Biodegradable compatibilized polymer blends for packaging applications: A literature review

Impacts of chitosan/pullulan/carvacrol film on the quality and microbial diversity of refrigerated goat meat

In this study, our previously prepared chitosan/pullulan film (CS/PU) and chitosan/pullulan/carvacrol film (CS/PU/CAR) were applied to goat meat preservation, the dynamic changes in quality and microbial communities of goat meat during chilled storage (4 °C) were investigated, and the fresh-keeping effects of the two biodegradable antibacterial films on goat meat were comprehensively evaluated. The results showed that when the goat meat was wrapped with CS/PU or CS/PU/CAR films during chilled storage, the total plate count and total volatile basic nitrogen (TVB-N) could be inhibited significantly, but the CS/PU/CAR film has a better fresh-keeping effect. Furthermore, during the chilled storage of goat meat, CS/PU/CAR film also could inhibit the production of alcohol compounds and the growth of Pseudomonas spp., thereby slowing down the meat's deterioration and extending the goat meat's shelf life to about 13 days. This study can provide a reference for the application of active packaging film of fresh goat meat.

Enhancing Polypropylene/Polyethylene Blend Performance Through Compatibilization for A Sustainable Future: A Mini Review Focusing on Establishing Bio-Derived Filler Based Hybrid Compatibilizer System

Polypropylene (PP) and polyethylene (PE) are widely used polymers but significantly contribute to plastic waste. Effective recycling of PP and PE is essential for reducing plastic pollution and enhancing sustainability. Collection of post-consumer PP and PE wastes forming comingled mixtures is routinely done due to the difficulty of sorting. While polymer blending offers a cost-effective way to recycle these mixtures, their inherent immiscibility limits the development of high-performance blends. This review provides an overview of recent advances in compatibilization strategies aimed at enhancing the PP/PE blend performance, with a focus on using bio-derived fillers as sustainable compatibilizers. Mechanical properties of the PP/PE blends compatibilized by various approaches, including non-reactive, reactive, and bio-derived filler compatibilizations are summarized and discussed in terms of their advantages and weaknesses. Simultaneous incorporation of bio-derived fillers and commercial compatibilizers potentially provides PP/PE blends with more desirable mechanical performance. Furthermore, the review summarizes the rheological and crystallization behaviors of compatibilized blends, emphasizing the significant impact of compatibilization on the processing-structure-property relationships within the blends. Current challenges and future directions in using bio-derived fillers to enhance PP/HDPE compatibilization are discussed. This review provides insight into a sustainable future by endowing plastic waste with desirable properties for broader applications.

Recent advances in sustainable biopolymer-based nanocomposites for smart food packaging: A review

The main goal of emerging food-packaging technologies is to address environmental issues and minimize their impact, while also guaranteeing food quality and safety for consumers. Bio-based polymers have drawn significant interest as a means to reduce the usage and environmental impact of petroleum-derived polymeric products. Therefore, this current review highlights on the biopolymer blends, various biodegradable bio-nanocomposites materials, and their synthesis and characterization techniques recently used in the smart food packaging industry. In addition, some insights on potential challenges as well as possibilities in future smart food packaging applications are thoroughly explored. Nanocomposite packaging materials derived from biopolymers have the highest potential for use in improved smart food packaging that possesses bio-functional properties. Nanomaterials are utilized for improving the thermal, mechanical, and gas barrier attributes of bio-based polymers while maintaining their biodegradable and non-toxic qualities. The packaging films that were developed exhibited enhanced barrier qualities against carbon dioxide, oxygen, and water vapour. Additionally, they demonstrated better mechanical strength, thermal stability, and antibacterial activity. More research is needed to develop and use smart food packaging materials based on bio-nanocomposites on a worldwide scale, while removing plastic packaging.

In-Line Chemical Composition Monitoring for the Injection Molding Process of Biodegradable Polymer Blends Using Simultaneous Measurement of Near-Infrared Diffuse Reflectance and Transmission Spectra

In the processing of polymer blends and composites, in-line near-infrared (NIR) spectroscopy enables monitoring of the composition and its composite uniformity and contributes to rapid process development and quality control. However, in the injection molding process, the study of the composition of polymer materials has been delayed due to high-pressure conditions. Our research group developed NIR probes for transmission and diffuse reflectance measurements that can withstand high-pressure and temperature conditions up to 130 MPa and 200 °C. In this research, transmission and diffuse reflectance spectra were measured inline during the injection molding process of polymer blends of poly(lactic acid) and polybutylene succinate adipate. The intensity of each polymer band in the second-derivative spectra exhibited a monotonic increase or decrease in response to changes in the blend ratio. Using transmission and diffuse reflectance spectra as explanatory variables of the partial least squares regression model simultaneously, the model showed high estimation accuracy for the entire region of the blend ratio. Finally, this model was applied to monitor the polymer changeover operation, and the change in the blend ratio in the molded product was successfully estimated in line.

Performance Enhancement of Biopolyester Blends by Reactive Compatibilization with Maleic Anhydride-Grafted Poly(butylene succinate-co-adipate)

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a very promising biodegradable copolyester of high interest in food packaging. Its inherent brittleness and narrow processing window make it necessary to blend it with flexible biopolyesters, such as poly(butylene succinate-co-adipate) (PBSA). However, the resultant biopolyester blends are thermodynamically immiscible, which impairs their performance and limits their applications. This study is the first to explore the use of poly(butylene succinate-co-adipate) grafted with maleic anhydride (PBS-g-MAH) as a novel reactive additive to compatibilize PHBV/PBSA blends. The compatibilizer was prepared by a reactive melt-mixing process of PBSA and maleic anhydride (MAH) using dicumyl peroxide (DCP) as an organic radical initiator, achieving a grafting degree (Gd) of 5.4%. Biopolyester blend films were thereafter prepared via cast extrusion and their morphological, thermal, mechanical, and barrier properties were characterized. Compatibilization by PBSA-g-MAH was confirmed by observing an improved phase interaction and lower dispersed domain sizes in the blends with 15 wt% PBSA. These compatibilized PHBV/PBSA blends were thermally stable up to 285 °C, showed enhanced ductility and toughness, as well as providing an improved barrier against water and limonene vapors and oxygen. These findings suggest that the use of MAH-grafted biopolyesters can represent an effective strategy to improve the properties of biopolyester blends and open up new opportunities for the application of PHBV-based formulations for food packaging.

