scholarly journals Micro- and Nanoparticulate Hydroxyapatite Powders as Fillers in Polyacrylate Bone Cement—A Comparative Study

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2736
Author(s):  
Anna Sobczyk-Guzenda ◽  
Paulina Boniecka ◽  
Anna Laska-Lesniewicz ◽  
Marcin Makowka ◽  
Hieronim Szymanowski
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Comparative Study ◽  
Surface Area ◽  
Setting Time ◽  
Charpy Impact ◽  
Cross Linking ◽  
Scanning Calorimetry ◽  
Bonding Agents

Acrylate polymer-based bone cements constitute the most popular bonding agents used in regenerative surgery. Due to their inferior biocompatibility, however, these materials are often enriched with ceramic additives including hydroxyapatite (HAp). The aim of this paper was to perform a comparative study of the acrylate cements filled with different content (3–21%) of nano- and microscale hydroxyapatite. The work concerns a comparison of times and temperatures of the cross-linking reaction, as well as morphology, glass transition temperature, and principal mechanical properties of the resulting composites. Before being used as a filler, both HAp forms were subjected to an in-depth characterization of their morphology, specific surface area, pore size distribution, and wettability as well as chemical composition and structure. For that purpose, such analytical techniques as scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, tensiometry, Brunauer–Emmett–Teller surface area analysis, differential scanning calorimetry, Shore D hardness test, and Charpy impact test were used. The results indicated a drop of cross-linking temperature and an extension of setting time with the addition of µHAp. The µHAp-filled acrylate composites were characterized by a globular surface morphology, higher glass transition temperature, and lower hardness and impact strength compared to nHAp-filled materials. This relationship was evident at higher nHAp concentrations.

The Effects of Cross-Linking and Strain on the Glass Transition Temperature of a Polymer Network

1980 ◽  
Vol 53 (4) ◽  
pp. 982-987 ◽  
Author(s):  
M. A. Sharaf ◽  
J. E. Mark
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Polymer Network ◽  
Thermal Shrinkage ◽  
Cross Linking ◽  
Scanning Calorimetry ◽  
Increase With Increase ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Abstract The glass transition temperature Tg of an elastomer is of great importance with regard to its utilization since at this temperature and below, the material can no longer exhibit rubberlike behavior. In the present study, networks were prepared from atactic poly(vinyl acetate) and poly(isobutyl methacrylate), both types of networks being inherently non-crystallizable and therefore immune from complications associated with strain-induced crystallization. The values of Tg were obtained by dilatometry, differential scanning Calorimetry, the measurement of viscoelastic losses, and irreversible thermal shrinkage. For both types of networks, Tg was found to increase with increase in degree of crosslinking and with increase in elongation. These results suggest that the most important effect of crosslinking and network elongation is a decrease in the mobility or entropy of the network chains.

scholarly journals Thermal analysis: basic concept of differential scanning calorimetry and thermogravimetry for beginners

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Nurul Fatahah Asyqin Zainal ◽  
Jean Marc Saiter ◽  
Suhaila Idayu Abdul Halim ◽  
Romain Lucas ◽  
Chin Han Chan
Keyword(s):  
Thermal Analysis ◽  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Commercial Application ◽  
Scanning Calorimetry ◽  
Teaching Activities ◽  
Sample Decomposition ◽  
Calibration Baseline

AbstractWe present an overview for the basic fundamental of thermal analysis, which is applicable for educational purposes, especially for lecturers at the universities, who may refer to the articles as the references to “teach” or to “lecture” to final year project students or young researchers who are working on their postgraduate projects. Description of basic instrumentation [i.e. differential scanning calorimetry (DSC) and thermogravimetry (TGA)] covers from what we should know about the instrument, calibration, baseline and samples’ signal. We also provide the step-by-step guides for the estimation of the glass transition temperature after DSC as well as examples and exercises are included, which are applicable for teaching activities. Glass transition temperature is an important property for commercial application of a polymeric material, e.g. packaging, automotive, etc. TGA is also highlighted where the analysis gives important thermal degradation information of a material to avoid sample decomposition during the DSC measurement. The step-by-step guides of the estimation of the activation energy after TGA based on Hoffman’s Arrhenius-like relationship are also provided.

scholarly journals Physical Aging Behavior of a Glassy Polyether

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 954
Author(s):  
Xavier Monnier ◽  
Sara Marina ◽  
Xabier Lopez de Pariza ◽  
Haritz Sardón ◽  
Jaime Martin ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Physical Aging ◽  
Glassy State ◽  
Aging Behavior ◽  
Scanning Calorimetry ◽  
Narrow Temperature Range ◽  
Glass Forming ◽  
Fast Scanning Calorimetry

The present work aims to provide insights on recent findings indicating the presence of multiple equilibration mechanisms in physical aging of glasses. To this aim, we have investigated a glass forming polyether, poly(1-4 cyclohexane di-methanol) (PCDM), by following the evolution of the enthalpic state during physical aging by fast scanning calorimetry (FSC). The main results of our study indicate that physical aging persists at temperatures way below the glass transition temperature and, in a narrow temperature range, is characterized by a two steps evolution of the enthalpic state. Altogether, our results indicate that the simple old-standing view of physical aging as triggered by the α relaxation does not hold true when aging is carried out deep in the glassy state.

Glass Transition Temperature in Confined Polymers

2006 ◽  
Vol 977 ◽  
Author(s):  
Rahmi Ozisik ◽  
Tong Liu ◽  
Richard W. Siegel
Keyword(s):  
Thin Films ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Nearest Neighbor ◽  
Scanning Calorimetry ◽  
Thin Film Thickness ◽  
Confined Polymers ◽  
Microscope Images ◽  
Scanning Electron

AbstractGlass transition temperature of polyetherimide (PEI) thin films and nanoporous PEI samples was investigated using differential scanning calorimetry. In both of these systems, the glass transition temperature decreased with respect to the bulk value. In the nanoporous system, scanning electron microscope images were used to characterize pore size distribution, and Monte Carlo simulations were performed to calculate the nearest neighbor pore-to-pore distances. Pore-to-pore distances and thin film thickness values were used to establish a quantitative analogy between thin films and nanoporous system.

scholarly journals Differential Scanning Calorimetry for Determining the Thermodynamic Properties of Selected Honeys

2015 ◽  
Vol 59 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Jolanta Tomaszewska-Gras ◽  
Sławomir Bakier ◽  
Kamila Goderska ◽  
Krzysztof Mansfeld
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermodynamic Properties ◽  
Sugar Content ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures ◽  
Complete Liquefaction

Abstract Thermodynamic properties of selected honeys: glass transition temperature (Tg), the change in specifi c heat capacity (ΔCp), and enthalpy (ΔH) were analysed using differential scanning calorimetry (DSC) in relation to the composition i.e. water and sugar content. Glass transition temperatures (Tg) of various types of honey differed significantly (p<0.05) and ranged from -49.7°C (polyfloral) to -34.8°C (sunflower). There was a strong correlation between the Tg values and the moisture content in honey (r = -0.94). The degree of crystallisation of the honey also influenced the Tg values. It has been shown that the presence or absence of sugar crystals influenced the glass transition temperature. For the decrystallised honeys, the Tg values were 6 to 11°C lower than for the crystallised honeys. The more crystallised a honey was, the greater the temperature difference was between the decrystallised and crystallized honey. In conclusion, to obtain reliable DSC results, it is crucial to measure the glass transition after the complete liquefaction of honey.

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