Stereolithography (SL) employs UV-curable resin as a raw material to create bulk and fragile objects. However, the poor performance of this resin restricts the practical applicability of SL.
IStudy: Dual curing vapor-grown carbon nanofiber-complementary 3D-printed resin: implications for improved stiffness and thermal resistance. Image credit: Marina Grigorievna / Shutterstock
In a recently published article in the journal ACS Applied Nanomaterials, researchers described dual-curing three-dimensional (3D) nanofibers supplemented with vapor-grown carbon nanofibers (SLR/VGCF) to enhance the overall performance of the printed workpiece and prevent Prepared printed SL resin nanocomposites. non-homogeneous treatment.
The dual-treated nanocomposites supplemented with 1% weight-by-weight (w/w) VGCFs had tensile strengths of 63.5 megapascals and Young’s modulus of 3.2 gigapascals. The nanoindentation test confirmed that the dual curing method helped to achieve the homogeneity of the nanocomposites. The as-prepared nanocomposites had excellent thermal properties, indicating their stability in high-temperature environments. The thermal conductivity of the nanocomposites supplemented with 2% w/w VGCFs increased by 79%.
Post-treatment methods in 3D printing technology
3D printing is an innovative and advanced manufacturing technology for creating customized stereoscopic objects with sophisticated architectures. SL is a 3D printing technology involving Vat polymerization process. It is used to generate versatile structures due to its highly surface quality and high resolution.
SL technology uses UV-curable SLR as raw material. In the printing process, the fast-scanning speed of laser light prevents the complete conversion of the unsaturated portions of the SLR, creating printed objects with deprived mechanical properties, which limits the application of SL 3D printing at the desktop level.
Ultraviolet (UV)-assisted post-curing after the printing process can overcome the above limitations. This curing process increases the conversion rate of unsaturated moieties into SLRs and improves mechanical properties. However, due to the poor absorption of UV light by SLRs, the depth of UV light penetration is limited, thereby restricting UV post-curing to the interior of the object. In addition, non-transparent SLRs further reduce the UV post-curing efficiency due to the colored fillers in the SLR.
To this end, the integration of UV irradiation into the printing process followed by thermal treatment can overcome UV-post-curing challenges. Thermal post-curing has more advantages than UV post-curing because the pre-post-curing process has no limitations in terms of object geometry and can facilitate complete polymerization of the object’s internal parts.
Strengthening polymers with nanofillers is an innovative strategy, offering remarkable properties and improving the practical applicability of polymers. VGCFs are nanofillers that exhibit superior properties such as prominent thermal and electrical conductivity when reinforced in polymer matrices.
Dual Curing VGCF-Complementary 3D-Printed Resin
In the present study, the researchers fabricated a dual-curing SLR through an efficient and easy method of incorporating a suitable thermal initiator (Ti) and comparing its efficacy with conventional UV post-curing SLRs. VGCFs were acidified to increase functional groups on their surface, thus enhancing their interfacial compatibility with the polymer matrix.
Acidified VGCFs immobilized with carboxyl groups were prepared using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The VGCF-based nanocomposites were fabricated using a desktop SL 3D printer, followed by thermal or UV post-curing treatment to obtain SLR-TI/VGCF and SLR/VGCF, respectively. The FTIR spectra of acidified VGCFs revealed characteristic peaks at the 3440- and 1730-cm inverses, confirming the hydroxyl (OH) and carbonyl (C = O) stretch vibrations of the carboxylic acid group.
Furthermore, the XPS spectra showed oxygen (O) 1s peaks at approximately 533 and 976 electronvolts, confirming the acidification of the VGCFs. The intensity of the carbon (C) 1s peak around 285 electronV was slightly decreased compared to that of pristine VGCF, suggesting oxidation of the acidified VGCF surface functional groups. In addition, a high-resolution XPS spectrum showed new peaks at binding energies of 287 and 288.6 electronvolts, corresponding to the Co and C = O groups.
The mechanical and thermal properties of the fabricated and cured VGCF-based nanocomposites were analyzed. The results showed that VGCF effectively improved the mechanical properties of SLR-Ti after thermal treatment. In addition, thermal post-curing pure resin and its nanocomposites withstand 700 times their own weight for 1 h at 180 °C without being damaged.
Briefly, the researchers demonstrated and characterized the 3D printing of SLR-Ti/VGCF nanocomposites. Thermal treatment as a post-curing method induced better mechanical properties and uniformity in nanocomposites than UV-assisted post-curing. Acidified VGCF improved the toughness of SLR-Ti and increased the tensile modulus and strength.
Dynamic mechanical analysis (DMA) showed that thermal process treated SLR-Ti/VGCF nanocomposites improved the glass transition temperature (T)Yes), resulting in a higher temperature shift after thermal-mediated post-curing. The heat distortion temperature (HDT) results confirmed that the fabricated nanocomposite subjected to thermal-mediated post-curing can be reliably applied in high-temperature environments.
The SLR-TI with 2% w/w VGCF had higher thermal conductivity (79%) than the clean SLR. The present work discussed a versatile solution for performing SL 3D printing and fabricating high-performance nanocomposite objects, broadening the practical applicability of SL 3D printing.
Lee, Y., Kankala, R. K., Weng, Z., and Wu, L. Physiotherapy. (2022). Dual curing vapor-grown carbon nanofiber-complementary 3D-printed resin: implications for improved stiffness and thermal resistance. ACS Applied Nano Materials. https://pubs.acs.org/doi/10.1021/acsanm.2c01774