Synergistic Polymer Blending Informs Efficient Terpolymer Design and Machine Learning Discerns Performance Trends for pDNA Delivery

Cationic polymers offer an alternative to viral vectors in nucleic acid delivery. However, the development of polymer vehicles capable of high transfection efficiency and minimal toxicity has remained elusive, and continued exploration of the vast design space is required. Traditional single polymer syntheses with large monomer bases are very time-intensive, limiting the speed at which new formulations are identified. In this work, we present an experimental method for the quick probing of the design space, utilizing a combinatorial set of 90 polymer blends, derived from 6 statistical copolymers, to deliver pDNA. This workflow facilitated rapid screening of polyplex compositions, successfully tailoring polyplex hydrophobicity, particle size, and payload binding affinity. This workflow identified blended polyplexes with high levels of transfection efficiency and cell viability relative to single copolymer controls and commercial JetPEI, indicating synergistic benefits from copolymer blending. Polyplex composition was coupled with biological outputs to guide the synthesis of single terpolymer vehicles, with high-performing polymers P10 and M20, providing superior transfection of HEK293T cells in serum-free and serum-containing media, respectively. Machine learning coupled with SHapley Additive exPlanations (SHAP) was used to identify polymer/polyplex attributes that most impact transfection efficiency, viability, and overall effective efficiency. Subsequent transfections on ARPE-19 and HDFn cells found that P10 and M20 were surpassed in performance by M10, contrasting with results in HEK293T cells. This cell type dependency reinforced the need to evaluate transfection conditions with multiple cell models to potentially identify moieties more beneficial to delivery in certain tissues. Overall, the workflow employed can be used to expedite the exploration of the polymer design space, bypassing extensive synthesis, and to develop improved polymer delivery vehicles more readily for nucleic acid therapies.

Enhancing Polymer Sustainability: Eco-Conscious Strategies

Polymer sustainability is a pressing concern in today's world driven by the increasing demand for environmentally friendly materials. This review paper provides a comprehensive overview of eco-friendly approaches towards enhancing the sustainability of polymers. It synthesized recent research and developments in various areas such as green polymer synthesis methods, biodegradable polymers, recycling technologies, and emerging sustainable alternatives. The environmental impact of traditional polymer production processes and the importance of adopting greener alternatives were critically examined. The review delved into the advancements in polymer recycling technologies like mechanical, chemical, and biological processes aimed at minimizing plastic waste and promoting a circular economy. The innovative approaches such as upcycling, hybrid methods etc., which offer promising solutions for addressing plastic pollution and achieving long-term sustainability goals were also analyzed. Finally, the paper discussed the challenges and future prospects of eco-friendly approaches for polymer sustainability, emphasizing the need for researchers and concerted efforts from scientists across industries and academia to drive meaningful change towards a more sustainable future.

Predicting compatibilized polymer blend toughness

Polymer blends can yield superior materials by merging the unique properties of their components. However, these mixtures often phase separate, leading to brittleness. While compatibilizers can toughen these blends, their vast design space makes optimization difficult. Here, we develop a model to predict the toughness of compatibilized glassy polymer mixtures. This theory reveals that compatibilizers increase blend toughness by creating molecular bridges that stitch the interface together. We validate this theory by directly comparing its predictions to extensive molecular dynamics simulations in which we vary polymer incompatibility, chain stiffness, compatibilizer areal density, and blockiness of copolymer compatibilizers. We then parameterize the model using self-consistent field theory and confirm its ability to make predictions for practical applications through comparison with simulations and experiments. These results suggest that the theory can optimize compatibilizer design for industrial glassy polymer blends in silico while providing microscopic insight, allowing for the development of next-generation mixtures.

Interface interactions driven antioxidant properties in olive leaf extract/cellulose nanocrystals/poly(butylene adipate-co-terephthalate) biomaterials

Functional packaging represents a new frontier for research on food packaging materials. In this context, adding antioxidant properties to packaging films is of interest. In this study, poly(butylene adipate-co-terephthalate) (PBAT) and olive leaf extract (OLE) have been melt-compounded to obtain novel biomaterials suitable for applications which would benefit from the antioxidant activity. The effect of cellulose nanocrystals (CNC) on the PBAT/OLE system was investigated, considering the interface interactions between PBAT/OLE and OLE/CNC. The biomaterials' physical and antioxidant properties were characterized. Morphological analysis corroborates the full miscibility between OLE and PBAT and that OLE favours CNC dispersion into the polymer matrix. Tensile tests show a stable plasticizer effect of OLE for a month in line with good interface PBAT/OLE interactions. Simulant food tests indicate a delay of OLE release from the 20 wt% OLE-based materials. Antioxidant activity tests prove the antioxidant effect of OLE depending on the released polyphenols, prolonged in the system at 20 wt% of OLE. Fluorescence spectroscopy demonstrates the nature of the non-covalent PBAT/OLE interphase interactions in π-π stacking bonds. The presence of CNC in the biomaterials leads to strong hydrogen bonding interactions between CNC and OLE, accelerating OLE released from the PBAT matrix.

