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A comparative study of the structural integrity of an opaque recycled poly(ethylene terephthalate) (rPET-O) has been carried out with two types of modified rPET-O by applying reactive extrusion techniques, namely (a) using a multi-epoxide reactive agent (REx-rPET-O) and (b) a 90/10 (wt/wt) rPET-O/polycarbonate (PC) blend. The chemical modifications introduced during reactive extrusion were confirmed using differential scanning calorimetry (DSC) and rheological dynamic analysis (RDA). For the quantification of the fracture parameters, an instrumented pendulum impact testing machine was used using specimens in SENB configuration. The structural modifications generated during reactive extrusion promote an increase of between 16 (REx-rPET-O) and 20% (rPET-O/PC) in the stress-intensity factor (KQ) compared to unmodified rPET-O. The most significant differences between both modifications are registered in the "specific work of fracture" (wf) (alternative parameter to the standardized impact strength), where an increase of 61% is reached for the case of rPET-O/PC and only 11% for REx-rPET-O. This trend can be attributed to the type of reactive modification that is generated, namely chain branching (REx-rPET-O) vs. the generation of a random copolymer "in situ" (rPET-O/PC). This copolymer decreases the crystallization capacity and degree of crystalline perfection of rPET-O, promoting an increase in the critical hydrostatic stress conditions for the generation of crazing and crack propagation. [ABSTRACT FROM AUTHOR]

Global food waste remains a significant economic and environmental burden throughout the food supply chain. Oxidative degradation and microbial growth are two of the most prominent causes of post‐manufacturing food spoilage and are thus often targets of active packaging technologies that seek to maintain or improve shelf life by adding preservative functionality to the packaging material. In non‐migratory active packaging, the active agent is bound to the polymer backbone preventing its migration to the foodstuff in support of consumer demands for cleaner labels. Critical to commercial translation of such non‐migratory active packaging technologies is identifying circumstances conducive to their optimal performance as well as those for which performance falls short of predicted behaviour. Here, we present an applications study to identify conditions of optimal performance of a non‐migratory radical scavenging active packaging material, polypropylene‐graft‐polyethyleneimine (PP‐g‐PEI5), synthesized by reactive extrusion of polyethylenimine with maleic anhydride functionalized polypropylene. Polyethylenimine was selected as an active agent for its reported radical scavenging and antimicrobial behaviour. Despite introduction of a hygroscopic and relatively low molecular weight active ligand, PP‐g‐PEI5 retained desirable low water vapour transmission rates (value) and excellent mechanical properties, supporting its covalent bonding to the base polymer. Interfacial pKa was determined via a pH‐dependent characterization of surface primary amine to be 10.07 (9.66–11.42, 95% CI), explaining its antioxidant mechanism at food and beverage relevant pH values (under 7) due to radical scavenging and not transition metal sequestering behaviour. Antimicrobial efficacy was demonstrated against gram‐positive Listeria monocytogenes. Finally, a viscosity‐dependent radical scavenging assay demonstrated the efficacy of PP‐g‐PEI5 as an antioxidant active packaging material in food products up to 812.9 cPs (2.98 nmol/cm2 Troloxeq). These results suggest that these active packaging materials would be most effective in inhibiting radical induced oxidative degradation in foods and beverages of acidic to neutral pH values and viscosities from liquid to loose gel, for example, preventing lipid oxidation in salad dressings or enhancing stability of natural colours in juices or smoothies. The reported active packaging material offers industry and consumers another tool for extending the shelf life of foods while addressing clean label market demands, which may help to decrease food waste by reducing losses post‐retail due to oxidative degradation and microbial growth. [ABSTRACT FROM AUTHOR]

Enhancing interfacial adhesion in polypropylene (PP)/recycled polyethylene terephthalate (rPET) blends is crucial for the effective mechanical recycling of these commercial plastic wastes. This study investigates the reactive extrusion of PP/rPET blends using a dual compatibilizer system comprising maleic anhydride grafted polypropylene (PP-g-MA) and various glycidyl methacrylate (GMA)-based compatibilizers. The effects of backbone structure and reactive group on the morphological, mechanical, and thermal characteristics were systematically studied. This study sheds light on the effective compatibilization mechanisms using characterization methods such as Fourier Transform Infrared Spectroscopy (FTIR) and morphological analyses (SEM). The results indicate that GMA-based compatibilizers play a bridging role between rPET and PP-g-MA, resulting in improved compatibility between the blend components. A combination of 3 phr PP-g-MA and 3 phr ethylene-methyl acrylate glycidyl methacrylate terpolymer (EMA-GMA) significantly improves interfacial adhesion, leading to synergistic enhancements of mechanical performance of the blend, up to 217% and 116% increases in elongation at break and impact strength, respectively, compared to the uncompatibilized sample. Moreover, a significant improvement in onset temperature for degradation is observed for the dual compatibilized sample, with 40 °C and 33 °C increases in onset temperature relative to the uncompatibilized and the single compatibilized samples. These findings underscore the immense potential of tailored multi-component compatibilizer systems for upgrading recycled plastic waste materials. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Manufacturing PHBV biocomposites with spent coffee ground (SCG) is an eco‐friendly approach of repurposing waste materials to improve sustainability. Although, as shown previously, pretreatments of SCG can improve its interaction with PHBV to obtain enhanced properties, the chemical or biological treatment could be time‐consuming, costly, and environmentally harmful. Therefore, this study developed a method of manufacturing PHBV/SCG biocomposites via a simple and industrially viable reactive extrusion method requiring no SCG pretreatment. The present work aims at investigating the impact of untreated SCG combined with different processing additives (peroxide, coagent, and chain extender) on the morphological, thermal, mechanical, and water absorption properties of PHBV‐based biocomposites. Overall, the introduction of the untreated SCG (10–30 wt.%, without processing additives) decreased the crystallinity (by 3.8%–6.8%), degradation temperature (Tpeak, by 6.2%–8.2%) and tensile strain (by 33%–43%) of PHBV. SCG addition had no significant effect on PHBV tensile strength or Young's modulus. However, the presence of processing additives decreased the melting temperature (by up to 4.5°C), crystallinity (by up to 8.4%) and Young's modulus (by up to 17%) and increased the degradation temperature (Tpeak, by up to 12.5°C) of the PHBV/SCG biocomposites (10% wt.% SCG). Lastly, SCG addition improved water absorption ability of PHBV by up to 250%, while the addition of peroxide further improved the water absorption ability by approximate 320%. The PHBV/SCG developed in this study have good renewability and biodegradability, improved water absorption property, reduced cost and acceptable mechanical properties. They are promising in applications where biodegradability is favorable and high mechanical performance is not required such as plant pots and containers. [ABSTRACT FROM AUTHOR]

