Macromolecular Materials and Engineering最新文献

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.

The tunability of the lower critical solution temperature (LCST) of poly(N-isopropylacrylamide) (PNIPAM) to lower or higher temperatures, as well as the ease of modulation of the LCST phase transition kinetics broadens the scope of application of PNIPAM-based materials in biomedical fields. This work reports a facile approach to formulate a smart, injectable cellulose nanofibril (CNF)/PNIPAM hybrid gel. Hofmeister salts are used to induce ion-mediated gelation of the nanofibrils and PNIPAM chains, resulting in an interpenetrating network (IPN) structure. From rheological measurements, the hybrid material displays excellent structural integrity at room temperature and tunable thermo-stiffening around body temperature. De-swelling kinetics can be modulated by varying the nature and concentration of the Hofmeister ion used. The successful realization of the IPN hybrid gel structure is dependent on the molecular weight of PNIPAM used. Moreover, the hybrid gels show good thermo-reversibility during thermal cycling, as well as excellent injectability and remarkable self-healing post-injection, owing to shear-thinning and thixotropic characters. Since rheology is a crucial technique in the analysis of soft matter and flow behavior is fundamental for the design and synthesis of application-specific viscoelastic materials, the work reported herein provides a rheological basis for careful design and synthesis of smart gels.

Front Cover: High power, sunlight-simulated UV light induces radical polymerizations of (meth)acrylate-based monomers. During this process, mono-radicals can be generated through the H-abstraction mechanism, while bi-radicals can arise from photodissociation or oxygen initiation mechanisms. The generated free radicals facilitate self-initiation and self-crosslinking, rendering this technology efficient for synthesizing polymer networks without the need for added initiators or crosslinkers. This is reported by Wenqing Yan and co-workers in article 2399456.

Electrospun nanofiber membranes (ENMs) have emerged as a cutting-edge solution for membrane distillation (MD), recognized for their highly porous and interconnected architecture. This distinctive structure enables them to offer minimal mass transfer resistance, making them exceptionally suited for high-efficiency membrane-based separation processes. However, the very porosity that defines their strength also renders them vulnerable to fouling, scaling, and wetting during operation, which in turn compromises their performance. Current research efforts are geared toward overcoming these obstacles by refining the surface design and characteristics of ENMs. This review delves into the latest advancements in surface-enhanced electrospun nanofiber membranes tailored for MD applications. It discusses the existing gaps in research and provides forward-looking insights into the future of ENMs, spotlighting the development of membranes with precisely tunable surface attributes for optimized performance.

Polyethylene terephthalate glycol (PETG) is a novel amorphous shape memory polymer with excellent printability for 4D printing. In this article, ethylene-vinyl acetate (EVA) is used as a biocompatible and non-toxic copolymer to improve plasticity and shape memory performance of PETG. PETG-EVA blends are prepared and 3D printed using a melt mixing method and an upgraded fused deposition modeling (FDM) with a pneumatic feeding system. The results of the thermal analysis show that the blends exhibit two tan-delta peaks, each related to their components, and morphology images confirm that they are biphasic and immiscible with good compatibility. The morphology of both EVA10 and EVA30 matrix droplets is observed, with the droplets being larger for EVA30. The use of a pneumatic feeding system, along with the ability to control the output melt flow, results in the best printing ability for EVA30, with minimal microholes between the grids and interlayer cracks. The tensile strength of PETG-EVA blends ranged from 25.38 to 20.14 MPa, with the highest tensile strength achieved for EVA30. The shape memory performance of all three blends is similar; with shape recovery exceeding 90% in 20 s. Blends with higher EVA content exhibited faster shape recovery within the first 10 s.

Flexible microwave absorber (MAR), vital in advanced applications such as wearable electronics and precision devices, are highly valued for their lightweight, exceptional electromagnetic waves (EWs), and ease of fabrication. However, optimizing the electromagnetic parameters of microwave absorption materials (MAMs) to enhance absorption ability and expand effective absorption broadband (EAB, reflection loss (RL) <−10 dB) is a considerable challenge. Herein, a permittivity-attenuation evaluation diagram (PAED) is constructed using parameter scanning based on the Materials Genome Initiative to determine the ideal electromagnetic parameters and thickness, optimize absorption efficiency, and obtain highly efficient absorbers. Guided by the PAED, a multilayer MAR consisting of a “matching-absorption-reflection layer” and a dielectric loss gradient aligned with the direction of EWs propagation is developed. This design significantly enhances the EWs penetration and ensures effective absorption, attributed to the well-matched impedance and attenuation characteristics. As anticipated, the microwave absorption of the absorber (density = 0.063 g cm⁻³) is optimized, with an RL of −34 dB at d = 4 mm and an EAB covering the entire X-band (8.2–12.4 GHz). This study presents a novel approach for establishing a material database for MAMs and developing high-performance absorbers characterized by thinness, lightness, broad operational frequency range, and robust absorption capacity.