The Effect of Processing Conditions on the Microstructure of Homopolymer High-Density Polyethylene Blends: A Multivariate Approach

In this work, a multivariate approach was utilized for gaining some insights into the processing-structure-properties relationships in polyethylene-based blends. In particular, two high-density polyethylenes (HDPEs) with different molecular weights were melt-compounded using a twin-screw extruder, and the effects of the screw speed, processing temperature and composition on the microstructure of the blends were evaluated based on a Design of Experiment-multilinear regression (DoE-MLR) approach. The results of the thermal characterization, interpreted trough the MLR (multilinear regression) response surfaces, demonstrated that the composition of the blends and the screw rotation speed are the two most important parameters in determining the crystallinity of the materials. Furthermore, the rheological data were examined using a Principal Component Analysis (PCA) multivariate approach, highlighting also in this case the most prominent effect of the weight ratio of the two base polymers and the screw rotation speed.

Biocomposites of Cellulose Isolated from Coffee Processing By-Products and Incorporation in Poly(Butylene Adipate-Co-Terephthalate) (PBAT) Matrix: An Overview

With its extensive production and consumption, the coffee industry generates significant amounts of lignocellulosic waste. This waste, primarily comprising coffee biomasses, is a potential source of cellulose. This cellulose can be extracted and utilized as a reinforcing agent in various biocomposites with polymer matrices, thereby creating high-value products. One such biodegradable polymer, Poly(butylene adipate-co-terephthalate) (PBAT), is notable for its properties that are comparable with low-density polyethylene, making it an excellent candidate for packaging applications. However, the wider adoption of PBAT is hindered by its relatively high cost and lower thermomechanical properties compared with conventional, non-biodegradable polymers. By reinforcing PBAT-based biocomposites with cellulose, it is possible to enhance their thermomechanical strength, as well as improve their water vapor and oxygen barrier capabilities, surpassing those of pure PBAT. Consequently, this study aims to provide a comprehensive review of the latest processing techniques for deriving cellulose from the coffee industry's lignocellulosic by-products and other coffee-related agro-industrial wastes. It also focuses on the preparation and characterization of cellulose-reinforced PBAT biocomposites.

Cross-linked poly(ester urethane)/starch composite films with high starch content as sustainable food-packaging materials: Influence of cross-link density

This study focused on the development of cross-linked poly(ester urethane)/starch (PEUST) composites containing 50 wt% starch content for food-packaging materials. The NCO-terminated poly(caprolactone-urethane) prepolymer (PCUP) was first synthesized through bulk condensation. Then, low-moisture starch (0.21 wt%) and PCUP-based PEUST films were fabricated through an intensive extrusion process, followed by thermo-compression molding. The chemical structure of PCUP and PEUST was confirmed using Fourier transform infrared spectroscopy. Moreover, a comprehensive evaluation was conducted to assess the influence of cross-link density on the physicochemical properties of the composite films. The results showed that an increase in the cross-link density within the composites improved component compatibility and tensile strength but reduced crystallinity, water sensitivity, hydrolytic degradability, and water vapor permeability (WVP) of the films. In addition, the cytotoxicity tests were conducted to evaluate the safety of the composite films, and the high cell viability demonstrated non-toxicity for food application. The PEUST-II films with moderate cross-link density exhibited a suitable degradation rate (27.7 % weight loss at degradation for 140 d), optimal tensile properties (tensile strength at break: 12.4 MPa; elongation at break: 352 %), and low WVP (68.4 g/(m2⋅24h) at 30 % relative humidity). These characteristics make them highly promising as fresh-keeping food packaging.

Flame retardancy of sustainable polylactic acid and polyhydroxybutyrate (PLA/PHB) blends

Nowadays, development of new biobased/biodegradable polymers from biological resources is of great interest from a sustainability standpoint. Polyhydroxybutyrate (PHB) and polylactic acid (PLA) are two biopolymers obtained from renewable resources. In this study, the flame-retardant effect of a newly developed flame retardant (FR) based on melamine in a PLA/PHB blend was studied. Several combinations containing this new FR combined with ammonium polyphosphate (APP) and sepiolite were introduced in a PLA/PHB blend. 20 wt% of FR were introduced into a matrix containing 75 wt% PLA and 25 wt% PHB blended with a microcompounder. According to pyrolysis combustion flow calorimeter (PCFC) analyses, all the FR formulations exhibited reduced flammability. The results revealed a considerable decrease in the peak of heat release rate (pHRR) by 33 % in the presence of the new FR while a reduction of about 60 % for combinations with APP and sepiolite. The new FR system significantly enhanced the fire behaviour of PLA/PHB blend. The work presents the first cone calorimeter analyses of PLA/PHB composites. The fire behaviour evolved from thin sample to a thick charring behaviour highlighted by an increase of the residue after cone calorimeter from 0 to 14.7 % with this FR system.

Recent developments in bio-based polyethylene: Degradation studies, waste management and recycling

Nowadays, the tendency to replace conventional fossil-based plastics is increasing considerably; there is a growing trend towards alternatives that involve the development of plastic materials derived from renewable sources, which are compostable and biodegradable. Indeed, only 1.5 % of whole plastic production is part of the small bioplastics market, even when these materials with a partial or full composition from biomass are rapidly expanding. A very interesting field of investigation is currently being developed in which the disposal and processing of the final products are evaluated in terms of reducing environmental harm. This review presents a compilation of polyethylene (PE) types, their uses, and current problems in the waste management of PE and recycling. Particularly, this review is based on the capabilities to synthesize bio-based PE from natural and renewable sources as a replacement for the raw material derived from petroleum. In addition to recent studies in degradation on different types of PE with weight loss ranges from 1 to 47 %, the techniques used and the main changes observed after degradation. Finally, perspectives are presented in the manuscript about renewable and non-renewable polymers, depending on the non-degradable, biodegradable, and compostable behavior, including composting recent studies in PE. In addition, it contributes to the 3R approaches to responsible waste management of PE and advancement towards an environmentally friendly PE.