In this article, the optical and structural properties of iPP/TiO2 nanocomposite fibres, considering three distinct extrusion speeds (25, 50 and 78 m/min) in addition to blank isotactic polypropylene samples were determined. Employing computed tomographic scans, localised optical defects in the nanocomposite fibres are unveiled, while refractive indices are examined by analysing transmitted intensity with incident light vibrating parallel and perpendicular to the fibre axis. The internal structure is further characterised through birefringence and density calculations. Mechanical properties, specifically stiffness, are probed by measuring elastic modulus values along the fibre. The investigation extends to the presence of TiO2 nanoparticles in the isotactic polypropylene matrix, inspecting their influence on the uniform morphology along and across the fibre. While the addition of TiO2 nanoparticles has many advantages, including enhanced properties, the study shows adverse effects on the morphological integrity of the fibres, particularly at higher extrusion rates. Micrographs are included to visually illustrate these findings, providing a comprehensive understanding of the complex interaction between extrusion rates, TiO2 nanoparticle incorporation, and the resulting optical and structural properties in iPP fibres. LAY DESCRIPTION: Computed tomographic scans of iPP/TiO2 nanocomposite fibers were used to investigate their optical and structural properties. Three samples of the nanocomposite fibers were extruded with extrusion speeds (25 m/min, 50 m/min, and 78 m/min) in addition to blank isotactic polypropylene sample were used in this study. Employing computed tomographic scans, localized optical defects in the nanocomposite fibers are unveiled, while refractive indices are examined by analyzing transmitted intensity with incident light vibrating parallel and perpendicular to the fiber axis. The internal structure on the molecular level was characterized through birefringence and density measurements. The effect of the extrusion speed on the structure of iPP/TiO2 nanocomposite samples was investigated through measuring their birefringence and density distributions along the fiber axis. The mechanical properties, specifically stiffness, are probed by measuring elastic modulus values along the fiber axis. The investigation extends to the presence of TiO2 nanoparticles in the isotactic polypropylene matrix, inspecting their influence on the uniform morphology along and across the fiber. Slow extrusion rates enhance the properties of iPP fiber, while fast extrusion introduces agglomerated sites which has drastic effect on the optical and structural properties of TiO2‐doped iPP fibers. Micrographs are included to visually illustrate these findings, providing a comprehensive understanding of the complex interaction between extrusion speed, TiO2 nanoparticle incorporation, and the resulting optical and structural properties in iPP fibers. [ABSTRACT FROM AUTHOR]

It is intended to investigate the influence of CNT dispersion, weight fraction and infill pattern on the tensile properties of 3D printed nanocomposites. The design of experiment is performed using Taguchi's method to analyze the minimum permutations of involved parameter levels. Prior to printing the nanocomposite samples, a pilot test is done to adjust the processing parameters. Then, nanocomposites samples are printed and tensile tests are performed on both nanocomposite filaments and 3D printed specimens measuring tensile strength and modulus. As the primary output of Taguchi method, the degree to which each involved parameter will influence the tensile properties of printed specimens is identified. Then, main effect, signal-to-noise ratio and variance analyses are performed. It is revealed that CNT dispersion plays the most important role on the tensile properties. Infill pattern and CNT weight fraction have got very close impact on the strength, while the influence of CNT weight fraction on modulus becomes much more pronounced that infill pattern. Finally, a confirmation test is done on a specific specimen whose adjusted parameters are not included in Taguchi's orthogonal array. The excellent agreement between predicted and measured properties of that sample verifies the proper performance of conducted Taguchi's analysis. [ABSTRACT FROM AUTHOR]

Poly(ethylene terephthalate) (PET), both bottle grade (PET‐B) and thermoform grade (PET‐T), are widely used in the packaging sector. However, only PET‐B is recycled and reused, while PET‐T needs to be separated from recycled PET bales. This study aims to assess the impact of solid‐state polymerization (SSP), chain extension and the combination of chain extension–SSP to transform PET‐B and PET‐T blends into PET‐T‐like material. The intrinsic viscosity (IV) values for PET‐B blends with 10–20 wt% of PET‐T are measured for the samples obtained in this study. The mechanical properties, such as tensile strength, modulus, elongation and impact strength, were also determined. The glass transition temperature, melting temperature, crystallinity and thermal degradation were also investigated. The findings suggest that the combination of SSP and chain extension leads to a significant improvement in IV and tensile strength, while SSP alone is less suitable to offer the desired IV values. © 2024 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

To improve melt strength and toughness of polyamide 6 (PA6), an on‐line UV radiation method is introduced into reaction extrusion to induce free radical reaction for efficient preparation of long‐chain branched PA6 materials. Trimethylolpropane triacrylate and glycidyl methacrylate are adopted as chain extenders to synergistically introduce long‐chain branches onto PA6 macromolecules. Gel permeation chromatography results show the increase of molecular weight of PA6, implying the successful graft of chain extenders onto molecular chains. Based on rheological measurement results, modified PA6 exhibits better melt strength than pure PA6 owing to a larger storage modulus. The elongation at break and impact strength of modified PA6 at T1G1 are about 5.3 and 2.2 times those of pure PA6, respectively, without sacrificing tensile strength. According to Fourier transform infrared spectroscopy results, we propose reaction mechanisms between trimethylolpropane triacrylate/glycidyl methacrylate and PA6 under on‐line UV radiation. This study offers a practical approach for the efficient preparation of long‐chain branched PA6, thereby broadening the potential applications of the material. Highlights: An on‐line UV radiation method is introduced into reaction extrusion.The melt strength and toughness of polyamide 6 are realized simultaneously at low cost.The synergistic effect mechanism of trimethylolpropane triacrylate and glycidyl methacrylate is proposed.Provides a feasible way to efficiently prepare long‐chain branched polyamide 6. [ABSTRACT FROM AUTHOR]

We report synthesis of a radical scavenging aminated thermoplastic polymer through reactive extrusion of polyethyleneimine (PEI) with a polypropylene and polypropylene‐graft‐maleic anhydride (PP‐g‐MA) meltblend. The reaction was confirmed using acid orange 7 (AO7) amine density assay, toluidine blue O (TBO) carboxylic acid density assay, Fourier transform infrared spectroscopy (FTIR), and a migration assay. FTIR spectra revealed a reduction of the asymmetric stretching of the maleic anhydride (MA) carbonyl group at 1777 cm−1 and the emergence of the maleimide carbonyl peak at 1702 cm−1. AO7 supported surface orientation of grafted amine groups by introduction of 7.22 nmol cm−2 primary amines, corresponding to the reduction of surface carboxylic acids quantified by TBO from 12.46 nmol cm−2 to 0.43 nmol cm−2. After incubation (40°C, 10 days) in ethanol, acetic acid, and water, < 0.1 mg cm−2 PEI migrated from the materials, supporting the covalent nature of the grafting. Antioxidant activity was demonstrated exhibiting 5.90 and 4.31 nmol Troloxeq cm−2 in aqueous and organic environments, respectively. Results indicate a successful condensation reaction during reactive extrusion, producing an aminated thermoplastic polymer with antioxidant activity for target applications such as food packaging, wastewater treatment, carbon capture, and others. [ABSTRACT FROM AUTHOR]

