Search Results (161)

Biodegradable polymers offer a promising solution to the growing issue of global microplastic pollution. To effectively replace conventional plastics, it is essential to develop strategies for tuning the properties of biodegradable polymers without relying on additives. Biaxial stretching promotes anisotropic crystallization in polymer domains, thereby altering the mechanical performance of polymer blends. In this study, we employed a design of experiment (DoE) approach to investigate the effects of biaxial stretching at three drawing temperatures (T_ds) and draw ratios (λs) on a biodegradable blend of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT), aiming to optimize both the strength and ductility. The DoE analysis revealed that the composition, the λ, the interaction between the λ and composition, and the interaction between the T_d and composition significantly affect the elongation at break (ε_Break). For the stress at break (σ_Break), the most influential factors were the interaction between the λ and PLA concentration; a three-way interaction among the λ, PLA, and T_d; the T_d; the λ; and finally the PLA concentration alone. The optimal ε_Break and σ_Break were achieved at a λ = 5 × 5 and T_d = 110 °C, with a composition of 10% PLA and 90% PBAT. The stretched samples exhibited higher crystallinity compared to the pressed samples across all compositions. This work demonstrates that in addition to the composition, the processing parameters, such as the λ and T_d, critically influence the mechanical properties, enabling performance enhancements without the need for compatibilizers or toxic additives. Full article

In response to the escalating plastic pollution crisis, the development of high-performance biodegradable materials is critical. Poly(butylene succinate) (PBS) is an important biodegradable polymer as it possesses excellent biodegradability and processability. But it suffers from limitations such as low mechanical strength, poor thermal stability, and high production costs. In this study, taxus residue (TF), a waste by-product, was utilized as a reinforcing filler to reduce PBS costs while enhancing its overall performance. To address the interfacial incompatibility between TF and PBS, branched PBS (T-PBS) was introduced as a compatibilizer. The TF was surface-modified via alkali treatment and silane coupling (KH550), and a series of PBS/TF/T-PBS composites with varying T-PBS viscosity grades were prepared by melt blending. The compatibilization mechanism of T-PBS and its influence on the composite structure, crystallization behavior, thermal stability, rheological, and mechanical properties were systematically investigated. Results show that the branched structure significantly enhanced T-PBS melt strength and reactivity. The introduction of T-PBS effectively improved interfacial compatibility between TF and PBS matrix, reducing phase separation and interfacial defects. Compared to uncompatibilized PBS/TF composites, those with appropriately viscous T-PBS exhibited improved tensile strength (increased by 19.7%) and elongation at break (increased by 78.8%), while flexural strength was also maintained at an enhanced level. The branched points acted as nucleating agents, increasing the onset temperature and degree of crystallinity. In the high-temperature region, the synergistic barrier effect from TF and char residue improved thermal stability (T_85% reached 408.19 °C). Rheological analysis revealed enhanced viscosity and elasticity of the system. This study provides a promising strategy and theoretical foundation for the high-value utilization of taxus waste and the development of high-performance biodegradable PBS-based composites. Full article

Starch extracted from the domestically cultivated Scala potato variety was explored as a renewable resource for the formulation of biodegradable thermoplastic starch (TPS)/polylactic acid (PLA) blends intended for environmentally friendly food packaging applications. The isolated starch underwent comprehensive physicochemical and structural characterization to assess its suitability for polymer processing. TPS derived from Scala starch was compounded with PLA, both with and without citric acid (CA) as a green compatibilizer to enhance phase compatibility. The resulting polymer blends were systematically analyzed using Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR–ATR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) to evaluate thermal and structural properties. Mechanical performance, water vapor permeability (WVP), water absorption (WA), and biodegradability in soil over 56 days were also assessed. The incorporation of citric acid improved phase miscibility, leading to enhanced structural uniformity, thermal stability, mechanical strength, and barrier efficiency. Bio-degradation tests confirmed the environmental compatibility of the developed blends. Overall, the results demonstrate the potential of Scala-based TPS/PLA systems, particularly those modified with citric acid, as viable candidates for sustainable food packaging, while highlighting the importance of further formulation optimization to balance functional and biodegradative performance. Full article