Biodegradability Assessment of Prickly Pear Waste-Polymer Fibers under Soil Composting

Nowadays, solving the problems associated with environmental pollution is of special interest. Therefore, in this work, the morphology and thermal and mechanical properties of extruded fibers based on polylactic acid (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) added to prickly pear flour (PPF) under composting for 3 and 6 months were evaluated. The highest weight loss percentage (92 ± 7%) was obtained after 6-month degradation of the PLA/PBAT/PPF/CO/AA blend, in which PPF, canola oil (CO), and adipic acid (AA) were added. Optical and scanning electron microscopy (SEM) revealed structural changes in the fibers as composting time increased. The main changes in the absorption bands observed by Fourier transform infrared spectroscopy (FTIR) were related to the decrease in -C=O (1740 cm-1) and -C-O (1100 cm-1) groups and at 1269 cm-1, associated with hemicellulose in the blends with PPF. Differential scanning calorimetry (DSC) showed an increase in the cold crystallization and melting point with degradation time, being more evident in the fibers with PPF, as well as a decrease in the mechanical properties, especially Young's modulus. The obtained results suggest that PPF residues could promote the biodegradability of PLA/PBAT-based fiber composites.

Biological and physiochemical studies of electrospun polylactid/polyhydroxyoctanoate PLA/P(3HO) scaffolds for tissue engineering applications

Polyhydroxyoctanoate, as a biocompatible and biodegradable biopolymer, represents an ideal candidate for biomedical applications. However, physical properties make it unsuitable for electrospinning, currently the most widely used technique for fabrication of fibrous scaffolds. To overcome this, it was blended with polylactic acid and polymer blend fibrous biomaterials were produced by electrospinning. The obtained PLA/PHO fibers were cylindrical, smaller in size, more hydrophilic and had a higher degree of biopolymer crystallinity and more favorable mechanical properties in comparison to the pure PLA sample. Cytotoxicity evaluation with human lung fibroblasts (MRC5 cells) combined with confocal microscopy were used to visualize mouse embryonic fibroblasts (MEF 3T3 cell line) migration and distribution showed that PLA/PHO samples support exceptional cell adhesion and viability, indicating excellent biocompatibility. The obtained results suggest that PLA/PHO fibrous biomaterials can be potentially used as biocompatible, biomimetic scaffolds for tissue engineering applications.

Mask-Assisted Deposition of Ti on Cyclic Olefin Copolymer Foil by Pulsed Laser Deposition

Cyclic olefin copolymer (COC) is a novel type of thermoplastic polymer gaining the attention of the scientific community in electronic, optoelectronic, biomedicine and packaging applications. Despite the benefits in the use of COC such as undoubted optical transparency, chemical stability, a good water-vapor barrier and biocompatibility, its original hydrophobicity restricts its wider applicability and optimization of its performances. Presently, we report on the optical and morphological properties of the films of COC covered with Ti in selected areas. The layer of Ti on COC was deposited by pulsed lased deposition processing. The Ti/COC film was characterized by UV-Vis spectroscopy indicating that its transmittance in the visible region decreased by about 20% with respect to the pristine polymer. The quality of the deposited Ti was assessed with the morphology by scanning electron (SEM) and atomic force microscopies (AFM). The modification of the wettability was observed by the sessile drop method indicating a reduction of the native hydrophilicity.

A Review on Biopolymer-Based Biodegradable Film for Food Packaging: Trends over the Last Decade and Future Research

In recent years, much attention has been paid to the use of biopolymers as food packaging materials due to their important characteristics and properties. These include non-toxicity, ease of availability, biocompatibility, and biodegradability, indicating their potential as an alternative to conventional plastic packaging that has long been under environmental scrutiny. Given the current focus on sustainable development, it is imperative to develop studies on biopolymers as eco-friendly and sustainable food packaging materials. Therefore, the aim of this review is to explore trends and characteristics of biopolymer-based biodegradable films for food packaging, analyze the contribution of various journals and cooperation between countries, highlight the most influential authors and articles, and provide an overview of the social, environmental, and economic aspects of biodegradable films for food packaging. To achieve this goal, a bibliometric analysis and systematic review based on the PRISMA method were conducted. Relevant articles were carefully selected from the Scopus database. A bibliometric analysis was also conducted to discuss holistically, comprehensively, and objectively biodegradable films for food packaging. An increasing interest was found in this study, especially in the last 3 years with Brazil and China leading the number of papers on biodegradable films for food packaging, which were responsible for 20.4% and 12.5% of the published papers, respectively. The results of the keyword analysis based on the period revealed that the addition of bioactive compounds into packaging films is very promising because it can increase the quality and safety of packaged food. These results reveal that biodegradable films demonstrate a positive and promising trend as food packaging materials that are environmentally friendly and promote sustainability.

Multi-Component Biodegradable Materials Based on Water Kefir Grains and Yeast Biomasses: Effect of the Mixing Ratio on the Properties of the Films

The use of biopolymeric materials is restricted for some applications due to their deficient properties in comparison to synthetic polymers. Blending different biopolymers is an alternative approach to overcome these limitations. In this study, we developed new biopolymeric blend materials based on the entire biomasses of water kefir grains and yeast. Film-forming dispersions with varying ratios of water kefir to yeast (100/0, 75/25, 50/50 25/75 and 0/100) underwent ultrasonic homogenisation and thermal treatment, resulting in homogeneous dispersions with pseudoplastic behaviour and interaction between both biomasses. Films obtained by casting had a continuous microstructure without cracks or phase separation. Infrared spectroscopy revealed the interaction between the blend components, leading to a homogeneous matrix. As the water kefir content in the film increased, transparency, thermal stability, glass transition temperature and elongation at break also increased. The thermogravimetric analyses and the mechanical tests showed that the combination of water kefir and yeast biomasses resulted in stronger interpolymeric interactions compared to single biomass films. The ratio of the components did not drastically alter hydration and water transport. Our results revealed that blending water kefir grains and yeast biomasses enhanced thermal and mechanical properties. These studies provided evidence that the developed materials are suitable candidates for food packaging applications.