Dithioacetals are heavily used in organic, material and medical chemistries, and exhibit huge potential to synthesize degradable or recyclable polymers. However, the current synthetic approaches of dithioacetals and polydithioacetals are overwhelmingly dependent on external catalysts and organic solvents. Herein, we disclose a catalyst‐ and solvent‐free acetal‐thiol click‐like reaction for synthesizing dithioacetals and polydithioacetals. High conversion, higher than acid catalytic acetal‐thiol reaction, can be achieved. High universality was confirmed by monitoring the reactions of linear and cyclic acetals (including renewable bio‐sourced furan‐acetal) with aliphatic and aromatic thiols, and the reaction mechanism of monomolecular nucleophilic substitution (SN1) and auto‐protonation (activation) by thiol was clarified by combining experiments and density functional theory computation. Subsequently, we utilize this reaction to synthesize readily recyclable polydithioacetals. By simple heating and stirring, linear polydithioacetals with M‾ ${\bar M}$ w of ~110 kDa were synthesized from acetal and dithiol, and depolymerization into macrocyclic dithioacetal and repolymerization into polydithioacetal can be achieved; through reactive extrusion, a semi‐interpenetrating polymer dynamic network with excellent mechanical properties and continuous reprocessability was prepared from poly(vinyl butyral) and pentaerythritol tetrakis(3‐mercaptopropionate). This green and high‐efficient synthesis method for dithioacetals and polydithioacetals is beneficial to the sustainable development of chemistry. [ABSTRACT FROM AUTHOR]

The chemical modification of proteins serves as a fundamental tool for understanding biological processes and enables the design of biofunctional materials. Among the available methodologies, photochemical strategies have garnered significant attention because of their remarkable biocompatibility and precise spatiotemporal reaction control. Developing novel reactions tailored to specific applications necessitates a comprehensive understanding of photoreactive properties, including catalyst structures, appropriate modifiers, and reaction conditions. This review discusses chemical modifications of proteins using an array of catalysts, including photoredox catalysts for single‐electron transfer (SET), catalysts for energy transfer, long‐wavelength excitable photocatalysts, genetically encoded photocatalysts, and artificial metalloenzymes. The discussion covers the unique attributes, mechanisms, practical applications, and future prospects of each catalyst‐driven reaction, shedding light on the evolving landscape of protein chemical modifications. [ABSTRACT FROM AUTHOR]

This study employed reactive extrusion to produce micro-composites of high-density polyethylene (HDPE) with different fractions of diatomaceous earth, both unmodified and modified, using a novel reversible crosslinking reaction agent (RXR) consisting of a combination of sulfur, organic peroxide, and an accelerator. The rheological behavior and crosslinking response of the system were measured using dynamic rheological analysis using a torque rheometer. The mechanical characteristics of the system were evaluated through tensile and impact tests. The thermal characteristics were analyzed using differential scanning calorimetry and thermogravimetric analysis, while the structural and morphological properties were analyzed using wide-angle X-ray scattering, Fourier infrared transform, and scanning electron microscope. The mechanical properties of the HDPE resin were diminished by the inclusion of the diatomaceous earth due to aggregation and inadequate interfacial connections, whereas the thermal stability remained unaffected. Furthermore, the presence of diatomaceous earth led to enhancements in both crystallinity and lamellar thickness. The addition of the RXR agent improved the tensile and impacts strengths, caused by the crosslinking reaction. However, it had a detrimental effect on the degree of crystallinity and the size of the crystals formed. Analysis of mechanical, rheological, and crystallization properties demonstrated that the incorporation of diatomaceous earth and the diatomaceous earth-RXR agent combination showed potential as additives for HDPE. [ABSTRACT FROM AUTHOR]

Solvent-free extrusion emulsification (SFEE) is a recently developed process for producing submicron particles of high viscosity polymers using a twin-screw extruder without hazardous solvents. Its rate dependency on mixing for catastrophic phase inversion makes the process knowingly sensitive to a variety of variables, included the manner by which it is started up. This study examined how transient dynamics at the beginning affects steady-state operations by varying the time for the surfactant-containing feed stream to reach its setpoint rate into the process, to better understand the mechanism of SFEE. The results showed that the path taken to reaching the setpoint conditions (i.e. transition time) determined process stability and whether successful emulsification occurred, not the actual setpoint conditions chosen. Combining particle size and residence time measurements with prior studies' data related to the rate of reactions benefiting interfacial growth between the polymer/water phases and inline rheological findings, this unusual transient sensitivity was attributed to insufficient surface-active species present creating a persistent segregated regime of the flow field in the first half of the dispersion zone that exhibits an unstable phase morphology. Returning to the desired operating window was only possible once this segregated regime was purged from the process. The study offers a continuous processing perspective to this phenomenon previously observable in batch for high viscosity oil phase systems. [ABSTRACT FROM AUTHOR]

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A multifunctional epoxy polymer wass used ass a chain extender for poly (butylene ssuccinate-co-terephthalate) (PBST), and the effects of chain extension condition on the propertiess of PBST/Talc (talcum powder) blendss were in-vesstigated during the melt-phasse reactive extrusion processss. The chain extender dossage, reaction temperature, and sscrew rotational sspeed were sstudied ass main factorss. The primary influence factors and their interactions were identified through an analyssiss of variance. The ressultss indicated that the influence of chain extender dossage iss mosst ssignificant, followed with a reaction temperature, whereass the influence of sscrew sspeed iss lessss. The melting and crysstallization temperaturess of PBST decreassed with an increasse in the chain extender dossage, and meanwhile its molecular weight, melt visscossity, and thermal sstability increassed. The modified PBST compounds* pressented an increasse in the breaking sitresis; but a decreasse in the breaking sstrain with an increasse in the chain extender dossage. Ressponsse ssurface analyssiss indicated that the optimal chain extenssion condition wass a chain extender dossage of 0. 66 %, a reaction temperature of 200 °C, and a sscrew sspeed of,300 r/min. [ABSTRACT FROM AUTHOR]

Poly(3‐hydroxybutyrate‐4‐hydroxybutyrate) (P34HB) copolyester is a new type of biodegradable polymer material, but it cannot meet the market requirements because of its poor thermal stability. In this work, P34HB with a low degree of cross‐linking was successfully prepared by incorporating a small amount of a multiple epoxy chain extender, known as Joncryl ADR‐4380 (styrene‐methacrylic acid glycidyl ester copolymer), through reactive extrusion. The rheological properties, thermal stability, thermal behavior, and mechanical properties of the materials were investigated. Fourier transform infrared spectroscopy and gel content test showed that there was a significant chemical interaction between P34HB and ADR4380, and a cross‐linked structure was produced. Compared with pure P34HB, the samples after chain extension showed improved rheological properties, with increased viscosity and melt elasticity due to the formation of a gel network. Thermogravimetric analysis, dynamic time scanning experiment, and melt flow index (MFI) provided strong evidence for the enhanced of thermal stability of P34HB. The onset decomposition temperature of P34HB increased by 13.5°C, and its MFI decreased from 23.30 to around 5 at 170°C, and the complex viscosity remained relatively stable with time after modification. In terms of mechanical properties, the maximum elongation at break increased by 88.08% due to the improvement of toughness. [ABSTRACT FROM AUTHOR]