Compatibilizers that enhance sustainability and improve the miscibility of polymer blend components have garnered significant attention. This study investigates the difference between the synthetic chain extender Joncryl^® ADR 4468 and the natural epoxidized linseed oil (ELO) Merginat 8510100 as compatibilizers for thermoplastic starch/poly (butylene succinate) (TPS/PBS) blends. Blends containing 40% TPS and 60% PBS were prepared with 1, 3, and 5 phr of each compatibilizer, along with a reference with no additives. The properties of these blends were evaluated using tensile testing, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), rheology, and scanning electron microscopy (SEM). The findings indicate that while Joncryl^® ADR 4468 significantly improved tensile strength, it also resulted in a brittle fracture. In contrast, ELO batches exhibited greater ductility, albeit with lower tensile strength. These differences are attributed to the chain extension and minor cross-linking effects of Joncryl^® ADR 4468, compared to the increased chain mobility arising from ELO’s plasticizing and compatibilizing actions. Supporting evidence for these observations includes increased cold crystallization temperature (T_cc) and melting temperature (T_m), greater storage modulus along with higher complex viscosity, strengthened interfacial adhesion, and fewer morphological defects in Joncryl^® ADR 4468 blends. These results highlight the importance of selecting an appropriate compatibilizer based on specific application requirements. Overall, this study addresses the knowledge gap regarding the loadings of Joncryl^® ADR 4468 and ELO in TPS/PBS blends and provides a basis for further optimization strategies, such as the incorporation of binary compatibilizers, alternative grafting-based compatibilizers, and twin-screw blending modifications. Full article

The influence of minor components on leaching molecular iodine (I₂) through polypropylene (PP)-based packaging from a povidone iodine-based (PVP-I) formulation, simulating an ophthalmic application, was evaluated. I₂ is a cheap, broad-spectrum, and multi-target antiseptic. Nevertheless, it is volatile, and the prolonged storage of I₂-based formulations is demanding in plastic packaging because of transmission through the material. Therefore, we explored the possibility of moderating the loss of I₂ from an iodophor formulation by introducing small amounts of molecular iodine into the polymer material commonly used in eyedropper caps, i.e., PP. Thus, PP was blended via an extrusion process with a polymeric complex containing iodine (such as PVP-I) or with a second polymeric component able to complex the I₂ released from an iodophor solution. The aim of this work was to introduce I₂ into PP-based polymer matrices without using organic solvents and indirectly, i.e., through the addition of components that could generate molecular iodine or complex it in the solid phase, as I₂ is heat-sensitive. To increase the miscibility between PP and PVP-I, poly(N-vinylpyrrolidone) (PVP) or a vinyl pyrrolidone vinyl acetate copolymer 55/45 (Sokalan) were added as compatibilizers. The PP-based binary and ternary blends, in granular or sheet form, were characterized thermally (Differential Scanning Calorimetry, DSC, and Thermogravimetric analysis, TGA), mechanically (tensile tests), morphologically (scanning electron microscopy (SEM)), and chemically (attenuated total reflectance Fourier transform infrared (ATR-FTIR)). Additionally, the variation in wettability induced by the introduction of the hydrophilic minority components was determined by static contact angle measurements (static contact angle (SCA)), and tests were carried out to determine the barrier properties against oxygen (oxygen transmission rate (OTR)) and molecular iodine. The I₂ leaching of the different blends was compared with that of PP by monitoring the I₂ retention in a buffered PVP-I solution via UV-vis spectroscopy. Overall, the experimental data showed the capability of the minority components in the blends to increase thermal stability as well as act as a barrier to oxygen. Additionally, the PP blend with PVP-I induced a reduction in molecular iodine leaching in comparison with PP. Full article

Despite its broad application due to its affordability, biodegradability, and natural antimicrobial and antioxidant activities, chitosan (CS) still exhibits limitations in mechanical strength and barrier effectiveness. Owing to its unique chemical characteristics, itaconic acid (IT) presents potential as a compatibilizing agent in polymeric blend formulations. Biodegradable polymers composed of chitosan (CS), itaconic acid (IT), and starch (S) were synthesized using two polymerization methods. The first method involved grafting IT onto CS at varying ratios of IT (4%, 6%, and 8% wt.), using 1% v/v acetic acid/water as the solvent and potassium persulfate as the initiator. In the second approach, starch (S) was blended with the copolymer P(CS-g-IT) at concentrations of 1%, 3%, and 5%, utilizing water as the solvent and glacial acetic acid as a catalyst. The resulting biodegradable films underwent characterization through FTIR, TGA, SEM, and mechanical property analysis. To further explore the effects of combining IT, starch, and carbon black, the blends, referred to as P[(CS-g-IT)-b-S], were also loaded with carbon black. This allowed for the evaluation of the materials’ physicomechanical properties, such as viscosity, tensile strength, elongation, and contact angle. The findings demonstrated that the presence of IT, starch, and carbon black collectively improved the films’ mechanical performance, physical traits, and biodegradability. Among the samples, the blended copolymer with 1% starch exhibited the highest mechanical properties, followed by the grafted copolymer with 8% IT and the blended copolymer mixed with carbon black at 7%. In contrast, the blended copolymer with 5% starch showed the highest hydrophilicity and the shortest degradation time compared to the grafted copolymer with 8% IT and the blended copolymer mixed with 7% carbon black. Full article

