Macromolecular Materials and Engineering最新文献

Petroleum-derived plastics are harmful to ecosystems because they are not decomposed in the natural environment. Therefore, the replacement of petroleum-derived plastics with biodegradable plastics has attracted considerable attention. UV-barrier films in the agricultural and packaging fields are mainly composed of petroleum-derived plastics, which have a negative impact on the ecosystem when they leak into the environment. Thermoplastic starch (TPS) is an inexpensive and sustainable biodegradable plastic that has recently attracted considerable attention. In this study, the addition of UV barrier properties and remolding ability to TPS for replacing petroleum-derived UV barrier films are investigated. Also, a biodegradable polyester coating is studied to improve the water resistance of the prepared UV-barrier TPS (U-TPS). To prepare U-TPS, a conjugated enamine structure is formed by reacting starch acetoacetate with diamine monomers during melt kneading. U-TPS exhibits high UV barrier properties across the UV regions (200–400 nm) owing to the presence of acetoacetyl groups and enamines. These results indicate the possibility of increasing the utilization of TPS in agriculture and as a packaging material.

Front Cover: The cover image of article 2400038 by Mostafa Baghani and co-workers shows the free shape recovery process of 3D printed PETG-ABS blend in terms of time at a recovery temperature of about 100 °C. This blend is prepared by melt mixing in the internal mixer at a temperature of 200 °C and 60 rpm for 6 minutes, and the final part is 3D printed by granule-based material extrusion method.

This study presents the development and 4D printing of magnetic shape memory polymers (MSMPs) utilizing a composite of polylactic acid (PLA), polymethyl methacrylate (PMMA), and Fe₃O₄ nanoparticles. The dynamic mechanical analysis reveals that the integration of Fe₃O₄ maintains the broad thermal transition without significantly affecting α-relaxation time, indicating high compatibility and homogeneous distribution of the nanoparticles within the polymer matrix. Field emission scanning electron microscopy further confirms the high compatibility of PLA and PMMA phases as well as uniform dispersion of Fe₃O₄ nanoparticles, essential for the effective transfer of heat during the shape memory process. Significantly, the incorporation of magnetic nanoparticles enables remote actuation capabilities, presenting a substantial advancement for biomedical applications. 4D-printed MSMP nanocomposites exhibit exceptional mechanical properties and rapid, efficient shape memory responses under both inductive and direct heating stimuli, achieving 100% shape fixity and 100% recovery within ≈85 s. They are proposed as promising candidates for biomedical implants, specifically for minimally invasive implantation of bone scaffolds, due to their rapid remote actuation, biocompatibility, and mechanical robustness. This research not only demonstrates the 4D printability of high-performance MSMPs but also introduces new possibilities for the application of MSMPs in regenerative medicine.

The spherulitic morphology of isotactic polypropylene can be transformed into the oriented fibrillar morphology through hot stretching processes with varying temperature (T_s) or altering strain (ε_t). The effects of T_s and ε_t on the structural characteristics of fibrillar crystals are comprehensively investigated with respect to crystal orientation, long periodic spacing, lamellar thickness (L_c), crystallinity (X_c), melting point, and chain relaxation behavior. Small-angle X-ray scattering patterns illustrate that the fibrillar crystals consist of alternated stacks of crystalline lamellae and amorphous layers. High T_s leads to a low orientation degree of lamellae, whereas large ε_t facilitates a high orientation level. The X_c and mean L_c are improved continuously with the increasing of T_s or ε_t, indicating a stretching-enhanced crystallization behavior driven by the two factors. The endothermic profiles reveal that new chain-folded lamellae with relatively thinner thickness form during the hot stretching process. The formation of thinner lamellae is dominated by the melting–recrystallization mechanism. This work would provide guidance for optimizing process conditions to manipulate the microstructure of hot-stretched semicrystalline polymers.

Sustainable functionalization of bacterial cellulose for cost-effective bionanocomposites with desired properties has received growing attention in recent years. This article presents the results of work aimed at obtaining bionanocomposite materials based on bacterial cellulose, a natural and eco-friendly material. Bacterial cellulose obtained from the Kombucha symbiotic culture of bacteria and yeast (SCOBY) fermentation process is functionalized by embedding with diatom frustules, silver nanoparticles (AgNPs), and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The effects of functionalization on mechanical, optical, plasmonic, electrical, chemiluminescent, and antimicrobial properties are evaluated. Morphological characteristics of the nanocomposites are studied using electron microscopy. Addition of diatom frustules introduced into the SCOBY culture media results in bionanocomposite materials with enhanced tensile strength and increased ultraviolet (UV) blockage properties. In situ functionalization of bacterial cellulose with AgNPs tunes plasmonic and chemiluminescent properties, revealing the biosensing potential of the material. Modified bacterial cellulose shows antimicrobial activity in experiments with gram-positive and gram-negative bacteria. Dual functionalization of bacterial cellulose with PEDOT:PSS and AgNPs results in improved electrical conductivity of the bionanocomposite. Overall, bottom-up physical functionalization approaches and the resulting bionanocomposite materials will open up new opportunities for the low-cost production of green materials and contribute to the development of a sustainable economy.