The canola oil industry generates significant waste as canola meal (CM) which has limited scope and applications. This study demonstrates the possibility of valorization of CM as a sustainable natural filler in a biodegradable polymer composite of Poly(lactic acid) (PLA). Generally, interfacial bonding between natural fibers and the polymer matrix in the composite is weak and non-uniform. One possible solution is to derivatize natural fibre to introduce interfacial bond strength and compatibility with the PLA polymer matrix. Here, CM was succinylated in a reactive extrusion process using succinic anhydride at 30 wt% to get 14% derivatization with 0.02 g of -COOH density per g of CM. The CM or succinylated CM at 5 and 15 wt% was co-extruded with amorphous PLA to get composite fibers. CM-PLA and succinylated CM-PLA biocomposites were foamed using a mild and green microcellular foaming process, with CO2 as an impregnating agent without any addition of organic solvents. The properties of the foams were analyzed using differential scanning calorimetry (DSC), Dynamic mechanical thermal analysis (DMTA), shrinkage, and imaging. The addition of CM or succinylated CM as a natural filler did not significantly change the glass transition temperature, melting point, percent crystallization, stiffness, and thermal stability of PLA foams. This suggests succinylation (modification) of CM is not a mandatory step for improving interphase compatibility with the amorphous PLA. The new PLA-CM foams can be a good alternative in the packaging industry replacing the existing petroleum-based polymer foams. Highlights: Valorization of CM as a sustainable natural filler in PLA biocomposite foams Modification of CM is not mandatory for interphase compatibility with the PLA PLA-CM foams have similar appearance and properties to control PLA foams New PLA-CM foams can be a good alternative in the packaging industry [ABSTRACT FROM AUTHOR]

In this study, a solid masterbatch of starch–iodine complex with 6.7 wt.% iodine was prepared in pellet form using a ZSK-30 twin-screw extruder. Thermogravimetric (TGA) and isothermal TGA analysis of the pellets revealed that there was no significant loss of iodine due to sublimation during reactive extrusion. These solid pellets demonstrated antifungal properties when applied to strawberries via dip coating in an aqueous solution, extending their shelf life from two days to eight days, thereby reducing fungal growth and visual decay. Furthermore, the solid pellets displayed antibacterial activity against E. coli, as evidenced by the clear zone of inhibition observed in the Kirby–Bauer test. To enhance practical application, these pellets were further blended with PLA-PBAT film formulations at 10 and 18% by wt. to make blown films with effective iodine loadings of 0.7 and 1.3% by wt. These films showed superior antibacterial activity against E. coli compared with PLA control films and the commercial silver antimicrobial-containing films during direct inoculation tests as per ISO 22196. Tensile strength and elongation at break in machine direction (MD) for the starch–iodine-containing blown films were comparable to the control films in MD, but tensile strength was reduced to 37–40% in the transverse direction (TD). This was due to a non-uniform dispersion of the starch–iodine complex in the films, as confirmed by the visual and SEM analyses. Thus, this study illustrates the practical utility of the solid starch–iodine complex as a safe and efficient means of introducing iodine into an environment, mitigating the typical hazards associated with handling solid iodine. [ABSTRACT FROM AUTHOR]

Humping is a common defect in direct energy deposition processes that reduces the geometric integrity of printed products. The available literature on humping detection is deemed reactive, as they focus on detecting late-stage melt pool spatial abnormalities. Therefore, this work introduces a novel, proactive indicator designed to detect early-stage spatiotemporal abnormalities. Specifically, the proposed indicator monitors the variability of instantaneous melt pool solidification-front speed (VIMPS). The solidification front dynamics quantify the intensity of cyclic melt pool elongation induced by early-stage humping. VIMPS tracks the solidification front dynamics based on the variance in the melt pool infrared radiations. Qualitative and quantitive analysis of the collected infrared data confirms VIMPS's utility in reflecting the intricate humping-induced dynamics and defects. Experimental results proved VIMPS' proactivity. By capturing early spatiotemporal abnormalities, VIMPS predicted humping by up to 10 s before any significant geometric defects. In contrast, current spatial abnormality-based methods failed to detect humping until 20 s after significant geometric defects had occurred. VIMPS' proactive detection capabilities enable effective direct energy deposition control, boosting the process's productivity and quality. [ABSTRACT FROM AUTHOR]

Extrusion is a versatile process capable of producing a variety of new and novel foods and ingredients, thus increasing manufacturing opportunities. Further, it could provide nutritious, safe, sustainable, and affordable foods, especially directed at individualized consumer needs. In addition to past research efforts, more investigations should be conducted in order to refine, redesign, or develop new extrusion processing technologies. The present review highlights the current advances made in new and novel food product development by considering the extrusion process, the influencing parameters, and product characteristics and properties; the most promising extrusion processes that can be used in novel food product and ingredient development, such as extrusion cooking, hot-melt extrusion, reactive extrusion, and extrusion-based 3D printing; the possibilities of using various raw materials in relation to process and product development; and the needs for product development modeling along with extrusion process design and modeling. In correlation with extruded product development, topics that merit further investigation may include structure formation, plant and animal biopolymers functionalization, biopolymer reactions, process simulation, modeling and control, engineering and mechanical aspects of extruders, analysis of pre-processing treatments, as well as prototyping, risk analysis, safety, sensory and consumer acceptance. [ABSTRACT FROM AUTHOR]

Multi-channeled nerve guidance conduit is a prospective way to repair peripheral nerve injury, which is still difficult to be fabricated. A novel extrusion-stretching method was utilized in this study to produce multi-walled carbon nanotubes (MWCNTs) loaded multi-channeled nerve conduits with improved flexibility and versatility. The channels and geography of the conduits were tunable. The results showed that the mechanical properties of the multi-channeled nerve conduits were suitable for peripheral nerve restoration. MWCNTs increased the biocompatibility of the multi-channeled nerve conduits. This study proved that the MWCNTs loaded multi-channeled produced by extrusion-stretching method have great potential to repair peripheral nerve injury. [ABSTRACT FROM AUTHOR]

Large-Scale Material Extrusion (LS-MEX) is increasingly being used in small-scale production and prototyping due to its ability to create components in new temporal and spatial dimensions. However, the use of this manufacturing process poses microscopic and macroscopic challenges not encountered in previous small-scale production systems. These challenges arise primarily from the prolonged retention of heat in the material, which leads to insufficient strength in the extruded strands at the macrostructural level. As a result, the component can collapse, a phenomenon known as 'slumping'. Thermal energy also influences microstructural changes, such as crystallisation kinetics, which affect properties such as the strength and stiffness of the final product. The duration and dynamics of thermal energy are influenced by manufacturing parameters and the possible use of additional peripheral equipment, which affects component quality. In this study, the influence of thermal energy on structural processes through simulations of polyamide 6 with 40% carbon fibres (PA6 wt.%40 CF) is investigated. The results show that by adjusting the process parameters and using modification units, the thermal profile of the material can be accurately controlled, which allows the microstructural processes to be precisely controlled. This leads to the targeted modification of the macroscopic material properties. The focus of this work is on the combination of numerical simulations of the LS-MEX process with semi-empirical methods for the analysis of crystallisation processes. The application of the Nakamura model, which is used throughout similar investigations, allows a detailed description and prediction of the crystallisation kinetics during the manufacturing process. The study shows that the absolute degree of crystallisation can be determined with simplified assumptions using a combination of thermal simulations and semi-empirical approaches. It was found that the absolute degree of crystallisation increases from the outer interface of the strand to the print bed across the cross-section. This can be attributed to the specific thermal boundary conditions and the resulting temperature profiles at different points. [ABSTRACT FROM AUTHOR]

