Papers by Tamara Calvo Correas
Express Polymer Letters
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Polymers
In order to continue the development of inks valid for cold extrusion 3D printing, waterborne, po... more In order to continue the development of inks valid for cold extrusion 3D printing, waterborne, polyurethane–urea (WBPUU) based inks with cellulose nanofibers (CNF), as a rheological modulator, were prepared by two incorporation methods, ex situ and in situ, in which the CNF were added after and during the synthesis process, respectively. Moreover, in order to improve the affinity of the reinforcement with the matrix, modified CNF was also employed. In the ex situ preparation, interactions between CNFs and water prevail over interactions between CNFs and WBPUU nanoparticles, resulting in strong gel-like structures. On the other hand, in situ addition allows the proximity of WBPUU particles and CNF, favoring interactions between both components and allowing the formation of chemical bonds. The fewer amount of CNF/water interactions present in the in situ formulations translates into weaker gel-like structures, with poorer rheological behavior for inks for 3D printing. Stronger gel-lik...
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Polymers
To prepare nonwoven mats constituted by submicrometric fibers of thermally responsive biopolyuret... more To prepare nonwoven mats constituted by submicrometric fibers of thermally responsive biopolyurethanes (TPU) modified with multiwalled carbon nanotubes (MWCNT), solution blow spinning (SBS) was used. The TPU was the product of synthesis using poly(butylene sebacate)diol, PBSD, ethyl ester L-lysine diisocyanate (LDI), and 1,3-propanediol (PD) (PBSe:LDI:PD) as reactants. TPU was modified by adding different amounts of MWCNT (0, 0.5, 1, 2, and 3 wt.%). The effect of the presence and amount of MWCNT on the morphology and structure of the materials was studied using field-emission scanning electron microscopy (FESEM) and Fourier-transform infrared spectroscopy (FTIR), respectively, while their influence on the thermal and electric behaviors was studied using differential scanning calorimetry (DSC) and capacitance measurements, respectively. The addition of MWCNT by SBS induced morphological changes in the fibrous materials, affecting the relative amount and size of submicrometric fibers ...
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Reactive and Functional Polymers
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Cellulose, 2021
Cellulose nanocrystals (CNC) have been studied as rheological modulator in order to improve the p... more Cellulose nanocrystals (CNC) have been studied as rheological modulator in order to improve the printing performance of a novel polycaprolactone-polyethylene glycol (PCL-PEG) waterborne polyurethane urea (WBPUU) based ink for direct ink writing 3D-printing technology. The cellulose nanocrystals are chemically bonded to the WBPU, since they were added during the synthesis of a WBPUU, in order to tune the rheological properties of the ink and thus, improve the printing performances. The WBPUU-CNC inks have been extensively characterized from the rheological viewpoint and have been subsequently used to print different pieces. To determine the capacity of the CNC to improve the printing performance of this type of inks, we establish the relationship between the rheological properties of the inks and their printing viability by an optimal window of compositions of the inks. Additionally, we have measured the mechanical and thermomechanical properties of printed WBPUU-CNC pieces to evaluate the effective reinforcement of in situ incorporated CNC in the WBPUU-CNC inks. The results showed that the addition of CNC accentuates the shear-thinning behaviour, presenting lower tan δ, especially at the lowest CNC contents compared with the matrix, which resulted in inks with excellent printable properties. Moreover, the shape fidelity is increased by the solid-like behavior due to the filler effect of CNC and confirmed by SEM images. Finally, a large increase in Young’s modulus and thermal and thermomechanical stability were observed on the printed pieces that contained only 0.5 wt% CNC compared to the matrix, suggesting the formation of effective interactions between CNC and WBPUU, as corroborated by FTIR, that lead to a greater reinforcement.
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Polymer Degradation and Stability, 2022
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Polymer Chemistry, 2021
Correction for ‘Synthesis and structural characterization of bio-based bis(cyclic carbonate)s for... more Correction for ‘Synthesis and structural characterization of bio-based bis(cyclic carbonate)s for the preparation of non-isocyanate polyurethanes’ by Kamila Błażek et al., Polym. Chem., 2021, DOI: 10.1039/d0py01576h.
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This work deals with the increase of the renewability of different porous and solid (thermoplasti... more This work deals with the increase of the renewability of different porous and solid (thermoplastic and crosslinked) polyurethanes and bionanocomposites, by the incorporation of different reactants and nanoentities from renewable sources. Moreover, the influence of the nature of the reactants and nanoentities and their content on the final properties has been deeply studied.Besides, the synthesized solid polyurethanes and bionanocomposites have shown shape-memory properties. Therefore, the effect of the programming conditions, content of the reactants and, in the case of the bionanocomposites, nanoentity nature and content on shape-memory properties has been thoroughly analyzed.