This article presents a comprehensive review of the advancements in the use of Date Palm Fiber (DPF) reinforced composites, highlighting their mechanical, thermal, and morphological properties and the enhancements achieved through various modification techniques. Date palm fibers, a sustainable and biodegradable resource, have garnered significant interest due to their potential in reducing environmental impact across several key industries, including building and construction, automotive, and packaging. The review discusses the effects of hybrid approaches and physical and chemical treatments on the mechanical properties of DPF composites, demonstrating improvements in tensile strength, elasticity, and flexural strength through optimized fiber-matrix bonding and reduced moisture absorption. Thermal behavior analyses through Thermogravimetric Analysis (TGA), Dynamic Mechanical Analysis (DMA), and thermal conductivity underscore the composites’ suitability for applications requiring high thermal stability and conductivity for insulation applications. Morphological studies reveal that surface-treated fibers integrate more effectively with various polymeric matrices, leading to enhanced composite performance. The practical applications of DPF composites are explored, emphasizing their role in promoting sustainable manufacturing practices. Challenges such as scalability, cost-efficiency, and performance consistency are addressed, alongside future perspectives that suggest a promising direction for further research and technological development in the field of natural fiber composites. This review aims to solidify the foundation for ongoing advancements and increase the adoption of DPF composites in commercial applications.

In this work, functional polymeric filters are prepared by electrospinning using four different non-ionic polymers or their blends together with deliberately selected additives, and then tested for quantification of the nano-sized powders. Particle gravimetry is used for the quantitative determination of the dusts. Validation studies are carried out using the ICP-OES technique. The polymeric fibers prepared with different contents consist of PS/PMMA, PVDF/EC/PMMA, chitosan, chitosan/PMMA and PMMA/PVDF, respectively. The ionic liquids of tetra-n-butylammonium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate and hexadecyltrimethylammonium bromide are used as additives for the preparation of the functional polymeric fibers. The prepared nanoscale dusts and electrospun fibers are characterized by SEM, XRD, XPS, and size distribution analysis techniques, respectively. Among them, the CTAB-modified chitosan fibers exhibit the highest dust retention efficiency. This study introduces a new approach to the quantification of nano-sized powders. In addition, it is concluded that the proposed method can be used in pre-concentration before testing, cleaning powders from the working environment and quantitative analysis of nanoscale powders. The presented materials can also be used to improve indoor air quality and potential worker exposure in workplaces.

This paper presents recent developments in graphene-based nanomaterial (GNM)-containing flame-retardant (FR) polyethylene (PE) composites for advanced applications and introduces knowledge gaps and potential solutions. Various nanomaterials have been used to improve the FR properties of PEs. Among these, GNMs score highly because of their superior performance and multifunctional characteristics. By offering a holistic overview of the fundamentals of the FR characteristics of GNMs, the processing and characterization of PE/GNM composites, and the critical aspects related to the development of FR PE/GNM composites for advanced applications, this review provides insights into advances in this area as well as prospects. Furthermore, the kinetics of the FR characteristics of PE and PE/GNM composites are critically discussed in the context of how the FR properties of PE/GNM composites can be tailored by modifying either the surface of the GNM, PE or both, an area seldom discussed in the literature. Moreover, the FR performance of PE/GNM composites is compared with PE/Expandable Graphite (EG) composites because EG has been recognized as a highly efficient and eco-friendly intumescent FR. In summary, this review offers new insights into the design of advanced PE/GNM composites for automotive, construction, aerospace, and electronic packaging applications.

Advanced manufacturing of 3D-structured materials enables the production of biomimetic muscle tissues. While models of muscle tissue exist, current approaches possess a limited ability to capture essential elements of the muscle tissue microarchitecture. Therefore, this paper aims to engineer the intrinsically complex muscle spindle-like ellipsoid geometry using a polymer melt-based electrohydrodynamic (EHD) printing system. EHD systems have conventionally reported fiber deposition in a layerwise fashion. However, without mitigation, the observed fiber sagging and residual charge phenomena for the melt electrowriting (MEW) process limit the ability to produce layered fibrous 3D constructs with in-plane fiber alignment. However, in this work, fiber sagging and residual charge phenomena are leveraged as part of the design intent to deposit nonoverlapping suspended fibers between two stationary walls toward spindle-like construct fabrication. Specifically, herein the structural and mechanical properties of the MEW-enabled spindle-like constructs are analyzed as a function of the process and design parameters that govern control over fiber sagging and residual charge. The results indicate that the collector speed and wall-to-wall distance are the key parameters for tuning the spindle morphology. Moreover, cycle number and fiber diameter are identified as effective parameters for tuning the spindle mechanical properties.