This is an editorial article. It has no abstract.
Cellulose nanomaterials (CNs) have been successfully applied to a variety of scientific areas in recent years with remarkable engineering utilities. As sustainable materials of huge abundance, CNs show significant potentials in fine-tune the microstructures and kinetics from the nano-level. This paper reviews recent key advancements of the use of CNs in the fields of pharmaceutical science and pharmacology. A broad overview of the development of CNs is provided, and the current methods to obtain the materials are discussed. The different types of processing techniques are reviewed, that are critical to the applications in pharmaceutical science and pharmacology. The key breakthroughs of applications in major fields are discussed, including oral administration, topical administration, tissue scaffolds, and antibacterial applications.
The objective of this study is to improve the mechanical performance of carbon fiber reinforced polymer (CFRP) adhesive joints, called ‘laminated joints’. The laminated joints are made by stacking two dry carbon fiber fabric halves together and molding using vacuum-assisted resin transfer molding (VARTM) process. An improved design of this joint was fabricated by overlapping the two half fabrics and adding extra carbon fiber fabric pieces. Four joints are considered in this work: a conventional laminated joint, two laminated joints with overlap, and a multiple-covers laminated joint. The composite joints are characterized in terms of static flexural and impact strength and fatigue performance. In addition, post-fracture analysis is performed using optical microscopy to identify the dependence of failure modes and its propagation in composite joints.
Boron nitride (BN) and silicon nitride (Si3N4) are very promising particulate fillers for production of photocurable composites dedicated to thermally conductive and electrically insulating protective coatings. Composites containing crosslinked methacrylate-based matrices filled with BN or Si3N4 (in amounts up to 5 wt%) were prepared in a fast in situ photocuring process with high conversion (>90%). The monomers were polyethylene glycol dimethacrylate and mono - methacrylate (50/50 by weight mixture). Investigations included determination of properties of the monomer/filler compositions, photocuring kinetics and thermal, conductive and mechanical properties of the resulting composites. It was found that addition of the fillers improves polymerization kinetics and mechanical properties compared to the pure polymer matrix. Despite the very low loading level a substantial improvement in thermal conductivity was obtained: a 4-fold increase after addition of only 2 wt% of Si3N4 and 2.5-fold increase after addition of 0.5 wt% of BN. SEM and AFM imaging (with nanoscopic Young’s modulus determination) revealed good matrix-filler adhesion for the both types of fillers, tendency of the particles to be preferentially located in the bulk rather than at the interface and formation of thermally conducting paths (for the Si3N4 filler).
This research work aims at the compatibilization of poly(lactic acid)/poly(butylene adipate-co-terephthalate), PLA/PBAT binary blends by using cottonseed oil derivatives, i.e. epoxidized (ECSO) and maleinized (MCSO) cottonseed oil. The potential of these vegetable oil-based compatibilizers are compared versus the effects of a conventional styreneacrylic oligomer. The base PLA/PBAT binary blend composition was 80 wt% PLA/20 wt% PBAT and the amount of compatibilizer was set to 1 and 7.5 wt%. The effects of the different compatibilizers were evaluated on PLA/PBAT films in terms of mechanical and thermal properties as well as blend’s morphology by field emission scanning electron microscopy (FESEM). Complementary, biodisintegration tests in controlled compost soil and surface properties were evaluated to assess the effects of the compatibilizers. Addition of 1 wt% ECSO and MCSO led to a remarkable increase in the elongation at break up to values over 100% with regard to neat PLA. Despite this, maximum elongation at break was obtained for the compatibilized PLA/PBAT blend with 7.5 wt% MCSO, reaching values of about 321.2% respect neat PLA keeping mechanical resistant properties, such as Young’s modulus and tensile strength, at high levels. Therefore, vegetable oil-derived compatibilizers stand out as environmentally friendly additives for PLA/PBAT binary blends with improved properties.
Tuning the viscoelastic features required for 3D printing of PVC-acrylate copolymers obtained by single electron transfer-degenerative chain transfer living radical polymerization (SET-DTLRP)
M. I. Calafel, R. H. Aguirresarobe, N. Sadaba, M. Boix, J. I. Conde, B. Pascual, A. Santamaria
Vol. 12., No.9., Pages 824-835, 2018
Vol. 12., No.9., Pages 824-835, 2018
Random poly (vinyl chloride-co-butyl acrylate) and poly (vinyl chloride-co-2-ethylhexyl acrylate copolymers obtained by single electron transfer-degenerative chain transfer living radical polymerization (SET- DTLRP) are investigated as potential candidates for 3D Printing. The analysis of the rheological implications of 3D Printing process allows establishing the basic viscoelastic conditions that the samples should fulfil to be printable, avoiding the ‘trial and error’ procedure. The effect of temperature and acrylates concentration on the rheological properties and 3D printing feasibility is contemplated. Eventually, thermal degradation is also considered. It is demonstrated that the copolymers which contain butyl acrylate comonomer, instead of 2-ethylhexyl acrylate, give raise to the best results. Although the study is carried out with PVCacrylate copolymers and a 3D printing device that possesses set up characteristics, it shows a way to work out sound strategies with other polymers and 3D printing machines.
The waterborne polyurethane (WPU)/hydroxyethyl cellulose (HEC) chemical hybrids were synthesized by incorporating vinyltrimethoxysilane (VTMS) modified HEC (VC) into the WPU. Effects of VC on the contact angle, gel content, thermal and mechanical properties of the cast films, and biodegradation in cellulase solution were evaluated. It was found that the VTMS modified HEC provided the WPU with multifunctional crosslinks as well as conventional reinforcing fillers and biodegradability.
In this study, cellulose nanofibers (CNFs) were derived from waste pineapple leaves with the aim of developing a nanocomposite with high impact strength and transparency. First, CNFs were prepared using an acid-base treatment and 2,2,6,6-tetramethylpiperidin-1-oxyl radical (TEMPO)-mediated oxidation, and then, the surface was modified with polymerized methyl methacrylate (MMA) using an eco-friendly method in an aqueous system. The MMA-modified CNF had an increased contact angle from 12.02 to 57.45°, and the surface hydrophobicity improved the interfacial compatibility between the CNF and polymethyl methacrylate (PMMA) matrix. At 1–3 wt% of the modified CNF, the impact strength of the nanocomposites was significantly improved by 2.7–22.9%. Moreover, this eco-friendly modification allowed CNFs to disperse homogeneously in the nanocomposite for excellent light transmittance. In conclusion, this eco-friendly modification can replace conventional solvent-based modification, allowing modified CNF to effectively reinforce the PMMA nanocomposite.