scholarly journals Prosthodontic Applications of Polymethyl Methacrylate (PMMA): An Update

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2299 ◽  
Author(s):  
Muhammad Sohail Zafar
Keyword(s):  
Mechanical Properties ◽  
Polymethyl Methacrylate ◽  
Physical And Mechanical Properties ◽  
Mechanical Reinforcement ◽  
Occlusal Splints ◽  
Dental Prostheses ◽  
Wide Range ◽  
Dental Applications ◽  
Artificial Teeth ◽  
Orthodontic Retainers

A wide range of polymers are commonly used for various applications in prosthodontics. Polymethyl methacrylate (PMMA) is commonly used for prosthetic dental applications, including the fabrication of artificial teeth, denture bases, dentures, obturators, orthodontic retainers, temporary or provisional crowns, and for the repair of dental prostheses. Additional dental applications of PMMA include occlusal splints, printed or milled casts, dies for treatment planning, and the embedding of tooth specimens for research purposes. The unique properties of PMMA, such as its low density, aesthetics, cost-effectiveness, ease of manipulation, and tailorable physical and mechanical properties, make it a suitable and popular biomaterial for these dental applications. To further improve the properties (thermal properties, water sorption, solubility, impact strength, flexural strength) of PMMA, several chemical modifications and mechanical reinforcement techniques using various types of fibers, nanoparticles, and nanotubes have been reported recently. The present article comprehensively reviews various aspects and properties of PMMA biomaterials, mainly for prosthodontic applications. In addition, recent updates and modifications to enhance the physical and mechanical properties of PMMA are also discussed.

Structure and properties of compact articles from high-alloyed iron powder with adding of boron nitride

2020 ◽  
pp. 39-48
Author(s):  
B. O. Bolshakov ◽  
◽  
R. F. Galiakbarov ◽  
A. M. Smyslov ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Grain Boundary ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Operating Conditions ◽  
Structure And Properties ◽  
Steam Turbines ◽  
Friction Forces ◽  
Wide Range

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.

Control of properties and structure of steel vessels by cooling in various media at the outlet of rolling and pressing lines

2021 ◽  
pp. 34-38
Author(s):  
R. L. Shatalov ◽  
V. A. Medvedev
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
Metal Structure ◽  
Machine Building ◽  
Regression Equations ◽  
Wide Range ◽  
Industrial Mineral ◽  
Cooling Media ◽  
Technological Limitations ◽  
Non Destructive

When controlling the mechanical properties and structure of vessels made of carbon structural steels manufactured by hot deformation on rolling and pressing lines (PPL) of machine-building enterprises of Russia, such cooling media as water, I20 industrial mineral oil, air are used. The applied cooling media are able to provide the workpieces with a given structure with a wide range of mechanical properties. However, the cooling media have a number of technological limitations and conditions of the use, non-compliance with which leads to reject. When cooled in oil, the probability of ignition is high; when cooled in water, hardening cracks may form, and air is not always able to provide the required rate and uniformity of heat transfer to the environment. The efficiency of control of physical and mechanical properties and structure of deformed vessels made of 50 steel by cooling in TERMAT polymer aqueous solutions in different concentrations on PPL of the plant of JSC NPO Pribor was studied. The effect of varying the concentration from 2 to 9% of TERMAT polymer on the formation of metal structure, as well as physical and mechanical properties of hot-deformed vessels was studied. The results of testing the strength and plastic characteristics of vessels by destructive and non-destructive control methods are presented. According to the results of physical and mechanical properties, regression equations were obtained with at least 95% reliability of R2, which establish the relationship between the controlled plastic and strength parameters of the vessel metal`s properties. The conducted researches allowed to compare the indicators of the main physical and mechanical properties of steel vessels at the PPL outlet and to propose methods of inhomogeneity control that reduce time and material costs by 5–10% during the tests.

Characteristics and Biocompatibility of the Hydroxyapatite Based Two Ternary Biocomposites

2016 ◽  
Vol 720 ◽  
pp. 130-140
Author(s):  
Berrak Bulut ◽  
Ziya Engin Erkmen ◽  
Eyup Sabri Kayali
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
Secondary Phase ◽  
In Vitro Test ◽  
Compression Tests ◽  
Vitro Test ◽  
Dental Applications ◽  
The Ideal