Melt Processible Biodegradable Blends of Polyethylene Glycol Plasticized Cellulose Diacetate with Polylactic Acid and Polybutylene Adipate-Co-Terephthalate

Enhancing the melt processability of cellulose is key to broadening its applications. This is done via derivatization of cellulose, and subsequent plasticization and/or blending with other biopolymers, such as polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT). However, derivatization of cellulose tends to reduce its biodegradability. Moreover, traditional plasticizers are non-biodegradable. In this study, we report the influence of polyethylene glycol (PEG) plasticizer on the melt processibility and biodegradability of cellulose diacetate (CD) and its blends with PLA and PBAT. CD was first plasticized with PEG (PEG-200) at 35 wt%, and then blended with PLA and PBAT using a twin-screw extruder. Blends of the PEG plasticized CD with PLA at 40 wt% and with PBAT at 60 wt% were studied in detail. Dynamic mechanical analysis (DMA) showed that PEG reduced the glass transition of the CD from ca. 220 °C to less than 100 °C, indicating effective plasticization. Scanning electron microscopy revealed that the CD/PEG-PBAT blend had a smoother morphology implying some miscibility. The CD/PEG-PBAT blend at 60 wt% PBAT had an elongation-to-break of 734%, whereas the CD/PEG-PLA blend had a tensile strength of 20.6 MPa, comparable to that of the PEG plasticized CD. After a 108-day incubation period under simulated aerobic composting, the CD/PEG-PBAT blend at 60 wt% PBAT exhibited a biodegradation of 41%, whereas that of the CD/PEG-PLA at 40 wt% PLA was 107%. This study showed that melt processible, biodegradable CD blends can be synthesized through plasticization with PEG and blending with PBAT or PLA.

Investigation of the Effects of Chain Extender on Material Properties of PLA/PCL and PLA/PEG Blends: Comparative Study between Polycaprolactone and Polyethylene Glycol

This study investigated the effect of the Joncryl concentration on the properties of polylactide/poly(ε-caprolactone) (PLA/PCL) and PLA/poly(ethylene glycol) (PEG) blends. The addition of Joncryl influenced the properties of both PLA-based blends. In the blend of PLA/PCL blends, the addition of Joncryl reduced the size of PCL droplets, which implies the compatibility of the two phases, while PLA/PEG blends showed a co-continuous type of morphology at 0.1% and 0.3 wt.% of Joncryl loading. The crystallinity of PCL and PEG was studied on both PLA/PCL and PLA/PEG blend systems. In both scenarios, the crystallinity of the blends decreased upon the addition of Joncryl. Thermal stabilities were shown to depend on the addition of Joncryl. The toughness increased when 0.5 wt.% of Joncryl was added to both systems. However, the stiffness of PLA/PCL decreased, while the stiffness of PLA/PEG increased with the increasing concentration of Joncryl. This study provides new insight into the effect of chain extenders on the compatibility of PLA-based blends.

The Effect of Epoxidized Soybean Oil on the Physical and Mechanical Properties of PLA/PBAT/PPC Blends by the Reactive Compatibilization

Poly (lactic acid) (PLA)/poly (butylene adipate-co-terephthalate) (PBAT)/poly (propylene carbonate) (PPC) multi-phase blends were prepared by melt processing technique under the presence of compatibilizer with various composition. The effect on the physical and the mechanical property with/without ESO was characterized with spectrophotometric analysis, mechanical properties, thermal properties, rheological properties and barrier properties, and the structure-properties relationship was assessed. ​​The functional groups of PPC were found to effective to improve an interaction with carboxyl/hydroxyl group of PLA/PBAT binary blends to enhance the mechanical and physical properties on multi-phase blend system. The presence of PPC in PLA/PBAT blend affected the reduction of voids on the interface phase resulting in enhancing the oxygen barrier properties. With addition of ESO, the compatibility of ternary blend was found to be enhanced since the epoxy group of ESO reacted with the carboxyl/hydroxyl group of PLA, PBAT, and PPC, and under the condition with critical content of 4 phr of ESO, the elongation behavior dramatically increased as compared to that of blends without ESO while affecting reduction of oxygen barrier properties. The effect of ESO as a compatibilizer was clearly observed from the overall performances of ternary blends, and the potential feasibility of the PLA/PBAT/PPC ternary blends as packaging materials was confirmed at this study.

Biodegradable Nanofibrillated Cellulose/Poly-(butylene adipate-co-terephthalate) Composite Film with Enhanced Barrier Properties for Food Packaging

Biodegradable composites consisting of Poly-(butylene adipate-co-terephthalate) (PBAT), thermoplastic starch, hydrophobically modified nanofibrillated cellulose (HMNC), and green surfactant (sucrose fatty acid ester) were prepared via the melt-mixing and film-blowing process (PBAT-HMNC). The composites were characterized using the Fourier transform infrared spectroscope (FT-IR), scanning electron microscope (SEM), and thermogravimetric analyzer (TGA). The mechanical and barrier properties were systematically studied. The results indicated that PBAT-HMNC composites exhibited excellent mechanical and barrier properties. The tensile strength reached the maximum value (over 13 MPa) when the HMNC content was 0.6% and the thermal decomposition temperature decreased by 1 to 2 °C. The lowest values of the water vapor transmission rate (WVTR) and the oxygen transmission rate (OTR) were obtained from the composite with 0.6 wt% HMNC, prepared via the film-bowing process with the values of 389 g/(m2·day) and 782 cc/(m2·day), which decreased by 51.3% and 42.1%, respectively. The Agaricus mushrooms still had a commodity value after 11 days of preservation using the film with 0.6 wt% HMNC. PBAT-HMNC composites have been proven to be promising nanocomposite materials for packaging.

