Light-cured dental composites characterization by Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 428-429
Author(s):  
B. M. Culbertson ◽  
M. L. Devinev ◽  
E. C. Kao
Keyword(s):  
Electron Microscopy ◽  
Mechanical Analysis ◽  
Service Performance ◽  
Dental Composite ◽  
Dental Composites ◽  
Neat Resin ◽  
Scanning Calorimetry ◽  
Research Meeting ◽  
Formulation Variables

The service performance of current dental composite materials, such as anterior and posterior restoratives and/or veneer cements, needs to be improved. As part of a comprehensive effort to find ways to improve such materials, we have launched a broad spectrum study of the physicochemical and mechanical properties of photopolymerizable or visible light cured (VLC) dental composites. The commercially available VLC materials being studied are shown in Table 1. A generic or neat resin VLC system is also being characterized by SEM and TEM, to more fully understand formulation variables and their effects on properties.At a recent dental research meeting, we reported on the differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) characterization of the materials in Table 1. It was shown by DSC and DMA that the materials are substantially undercured by commonly used VLC techniques. Post curing in an oral cavity or a dry environment at 37 to 50°C for 7 or more hours substantially enhances the cure of the materials.

scholarly journals Study on Structure, Thermal Behavior, and Viscoelastic Properties of Nanodiamond-Reinforced Poly (vinyl alcohol) Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1426
Author(s):  
Tomáš Remiš ◽  
Petr Bělský ◽  
Tomáš Kovářík ◽  
Jaroslav Kadlec ◽  
Mina Ghafouri Azar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Analysis ◽  
Single Step ◽  
Poly Vinyl Alcohol ◽  
Scanning Calorimetry ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Primary Particles ◽  
Solution Casting Method ◽  
Average Size

In this work, advanced polymer nanocomposites comprising of polyvinyl alcohol (PVA) and nanodiamonds (NDs) were developed using a single-step solution-casting method. The properties of the prepared PVA/NDs nanocomposites were investigated using Raman spectroscopy, small- and wide-angle X-ray scattering (SAXS/WAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was revealed that the tensile strength improved dramatically with increasing ND content in the PVA matrix, suggesting a strong interaction between the NDs and the PVA. SEM, TEM, and SAXS showed that NDs were present in the form of agglomerates with an average size of ~60 nm with primary particles of diameter ~5 nm. These results showed that NDs could act as a good nanofiller for PVA in terms of improving its stability and mechanical properties.

scholarly journals Preparation and Characterization of Talc Filled Thermoplastic Polyurethane/Polypropylene Blends

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Emi Govorčin Bajsić ◽  
Vesna Rek ◽  
Ivana Ćosić
Keyword(s):  
Thermal Properties ◽  
Thermoplastic Polyurethane ◽  
Mechanical Analysis ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Polypropylene Blends ◽  
Pp Blends ◽  
The Degree Of Crystallinity ◽  
Better Than

The effect of the addition of talc on the morphology and thermal properties of blends of thermoplastic polyurethane (TPU) and polypropylene (PP) was investigated. The blends of TPU and PP are incompatible because of large differences in polarities between the nonpolar crystalline PP and polar TPU and high interfacial tensions. The interaction between TPU and PP can be improved by using talc as reinforcing filler. The morphology was observed by means of scanning electron microscopy (SEM). The thermal properties of the neat polymers and unfilled and talc filled TPU/PP blends were studied by using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The addition of talc in TPU/PP blends improved miscibility in all investigated TPU/T/PP blends. The DSC results for talc filled TPU/PP blends show that the degree of crystallinity increased, which is due to the nucleating effect induced by talc particles. The reason for the increased storage modulus of blends with the incorporation of talc is due to the improved interface between polymers and filler. According to TGA results, the addition of talc enhanced thermal stability. The homogeneity of the talc filled TPU/PP blends is better than unfilled TPU/PP blends.