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Materials, 2021
In this work, polycaprolactone–polyethylene glycol (PCL–PEG) based waterborne polyurethane–urea (... more In this work, polycaprolactone–polyethylene glycol (PCL–PEG) based waterborne polyurethane–urea (WBPUU) inks have been developed for an extrusion-based 3D printing technology. The WBPUU, synthesized from an optimized ratio of hydrophobic polycaprolactone diol and hydrophilic polyethylene glycol (0.2:0.8) in the soft segment, is able to form a physical gel at low solid contents. WBPUU inks with different solid contents have been synthesized. The rheology of the prepared systems was studied and the WBPUUs were subsequently used in the printing of different pieces to demonstrate the relationship between their rheological properties and their printing viability, establishing an optimal window of compositions for the developed WBPUU based inks. The results showed that the increase in solid content results in more structured inks, presenting a higher storage modulus as well as lower tan δ values, allowing for the improvement of the ink’s shape fidelity. However, an increase in solid conte...
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Polymers, 2021
3D printing has exponentially grown in popularity due to the personalization of each printed part... more 3D printing has exponentially grown in popularity due to the personalization of each printed part it offers, making it extremely beneficial for the very demanding biomedical industry. This technique has been extensively developed and optimized and the advances that now reside in the development of new materials suitable for 3D printing, which may open the door to new applications. Fused deposition modeling (FDM) is the most commonly used 3D printing technique. However, filaments suitable for FDM must meet certain criteria for a successful printing process and thus the optimization of their properties in often necessary. The aim of this work was to prepare a flexible and printable polyurethane filament parting from a biocompatible waterborne polyurethane, which shows potential for biomedical applications. In order to improve filament properties and printability, cellulose nanofibers and graphene were employed to prepare polyurethane based nanocomposites. Prepared nanocomposite filame...
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International Journal of Pharmaceutics, 2021
Curcumin and chloramphenicol are drugs with different solubility properties in physiological cond... more Curcumin and chloramphenicol are drugs with different solubility properties in physiological conditions due to their hydrophobic and hydrophilic structure, respectively. In this work, sodium alginate-cellulose nanofibers (SA-CNF) based inks loaded with curcumin and/or chloramphenicol have been developed for syringe extrusion 3D printing technology. Printability and shape fidelity of the drug-loaded inks were analyzed through rheological characterization. Suitable drug-loaded inks were 3D printed showing shape fidelity, and samples were either freeze-dried or crosslinked with Ca2+ and air-dried to achieve functional pharmaceutical forms with different morphological characteristics. In vitro drug delivery tests were carried out from the resulted forms and it was observed that the release performed faster in freeze-dried than in Ca2+ crosslinked/air-dried ones for all cases, resulting in two different methods for controlling drug delivery over time. The differences in aqueous solubility of the drugs, the different CNF content of the inks and the surface area of the samples also played an important role in drug delivery, involving strategies to control the release over an extended duration.
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Journal of Materials Research and Technology, 2021
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Journal of Applied Polymer Science, 2019
ABSTRACTThermoset polyurethanes (PUs) were prepared from a polyol derived from castor oil, 4,4′‐m... more ABSTRACTThermoset polyurethanes (PUs) were prepared from a polyol derived from castor oil, 4,4′‐methylene diphenyl diisocyanate (MDI) and different trifunctional low‐molecular‐weight crosslinkers, biobased glycerol (Gly) and petroleum‐derived trimethylolpropane (TMP). The synthesis was carried out in bulk and without catalyst via one‐step polymerization varying the components equivalent weight ratio, Polyol:MDI:Gly and Polyol:MDI:TMP, respectively. The physicochemical, morphological, thermal, dynamic–mechanical, and mechanical properties of the PUs were determined. The success of the reaction between the polyol and MDI was confirmed by Fourier transform infrared spectroscopy. The dynamic–mechanical and the mechanical properties as well as hardness were determined and related to the concentration of the low‐molecular‐weight crosslinkers utilized (Gly or TMP). However, important differences were observed between the synthesized two series, due to phase separation produced during the c...
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Materials Science and Engineering: C, 2018
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Journal of Applied Polymer Science, 2018
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Progress in Organic Coatings, 2018
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Proceedings, 2018
As a consequence of the high production and simultaneous consumption of polyurethanes (PU) a grea... more As a consequence of the high production and simultaneous consumption of polyurethanes (PU) a great volume of PU waste is landfilled. In this scenario, suitable and efficient routes for PU waste recycling have been searched for many years. In this work two series of PUs using different recycled PU sources were synthesized: a thermoplastic PU series using a glycolysated polyol obtained from the glycolysis of elastomeric PU waste (chemical recycling) and a PU flexible foam series loaded with PU dust waste created in the shaping of PU surf tables (mechanical recycling). Results showed that the incorporation of recycled components in the formulation improved mechanical properties both in the case of thermoplastic polyurethanes and polyurethane foams. The optimum glycolysated polyol was fixed in 15% over the total polyol weight for thermoplastic PUs. In the case of foams, a maximum of 20% PU dust over the polyol weight was incorporated.
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Papers by Tamara Calvo Correas