Correlation between chain structures of corn starch and properties of its film prepared at different degrees of disorganization

This study investigated the relationship between the chain structure of corn starch and the properties of corn starch-based films formed with starch pastes with different degrees of disorganization (70, 80, and 90 °C). The degree of gelatinization, chain length distribution, amylose content, and molecular weight of the corn starch were determined by the water absorption index, ion chromatography, spectrophotometry, and gel chromatography, respectively. The thickness, surface roughness, solubility, water content, water vapor permeability, mechanical properties, and maximum thermal degradation rate of corn starch-based films formed with starch pastes with different degrees of disorganization were evaluated. The moisture content, thickness and surface roughness of films formed with the starch pastes decreased. At the same time, the solubility, elongation at break, water vapor permeability, and molecular weight distribution increased with increasing heat treatment temperature. The maximum thermal degradation rate and tensile strength of the corn starch-based films formed with the starch pastes decreased with increasing heat treatment temperature. The gradual decrease in the amylose content of corn starch-based films formed with starch paste with increasing heat treatment temperature led to a change in the performance of the corn starch-based films.

Blending of Low-Density Polyethylene and Poly(Butylene Succinate) (LDPE/PBS) with Polyethylene-Graft-Maleic Anhydride (PE-g-MA) as a Compatibilizer on the Phase Morphology, Mechanical and Thermal Properties

It is of significant concern that the buildup of non-biodegradable plastic waste in the environment may result in long-term issues with the environment, the economy and waste management. In this study, low-density polyethylene (LDPE) was compounded with different contents of poly(butylene succinate) (PBS) at 10-50 wt.%, to evaluate the potential of replacing commercial plastics with a biodegradable renewable polymer, PBS for packaging applications. The morphological, mechanical and thermal properties of the LDPE/PBS blends were examined in relation to the effect of polyethylene-graft-maleic anhydride (PE-g-MA) as a compatibilizer. LDPE/PBS/PE-g-MA blends were fabricated via the melt blending method using an internal mixer and then were compression molded into test samples. The presence of LDPE, PBS and PE-g-MA individually in the matrix for each blend presented physical interaction between the constituents, as shown by Fourier-transform infrared spectroscopy (FTIR). The morphology of LDPE/PBS/PE-g-MA blends showed improved compatibility and homogeneity between the LDPE matrix and PBS phase. Compatibilized LDPE/PBS blends showed an improvement in the tensile strength, with 5 phr of compatibilizer providing the optimal content. The thermal stability of LDPE/PBS blends decreased with higher PBS content and the thermal stability of compatibilized blends was higher in contrast to the uncompatibilized blends. Therefore, our research demonstrated that the partial substitution of LDPE with a biodegradable PBS and the incorporation of the PE-g-MA compatibilizer could develop an innovative blend with improved structural, mechanical and thermal properties.

A road map on synthetic strategies and applications of biodegradable polymers

Biodegradable polymers have emerged as fascinating materials due to their non-toxicity, environmentally benign nature and good mechanical strength. The toxic effects of non-biodegradable plastics paved way for the development of sustainable and biodegradable polymers. The engineering of biodegradable polymers employing various strategies like radical ring opening polymerization, enzymatic ring opening polymerization, anionic ring opening polymerization, photo-initiated radical polymerization, chemoenzymatic method, enzymatic polymerization, ring opening polymerization and coordinative ring opening polymerization have been discussed in this review. The application of biodegradable polymeric nanoparticles in the biomedical field and cosmetic industry is considered to be an emerging field of interest. However, this review mainly highlights the applications of selected biodegradable polymers like polylactic acid, poly(ε-caprolactone), polyethylene glycol, polyhydroxyalkanoates, poly(lactide-co-glycolide) and polytrimethyl carbonate in various fields like agriculture, biomedical, biosensing, food packaging, automobiles, wastewater treatment, textile and hygiene, cosmetics and electronic devices.

Machine-Learning-Based Predictions of Polymer and Postconsumer Recycled Polymer Properties: A Comprehensive Review

There has been a tremendous increase in demand for virgin and postconsumer recycled (PCR) polymers due to their wide range of chemical and physical characteristics. Despite the numerous potential benefits of using a data-driven approach to polymer design, major hurdles exist in the development of polymer informatics due to the complicated hierarchical polymer structures. In this review, a brief introduction on virgin polymer structure, PCR polymers, compatibilization of polymers to be recycled, and their characterization using sensor array technologies as well as factors affecting the polymer properties are provided. Machine-learning (ML) algorithms are gaining attention as cost-effective scalable solutions to exploit the physical and chemical structures of polymers. The basic steps for applying ML in polymer science such as fingerprinting, algorithms, open-source databases, representations, and polymer design are detailed in this review. Further, a state-of-the-art review of the prediction of various polymer material properties using ML is reviewed. Finally, we discuss open-ended research questions on ML application to PCR polymers as well as potential challenges in the prediction of their properties using artificial intelligence for more efficient and targeted PCR polymer discovery and development.