Polylactide (PLA) was melt blended with low amounts of poly (butylene adipate‐co‐terephthalate) (PBAT) using a simple reactive extrusion process herein, aiming to address the inherent brittleness of PLA without significantly compromising its stiffness. PLA/PBAT (90/10) blends with a small amount of peroxide (0.02 phr) and a second crosslinker agent triallyl isocyanurate (TAIC) were produced to explore the structure‐performance relationship evolution in reactive extrusion. The results showed that the PLA blend with an appropriate amount of TAIC (i.e., 0.3 phr) exhibited a remarkable increase in elongation at break, reaching as high as 96%. The sample with high elongation also demonstrated a high stiffness, boasting a Young's modulus of 2.4 GPa and a yield strength of 43 MPa. It was evident that the combination of enhanced compatibility and optimized homogeneous PBAT phase size of approximately 0.6 μm worked synergistically to enhance the toughness of PLA. Conversely, higher TAIC contents resulted in over‐crosslinking, despite considerable improvements in compatibility. This study offers a versatile, scalable, and practical method to prepare fully biodegradable PLA blends with high toughness. [ABSTRACT FROM AUTHOR]

Decades of measurements of the thermophysical properties of hot metals show that pulsed Joule heating is an effective method to heat solid and liquid metals that are chemically reactive or difficult to contain. To extend such measurements to hundreds of GPa pressure, pulsed heating methods have recently been integrated with diamond anvil cells. The recent design used a low-side switch and active electrical sensing equipment that was prone to damage and measurement error. Here, we report the design and characterization of new electronics that use a high-side switch and robust, passive electrical sensing equipment. The new pulse amplifier can heat ∼ 5 to 50 μm diameter metal wires to thousands of kelvin at tens to hundreds of GPa using diamond anvil cells. Pulse durations and peak currents can each be varied over three orders of magnitude, from 5 µs to 10 ms and from 0.2 to 200 A. The pulse amplifier is integrated with a current probe. Two voltage probes attached to the body of a diamond anvil cell are used to measure voltage in a four-point probe geometry. The accuracy of four-point probe resistance measurements for a dummy sample with 0.1 Ω resistance is typically better than 5% at all times from 2 µs to 10 ms after the beginning of the pulse. [ABSTRACT FROM AUTHOR]

Plasma surface modification of polymers is a well‐established method applied to increase the surface energy of these materials, where the capacity of cold plasmas to generate free radicals and functionalize the surface with polar groups is widely reported in the literature. This article provides a comprehensive literature review on plasma surface treatment, plasma‐induced grafting, and plasma polymerization, evaluating how these techniques can be applied to modify the bulk properties of polymers. A novel process of plasma‐induced polymer bulk functionalization in the melt state is introduced, where an atmospheric pressure plasma jet could be applied to a continuous reactive extrusion process, enhancing the production of graft copolymers for compatibilization of polymeric blends and fiber composites. [ABSTRACT FROM AUTHOR]

Abstract Grafting polymers with reactive maleic anhydride is a common approach for the synthesis of new material with the capability of acting as a compatibilizer in polymer blends. Accordingly, this research showed a new approach for grafting maleic anhydride onto renewable cellulose acetate using an initiator. The grafting process through extrusion showed good stability with continuous production of all grafted samples. Moreover, two different grafting processes, namely one‐step and two‐step processes, were shown to produce materials with very similar characteristics. Grafting of maleic anhydride onto cellulose acetate by reacting with its hydroxyl groups was confirmed by both Fourier transform infrared spectroscopy and nuclear magnetic resonance analysis. Rheological studies also demonstrated the enhanced flowability and lower viscosity of the grafted material in comparison to the plasticized cellulose acetate. Highlights Grafting maleic anhydride onto plasticized cellulose acetate by reactive extrusion. Detection of grafted maleic anhydride onto cellulose acetate through NMR analysis. High thermal stability of grafted materials. Significant reduction in viscosity of plasticized cellulose acetate after grafting

Screw extruders as continuous flow reactors allow the synthesis of new polymers, preparation of polymer blends and composites, and modification or functionalization of commercially available polymers. Literature data shows that the twin screw extrusion is the most popular solution used for this purpose. In contrast, the number of scientific papers on alternative methods, such as multi-screw extruders, is somewhat limited. This paper is the first review of the application of planetary roller extruders in the compounding and reactive processing of polymer blends and composites. To fill current knowledge gaps, we discuss the advantages and disadvantages of planetary roller extruders compared to other screw extruders. Moreover, we summarize recent advances in planetary roller extrusion in producing thermal sensitive and biodegradable polymeric materials, rubber compounds, materials for 3D printing, or plastics and rubber recycling. This work also proposes the possible scenarios for further sustainable development of polymer blends and composites using planetary roller extruders.

Starch-based films reinforced with Canna edulis Ker fiber were developed by a reactive extrusion process in which an esterification reaction was generated using maleic anhydride as a modifying agent and glycerin as a plasticizer. A Box-Behnken experimental design and the response surface methodology allowed modeling of the mechanical and physicochemical properties and their subsequent optimization to obtain flexible or rigid materials with different approaches in food packaging. The optimal composition for the rigid and flexible material was 10 and 2 % (w/w) lignocellulosic fibers, 30 and 30 % (w/w) glycerol, and 4 and 4 % (w/w) maleic anhydride, respectively. Glycerol and maleic anhydride were the key variables that influenced the water solubility and water absorption of the materials. The values of the rigid and flexible material properties of elastic modulus, tensile strength, elongation at break, water solubility, and water absorption were 2.58 and 1.51 GPa, 112.04 and 104.56 Mpa, 6.58 and 10.44 %, 21.63 and 21.85 %, and 139.72 and 141.06, respectively.

