Macromolecular Materials and Engineering最新文献

Poly(lactic acid) (PLA), a polymer derived from renewable resources, is an increasingly popular choice for packaging. However, its inherently low melt strength, due to its linear molecular structure, limits its performance in processes such as foaming and thermoforming. This study introduces a method to enhance PLA's processability by employing electron beam irradiation with trimethylolpropane triacrylate (TMPTA) as a crosslinking agent. Through optimization using response surface methodology, ideal conditions of 5.5 kGy irradiation and 0.87 wt.% TMPTA was identified, facilitating structural modifications inferred to include long-chain branching, which led to improved rheological, thermal, and mechanical responses. When foamed in a PLA/polyethylene (70/30 wt.%) blend, PLA modified under these conditions exhibited a more refined cell structure and enhanced tensile properties compared to foams made from untreated PLA. This research demonstrates a modification pathway that advances PLA's suitability for diverse packaging and insulation applications by modulating its functional performance.

In this study, polylactic acid (PLA)/polybutylene adipate-co-terephthalate (PBAT)/Joncryl blends are prepared via film extrusion, compression molding, and injection molding to investigate the effects of processing sequence and compatibilization on interfacial interactions and final properties. Joncryl is added at 0.5 and 1 wt.% to assess its impact on phase adhesion, crystallinity, and mechanical performance. Results reveal that the two-step blending process, where Joncryl is first reacted with either PLA or PBAT, results in more uniform dispersion and enhanced interfacial interactions compared to the single-step method. Notably, the (70/30) PLA/PBAT blend incorporating 1 wt.% Joncryl via two-step blending shows tensile strength improvements of ≈6% and 15%, and elongation increases of ≈491% and 335.5% for (PLA+1J)/PBAT and (PBAT+1J)/PLA, respectively. For injection-molded samples, 0.5 wt.% Joncryl added through two-step blending improves elongation and impact strength by ≈75% and 140% in (PBAT+0.5J)/PLA. Film-extruded samples exhibit higher tensile strength than compression-molded ones due to better phase dispersion, orientation, and interfacial bonding enabled by slit-die extrusion and stretching. In contrast, compression molding lacks orientation effects, resulting in lower mechanical strength. These findings highlight the critical role of blending sequence and processing method in tailoring biodegradable PLA/PBAT blends for improved performance in packaging and related applications.

Biobased recyclable elastomers are interesting sustainable alternatives to existing fossil fuel-based and/or non-recyclable elastomers in diverse applications. Herein, a novel biobased thermoplastic elastomer, polyamide 36,10 (PA36,10), is synthesized by one-pot condensation polymerization without the use of harmful chemicals or solvents. Its chemical structure and molecular weights are characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance, and gel permeation chromatography. The glass transition temperature and melting temperature of the PA36,10, determined from differential scanning calorimetry, are −4 and 95 °C, respectively. The tensile strength and elongation at break are 16.80 ± 0.18 MPa and 1636 ± 108%, with Shore A and Shore D hardnesses of 97 and 47, as well as relatively good resilience. PA36,10 is foamed by extrusion using a 3 wt.% common blowing agent, ammonium bicarbonate. The resulting foam shows a bulk density of 0.67 ± 0.16 g.cm⁻³, with a compressive yield strength of 5.61 ± 0.71 MPa. The new biobased recyclable PA36,10 may find various potential applications in the elastomers industry.

As a way of recycling epoxy thermoset materials, they were blended with polycaprolactone (PCL) and processed in the form of filament to be used for fused deposition modeling (FDM) 3D printing. Three different epoxy materials were considered: a lab-cured epoxy resin, a lab-cured epoxy/PCL blend, and a commercial epoxy composite containing fiberglass (FR4). These three thermosets were milled and mixed with pure PCL. The distribution of the epoxy in the PCL matrix was analyzed by Fourier Transform Infrared Spectroscopy (FTIR) coupled to a microscope. The filler FR4 and DGEBA were adequately distributed in the matrix. The rheological study anticipated good adhesion between the layers, without clogging at printing temperatures. The rheological model also predicted filament buckling. Because of that, external assistance (PLA) was required to obtain appropriate printed samples, avoiding buckling. The mechanical properties of the specimens were determined by tensile tests and compared with injection molded specimens. It was observed that the incorporation of the epoxy thermoset to the PCL matrix enhanced Young's modulus of PCL. Very similar results were obtained between 3D printed and injected samples. The proposed method could be of significant interest in employing thermoset epoxy waste as a cost-effective reinforcement for fuse filament 3D printing materials.

Continuous progress in the applications of electroactive polymers caused the need for blends with stable morphology and superior performance to increase. Employing interfacial stereocomplex crystallization had been suggested to satisfy these requirements. The Effects of phase behaviors on the viscoelastic response, morphology, and miscibility in the biocompatible electroactive blends of poly vinylidene fluoride (PVDF), poly L-lactic acid (PLLA), and poly D-lactic acid (PDLA) are investigated in one-step reactive meltmixing by adding the Joncryl chain extender via the small amplitude oscillatory shear (SAOS) experiments, dynamic mechanical thermal analysis (DMTA), temperature modulated differential scanning calorimetry (TMDSC), and field emission scanning electron microscopy (FESEM). The presence of the Joncryl causes the formation of branched copolymer compatibilizers (BCCs) during the meltmixing of the immiscible PVDF/PLLA/PDLA blends. BCCs are localized at the interface and enhance the interfacial adhesion, compatibility, and mechanical properties. Dielectric relaxation, rheological tests, and transmission electron microscopy (TEM) confirm the formation of a rigid thin layer of stereocomplex crystals at the interface, resulting in the formation and stabilization of the co-continuous morphology, by suppressing the migration of BCCs and coarsening and coalescence. The crystallization mechanism and crystal structure for each component are exploredby Non-isothermal DSC, X-ray, and Fourier-transformed infrared (FTIR) spectroscopy.