Hydroxyapatite (HA) is a very popular bioceramic for orthopedic and dental applications. Although HA has excellent biocompatibility, its inferior mechanical properties make it unsuitable for load-bearing implant applications. Therefore, HA should be strengthened by a secondary phase for robust mechanical properties. The aim of this study was to compare the properties of HA-Al2O3 (HAC) and HA-ZrO2 (HZC) composites with the addition of 5 and 10 wt% commercial inert glass (CIG); independently. The mixture powders were pressed and then, the pellets were sintered between 1000-1300 °C for 4 hours. Microstructural characterizations were carried out using SEM + EDS and XRD, while hardness and compression tests were done to measure mechanical properties. In order to investigate the biocompatibility behavior of the samples in vitro and in vivo tests were performed. The mechanical properties of HAC composites increased with rising CIG content and increasing sintering temperature. For HZC composites, increasing CIG content caused an elevation in hardness and a decrease in compressive strength values at 1300 °C. The composites having the best physical and mechanical properties also showed improved bioactive properties at in vitro test. In this study, the ideal composite was selected as HZC5 sintered at 1200 °C depending on the microstructure, mechanical and biocompatibility properties.

scholarly journals Fabrication and Characterization of Polylactic Acid Electrospun Scaffolds Modified with Multi-Walled Carbon Nanotubes and Hydroxyapatite Nanoparticles

Biomimetics ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 43
Author(s):  
Athanasios Kotrotsos ◽  
Prokopis Yiallouros ◽  
Vassilis Kostopoulos
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Polylactic Acid ◽  
Physical And Mechanical Properties ◽  
Polymeric Materials ◽  
Cost Effective ◽  
Electrospinning Process ◽  
Wide Range ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The solution electrospinning process (SEP) is a cost-effective technique in which a wide range of polymeric materials can be electrospun. Electrospun materials can also be easily modified during the solution preparation process (prior SEP). Based on this, the aim of the current work is the fabrication and nanomodification of scaffolds using SEP, and the investigation of their porosity and physical and mechanical properties. In this study, polylactic acid (PLA) was selected for scaffold fabrication, and further modified with multi-walled carbon nanotubes (MWCNTs) and hydroxyapatite (HAP) nanoparticles. After fabrication, porosity calculation and physical and mechanical characterization for all scaffold types were conducted. More precisely, the morphology of the fibers (in terms of fiber diameter), the surface properties (in terms of contact angle) and the mechanical properties under the tensile mode of the fabricated scaffolds have been investigated and further compared against pristine PLA scaffolds (without nanofillers). Finally, the scaffold with the optimal properties was proposed as the candidate material for potential future cell culturing.

scholarly journals Analysis of efficiency of drilling equipment use in mining operations

2021 ◽  
Vol 315 ◽  
pp. 02018
Author(s):  
Yuriy Masaev ◽  
Vladislav Masaev ◽  
Yuriy Drozdenko
Keyword(s):  
Mechanical Properties ◽  
Energy Intensity ◽  
Physical And Mechanical Properties ◽  
Structural Features ◽  
Ore Deposits ◽  
Mining Operations ◽  
Drilling Equipment ◽  
Wide Range ◽  
Mine Workings ◽  
Underground Method

When developing coal and ore deposits by underground method, it is necessary to carry out a large volume of preparatory mine workings using drilling and blasting operations. Minerals are found in rocks under various conditions and their physical and mechanical properties change in a wide range. Under such conditions, it is necessary to use drilling machines this different to the principle of action and structural features. The article considers geometric parameters of roc cutters, peculiarities of drilling modes, affecting energy intensity and drilling productivity in rocks with different strength coefficient.

scholarly journals Research of dimensional-mass characteristics and physical and mechanical properties of bulbs and heaves of seed onion (Stuttgarter Risen variety) in the period of selection

2020 ◽  
pp. 72-75
Author(s):  
Alexander Gennadievich Aksenov ◽  
Aleksey Viktorovich Sibirev
Keyword(s):  
Mechanical Properties ◽  
Average Distance ◽  
Physical And Mechanical Properties ◽  
Large Change ◽  
Average Value ◽  
Wide Range ◽  
Working Bodies ◽  
Object Of Study ◽  
Range Of Variation ◽  
Left Middle

The aim of the research was to determine the size-mass and physico-mechanical properties of bulbs and heaves of seed onion of the Stuttgart Riesen variety during the selection period. The results of studies of the size-mass characteristics of bulbs and roll onion sets of the Stuttgart Riesen variety from the standpoint of creating the working bodies of machines for its cultivation and harvesting are presented. The results of previous studies of onion sets of other varieties are considered. The technique and equipment used in the research are described. The results of the studies are presented in the form of distribution histograms, the analysis of the studies was carried out by the method of variation statistics. Object of study: bulbs and roll onion sets of the Stuttgart Riesen variety. It is established that the value of the onion set form index lies in the range of 0.,82- 1,10. An analysis of the results shows that more than 90% of the bulbs have a rounded shape, approaching the shape of a sphere, the rest are flat-rounded. The main values of the width of the onion-set roll are in the range 53.,0 65,0 cm, with an average value of 59 cm, in addition, we can conclude that there is no large change in thickness in the cross section of the roll, while the average value of the thickness of the roll (left , middle, right) is within 5.4; 6.7; 5.2 cm with an average value of 6.4 cm. The average distance between the onion set rolls during the selection period is 113.4 cm, the maximum is 121 cm, and the minimum is 111.2 cm. The mass of a heap of 1 running meter of onion set roll characterizes the density of the onion set roll is 12.82 kg. However, the minimum and maximum values of this indicator have a wide range of variation from 12.0 to 15.0 kg.