The increasing accumulation of plastic waste—especially from packaging and post-consumer sources—calls for the development of sustainable recycling strategies. Due to the challenges associated with sorting mixed waste, directly processing waste streams offers a practical approach. Polyethylene terephthalate (PET) and high-density polyethylene (HDPE) are common consumer plastics, but they are difficult to recycle together due to immiscibility and degradation. In mixed waste, recycled HDPE (r-HDPE) often contaminates the recycled PET (r-PET) stream. Additive manufacturing (AM) offers a promising solution to upcycle these mixed polymers into functional products with minimal waste. This study investigates the processing and characterization of r-PET/r-HDPE blends for AM, focusing on the role of compatibilizers in enhancing their properties. Blends were melt-compounded using a twin-screw extruder to improve dispersion, followed by direct pellet-based 3D printing. A compatibilizer (0–7 php) was incorporated to improve miscibility. Rheological testing showed that the 5 php compatibilizer optimized viscosity and elasticity, ensuring smoother extrusion. Thermal analysis revealed a 30 °C increase in crystallization temperature and a shift in decomposition temperature from 370 °C to 400 °C, indicating improved thermal stability. Mechanical testing showed a tensile strength of 35 MPa and 17% elongation at break at optimal loading. Scanning electron microscopy (SEM) confirmed reduced phase separation and improved morphology. This work demonstrates that properly compatibilized r-PET/r-HDPE blends enable sustainable 3D printing without requiring polymer separation. The results highlight a viable path for the conversion of plastic waste into high-value, customizable components, contributing to landfill reduction and advancing circular economy practices in polymer manufacturing. Full article

Personal protection from mosquitos is dominated by topically applied aerosol sprays or lotions, which demonstrate efficacy durations of no longer than 10 h, thus encouraging the research and development of long-term insect-repelling devices. Repellent-loaded polymeric matrices have driven the development of insect-repelling apparel fabrics; however, most efforts either fail to offer the tensile properties demanded from apparel applications or only demonstrate repellency durations for multiple days. This study utilizes poly-D,L-lactic acid (PDLLA) as a compatibilizer between Nylon 12 and nootkatone for enhanced nootkatone retention throughout fabric manufacturing processes. Nootkatone-infused Nylon 12/PDLLA composites demonstrate up to a 14% increase in nootkatone retention throughout fabric manufacturing compared to pure Nylon 12, underscoring the importance of polymer/substrate miscibility on substrate retention. Moreover, while nootkatone-infused Nylon 12 filaments demonstrate decreasing tensile stress at breaks with increasing nootkatone content, Nylon 12/PDLLA filaments exhibit similar tensile properties regardless of nootkatone content. The PDLLA domains are suspected to behave as reservoirs for excess nootkatone to prevent its role as a defect within the Nylon 12 matrix. The resulting knits exhibit significant mosquito repellencies over 24 h dependent on the nootkatone concentration, thus demonstrating potential to embed insect repellent within high-performance polymeric filaments with effective mosquito repellencies. Therefore, the incorporation of PDLLA as a compatibilizer holds significant potential for enhanced nootkatone retention during Nylon 12 fabric manufacturing. Full article

The concern for the environment and sustainability has intensified the search for alternative materials to replace non-degradable plastics. Poly(butylene adipate-co-terephthalate) (PBAT) is a bioplastic that has been extensively studied due to its excellent mechanical properties, which are similar to those of low-density poly(ethylene) (LDPE). However, the high cost of this polymer still hinders its wider application. Among the different approaches that have been studied, blending PBAT with thermoplastic starch (TPS) could be an interesting solution to reduce the cost of the material and increase the degradability of the blends. This review covers most of the work reported in recent years on PBAT/TPS blends, including the effects of starch plasticizers, starch modifications, processing methods, use of chain extenders, various compatibilizers, and additives used for different applications. Full article