Biopolymer Blends of Poly(lactic acid) and Poly(hydroxybutyrate) and Their Functionalization with Glycerol Triacetate and Chitin Nanocrystals for Food Packaging Applications

Polylactic acid (PLA) is a biopolymer that has potential for use in food packaging applications; however, its low crystallinity and poor gas barrier properties limit its use. This study aimed to increase the understanding of the structure property relation of biopolymer blends and their nanocomposites. The crystallinity of the final materials and their effect on barrier properties was studied. Two strategies were performed: first, different concentrations of poly(hydroxybutyrate) (PHB; 10, 25, and 50 wt %) were compounded with PLA to facilitate the PHB spherulite development, and then, for further increase of the overall crystallinity, glycerol triacetate (GTA) functionalized chitin nanocrystals (ChNCs) were added. The PLA:PHB blend with 25 wt % PHB showed the formation of many very small PHB spherulites with the highest PHB crystallinity among the examined compositions and was selected as the matrix for the ChNC nanocomposites. Then, ChNCs with different concentrations (0.5, 1, and 2 wt %) were added to the 75:25 PLA:PHB blend using the liquid-assisted extrusion process in the presence of GTA. The addition of the ChNCs resulted in an improvement in the crystallization rate and degree of PHB crystallinity as well as mechanical properties. The nanocomposite with the highest crystallinity resulted in greatly decreased oxygen (O) and carbon dioxide (CO₂) permeability and increased the overall mechanical properties compared to the blend with GTA. This study shows that the addition ChNCs in PLA:PHB can be a possible way to reach suitable gas barrier properties for food packaging films.

New Materials Based on Molecular Interaction between Hyaluronic Acid and Bovine Albumin

In this work, the interactions between hyaluronic acid and bovine serum albumin were investigated. The film-forming properties of the mixture were proven, and the mechanical and surface properties of the films were measured. The results showed the interactions between hyaluronic acid and albumin, mainly by hydrogen bonds. Molecular docking was used for the visualization of the interactions. The films obtained from the mixture of hyaluronic acid possessed different properties to films obtained from the single component. The addition of bovine serum albumin to hyaluronic acid led to a decrease in the mechanical properties, and to an increase in the surface roughness of the film. The new materials that have been obtained by blending can form a new group of materials for biomedicine and cosmetology.

Poly(Lactic Acid)-Based Graft Copolymers: Syntheses Strategies and Improvement of Properties for Biomedical and Environmentally Friendly Applications: A Review

As a potential replacement for petroleum-based plastics, biodegradable bio-based polymers such as poly(lactic acid) (PLA) have received much attention in recent years. PLA is a biodegradable polymer with major applications in packaging and medicine. Unfortunately, PLA is less flexible and has less impact resistance than petroleum-based plastics. To improve the mechanical properties of PLA, PLA-based blends are very often used, but the outcome does not meet expectations because of the non-compatibility of the polymer blends. From a chemical point of view, the use of graft copolymers as a compatibilizer with a PLA backbone bearing side chains is an interesting option for improving the compatibility of these blends, which remains challenging. This review article reports on the various graft copolymers based on a PLA backbone and their syntheses following two chemical strategies: the synthesis and polymerization of modified lactide or direct chemical post-polymerization modification of PLA. The main applications of these PLA graft copolymers in the environmental and biomedical fields are presented.

In Situ Formation of Microfibrillar PBAT in PGA Films: An Effective Way to Robust Barrier and Mechanical Properties for Fully Biodegradable Packaging Films

Poly(glycolic acid) (PGA) is a semicrystalline biodegradable polyester with high gas barrier properties. However, due to its poor processability and low ductility, PGA could hardly find applications in the packaging field. Here, a strategy was adopted for in situ generation of high-aspect-ratio flexible microfibrils with strong interface affinity for the PGA matrix. Because poly(butylene adipate-co-terephthalate) (PBAT) possesses impressive ductility, it was selected as the "fibrillar toughening phase" to enhance the ductility of PGA. Moreover, a chain extender was used to enhance the interfacial adhesion between the two polymers. The extrusion blown film technique was then used to develop fully biodegradable PGA/PBAT films with a superior combination of excellent barrier performance and robust mechanical properties. The PBAT phase can in situ form microfibrils under the influence of extensional flow. Simultaneously, the synergetic function of the extensional flow field could effectively promote the motion of the PGA molecular chain to develop an oriented crystalline microstructure. Because of the aligned oriented lamellar crystal of PGA and oriented PBAT fibril structures serving as robust "barrier walls" 60PGA/ADR blown films demonstrated dramatically improved resistance to oxygen and water vapor, with 59 and 44 times lower oxygen permeability and water vapor permeability, respectively, when compared to the neat PBAT blown film. As a result, PGA/PBAT blown films offer a variety of benefits, including superior ductility, toughness, and a strong gas barrier property. The potential of these films to degrade makes them a viable contender for replacing classical nondegradable packing films.

Review of the Developments of Bacterial Medium-Chain-Length Polyhydroxyalkanoates (mcl-PHAs)

Synthetic plastics derived from fossil fuels—such as polyethylene, polypropylene, polyvinyl chloride, and polystyrene—are non-degradable. A large amount of plastic waste enters landfills and pollutes the environment. Hence, there is an urgent need to produce biodegradable plastics such as polyhydroxyalkanoates (PHAs). PHAs have garnered increasing interest as replaceable materials to conventional plastics due to their broad applicability in various purposes such as food packaging, agriculture, tissue-engineering scaffolds, and drug delivery. Based on the chain length of 3-hydroxyalkanoate repeat units, there are three types PHAs, i.e., short-chain-length (scl-PHAs, 4 to 5 carbon atoms), medium-chain-length (mcl-PHAs, 6 to 14 carbon atoms), and long-chain-length (lcl-PHAs, more than 14 carbon atoms). Previous reviews discussed the recent developments in scl-PHAs, but there are limited reviews specifically focused on the developments of mcl-PHAs. Hence, this review focused on the mcl-PHA production, using various carbon (organic/inorganic) sources and at different operation modes (continuous, batch, fed-batch, and high-cell density). This review also focused on recent developments on extraction methods of mcl-PHAs (solvent, non-solvent, enzymatic, ultrasound); physical/thermal properties (Mw, Mn, PDI, Tm, Tg, and crystallinity); applications in various fields; and their production at pilot and industrial scales in Asia, Europe, North America, and South America.

