Journal of Polymer Science最新文献

Fused deposition modeling (FDM) faces significant challenges in producing unsupported overhangs, particularly regarding dimensional accuracy and surface quality. While support structures can address these issues, they increase material waste and post-processing requirements. This study investigates how process parameters affect the quality of unsupported inclined surfaces in FDM printing, aiming to optimize fabrication without support structures. Test specimens with three surface inclination angles—75° (Surface-1), 60° (Surface-2), and 45° (Surface-3)—were produced using acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and polyethylene terephthalate glycol (PETG). The study employed an L27 Taguchi orthogonal array to evaluate five key process parameters: material type (MT), infill pattern (IP), wall thickness (WT), infill density (ID), and layer thickness (LT). Dimensional deviations and surface roughness were measured across all angled regions. Dimensional deviations remained below 2.3% across all specimens. ANOVA revealed LT and MT as the most significant factors affecting both dimensional accuracy and surface roughness (p < 0.001), with LT showing the highest contribution to surface roughness variance (F values > 500). Surface roughness improved with decreasing surface angles, while dimensional accuracy showed an inverse trend. Artificial neural network (ANN) models developed for predicting quality metrics achieved R ² values exceeding 0.90. This study establishes a comprehensive framework integrating Taguchi design, statistical analysis, and machine learning (ML) for optimizing unsupported overhang fabrication in FDM. The findings reveal crucial relationships between process parameters and part quality, demonstrating that carefully controlled parameter selection can achieve acceptable quality without support structures. The developed predictive models offer a reliable tool for parameter optimization in FDM manufacturing of unsupported overhangs.

This study utilizes the homopolymer, poly(sodium 2-acrylamido-2-methylpropanesulfonate) (PAMPSNa₉₀) to synthesize the thermo-responsive ionic liquid polymer P[AMPS][P₄₄₄₈]₉₀ by exchanging the counter cation, sodium (Na⁺) of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) with tributyl(octyl)phosphonium bromide ([P₄₄₄₈ ⁺]Br). Furthermore, a two-step synthesis approach was employed to create a dual thermo-responsive water-soluble diblock copolymer PAMPSNa₉₀-b-PNIPAM₂₇₉ composed of PAMPSNa₉₀ and poly(N-isopropylacrylamide) (PNIPAM) via reversible addition-fragmentation chain transfer polymerization. Later a modification was carried out to exchange the counter cation Na⁺ in PAMPSNa₉₀-b-PNIPAM₂₇₉ with [P₄₄₄₈ ⁺], resulting in the P[AMPS][P₄₄₄₈]₉₀-b-PNIPAM₂₇₉. The individual synthesized polymers were extensively characterized using proton nuclear magnetic resonance spectroscopy and gel permeation chromatography to infer their correct synthesis composition and molecular weight. Turbidity, measured by the percentage transmittance, revealed the thermo-responsive behavior of these synthesized blocks. The hysteresis phenomenon of heating/cooling for each synthesized polymer was identified as single or dual cloud point temperature, depending on the applied stimuli such as polymer concentration, temperature rate, and sonication. Scattering techniques, such as dynamic light scattering and small-angle neutron scattering, were employed to obtain insight into the size/shape of the self-aggregates formed in an aqueous solution environment, which is supported using transmission electron microscopy.

High temperature resins are of interest in many applications including use in extreme environments including atmospheric reentry. Finding methodology to reduce additives while increasing processability for these resins while simultaneously relying less on petroleum-based products is of high importance so that large-scale manufacturing becomes more accessible. Herein, we report the synthesis of a series of new vanillin-oxydianiline (Vn-ODA) based phthalonitrile (PN) resins. These resins contain the bio-based monomer, vanillin, along with internal initiators via an imine linkage formed by the vanillin and ODA molecules, eliminating the requirement for additives to initiate curing. The resulting resins exhibit good thermo-oxidative properties with char yields under N₂ above 75% and thermolytic degradation above 490°C under air. Furthermore, the meta- and para- resins exhibit promising processing windows with low melt temperatures and a T _g above final cure temperature.

For the proton exchange membrane (PEM) applying in vanadium flow battery (VFB), it is difficult to separate the electrolyte ions at two electrodes while conducting protons. In this work, a novel composite membrane is developed, organically modified-MXene (MDP) filled sulfonated poly(ether ether ketone) (SPEEK) membrane, where MDP is prepared through co-coating the polydopamine (PDA) and polyethyleneimine (PEI) on the surface of MXene. The two-dimensional structure of MXene can effectively reduce the vanadium ions permeation, while the surface functional groups from the coating layer can assist in proton transport, thus enhancing the membrane selectivity. The membrane with only 1.0 wt% MDP (SPEEK/MDP-1) achieves maximum selectivity of 7.1 × 10⁷ S min cm⁻³. Furthermore, the energy efficiency (EE) of the VFB loaded with SPEEK/MDP-1 reaches ~92.5% at 40 mA cm⁻² current density. This work provides a new direction for enhancing the properties of PEM used in VFB applications.

The widespread use of polycaprolactone (PCL) in electrospun scaffolds for biomedical applications is often hindered by the reliance on toxic halogenated solvents such as chloroform and dichloromethane. In this study, an innovative green solvent system based on acetone and dimethyl carbonate (DMC) is proposed for the electrospinning of PCL, aiming to reduce environmental and health risks while preserving fiber quality for biomedical applications. The acetone: DMC mixture was optimized for solubility, volatility, and electrospinnability to produce bead-free, uniform nanofibers with morphological tunability. Physicochemical properties, including mechanical properties, percentage of swelling, degradation, and Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis, were conducted on the electrospun membranes. Initial in vitro experiments confirm the biocompatibility of the resultant membranes, supporting their application in tissue engineering and drug delivery. This green solvent method offers a sustainable and safer approach for electrospinning PCL, without compromising its functional properties.