The rapid advancement of sustainable materials has driven the need for high-performance polymer nanocomposites with superior mechanical, thermal, and structural properties. In this study, a novel RPET/PA-11/Joncryl^® nanocomposite reinforced with halloysite nanotubes (HNTs) is developed for the first time, marking a significant breakthrough in polymer engineering. Six different proportions of HNT (0, 1, 2, 3, 4, and 5 phr) are introduced to the blend of rPET/PA-11/Joncryl^® through a twin-screw extruder and injection moulding machine. The incorporation of HNTs into the RPET/PA-11 matrix, coupled with Joncryl^® as a compatibilizer, results in a synergistic enhancement of material properties through improved interfacial adhesion, load transfer efficiency, and nanoscale reinforcement. Comprehensive characterization reveals that the optimal formulation with 2 phr HNT (NCS-H2) achieves remarkable improvements in tensile strength (56.14 MPa), flexural strength (68.34 MPa), and Young’s modulus (895 MPa), far exceeding conventional polymer blends. Impact resistance reaches 243.46 J/m, demonstrating exceptional energy absorption and fracture toughness. Thermal analysis confirms enhanced stability, with an onset degradation temperature of 370 °C, attributing the improvement to effective matrix–filler interactions and restricted chain mobility. Morphological analysis through FESEM validates uniform HNT dispersion at optimal loading, eliminating agglomeration-induced stress concentrators and reinforcing the polymer network. The pioneering integration of HNT into RPET/PA-11/Joncryl^® nanocomposites not only bridges a critical gap in sustainable polymers but also establishes a new benchmark for polymer nanocomposites. This work presents an eco-friendly solution for engineering applications, offering mechanical robustness, thermal stability, and recyclability. The results form the basis for next-generation high-performance materials for industrial use in automotive, aerospace, and high-strength structural applications. Full article

The immiscibility of thermoplastic starch (TPS) and polybutylene succinate (PBS) complicates the thermal processing of these materials. This study provides the first comparative assessment of two compatibilizers with differing reaction mechanisms, Joncryl^® ADR 4468 and epoxidized linseed oil (ELO), for the optimization of biobased TPS/PBS blends. A total of 13 batches, varying in compatibilizer and blend composition, were processed via hot melt extrusion and injection molding to produce pellets. Blends were analyzed using tensile and impact testing, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), rheology, and scanning electron microscopy (SEM). The findings suggest that both compatibilizers can improve the compatibility of these blends, as evidenced by higher glass transition temperatures (T_g) compared to the reference batch (100-0-N/A). Joncryl^® ADR 4468 batches exhibit superior tensile strength and Young’s moduli, while ELO batches demonstrate greater elongation at break. The enhanced processability observed in Joncryl^® ADR 4468 is attributed to the increased polymer chain entanglement and molecular weight, whereas ELO facilitates greater chain mobility due to its plasticizing effect. These differences arise from the distinct mechanisms of action: Joncryl^® ADR 4468 promotes chain extension and crosslinking, whereas ELO mainly enhances flexibility through plasticization. Overall, this study provides a comparative assessment of these compatibilizers in TPS/PBS blends, laying the groundwork for future investigations into optimizing compatibilizer concentration and blend composition. Full article

The present work deals with the mixing of two green polymers at several definite ratios that led to the receiving of biodegradable polylactic acid (PLA)/polycaprolactone (PCL) blends possessing well-expressed macromechanical and shape memory properties. Four non-compatibilized polymer compositions were prepared by using a twin-screw melt extrusion technique, allowing for a homogeneous dispersion of the PCL droplets in the PLA matrix and higher interfacial adhesion between the two phases. The mechanical behavior of the specimens was estimated by tensile experiments conducted at three particular crosshead velocities. It was established that the addition of PCL as a soft segment redounded to an increment of the toughness and elongation at ultimate strength of the polymer composite at the expense of the maximum tensile stress and Young’s modulus. These latter two parameters were found to be more sensitive, in terms of reaching high values, to the content of PLA as a hard segment in the polymer blend. Performing thermoresponsive shape memory tests disclosed an overwhelming reversibility between the temporary and permanent states of the composite materials, including significant shape fixation ($R_f$) and shape recovery ($R_r$) rates. SEM analysis of the PLA/PCL compositions revealed a distinct phase-separated microstructure, confirming the immiscibility of the two polymers in the blend. Full article

