Dental modeling resins have been developed for use in areas where highly precise resin structures are needed. The manufacturers claim that these polymethyl methacrylate/methyl methacrylate (PMMA/MMA) resins show little or no shrinkage after polymerization. This study examined the polymerization shrinkage of five dental modeling resins as well as one temporary PMMA/MMA resin (control). The morphology and the particle size of the prepolymerized PMMA powders were investigated by scanning electron microscopy and laser diffraction particle size analysis, respectively. Linear polymerization shrinkage strains of the resins were monitored for 20 minutes using a custom-made linometer, and the final values (at 20 minutes) were converted into volumetric shrinkages. The final volumetric shrinkage values for the modeling resins were statistically similar (P > 0.05) or significantly larger (P < 0.05) than that of the control resin and were related to the polymerization kinetics (P < 0.05) rather than the PMMA bead size (P = 0.335). Therefore, the optimal control of the polymerization kinetics seems to be more important for producing high-precision resin structures rather than the use of dental modeling resins.
Download full-text PDF |
Source |
---|---|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3977089 | PMC |
http://dx.doi.org/10.1155/2014/914739 | DOI Listing |
Polymers (Basel)
December 2024
Adamant Composites Ltd., Agias Lavras & Stadiou, 26504 Patras, Greece.
Hydrogen, as a zero-emission fuel, produces only water when used in fuel cells, making it a vital contributor to reducing greenhouse gas emissions across industries like transportation, energy, and manufacturing. Efficient hydrogen storage requires lightweight, high-strength vessels capable of withstanding high pressures to ensure the safe and reliable delivery of clean energy for various applications. Type V composite pressure vessels (CPVs) have emerged as a preferred solution due to their superior properties, thus this study aims to predict the performance of a Type V CPV by developing its numerical model and calculating numerical burst pressure (NBP).
View Article and Find Full Text PDFPolymers (Basel)
December 2024
Glidewell Dental, Irvine, CA 92612, USA.
The aim of this study was to evaluate the mechanical properties and degree of conversion of a novel 3D-printing model resin and compare it to eight commercially available model resins. An experimental resin formulated by our proprietary resin technology along with DentaModel, NextDent 2, KeyModel Ultra, Rodin Model, Die and Model 2, DMR III, LCD Grey, and Grey Resin were used in this study. Parallelepiped specimens (2 × 2 × 25 mm, n = 5) were printed and measured for their flexural strength (FS), flexural modulus (FM), and modulus of resilience (MR) in accordance with ISO-4049.
View Article and Find Full Text PDFPolymers (Basel)
December 2024
Department of Mechanical Engineering, Federal University of Campina Grande, Campina Grande 58429-900, PB, Brazil.
Recently, the liquid composite molding technique (LCM) has been used for producing fiber-reinforced polymer composites, since it allows the molding of complex parts, presenting good surface finishing and control of the mechanical properties of the product at the end of the process. Studies in this area have been focused on resin transfer molding (RTM), specifically on the resin rectilinear infiltration through the porous preform inserted in the closed cavity neglecting the sorption effect of the polymeric fluid by the reinforcement. Thus, the objective of this work is to predict resin radial flow in porous media (fibrous preform), including the effect of resin sorption by fibers considering a one-dimensional approach.
View Article and Find Full Text PDFPolymers (Basel)
December 2024
School of Mechanical and Electrical Engineering, Changchun University of Science and Technology, Changchun 130022, China.
The curing process of hair-pin motor stator insulation is critical, as residual stress increases the risk of partial discharge and shortens a motor's lifespan. However, studies on the stress-induced defects during insulation varnish curing remain limited. This research integrates three-dimensional numerical simulations and experimental analysis to develop a curing model based on unsaturated polyester imide resin, aiming to explore the mechanisms of residual stress formation and optimization strategies.
View Article and Find Full Text PDFPolymers (Basel)
December 2024
Centro de Física de Materiales (CSIC-UPV/EHU)-Materials Physics Center (MPC), P. M. de Lardizábal 5, 20018 San Sebastián, Spain.
This work connects the calorimetric responses of different rubber-resin blends with varying resin contents with their alpha relaxation dynamics. We used differential scanning calorimetry and broadband dielectric spectroscopy to characterize the calorimetric and dielectric responses of styrene-butadiene, polybutadiene, and polyisoprene with different resin contents. To model the results, we used the Gordon-Taylor equation combined with an extension of the Adam-Gibbs approach.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!