Glycidyl-based chain extenders are broadly used as processing aids to enhance the physical properties of polyesters, but glycidyl-containing compounds have severe toxicity concerns. Reported herein are glycidyl-free chain extenders produced via the grafting of 9-(oxiran-2-yl)nonyl methacrylate (EAT) and 8-(3-octyloxiran-2-yl)octyl methacrylate (EAI) on biodegradable poly(e-caprolactone) (PCL). EAI and EAT were grafted onto PCL via free radical grafting using melt extrusion to produce PCL-epoxy-grafted PCL-g-EAI and PCL-g-EAT. The obtained PCL-g-EAI and PCL-g-EAT were characterized by 1H nuclear magnetic resonance (NMR) spectroscopy, intrinsic viscosity measurements, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and size exclusion chromatography (SEC). Using reactive melt extrusion, PCL-g-EAI and PCL-g-EAT were tested as potential chain extenders for poly(lactic acid) (PLA). PCL-g-EAI showed comparable or better mechanical properties than those of the commercial chain extender Joncryl ADR. A cytotoxicity assay has been conducted on PLA samples with the new chain extender and showed the absence of cytotoxicity in all samples. The outcomes reported in this paper offer new opportunities for the development of safer chain extenders. [ABSTRACT FROM AUTHOR]

Parts made through additive manufacturing (AM) often exhibit mechanical anisotropy due to the time-based deposition of material and processing parameters. In polymer material extrusion (MEX), printed parts have weak points at layer interfaces, perpendicular to the direction of deposition. Poly(lactic acid) with chopped carbon fiber was printed on a large-format pellet printer at various extrusion rates with the same tool pathing to measure the fiber alignment with deposition via two methods and relate it to the ultimate tensile strength (UTS). Within a singular printed bead, an X-ray microscopy (XRM) scan was conducted to produce a reconstruction of the internal microstructure and 3D object data on the length and orientation of fibers. From the scan, discrete images were used in an image analysis technique to determine the fiber alignment to deposition without 3D object data on each fiber's size. Both the object method and the discrete image method showed a negative relationship between the extrusion rate and fiber alignment, with −34.64% and −53.43% alignment per extrusion multiplier, respectively, as the slopes of the linear regression. Tensile testing was conducted to determine the correlation between the fiber alignment and UTS. For all extrusion rates tested, as the extrusion multiplier increased, the percent difference in the UTS decreased, to a minimum of 8.12 ± 14.40%. The use of image analysis for the determination of the fiber alignment provides a possible method for relating the microstructure to the meso-property of AM parts, and the relationship between the microstructure and the properties establishes process–structure–property relationships for large-format AM. [ABSTRACT FROM AUTHOR]

Heat seal and mechanical properties of 1‐octene grafted low density polyethylene films containing various concentrations of Dicumyl peroxide as the initiator and 1‐octene grafting agent is investigated through using experimental measurements. The results of differential scanning calorimeter (DSC) measurements revealed that the melting temperature shifts to higher values and the peak of the DSC curve becomes wider with the increase of 1‐octene concentrations. Thermogravimetric analysis (TGA) revealed a higher thermal stability up to 20 °C for 1‐octene grafted PE compared with neat LDPE alloy. The results of stress–strain measurements revealed that the 1‐octene grafted PE alloys has higher tensile strength in comparison with neat PE alloy and samples containing only DCP initiator. The results of heat seal analysis indicated that both DCP initiator and 1‐octene tended to offer a moderate increase peel strength of PE alloy. DMTA measurements for various grafted PE alloys show a higher damping factor in comparison with neat LDPE alloy. Rheological measurements indicated a higher storage modulus up to 25% and higher complex viscosity for grafted PE samples containing 1‐octene comonomer. [ABSTRACT FROM AUTHOR]

Screw extruders as continuous flow reactors allow the synthesis of new polymers, preparation of polymer blends and composites, and modification or functionalization of commercially available polymers. Literature data shows that the twin screw extrusion is the most popular solution used for this purpose. In contrast, the number of scientific papers on alternative methods, such as multi-screw extruders, is somewhat limited. This paper is the first review of the application of planetary roller extruders in the compounding and reactive processing of polymer blends and composites. To fill current knowledge gaps, we discuss the advantages and disadvantages of planetary roller extruders compared to other screw extruders. Moreover, we summarize recent advances in planetary roller extrusion in producing thermal sensitive and biodegradable polymeric materials, rubber compounds, materials for 3D printing, or plastics and rubber recycling. This work also proposes the possible scenarios for further sustainable development of polymer blends and composites using planetary roller extruders. [ABSTRACT FROM AUTHOR]

In this study, all‐green biocomposites based on poly(lactic acid) (PLA)/rice straw (RS) as an agricultural waste were prepared, and the physical, structural, and mechanical properties of these biocomposites were enhanced by alkali‐pulping of RS and chemical grafting of PLA onto the lignocellulosic fiber. The reactive compatibilizers of maleic anhydride grafted PLA (PLA‐g‐MA) were obtained through a reactive extrusion process at different processing conditions. The probable chemical reactions between the functional groups of PLA‐g‐MA with hydroxyl groups of RS pulp as well as the end groups of PLA chains can effectively improve the interfacial adhesion between the filler and matrix. However, the findings confirm the great importance of PLA‐g‐MA chemical structure in controlling the biocomposite performance. By choosing proper processing conditions for preparing PLA‐g‐MA and incorporating this compatibilizer into the PLA/treated RS biocomposite, Young modulus, tensile strength, impact strength, and tensile toughness of the PLA/RS biocomposite increased by 101%, 156%, 96%, and 327%, respectively. [ABSTRACT FROM AUTHOR]

Grafting polymers with reactive maleic anhydride is a common approach for the synthesis of new material with the capability of acting as a compatibilizer in polymer blends. Accordingly, this research showed a new approach for grafting maleic anhydride onto renewable cellulose acetate using an initiator. The grafting process through extrusion showed good stability with continuous production of all grafted samples. Moreover, two different grafting processes, namely one‐step and two‐step processes, were shown to produce materials with very similar characteristics. Grafting of maleic anhydride onto cellulose acetate by reacting with its hydroxyl groups was confirmed by both Fourier transform infrared spectroscopy and nuclear magnetic resonance analysis. Rheological studies also demonstrated the enhanced flowability and lower viscosity of the grafted material in comparison to the plasticized cellulose acetate. Highlights: Grafting maleic anhydride onto plasticized cellulose acetate by reactive extrusion.Detection of grafted maleic anhydride onto cellulose acetate through NMR analysis.High thermal stability of grafted materials.Significant reduction in viscosity of plasticized cellulose acetate after grafting [ABSTRACT FROM AUTHOR]

The aggregation of plastic waste results in immiscible polymer blends with inferior properties. This study explores the application of irradiation technology on polymer processing for its potential to increase the compatibility of immiscible polymer blends composed of poly(ethylene terephthalate) (PET) and linear low‐density polyethylene (LLDPE). When PET is radiated, it undergoes chain‐scission reactions resulting in the formation of free radicals. The extended lifespan of these free radicals in post‐irradiated PET provides an opportunity for inducing interface reactions with LLDPE during compounding through reactive extrusion. PET was irradiated with up to 50 and 200 kGy irradiation absorbance doses of gamma irradiation and then compounded with LLDPE in a twin‐screw extruder at three blend compositions. Analysis of rheological, morphological, and mechanical properties demonstrates the compatibility improvement in this immiscible polymer blend attributed to irradiation‐induced free radical interface reactions using post‐irradiated PET up to 50 kGy to conduct the reactive extrusion process. Highlights: Reactive extrusion process with post‐irradiated PET.Formation of interface reactions.Improving the compatibility of immiscible polymer blend. [ABSTRACT FROM AUTHOR]