Enhancing the Thermal and Mechanical Characteristics of Polyvinyl Alcohol (PVA)-Hemp Protein Particles (HPP) Composites

2021 ◽  
Vol 36 (2) ◽  
pp. 137-143
Author(s):  
S. A. Awad
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Composite Films ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
Solution Casting Method ◽  
Protein Particles

Abstract This paper aims to describe the thermal, mechanical, and surface properties of a PVA/HPP blend whereby the film was prepared using a solution casting method. The improvements in thermal and mechanical properties of HPP-based PVA composites were investigated. The characterization of pure PVA and PVA composite films included tensile tests, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results of TGA and DSC indicated that the addition of HPP increased the thermal decomposition temperature of the composites. Mechanical properties are significantly improved in PVA/HPP composites. The thermal stability of the PVA composite increased with the increase of HPP filler content. The tensile strength increased from 15.74 ± 0.72 MPa to 27.54 ± 0.45 MPa and the Young’s modulus increased from 282.51 ± 20.56 MPa to 988.69 ± 42.64 MPa for the 12 wt% HPP doped sample. Dynamic mechanical analysis (DMA) revealed that at elevated temperatures, enhanced mechanical properties because of the presence of HPP was even more noticeable. Morphological observations displayed no signs of agglomeration of HPP fillers even in composites with high HPP loading.

Comparative investigation of physical, mechanical and thermomechanical characterization of dental composite filled with nanohydroxyapatite and mineral trioxide aggregate

e-Polymers ◽  
2017 ◽  
Vol 17 (4) ◽  
pp. 311-319 ◽  
Author(s):  
Anoj Meena ◽  
Harlal Singh Mali ◽  
Amar Patnaik ◽  
Shiv Ranjan Kumar
Keyword(s):  
Compressive Strength ◽  
Dynamic Mechanical Analysis ◽  
Storage Modulus ◽  
Water Sorption ◽  
Mineral Trioxide Aggregate ◽  
Mechanical Analysis ◽  
Comparative Investigation ◽  
Dental Composite ◽  
Dynamic Mechanical

AbstractThis study presents comparative investigation of adding nanohydroxyapatite (HA) (5–20 wt.%) and mineral trioxide aggregate (MTA) (5–20 wt.%) on the physical, mechanical and thermomechanical characterization of dental composite. The performances of both experimental composites were assessed through various physical, mechanical and thermomechanical tests such as void content test, microhardness test, compressive strength test, dynamic mechanical analysis and thermogravimetric analysis. The result of experiment indicated that the addition of 5 wt.% of HA increased the water sorption, hardness and compressive strength by 50.47%, 13.46% and 62.35%, respectively, whereas the addition of 5 wt.% of MTA increased the water sorption, hardness and compressive strength by 19.23%, 100% and 5.44%, respectively. Dynamic mechanical analysis results revealed that the addition of 5 wt.% HA increased the storage modulus by 10.21%, whereas the addition of 5 wt.% of MTA decreased the storage modulus by 11.79%. The filler HA proved to be better choice in term of thermal stability behavior as compare to MTA filler.

An Elastic/Viscoplastic Finite Element Model for Predicting Polymerization Stresses in Light-Activated Dental Composites

2003 ◽  
Author(s):  
Gayle A. Laughlin ◽  
John L. Williams ◽  
J. David Eick
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Numerical Approach ◽  
Mechanical Analysis ◽  
Dental Composite ◽  
Time Dependent ◽  
Dental Composites ◽  
Cavity Preparation ◽  
Constitutive Parameters ◽  
Perzyna's Theory

The purpose of this paper is to apply a finite deformation, elastic/viscoplastic approach to predict curing stresses in three light-cured dental composites, using Perzyna’s theory. Time-dependent constitutive parameters were obtained from mercury dilatometry, dynamic mechanical analysis and constrained shrinkage strerss testing. The numerical approach was verified by using the results of an experiment on a simple aluminum tooth model of a cavity preparation that was bulk-filled with light-cured dental composite restorative materials. The numerically predicted strain patterns were similar to those seen experimentally for the three different dental composites.

scholarly journals Preparation and Characterization of Levofloxacin-Loaded Nanofibers as Potential Wound Dressings