Development and Characterization of Polylactide Blends with Improved Toughness by Reactive Extrusion with Lactic Acid Oligomers

In this work, we report the development and characterization of polylactide (PLA) blends with improved toughness by the addition of 10 wt.% lactic acid oligomers (OLA) and assess the feasibility of reactive extrusion (REX) and injection moulding to obtain high impact resistant injection moulded parts. To improve PLA/OLA interactions, two approaches are carried out. On the one hand, reactive extrusion of PLA/OLA with different dicumyl peroxide (DCP) concentrations is evaluated and, on the other hand, the effect of maleinized linseed oil (MLO) is studied. The effect of DCP and MLO content used in the reactive extrusion process is evaluated in terms of mechanical, thermal, dynamic mechanical, wetting and colour properties, as well as the morphology of the obtained materials. The impact strength of neat PLA (39.3 kJ/m2) was slightly improved up to 42.4 kJ/m2 with 10 wt.% OLA. Nevertheless, reactive extrusion with 0.3 phr DCP (parts by weight of DCP per 100 parts by weight of PLA–OLA base blend 90:10) led to a noticeable higher impact strength of 51.7 kJ/m2, while the reactive extrusion with 6 phr MLO gave an even higher impact strength of 59.5 kJ/m2, thus giving evidence of the feasibility of these two approaches to overcome the intrinsic brittleness of PLA. Therefore, despite MLO being able to provide the highest impact strength, reactive extrusion with DCP led to high transparency, which could be an interesting feature in food packaging, for example. In any case, these two approaches represent environmentally friendly strategies to improve PLA toughness.

Analysis of Selected Properties of Microporous PLA as a Result of Abiotic Degradation

In the study, an investigation was made into the hydrolytic degradation behavior of the microporous polylactide (PLA) in the initial stage in three biological buffer solutions with various pH-simulating body fluids in comparison with pure PLA. Studies also include the analysis of selected mechanical properties and physical structures. A microporous PLA was obtained by melt extrusion using a chemical blowing agent. The rate of Mw decrease induced by hydrolysis over 35 days of microporous PLA was roughly comparable to the pure material. The rate of depolymerization was slightly accelerated at an acid pH due to acid-catalyzed hydrolysis at the end of the observed period. The mechanical analysis showed the influence of various pH on the obtained results.

Recycling of Pretreated Polyolefin-Based Ocean-Bound Plastic Waste by Incorporating Clay and Rubber

Plastic waste found in oceans has become a major concern because of its impact on marine organisms and human health. There is significant global interest in recycling these materials, but their reclamation, sorting, cleaning, and reprocessing, along with the degradation that occurs in the natural environment, all make it difficult to achieve high quality recycled resins from ocean plastic waste. To mitigate these limitations, various additives including clay and rubber were explored. In this study, we compounded different types of ocean-bound (o-HDPE and o-PP) and virgin polymers (v-LDPE and v-PS) with various additives including a functionalized clay, styrene-multi-block-copolymer (SMB), and ethylene-propylene-based rubber (EPR). Physical observation showed that all blends containing PS were brittle due to the weak interfaces between the polyolefin regions and the PS domains within the polymer blend matrix. Blends containing clay showed rough surfaces and brittleness because of the non-uniform distribution of clay particles in the polymer matrix. To evaluate the properties and compatibility of the blends, characterizations using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and small-amplitude oscillatory shear (SAOS) rheology were carried out. The polymer blend (v-LDPE, o-HDPE, o-PP) containing EPR showed improved elasticity. Incorporating additives such as rubber could improve the mechanical properties of polymer blends for recycling purposes.

High poly ε-caprolactone biodegradation activity by a new Acinetobacter seifertii isolate

Poly(ε-caprolactone; PCL) is an attractive biodegradable polymer that has been increasingly used to solve environmental problems caused by plastic wastes. In the present study, 468 bacterial isolates were recovered from soil samples and screened for PCL degradation activity. Of the isolates, 37 (7.9%) showed PCL depolymerase activity on PCL agar medium, with the highest activity being by isolate S22 which was identified using 16S rRNA and rpoB gene sequencing as Acinetobacter seifertii. Scanning electron microscopy and Fourier transform infrared spectroscopy confirmed the degradation of PCL films after treatment with A. seifertii S22. The PCL depolymerase activity of A. seifertii S22 relied on the activity of esterase which occurred at an optimum temperature of 30-40 °C. The highest PCL depolymerase activity (35.5 ± 0.7 U/mL) was achieved after culturing A. seifertii S22 for 6 h in mineral salt medium (MSM) containing 0.1% Tween 20 and 0.02% ammonium sulfate as the carbon and nitrogen sources, respectively, which was approximately 20-fold higher than for cultivation in MSM supplemented with 0.1% PCL as sole carbon source. The results suggested that A. seifertii S22 or its enzymes could be used for PCL bioplastic degradation.

Chitosan/Silk Fibroin Materials for Biomedical Applications-A Review

This review provides a report on recent advances in the field of chitosan (CTS) and silk fibroin (SF) biopolymer blends as new biomaterials. Chitosan and silk fibroin are widely used to obtain biomaterials. However, the materials based on the blends of these two biopolymers have not been summarized in a review paper yet. As these materials can attract both academic and industrial attention, we propose this review paper to showcase the latest achievements in this area. In this review, the latest literature regarding the preparation and properties of chitosan and silk fibroin and their blends has been reviewed.