Stimuli‐responsive polymers have found applications as shape‐memory materials, optical switches, and sensors, but the installation of these responsive properties in non‐polar and inert polyolefins is challenging. In this contribution, a series of spiropyran (SP)‐based comonomers are synthesized and copolymerized with ethylene or ethylene/cyclic monomers. In addition to great mechanical and surface properties, these functionalized polyolefins responded to light, heat, and force, which induced changes in the polymer structure to transmit color or mechanical signals. These interesting responsive properties are also installed in a series of commercial polyolefin materials through reactive extrusion, making the scalable production of these materials possible. [ABSTRACT FROM AUTHOR]

The inherent flammability of polymeric materials poses a potential threat to life and the environment. From a perspective of material renewability and environmental concern, some phosphorus-rich biomass compounds have been considered as effective replacements for conventional intumescent-based flame retardants. In this work, with the aim of suppressing the potential fire hazard of highly flammable polypropylene in a sustainable strategy, a green and facile method was proposed to synthesize ZIF-67 and further used to synergistically improve the performance of phytic acid-based intumescent flame retardants. Diverging from conventional solvothermal synthesis strategies, ZIF-67 was directly prepared with polymer matrix via a solvent-free reactive extrusion method with a notable space time yield. The reaction-to-fire properties were comprehensively investigated under forced combustion bench-scale fire conditions using a cone calorimeter with an external heat flux of 50 kW m−2. It was found that flame retardancy behaviors remain competitive when replacing 10 mass% of expandable graphite with phytic acid component. With the addition of ZIF-67, the heat release (53% reduction), smoke production (22% reduction), char structure stability (35% increment), and specific extinction area (19% reduction) behaviors were further improved due to the development of compact phospho-carbonaceous networks during combustion. Considering these excellent synergistic improvements, it provides a new potential direction to efficiently fabricate biomass-based flame retardants. [ABSTRACT FROM AUTHOR]

Growing concerns over synthetic plastic pollution have spurred interest in biodegradable food packaging. Starch edible films are an eco-friendly alternative that can enhance the shelf life of fruits and vegetables thanks to their excellent oxygen barrier properties. Nonetheless, Starch edible films have several disadvantages, such as low water resistance and poor mechanical properties. Modifying starch through reactive extrusion, particularly succinylation, offers a solution. Therefore, this research aims to prepare edible films using starch modified by succinylation with different safe-food-use degrees of substitution (DS, 0–0.05) through the extrusion process and Glycerol Content (GC, 15–30%). The succinylated starch edible films' (SSEF) functional properties and their effectiveness as a coating for mango preservation were evaluated. Results show that as the DS increased, SSEF had lower barrier properties and higher mechanical properties. Additionally, mangoes coated with SSEF exhibited better postharvest quality (weight loss, ΔE, firmness, pH, TA, and °Brix) than control fruit. [ABSTRACT FROM AUTHOR]

The extraordinary physical properties of multiwalled carbon nanotubes (MWCNTs) are yet to be fully realised in polyamide-6 (PA6) nanocomposites, due to difficulty in dispersion of MWCNTs within PA6 matrix, owing to high toughness of PA6 and agglomerating properties of MWCNTs. In this study, MWCNTs of high aspect ratio prepared by chemical vapour deposition (CVD) method are melt-mixed with 0.1–0.5 parts-per-hundred ratios (phr) into PA6 matrix by twin-screw extrusion. The high shearing force of co-rotating twin-screws and intermixing of the components along the back-flow channel of extruder assured uniformly dispersed MWCNTs within PA6 system. A 30.2% rise in yield strength and an 82.6% rise in Young's modulus were noticed for 0.1 phr MWCNTs/PA6 tensile specimens over neat PA6 specimens during tensile testing. A strain hardening behaviour was shown by neat PA6, which was persistent in all its composites containing MWCNTs. A distinct trend in storage and loss behaviour, as well as 14 °C and 11 °C rise in glass transition temperatures (Tg) in loss modulus and loss factor curves, respectively, were observed for 0.5 phr MWCNTs' reinforcement in dynamic mechanical analysis (DMA), which indicated an effective PA6–MWCNTs interaction. The improvements in crystallization and melting temperatures, as well as crystallinity values in differential scanning calorimetry (DSC) indicated nucleating effects of MWCNTs towards stable crystallization of PA6 molecules. The shifting and rise in intensity peaks in XRD and Raman spectroscopy curves supported the reinforcing effect of MWCNTs within PA6 matrix. These nanocomposites are beneficial for fabricating high mechanical and thermal stability-required components in automobiles, aerospace, and biomedicals. [ABSTRACT FROM AUTHOR]

Poly(tetrafluoroethylene) (PTFE) is well known for its very low friction coefficient and thus widely used for antifriction applications, e.g., sliding lacquers, for many years. Because of the high wear rate and cold flow of the original polymer, PTFE is usually added in higher amounts to other polymer matrices as a lubricant. However, the incompatibility of PTFE requires lots of efforts to perform a homogeneous breaking down of agglomerates and particle distribution as well as dispersion stabilization of the physical mixtures during application and curing. PTFE can be functionalized by high energy irradiation and subsequently compatibilized with a polymer matrix by reactive extrusion resulting in chemical bonding of both polymers via suitable reactive groups. In this manner, poly(amide imide) (PAI) was coupled to γ-radiation modified PTFE micro-powder prior to the dispersion procedure. This study deals with the thermal and crystallization behavior of the PTFE lubricant in chemical bonded (cb) PAI-PTFEcb compound thin layers in comparison with those of the plain radiation modified PTFE depending on the cooling rate by DSC, Flash-DSC and WAXS. A morphological characterization of the extrudate as well as the coating gives information about the fragmentation and distribution of the PTFE phase in the PAI matrix. Furthermore, mechanical and surface properties of sliding lacquer films were analyzed after application on steel substrates by varying dry film thickness and curing. [ABSTRACT FROM AUTHOR]

