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This study presents a comparative analysis of carbon fiber reinforced polymer (CFRP) composites manufactured through vacuum assisted resin infusion (VARI) using a traditional epoxy resin (E), a fully‐recyclable epoxy resin system with (BBR10) and without (BBR) the addition of a reactive diluent (R*Diluent). Various mechanical and thermal tests were conducted to assess their performance. The BBR10 laminate, incorporating 10 wt% R*Diluent, exhibited competitive mechanical performance, comparable to traditional (E) and fully‐recyclable laminates (BBR). Despite a slightly lower ultimate tensile strength (UTS) compared with BBR, BBR10 demonstrated improved flexural strength and modulus. Low‐velocity impact testing confirmed comparable strength between VARI‐produced composites with the recyclable matrix (BBR and BBR10) and the traditional one (E). X‐ray mCT investigations revealed distinct void arrangements in the CFRP laminates. Additionally, a chemical approach was employed for recovering high fractions of fibers from CFRP laminates with a recyclable matrix (BBR and BBR10). Chemical recycling achieved an almost 100% yield for long carbon fibers. Highlights: Comparative analysis of CFRP composites manufactured through VARI.Diluent addition allowed to tailor the recyclable epoxy viscosity.Mechanical characterization of traditional and fully recyclable epoxy resins.Investigation by X‐ray mCT of potential flaws and manufacturing defects.Chemical recycling of CFRP laminates with a recyclable matrix. [ABSTRACT FROM AUTHOR]

The aim of this study was to explore the thermal properties of epoxy–acrylate blends for the liquid crystal display (LCD) 3D printing technique. Starting from an epoxy–acrylate blend with a ratio of epoxy to acrylate of 50:50, the effect of adding a reactive monofunctional epoxy diluent was evaluated. The diluent was a resin composed by oxirane, mono[(C12-14 alkyl) methyl] derivatives selected for its low viscosity (i.e., 1.8 Poise) at room temperature and its reactivity. The diluent content varied from 15 to 25 wt% and, for all the formulation, double curing cycles, where thermal curing followed photocuring, were studied. The effect of different curing temperatures was also evaluated. The control of the diluent content and of the curing temperature allowed tailoring of the thermomechanical resin properties while improving the resin's processability. The glass transition ranged from 115.4 °C to 90.8 °C depending on the combination of diluent content and post-curing temperature. The resin developed displayed a faster processing time tested on a reference part with printing time of 4 h and 20 min that was much lower than the printing times (7 and 16 h) observed for the starting formulations. [ABSTRACT FROM AUTHOR]

In this work, a quadratic polynomial regression model was developed to aid practitioners in the determination of the refractive index value of transparent 3D printable photocurable resins usable for micro-optofluidic applications. The model was experimentally determined by correlating empirical optical transmission measurements (the dependent variable) to known refractive index values (the independent variable) of photocurable materials used in optics, thus obtaining a related regression equation. In detail, a novel, simple, and cost-effective experimental setup is proposed in this study for the first time for collecting the transmission measurements of smooth 3D printed samples (roughness ranging between 0.04 and 2 μm). The model was further used to determine the unknown refractive index value of novel photocurable resins applicable in vat photopolymerization (VP) 3D printing techniques for manufacturing micro-optofluidic (MoF) devices. In the end, this study proved how knowledge of this parameter allowed us to compare and interpret collected empirical optical data from microfluidic devices made of more traditional materials, i.e., Poly(dimethylsiloxane) (PDMS), up to novel 3D printable photocurable resins suitable for biological and biomedical applications. Thus, the developed model also provides a quick method to evaluate the suitability of novel 3D printable resins for MoF device fabrication within a well-defined range of refractive index values (1.56; 1.70). [ABSTRACT FROM AUTHOR]

SiO2, ZrO2 and SiO2–ZrO2 composites at different percentages of zirconia were synthesized by the sol–gel method and spectroscopically characterized by Fourier transform infrared (FTIR) spectroscopy. Different series of composites were prepared and analyzed, as it is and with a post-preparation conditioning at 600 and 1000 °C, respectively. The calcination were carried out to verify the changing in composite structure and whether these treatments will affect the subsequently characterization. In fact, silica, zirconia and their composites were than subjected to oxidative degradation up to 800 °C by the means of thermogravimetric analysis (TGA). Residues, obtained at 800 °C by the thermogravimetric (TG) scans, were analyzed by FTIR to evaluate the differences with the spectra of the composites obtained before TGA. TG curves were discussed to describe the thermal behavior of the prepared composites and to highlight the influence of zirconia amount on the composites degradation behavior. [ABSTRACT FROM AUTHOR]

This study focuses on the characterization of 3D printed parts by fused deposition modelling (FDM) technique made from a composite filament, highly loaded of stainless-steel microparticles, prepared at different infill density (0, 50, 100%). Thermo-mechanical properties, morphological aspects and heat transport behaviour of the developed specimens have been investigated by dynamic-mechanical analysis (DMA), thermal diffusivity measurements and scanning electron microscopy (SEM). Experimental results allowed to attest a drastic reduction of storage modulus in the range of testing temperatures by reducing the infill density. In the meantime, an increment of dissipation factor was shown in lesser stiff samples at temperatures near to the ambient. The same increasing trend did not appear in the case of thermal diffusion that showed closer values for samples at 0 and 50% of infill, and an augment in the case of infilling level of 100%. This outcome, explained through SEM pictures, was attributed to the difficulty in realization of perfect empty internal structures within 3D parts. A supporting analysis by IR spectroscopy was conducted on the composite surface to gain qualitative information about constituting polymer filament. Further considerations on the porosity of systems have been obtained elaborating SEM micrographs with ImageJ software. [ABSTRACT FROM AUTHOR]

Development of pH-dependent systems for colon delivery of natural active ingredients is an attractive area of research in the field of nutraceutical products. This study was focused on Eudraguard ® resins, that are methacrylate copolymers approved as "food grade" by European Commission and useful for the production of food supplements. In particular, Eudraguard ® Biotic (EUG-B), characterized by a pH-dependent solubility and Eudraguard ® Control (EUG-C), whose chemical properties support a prolonged release of the encapsulated compounds, were tested. To obtain EUG microparticles, different preparation techniques were tested, in order to optimize the preparation method and observe the effect upon drug encapsulation and specific colonic release. Unloaded microparticles were initially produced to evaluate the influence of polymer characteristics on the formulation process; subsequently microparticles loaded with quercetin (QUE) as a low solubility model drug were prepared. The characterization of microparticles in the solid-state (FT-IR spectroscopy, differential scanning calorimetry and X-ray diffractometry) indicated that QUE was uniformly dispersed in a non-crystalline state in the polymeric network, without strong signs of chemical interactions. Finally, to assess the ability of EUG-C and EUG-B to control the drug release in the gastric environment, and to allow an increased release at a colonic level, suitable in vitro release tests were carried out by simulating the pH variations along the gastro-intestinal tract. Among the evaluated preparation methods, those in which an aqueous phase was not present, and in particular the emulsion-solvent evaporation method produced the best microparticle systems. The in vitro tests showed a limited drug release at a gastric level and a good specific colon release.