The reproducibility of electrospun fibrous microarchitecture remains limited by the interaction between jet instability and deposition history. This study evaluated four programmed needle trajectories—Spiral, Static, Waves, and Zig-Zag—using a hybrid electrospinning–3D-printing motion platform. Four independent deposition runs were produced per trajectory (n = 4), yielding 16 SEM datasets and 16 tensile specimens. SEM images were calibrated automatically from the 50 µm scale bar and analyzed using a common physical ROI, skeleton-based fiber-diameter estimation, pore-opening analysis, spatial coverage, segment orientation, and 2D FFT descriptors. The four motion programs generated distinct and reproducible macroscopic deposition paths, while the replicated whole-ROI scalar descriptors showed substantial overlap: mean fiber diameter, pore opening, coverage, porosity, FFT alignment, and angular spread did not differ significantly among trajectories (one-way ANOVA p = 0.726–0.985 for the principal descriptors; Kruskal–Wallis p = 0.608–0.931). PCA likewise showed substantial overlap in the reduced global-descriptor space. Maximum tensile stress was 0.185 ± 0.052, 0.227 ± 0.079, 0.214 ± 0.147, and 0.189 ± 0.051 MPa for Spiral, Waves, Static, and Zig-Zag, respectively, without a significant inter-trajectory difference (p = 0.900). These results support a two-scale interpretation: programmed XYZ geometry provides deterministic control of the macroscopic deposition path and changes the spatial history of fiber landing and overlap, whereas fiber formation and whole-ROI averaged morphology remain strongly governed by electrohydrodynamic/material conditions and deposition-to-deposition variability. These findings demonstrate the feasibility of integrating electrospinning with programmable XYZ needle motion within a custom-designed platform. Although the programmed trajectories define distinct needle-motion geometries, no statistically significant differences were detected in the principal global morphological or mechanical descriptors under the investigated conditions.
Drilling fluids play a critical role in efficient cuttings transport, suspension of drilled solids, hydraulic performance, and wellbore stability, making rheological control essential for safe and efficient drilling operations. However, conventional viscosifiers may have limited performance under demanding drilling conditions, motivating the development of nanocomposite–polymer systems with enhanced rheological tunability. The work in this article explores the viscosities of drilling fluid following the incorporation of a hydrothermally synthesized nanocomposite material formed through the interaction of titanium and graphene oxide, and a biopolymer, sodium alginate. A response surface methodology (RSM) approach based on concentration was employed to systematically observe the effects of these two different entities on the viscosity of the drilling fluid. During testing, 13 experimental runs were conducted to assess the influence of particle concentration on plastic viscosity and apparent viscosity. A strong correlation was established between the experimental test runs and the predictive model generated using this RSM, with R2 = 96.30% (adjusted R2 = 93.65% and predicted R2 = 84.13%) for plastic viscosity and R2 = 96.97% (adjusted R2 = 94.80% and predicted R2 = 85.04%) for apparent viscosity, and all 95% relative errors below 15%. ANOVA showed that the nanocomposite concentration was the significant parameter with p-value < 0.05 in both plastic viscosity and apparent viscosity, whereas the linear effect of sodium alginate was not significant as it demonstrated p-values > 0.05. Increasing the nanocomposite from 0.35 to 3.5 g at 0.35 g of sodium alginate raised the predicted plastic viscosity from 9.55 to 23.95 cP (+150%) and the apparent viscosity from 18.83 to 38.03 cP (+101%). The graphene oxide provides the anchoring sites to TiO2 nanoparticles that ultimately increase the inter-particle contact and exert an influence on both the viscosities. Additionally, in aqueous media, TiO2 nanoparticles hydroxylate, thus forming hydrogen bonding with graphene oxide. This interaction reduces the slippage effect of TiO2 nanoparticles between the fluid layers and eventually increases the friction force of the system. Furthermore, the sodium alginate adsorbs onto the large surface area of the nanomaterial, minimizing nanoparticle aggregation and forming a stable suspension, which in turn increases the viscosity. However, the influence of the biopolymer was minimal compared with the nano-dimension nanocomposite material. Overall, the findings offer valuable insights into the synergistic effects of biopolymers and nanocomposites in improving the lifting and transportation of drill cuttings, and in mitigating wellbore instability issues.