2017 ◽  
Vol 63 (2) ◽  
pp. 66-69 ◽  
Author(s):  
Noémi Pásztor ◽  
Emőke Rédai ◽  
Zoltán-István Szabó ◽  
Emese Sipos
Keyword(s):  
Electron Microscopy ◽  
Electrospun Nanofibers ◽  
Electrospinning Process ◽  
Wound Dressings ◽  
Dissolution Testing ◽  
Electrospun Nanofiber ◽  
Scanning Calorimetry ◽  
Rapid Release ◽  
Scanning Electron

Abstract Objective: The study aimed at obtaining and characterizing levofloxacin-loaded, poly(ε-caprolactone) electrospun nanofiber formulations to be used as antibacterial wound dressings. Methods: Drug-loaded nanofibers were obtained by the electrospinning process and their morphology was determined using scanning electron microscopy. Structural analysis of the prepared nanofibers was carried out using differential scanning calorimetry and dissolution testing was performed in order to determine drug release. Results: Both nanofiberous formulations (containing 20 % and 50 % w/w levofloxacin) showed dimensions in the range of few hundred nanometers. Thermograms indicated that the formulation containing 20% levofloxacin was totally amorphized, showing a rapid release of the active, in 20 minutes. Conclusions: The poly(ε-caprolactone)-based electrospun nanofibers, containing levofloxacin presented suitable characteristics for obtaining potential antibacterial wound dressings.

scholarly journals Synthesis and Characterization of Orotic Acid Loaded Chitosan Inclusion Complex

2020 ◽  
Vol 10 (01) ◽  
pp. 1-4
Author(s):  
ABM Helal Uddin ◽  
Abdelkader Hassani ◽  
Abul K. Azad ◽  
Hamid H. Enezei ◽  
Siti A. Hussain
Keyword(s):  
Electron Microscopy ◽  
Inclusion Complex ◽  
Orotic Acid ◽  
Drug Delivery Systems ◽  
Freeze Drying ◽  
Synthesis And Characterization ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron

The current study aims to improve drug release properties of orotic acid loaded with chitosan inclusion complex (OA/CS). The OA/CS inclusion complex was synthesized using the freeze-drying technique. The characterization of inclusion OA/CS was carried out using fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), differential scanning calorimetry (DSC), zeta sizer, and transmission electron microscopy (TEM). Furthermore, the size of OA/CS ranged between 58 nm and 200 nm, and the zeta potential was 30 mV. Thus, this study indicates that OA/CS has a promising future to develop a carrier for drug delivery systems further.

scholarly journals Synthesis and characterization of four new lanthanide complexes coordinate with β-diketone ligands and 1,10-phenanthroline or 2,2-dipyridine

2020 ◽  
Vol 9 (11) ◽  
pp. e45791110207
Author(s):  
Yuri Johann Vilar de Brito ◽  
Crislene Rodrigues da Silva Morais ◽  
Yohanna Jamilla Vilar de Brito ◽  
Daniella Cibele Bezerra
Keyword(s):  
Electron Microscopy ◽  
Lanthanide Complexes ◽  
Synthesis And Characterization ◽  
Direct Reaction ◽  
Scanning Calorimetry ◽  
Solubility Test ◽  
Microscope Images ◽  
Scanning Electron

In this work the complexes Ln(β-dik)3L (where Ln= Nd+3 e Er+3, β-dik= 4,4,4-trifluoro-1-phenyl-1,3-butanedione (Btfa) and L= 1,10-Phenanthroline (Phen) or 2,2’-Bipyridyl (Bipy)), were synthesized from the direct reaction of LnCl3 with β-diketone and the ligands. The purpose was to create new lanthanide complexes with perspectives of use in markers. After the syntheses, the complexes were characterized by Solubility Test, Scanning Electron Microscopy (SEM) and the thermal properties of compounds were studied using Thermogravimetry Analisys (TGA), Differential Scanning Calorimetry (DSC) and Determination of Melting/Decomposition Intervals. Based on the verified properties, the solubility test found that the complexes are not soluble in chloroform and water. The microscope images showed an excellent crystallization of the complexes. The complexes are stable up to 120°C, after this temperature they show a peak in the DSC referring to the fusion and the beginning of decomposition. The values of activation energy suggests the following decreasing order of stability: Er(Btfa)3Phen>Nd(Btfa)3Phen>Er(Btfa)3Bipy>Nd(Btfa)3Bipy.

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