scholarly journals Effects of pre-mature harvest and heat exposure on physical and mechanical properties of Pandanus tectorius leaves

2017 ◽  
Author(s):  
John A Toman
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Heat Exposure ◽  
Physical And Mechanical Properties ◽  
Maximum Growth ◽  
Mechanical Efficiency ◽  
French Polynesia ◽  
Plant Materials ◽  
Wide Range ◽  
Pandanus Tectorius

Plant materials have long been utilized for human use because of their wide range of physical properties and incredible mechanical efficiency as eco-friendly structures. One example of their use today is the practice of using the sturdy leaves of Pandanus tectorius for thatching purposes. An increase in modern demand for P. tectorius is pressuring farmers to deviate from traditional harvesting methods in an attempt to increase leaf yield. With little knowledge of the repercussions of their new practice, modern farmers are pre-maturely harvesting leaves through heat-induced leaf drying while the leaves remain on the tree. In this study, life-history characteristics, physical and mechanical properties of P. tectorius leaves on Mo’orea, French Polynesia are examined to determine whether or not this deviation from traditional harvest methods reduces leaf efficacy as a thatching material. Quantitative measures of P. tectorius leaves suggest that pre-mature harvest does not alter the size of collected leaves for thatch because most leaves on a tree have already reached maximum growth. Heat-induced leaf drying, however, reduces the tensile strength of P. tectorius leaves by about 25%. Further research may find that this loss in leaf tensile strength may correlate to less robust roofing structures, hindered longevity and ultimately an increase in energy cost to repair and rebuild such structures.

scholarly journals Improving the surface quality and mechanical properties of selective laser sintered PA2200 components by the vibratory surface finishing process

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Hamaid M. Khan ◽  
Tolga B. Sirin ◽  
Gurkan Tarakci ◽  
Mustafa E. Bulduk ◽  
Mert Coskun ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Tensile Strength ◽  
Additive Manufacturing ◽  
Microstructural Analysis ◽  
Surface Hardness ◽  
Physical And Mechanical Properties ◽  
Surface Finishing ◽  
Finishing Process ◽  
Wide Range

Abstract This paper attempts to improve the physical and mechanical properties of selective laser sintered polyamide PA2200 components through a vibratory surface finishing process by inducing severe plastic deformation at the outer surface layers. The industrial target of additive manufacturing components is to obtain structures having surface roughness, hardness, and other mechanical properties equivalent to or better than those produced conventionally. Compared to the as-built SLS PA2200 samples, vibratory surface finishing treated specimens exhibited a smooth surface microstructure and more favorable roughness, hardness, and tensile strength. Also, the duration of the vibratory surface finishing process showed a further improvement in the surface roughness and hardness of the SLS samples. Compared to the as-built state, the roughness and hardness of the surface-treated samples improved by almost 90% and 15%, respectively. Consequently, microstructural analysis indicates that lower surface roughness and enhanced surface hardness is a crucial factor in influencing the overall tensile strength of SLS-PA2200 components. We consider that the combination of VSF and SLS processes can successfully handle a wide range of potential applications. This study also highlights the efficiency and applicability of the vibratory surface finishing process to other additive manufacturing processes and materials. Graphic abstract

Polymer Substrates for Flexible Electronics: Achievements and Challenges

2010 ◽  
Vol 93-94 ◽  
pp. 5-8 ◽  
Author(s):  
Iryna Yakimets ◽  
Duncan MacKerron ◽  
Peter Giesen ◽  
Keith J. Kilmartin ◽  
Marloes Goorhuis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behaviour ◽  
Flexible Electronics ◽  
Physical And Mechanical Properties ◽  
Polymer Materials ◽  
Polyethylene Naphthalate ◽  
Polymer Substrates ◽  
Micro Scale ◽  
Wide Range ◽  
Micro Deformation

Flexible electronics technology can potentially result in many compelling applications not satisfied by the rigid Si-based conventional electronics. Commercially available foils such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) have emerged as the most suitable polymer materials for wide range of flexible electronics applications. Despite the enormous progress which has been recently done on the optimization of physical and mechanical properties of PET and PEN foils, their dimensional stability at the micro-scale is still an issue during patterning of wiring by means of lithography. Consequently, the measurement of in-plane micro-deformation of foil is of great importance for understanding and predicting its thermal, hydroscopic and mechanical behaviour during processing.

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