In this study, for the first time thermoplastic polyurethane (TPU), fish skin gelatin (FSG), and H. perforatum oil (HPO) combine to form a new nanofiber material by using the emulsion electrospinning technique. Scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA) are used for the characterization studies. Moreover, antibacterial activities, in vitro wound healing and cytotoxicity of the TPU mats are also investigated. The SEM investigations reveal that the average diameters of defect-free TPU nanofiber mats with diverse HPO concentrations are ≈400–500 nm and suitable to mimic the native extracellular matrix (ECM) with these values. Moreover, although there is no antibacterial activity in the control TPU mat, the addition of the tannic acid crosslinker and 12% of HPO to the nanofiber mat acquires a 31.3% inhibition against Staphylococcus aureus and a 21.0% against Escherichia coli. Furthermore, the TPU nanofiber mat with the highest HPO concentration (12%) is non-toxic to the cells and tends to promote healing in vitro assay. Overall results indicate that the wound healing properties of the obtained HPO-encapsulated TPU nanofiber mats can be a promising candidate for wound dressing applications.

With the emergence of 3D bioprinting, tissue repair strategies have become more sophisticated and multifunctional. Natural biomaterials like alginate and gelatin have been widely studied to formulate bioinks due to their excellent biocompatibility and biodegradable characteristics. However, the requirement for balanced features combining adjustable degradation rate, printability, and biological functionality is still hard to achieve. In this study, alginate dialdehyde (ADA) – gelatin (GEL) based hydrogels have been supplemented with mesoporous bioactive glass nanoparticles (MBGNs) and human platelet lysate (HPL) to enhance the biological performance. MBGNs can reduce the degradation of ADA-GEL 3D printed scaffolds and induce a mineralization effect while HPL is added as a source of growth factors. Improved printability and higher shape fidelity are observed by incorporating 0.1% (w/v) MBGNs, however, the addition of HPL led to a slight decrease in 3D printed shape fidelity. On the other hand, MBGNs and HPL both presented positive effects to improve cell activity and viability, which is characterized by using MC3T3-E1 pre-osteoblast cells. The ADA-GEL-based hydrogel with the incorporation of 0.1% (w/v) MBGNs and 5% (v/v) HPL shows the most balanced features, making it a promising biomaterial for 3D bioprinting of bone tissue scaffolds.

This study presents a hybrid modeling approach that integrates Kragelsky’s friction law and Archard’s wear law with an artificial neural network (ANN) to predict the coefficient of friction (COF) and specific wear rate (SWR) in epoxy-based self-lubricating composites reinforced with graphite and MoS₂. Given the complex, nonlinear interactions among tribological parameters such as contact pressure, sliding speed, hardness, and filler composition, traditional empirical models often fail to capture wear behavior accurately. The proposed ANN architecture comprises an input layer, three hidden layers employing sigmoid, ReLU, and power activation functions, and an output layer predicting COF and SWR. The network is trained using a feed-forward method with backpropagation to minimize prediction error. SEM analysis reveals that graphite imparts superior wear resistance compared to MoS₂. The ANN achieved significantly higher prediction accuracy for graphite-reinforced composites. For COF, graphite yielded an MSE of 0.00073 and R² of 0.9047, while MoS₂ showed an MSE of 0.00318 and R² of 0.5567. For SWR, graphite attained an MSE of 1.3351 and R² of 0.9809, compared to MoS₂ with an MSE of 1.6993 and R² of 0.8271. The reduced performance in MoS₂ predictions is attributed to its oxidative degradation forming MoO₃. The model also offers 3D surface simulations, aiding in composite design optimization and reducing experimental costs.

This study presents the development of high-performance poly(vinylidene fluoride) (PVDF) based piezoelectric nanocomposites incorporating branched carbon nanotubes (bCNTs) and zinc oxide nanowires (ZnO NWs) through a scalable melt mixing process. ZnONWs with uniform morphology (mean diameter: 36.5 nm) are successfully synthesized and characterized. FTIR analysis confirms that incorporating bCNTs into PVDF significantly enhances the β-phase content, while adding ZnO NWs (1–10 wt.%) resulted in progressive intensification of β-phase characteristic peaks, with higher ZnO content showing stronger electroactive phase formation. The optimized composition (PVDF/0.5 wt.% bCNTs/5 wt.% ZnO NWs) demonstrates superior piezoelectric performance with a power density of 5.62 µW cm⁻², voltage output of 1.55 V, and current output of 14.48 µA. Moreover, the composite exhibits excellent mechanical properties with a tensile strength of 48 MPa and maintains stable performance under cyclic loading. The enhanced performance is attributed to the synergistic effect between bCNTs and ZnO NWs, optimal β-phase formation, and efficient charge transfer pathways. This study demonstrates the potential of melt-mixed PVDF nanocomposites for practical energy harvesting applications.