We designed three‐dimensional (3D) structures through a combination of glass fiber cloth and in situ formation of nano polyphenylene oxide (PPE) fibers during the fabrication process of thermosetting cyanate ester/bismaleimide composites and developed a self‐stitching technique based on PPE fiber and interpenetrating polymer networks (IPNs) for aiding the crack self‐healing. The building of 3D structure effectively improves the interface interaction between fiber and matrix and suppresses the crack propagation process in composite, leading to significant enhancement in the mechanical properties. When PPE content is 20%, the interlaminar shear strength, flexural strength, impact strength, and tensile strength of the resulting composite are 98%, 74%, 95%, and 101% higher than those of the composite without PPE. The resulting composites possess excellent thermomechanical and lower dielectric properties. Because IPNs within composites can create interspaces and easily deform above glass‐transition temperature, PPE components may penetrate through the interspaces under thermal expansion force, and the contraction stresses of polymers generate strong locking effects in composite after cooling to room temperature, then the crack surfaces of composites can be stitched by PPE fibers, significantly recovering the mechanical properties. The healing efficiency of the composite with 30% PPE after impact and then heating at approximately 280°C can reach 96%. Highlights: 3D structures were constructed during the fabrication process of glass‐fiber‐reinforced thermosetting cyanate ester/bismaleimide composite.A self‐stitching technique was developed for aiding the crack self‐healing of composite.3D structures significantly improved the interface interaction between fiber and matrix in laminated composite.The mechanical properties of the resulting composite could be significantly improved by 3D structures.The healing efficiency of the healed composite could reach 96%. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) is one of the most extensively used commodity plastics. In terms of eco-friendliness, it is worth considering preparing high-lignin-filled PP. This study explores the incorporation of high lignin content, derived from acetic acid lignin (AAL) and Kraft lignin (KL), into PP through twin-screw extrusion and injection molding. The challenge lies in maintaining mechanical performance. A compatibilizer—specifically, maleic anhydride-grafted polypropylene (MAPP)—is employed to enhance lignin–PP compatibility by chemically bonding with lignin and physically associating with the PP phase. Results indicate that KL maintains better dispersity than AAL. Compatibilizers with a high maleic anhydride (MA) level (≥0.8 wt.%) and moderate melt flow index (MFI) in the range of 60–100 g 10 min⁻¹ prove favorable in constructing a reinforced PP/KL network. Optimizing with 40 wt.% lignin content and 10 parts per hundred (pph) of compatibilizer yields blends with mechanical performance comparable to neat PP, exhibiting a notable increase in modulus and heat deflection temperature (HDT). Furthermore, utilizing PP/lignin blends can lead to a 20% reduction in expenses and approximately 40% reduction in PP-induced greenhouse gas (GHG) emissions. This approach not only reduces PP costs but also adds value to lignin utilization in a sustainable and cost-effective manner. [ABSTRACT FROM AUTHOR]

Global growing concern on plastics disposal and their environmental impact has impulsed the development of lower impact biodegradable plastics, however their functional properties and processability are still limited. In this study, thermoplastic starch (TPS) was synthetized through reactive extrusion (REX) to obtain single oxidized thermoplastic (O-TPS) and single maleated thermoplastic (MA-TPS), as well as, dual (oxidized-maleated thermoplastic (O-MA-TPS) modified starches aiming to incorporate new functionalities, diminish the viscosity and improve TPS processability. Spectroscopic analysis showed different band intensities as a result of TPS modification. TPS presented B-type and V-type crystal structures. O-MA-TPS showed the lowest percentage of crystallinity and complex viscosity values compared to single modified TPS because the combination of modifications. The specific mechanical energy decreased with respect to chemical modifications of starch (TPS > O-TPS > MA-TPS > O-MA-TPS), which were associated with the diminishing of viscosity resulting from the modification and starch-glycerol interactions. These starches can be incorporated into mixtures with other plastic polymers, by allowing better mixing (minor viscosity difference) and the replacement of a greater amount of plastic with TPS or in applications where a TPS with lower viscosity and easier processability is required. [ABSTRACT FROM AUTHOR]

The development of green technologies to produce new biobased materials can minimize the dependence on fossil-based resources. The current study aimed to modify cellulose extracted from oat hull by employing a simple and ecofriendly process based on reactive extrusion using sodium trimetaphosphate (STMP) and tartaric acid (TA) as esterifying and cross-linking agents. STMP and TA were used at different concentrations (0, 5, 12.5, and 20% for TA and 0.025, 0.05, 0.1% for STMP). Reactive extrusion with STMP and TA did not change the morphology and crystallinity pattern of cellulose. Crystallinity indices ranged from 33 to 37% in modified samples, which presented higher affinity by the nonpolar solvent in wettability test and higher oil absorption capacity (7.26–8.60 g/g) when compared to unmodified cellulose (1.78 g/g). Reactive extrusion can be an effective and scalable technology for the modification of cellulose, resulting in materials with new characteristics and some advantages, such as low cost, short reaction times, low effluent generation and the use of nontoxic materials in all processes. [ABSTRACT FROM AUTHOR]

Thermoset polyurethanes (PUs) pose recycling challenges due to their crosslinked structure. This study investigates the possibility to directly reprocess PU foams through (dynamic) carbamate exchange using reactive extrusion. By varying compounding temperature and catalyst (dibutyltin dilaurate, DBTDL) concentration, the extrusion process is examined using torque measurements. We clearly show that it is possible to reprocess the PU foam at temperatures well below 200°C and that DBTDL catalyst greatly enhances bond exchange rates during compounding. Reproducible extrusions at 160°C with 0.3 wt% DBTDL result in a material with a gel fraction of 0.90 displaying typical dynamic covalent network behavior, as confirmed by stress relaxation measurements. The measured characteristic relaxation times display an Arrhenius‐type temperature dependence with an activation energy of 41 kJ/mol. Successful extrusion of fully crosslinked PU foam at milder temperatures with DBTDL catalyst demonstrates potential for PU foam recycling using reactive extrusion, and generally highlights the feasibility of dynamic crosslink reconfiguration for waste reduction and improved sustainability. [ABSTRACT FROM AUTHOR]

High‐density polyethylene (HDPE) and isotactic polypropylene (iPP) are widely used in industrial and residential applications due to their low cost and chemical stability, thus their recycling process can contribute to a circular economy. However, both polymers are non‐polar materials, and the incompatibility with most other materials leads to substantially inferior properties of blends. In this work, we propose a flexible compatibilization strategy to improve the compatibility of HDPE/iPP blends. Ozone is adopted to induce reactive extrusion for rapid oxidation of HDPE and chain‐branching reactions for both HDPE and HDPE/iPP blends. During extrusion process, ozone oxidizes HDPE effectively in a short time and introduces oxygen‐containing groups such as carbonyl and ester groups, which improves the hydrophilicity. The addition of trimethylolpropane triacrylate (TMPTA) could promote branching reaction and facilitate the formation of HDPE‐g‐iPP copolymers, which improved the compatibility for HDPE/iPP. As a result, the impact strength of ozone‐modified HDPE and HDPE/iPP blends increased by 22 % and 82 %, respectively, and the tensile strength also increased. This strategy would have potential applications in the field of sorting‐free and solvent‐free recycling of waste polyolefin plastics. [ABSTRACT FROM AUTHOR]

Given the environmental benefits, poly(vinylidene fluoride) (PVDF)‐based composite powder coating was developed without using any harmful solvent. However, it still remains poor adhesion to substrates and low compatibility to acrylic resin issues. To address these challenges, PVDF was grafted with glycidyl methacrylate (GMA) through a facile and scalable reactive extrusion method. The resulting product, PVDF‐g‐GMA, was then mixed with different contents of polymethyl methacrylate (PMMA), and the mixing was sprayed onto aluminum substrates. The PVDF‐g‐GMA/PMMA powder coating shows the excellent adhesion and corrosion resistance, particularly when the PMMA content is 30 wt%, owning to the good compatibility of PVDF‐g‐GMA and PMMA. This work opens up a new possibilities for the development of advanced composite powder coatings with improved performance characteristics. [ABSTRACT FROM AUTHOR]