Polymer matrix composites are used in many components in the automotive sector due to their high specific mechanical properties, and their use in energy-absorbing structures provides significant reductions in vehicle weight. In this study, the energy absorption behavior and load-carrying capacity of nested glass fiber reinforced epoxy composite (GFRP) tubes with and without expanded polypropylene (EPP) foam filling were investigated under quasi-static axial loading. Three nesting arrangements of three concentric tubes were tested: equal-length, short-to-long and long-to-short. Foam filling increased the load-carrying capacity and the absorbed energy of all nested configurations. For the equal-length configuration, EPP foam filling increased the mean crushing force and absorbed energy by approximately 34%, while the specific energy absorption (SEA) improved by about 12%. In the short-to-long configuration, foam filling increased the absorbed energy by approximately 30%, whereas in the long-to-short configuration the increase was approximately 19%; however, the SEA increased by only 6% in the short-to-long configuration and remained practically unchanged in the long-to-short configuration, and the maximum force increased by 24–40% with foam filling. Among the investigated arrangements, the equal-length nested tubes exhibited the highest energy absorption, while the short-to-long configuration provided the lowest initial force and a stepwise load progression due to sequential tube activation. The long-to-short configuration demonstrated intermediate behavior with relatively higher force levels and moderate energy absorption. The results indicate that both foam filling and nesting arrangement govern the quasi-static crushing response of nested composite tubes and that the gain in absorbed energy due to foam filling must be weighed against the added mass and the higher transmitted force.
This study addresses the development, thermal characterisation, and dimensional stability of circular composites based on a post-industrial recycled polypropylene (rPP) matrix from household appliances. The matrix was reinforced with natural (B600 and BC300) and recycled (SIS250, PWC500, and ZZC500) cellulosic fibres at 10%, 20%, and 30% dosages, using 3% MAPP as a compatibilizer. Processing was conducted via twin-screw extrusion and injection moulding. Systematic evaluations (TGA-DTG, DSC, and DIL) showed a minor reduction (2.6–5.1%) in thermal degradation onset, maintaining a safe processing window. Cellulosic fibres generally promoted matrix crystallization through heterogeneous nucleation, increasing matrix crystallinity up to 39.3% in composite B600-30 compared to 20.4% for the reference rPP matrix. Furthermore, the reinforcements acted as dimensional stabilizers, reducing the linear thermal expansion coefficient (α40−120) by up to 28.9% (ZZC500-30) while increasing thermal conductivity by up to 32.7% (B600 series). This approach demonstrates a viable upcycling strategy, yielding high-secondary-content circular composites by combining post-industrial recycled polypropylene matrices with reinforcements (virgin wood cellulose benchmarks (B600 and BC300), pre-consumer recycled cellulose (PWC500), post-consumer recycled cellulose (ZZC500), and recycled technical sisal (SIS250), complemented by 3 wt.% commercial MAPP compatibilizer.
Re-aligned recycled carbon fiber (rCF) yarns provide a complementary architecture to aligned rCF tapes, enabling load-path-oriented reinforcement placement with potential for automated near-net-shape preforming and three-dimensional formability. This study investigates hybrid rCF/polyamide 11 (PA11) wrap yarns produced through roller carding, hollow-spindle wrap spinning, tailored fiber placement (TFP), and consolidation. Two rCF/PA11 yarn formulations with nominal fiber/matrix mass ratios of 72/28 and 80/20 were developed, yielding fiber volume fractions of 54.4 and 58.5 vol.%, respectively. Mechanical characterization focused on UD coupon testing under axial tensile, transverse tensile, and shear loading. For the rCF/PA11 72/28 and 80/20 formulations, longitudinal tensile testing yielded moduli of 57.8 ± 4.2 and 64.3 ± 6.3 GPa and strengths of 920 ± 41 and 815 ± 86 MPa, respectively. The 72/28 material additionally exhibited an in-plane shear modulus of 1.87 ± 0.03 GPa and shear strength of 48.7 ± 1.4 MPa. Relative to the previously reported aligned rCF/PA11 tape laminates at a comparable fiber volume content, albeit with distinct processing machinery, the 72/28 yarn laminate showed higher longitudinal modulus and longitudinal strength but substantially lower transverse and shear properties, suggesting a possible architectural trade-off associated with discrete yarn lanes, helical wrapping, and TFP preforming. A conrod-shaped preliminary structural benchmark manufactured from rCF/PA11 72/28 sustained 11.3 ± 0.5 kN at a mass of 23.0 ± 1.0 g, corresponding to a 71% higher specific load capacity than the aluminum reference. Proof-of-concept thermoforming of three double-curved shell demonstrators confirmed the capability of the yarn-based preforms to form complex three-dimensional geometries, although local fiber alignment defects highlighted the need for improved draping control. A screening life-cycle assessment estimated 0.42 kg CO2-eq per rCF/PA11 benchmark part, representing reductions of approximately 63% relative to the virgin-CF/PA12 stretch-broken yarn route and 52% relative to virgin-CF/epoxy routes. The results demonstrate the potential of rCF/PA11 wrap yarns as high-fiber-content textile intermediates for load-path-oriented TFP preforming and subsequent three-dimensional thermoforming.
