Segmented Polyurethanes and Thermoplastic Elastomers from Elemental Sulfur with Enhanced Thermomechanical Properties and Flame Retardancy

2021 ◽  
Vol 60 (42) ◽  
pp. 22900-22907
Author(s):  
Kyung‐Seok Kang ◽  
Anthony Phan ◽  
Chisom Olikagu ◽  
Taeheon Lee ◽  
Douglas A. Loy ◽  
...  
2021 ◽  
Vol 7 ◽  
pp. 49-55
Author(s):  
N. T. Kakhramanov ◽  
◽  
A. J. Guliyev ◽  
M. I. Abdullin ◽  
Kh. V. Allahverdiyeva ◽  
...  

The paper presents the results of a study of the thermodefomational characteristics of dynamically vulcanized thermoplastic elastomers based on random polypropylene and nitrile butadiene rubber (SKN). In order to improve the compatibility of polymer mixtures, Exxelor PO1200, a grafted copolymer of polypropylene with maleic anhydride, was used as a compatibilizer. The concentration of maleic anhydride in the composition of the grafted copolymer was 3.0 wt. %. It was shown that as a result of the loading of the compatibilizer, it seemed possible to improve the compatibility of bipolar mixtures, in which there was no separation between the components of the mixture. It was found that with the load of 30 wt. % SKN-18, as well as 40 wt. % SKN-26 or SKN-40 into the composition of random polypropylene, the polymer composition exhibits the properties of thermoplastic elastomers, as a result of which plastic deformation is replaced by a highly elastic characteristic for rubbers. The temperature regions of the solid, highly elastic, and viscous flowing states are determined. In order to give polymer blends greater elasticity, they were vulcanized using crosslinking agents such as dicumyl peroxide and sulfur. It is shown how, in the process of increasing the concentration of dicumyl peroxide from 0.25 to 1.0 wt. %, the thermomechanical properties of dynamically vulcanized thermoplastic elastomers significantly change. It was found that with the introduction of dicumyl peroxide in an amount equal to 1.0 wt. %, the melt flowability of vulcanized materials almost completely lose their ability to flow, and pass from a highly elastic state to a glassy one. With the load of sulfur in an amount of 1.0 to 10 wt. %, the melt flowability of the vulcanized thermoplastic elastomers is preserved.


2020 ◽  
Vol 14 (2) ◽  
pp. 84-90 ◽  
Author(s):  
Krzysztof Wałęsa ◽  
Ireneusz Malujda ◽  
Krzysztof Talaśka ◽  
Dominik Wilczyński

AbstractMost industrial machines use belt transmission for power transfer. These mechanisms often use the round belts of several millimetres in diameter that are made of thermoplastic elastomers, especially polyurethane. Their production process calls for bonding the material, which is often performed by hot plate butt welding. In order to achieve proper design of an automatic welding machine, the authors analysed the hot plate welding process of round belts. This process consists of five phases. It is necessary to recognize all the physical phenomena that occur during welding, especially those connected with thermomechanical properties of material. This knowledge is necessary to determine the temperature distribution during each step of the process. The paper presents a standard welding cycle together with an explanation of the physical phenomena in each phase. An analysis of these fundamentals will be used to derivate the function of temperature distribution during all process phases. In addition, some assumptions for calculation of temperature distribution and some fundamental physic correlations were presented.


2018 ◽  
Vol 9 (17) ◽  
pp. 2290-2294 ◽  
Author(s):  
Yueyan Zhang ◽  
Tristan S. Kleine ◽  
Kyle J. Carothers ◽  
David D. Phan ◽  
Richard S. Glass ◽  
...  

The first example of a sulfur copolymer with amine groups poly(sulfur-random-vinylaniline) was synthesized and successfully post-functionalized to improve the thermomechanical properties of these materials.


Author(s):  
V.K. Berry

There are two strains of bacteria viz. Thiobacillus thiooxidansand Thiobacillus ferrooxidanswidely mentioned to play an important role in the leaching process of low-grade ores. Another strain used in this study is a thermophile and is designated Caldariella .These microorganisms are acidophilic chemosynthetic aerobic autotrophs and are capable of oxidizing many metal sulfides and elemental sulfur to sulfates and Fe2+ to Fe3+. The necessity of physical contact or attachment by bacteria to mineral surfaces during oxidation reaction has not been fairly established so far. Temple and Koehler reported that during oxidation of marcasite T. thiooxidanswere found concentrated on mineral surface. Schaeffer, et al. demonstrated that physical contact or attachment is essential for oxidation of sulfur.


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