The properties of compatibilized blends of polyethylene (PE) and polypropylene (PP), having reduced macromolecular entanglements, were studied. The density of PP macromolecular entanglements was controlled by prior disentangling in solution. The polymer ratio in the blend was 4:1 or 1:4. An ethylene–octene copolymer was used as a compatibilizer. The melt blending process resulted in good dispersion of the minority component, with slightly larger inclusions when more disentangled PP was used. Rheological studies confirmed the achievement of different entanglement densities of PP macromolecules in the blends. The partial disentanglement did not affect the thermal stability of the blends. During the isothermal crystallization studies, faster growth of PP spherulites was observed in the blend with reduced entanglements, which also influenced the entire crystallization process. The recovery time of equilibrium entanglement was investigated and it turned out to be 45 min if the blend was annealed at 190 °C, which was shorter than in the analogous homopolymer. Studies of tensile properties showed that in blends with a majority share of polyethylene, the elongation at break increased with the disentanglement of the minority component, due to better bonding of the blend components and thus the reduction in microcavitation. Full article

Polylactic acid (PLA) is a biodegradable polymer with high tensile strength, high stiffness, and biocompatibility, but its brittleness and hydrophobicity limit its applications. This study aims to address these limitations by blending PLA with polycaprolactone (PCL) to enhance flexibility and with polyethylene oxide (PEO) to improve hydrophilicity. Unlike conventional approaches where PEO serves as a plasticizer, this study investigated PEO as a major blend component. Electrospinning and solvent casting, which differ in their solvent evaporation rates, were employed to fabricate thin films of neat PLA and PLA blends to examine their influence on mechanical and surface properties. Polymer solutions were prepared using a dichloromethane (DCM)/dimethylformamide (DMF) mixture known to enhance the electrospinning process. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) were used to investigate crystallinity of polymers and their interactions, while scanning electron microscopy (SEM) and atomic force microscopy (AFM) provided insights into phase separation and fiber morphology. Uniaxial tensile testing and water contact angle measurements were conducted to evaluate mechanical properties and surface properties, respectively. The results showed that electrospun PLA films exhibited higher elongation at break and ultimate strength but lower Young’s modulus than solvent-cast PLA films. Electrospun films of PLA/PCL blends demonstrated improved elongation at break while retaining Young’s modulus comparable to that of electrospun PLA films, unlike their solvent-cast counterparts. In contrast, PLA/PEO blends exhibited enhanced hydrophilicity in both processing methods but showed a marked reduction in mechanical properties. In summary, electrospun films consistently outperformed solvent-cast films in terms of flexibility and mechanical integrity, primarily due to their fibrous structure, suppressed phase separation, and reduced crystallinity. This study uniquely demonstrates that electrospinning enables the fabrication of phase-separated PLA/PEO blends with mechanical integrity despite PEO’s inherent immiscibility with PLA and incompatibility in the solvent mixture. Furthermore, electrospinning proves to be an effective processing method for producing PLA blend films with enhanced flexibility and hydrophilicity without the need for plasticizers or compatibilizers. Full article

To develop novel materials through the recycling of waste polymers and to enhance their mechanical and thermal properties, composites were synthesized using chain extenders (CEs), compatibilizers (PP-g-MA), and short carbon fiber (CF) reinforcements within recycled polyamide 6 (rPA6) and polypropylene (rPP) blends. The recycling of waste polymers holds paramount importance in the context of environmental sustainability. This study investigates the role of additives in effectively improving the properties of recycled polymers. The composites were fabricated using the twin-screw extrusion method and subjected to a comprehensive range of characterizations, including Fourier Transform Infrared Spectroscopy (FTIR), differential scanning calorimetry (DSC), molecular weight analysis, melt flow index (MFI), heat deflection temperature (HDT), tensile testing, impact testing, and Scanning Electron Microscopy (SEM). Additionally, ANOVA statistical methods were applied to analyze HDT, tensile, and impact test results. The findings of this research demonstrate that chain extenders and compatibilizers significantly enhance the mechanical properties of rPA6/rPP blends, while carbon fiber reinforcements markedly improve both tensile strength and impact resistance. Furthermore, the incorporation of rPP led to an approximately 4% reduction in hardness values; however, this loss was effectively compensated by the addition of chain extenders and CF reinforcements, resulting in an overall increase in hardness. It was observed that chain extenders enhanced the elastic modulus and tensile strength by reinforcing interphase bonding, whereas CF reinforcements strengthened the polymer matrix, leading to improved impact resistance. These findings emphasize the synergistic role of chain extenders, compatibilizers, and CF reinforcements in enhancing the mechanical properties of rPA6/rPP blends. The study underscores recycling as both an environmentally beneficial and effective strategy for developing durable, high-performance composites for industrial use. Consequently, the utilization of recycled polymers contributes substantially to the circular and sustainable materials economy, demonstrating the potential for the widespread industrial adoption of such composites. Full article