The Effect of Polonium Alpha Rays on the Physical Properties of Polyethylene and of Polymethyl Methacrylate

1961 ◽  
Vol 15 (5) ◽  
pp. 553 ◽  
Author(s):  
Ruth F. Itzhaki ◽  
Peter Alexander
1992 ◽  
Vol 269 ◽  
Author(s):  
Edmund H. Moore ◽  
David E. Clark ◽  
Ronald Hutcheon

ABSTRACTCompact samples of alumina and polymethyl methacrylate have been heated in a 2.45 GHz microwave cavity and by conventional heating in an electric furnace. Various heating schedules have been used to effect the removal of the polymeric binder by thermal decomposition. Dielectric properties, porosity and other physical properties have been investigated in order to better understand the binder removal process in a microwave field. Results of the study emphasize the amount of carbon residuals remaining in the bulk.


2013 ◽  
Vol 14 (6) ◽  
pp. 1115-1121
Author(s):  
N Simhachalam Reddy ◽  
R Narendra ◽  
Sashi Deepth Reddy ◽  
CR Sashi Purna ◽  
M Chandra Shekar ◽  
...  

ABSTRACT The denture bases made by using polymethyl methacrylates of Acrylic resin family have excellent physical properties, simple to process and easy to reline, rebase and repair. One of the inherent disadvantages of this material is the liability to break during function. The strength assessment of acrylic resins have been made generally by transverse deflection tests. Aim To evaluate the impact strength valves of certain brands of commercially available denture base resins and suggest their suitability. Materials and methods The denture bases we made using polymethyl methacrylates of acrylic resin family because they have excellent physical properties, simple to process and easy to reline and rebase. Six commercial brands of polymethyl methacrylate, namely Stellon (DPI-India), Acralyn-H (Asian Acrylate, India), Trevalon (Dentsply-England), Lucitone 199 (Dentsply/ York division), Acralyn-H (Super Unbreakable), Trevalon HI (Dentsply, Detray division, England) were tested by breaking them using Analog Pendulum (ASTM D 256). Results From the entire study the maximum impact strength was reported for Acralyn-H super unbreakable (Asian Acrylates, India) 62.19 joules. Conclusion All the analysis led to conclusion that there is basic change in material composition within and among the different groups of denture base resins. Clinical implications The complete dentures made using denture base resins with high impact strength valves (e.g. Acralyn-H super unbreakable) will be more durable and can be used by the patient for considerable period of time, i.e. beyond 4 to 5 years. How to cite this article Narendra R, Reddy NS, Reddy SD, Purna CRS, Shekar MC, Balasubramanyam S. A Comparative Evaluation of Impact Strength of Conventionally Heat Cured and High Impact Heat Cured Polymethyl Metharylate Denture Base Resins: An in vitro Study. J Contemp Dent Pract 2013;14(6): 1115-1121.


2017 ◽  
Vol 29 (1) ◽  
pp. 244-253 ◽  
Author(s):  
Nabila Haddadine ◽  
Karima Agoudjil ◽  
Khaled Abouzeid ◽  
Carlos E. Castano ◽  
Naima Bouslah ◽  
...  

2020 ◽  
Vol 869 ◽  
pp. 175-181
Author(s):  
Victor Klushin ◽  
Ekaterina Shabliy ◽  
Nina Smirnova

For the first time, the possibility of synthesis of 2,5-furandicarboxylic acid (FDCA) and 5,5-oxy-bis (methylene) bis-furane-2-caboxylic acid (OBFA) diesters and using them as plasticizers of various polymers have been studied. The most effective method for the synthesis of furan diesters is the direct esterification of FDCA or OBFA with the corresponding aliphatic diols С4-С10. Methods for the synthesis of these diesters with the yield of the target product from 45 to 85 % have been developed. The physical properties and plasticizing ability of the obtained 14 diesters were investigated. The plasticizing ability of the obtained diesters with respect to polyvinyl chloride (PVC), polystyrene (PS) and polymethyl methacrylate (PMMA) was studied. The plasticizing effect depends on the chain length of the aliphatic diol and the nature of the polymer. In general, the synthesized diesters have a stronger plasticizing effect on PS than on PVC and PMMA due to the higher stiffness of the PS chain. The plasticizing ability of the synthesized furan diesters that can be obtained from renewable plant materials is slightly inferior to industrial plasticizers based on phthalic and adipic acids, and are potentially able to replace standard plasticizers derived from hydrocarbons.


1958 ◽  
Vol 31 (4) ◽  
pp. 829-837
Author(s):  
F. M. Merrett

Abstract The concept of “tailor-made” macromolecules when applied to graft polymers implies an effective correlation between the chemical and physical properties of the component parts and the technological properties of the resultant whole. Earlier experiments have indicated that, for a given graft macromolecule of natural rubber and polymethyl methacrylate, one extreme physical configuration could readily be effected in solution, viz., with the rubber trunk chains collapsed and the methyl methacrylate side chains extended. The complementary configuration—rubber chains extended and the methyl methacrylate chains collapsed—seemed equally easy of achievement. If these configurations could be carried through to the solid state then comparison of the properties of the dry rubbers would provide one such correlation between established physical configurations and resultant technological properties. The evidence for these definite configurations is briefly described below followed by preparative methods for bulk quantities of the dry rubbers and the evaluation of their technological properties.


2013 ◽  
Author(s):  
Noor Afizah Rosli ◽  
Ishak Ahmad ◽  
Ibrahim Abdullah ◽  
Farah Hannan Anuar

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