanical performance in 3D printing. From our previous study, the binary blend composites from PLA and poly(butylene adipate-co-terephthalate) (PBAT) with nano talc (PLA/PBAT/nano talc) at 70/30/10 showed an improvement in toughness and printability in FDM 3D printing. Nevertheless, interlayer adhesion, anisotropic characteristics, and heat resistance have been promoted for further application in FDM 3D printing. In this study, binary and ternary blend composites from PLA/PBAT and poly(butylene succinate) (PBS) with nano talc were prepared at a ratio of PLA 70 wt. % and blending with PBAT or PBS at 30 wt. % and nano talc at 10 wt. %. The materials were compounded via a twin-screw extruder and applied to the filament using a capillary rheometer. PLA/PBAT/PBS/nano talc blend composites were printed using FDM 3D printing. Thermal analysis, viscosity, interlayer adhesion, mechanical properties, and dimensional accuracy of binary and ternary blend composite 3D prints were investigated. The incorporation of of PBS-enhanced crystallinity of the blend composite 3D prints resulted in an improvement to mechanical properties, heat resistance, and anisotropic characteristics. Flexibility of the blend composites was obtained by presentation of PBAT. It should be noted that the core-shell morphology of the ternary blend influenced the reduction of volume shrinkage, which obtained good surface roughness and dimensional accuracy in the ternary blend composite 3D printing.

Poly(lactic acid) (PLA)/Poly(butylene succinate-co-adipate) (PBSA) Compatibilized Binary Biobased Blends: Melt Fluidity, Morphological, Thermo-Mechanical and Micromechanical Analysis

In this work poly(lactic) acid (PLA)/poly(butylene succinate-co-adipate) (PBSA) biobased binary blends were investigated. PLA/PBSA mixtures with different compositions of PBSA (from 15 up to 40 wt.%) were produced by twin screw-extrusion. A first screening study was performed on these blends that were characterized from the melt fluidity, morphological and thermo-mechanical point of view. Starting from the obtained results, the effect of an epoxy oligomer (EO) (added at 2 wt.%) was further investigated. In this case a novel approach was introduced studying the micromechanical deformation processes by dilatometric uniaxial tensile tests, carried out with a videoextensometer. The characterization was then completed adopting the elasto-plastic fracture approach, by the measurement of the capability of the selected blends to absorb energy at a slow rate. The obtained results showed that EO acts as a good compatibilizer, improving the compatibility of the rubber phase into the PLA matrix. Dilatometric results showed different micromechanical responses for the 80–20 and 60–40 blends (probably linked to the different morphology). The 80–20 showed a cavitational behavior while the 60–40 a deviatoric one. It has been observed that while the addition of EO does not alter the micromechanical response of the 60–40 blend, it profoundly changes the response of the 80–20, that passed to a deviatoric behavior with the EO addition.

Biodegradable kinetics and behavior of bio-based polyblends under simulated aerobic composting conditions

The current study evaluates aerobic biodegradation of melt extruded poly(lactic acid) PLA based blends under composting conditions. Samples of neat PLA (NPLA) and bio-based polyblend composites of PLA/LLDPE (linear low-density polyethylene) having different concentration of MCC (microcrystalline cellulose crystal) were analyzed to understand the biodegradation behavior of these blends under simulated composting conditions. Biodegradation kinetics revealed that higher content of MCC and PLA accelerated the biodegradation process of the polymeric blends. Increase in the spherulite growth size and decrease in the spherulite density of the biodegraded samples confirmed the decline in amorphous portion of the test samples due to microbial assimilation, leaving behind the crystalline portion. Surface morphological analysis revealed that the samples of PLA/LLDPE/MCC blends underwent surface erosion prior to bulk biodegradation (50-80%) until the 90th day and the PLA formed fibril-like structures after degradation. This study would help in the design and preparation of biodegradable bio-based commercial blends in the future.