Kinetics of interaction of palm ethyl biodiesel with three different polymer materials

2008 ◽  
Vol 21 (12) ◽  
pp. 1068-1071 ◽  
Author(s):  
Giselle Lutz ◽  
Julio F. Mata-Segreda
Author(s):  
A. A. Dalinkevich ◽  
◽  
L. V. Fomin ◽  
V. V. Melnikov ◽  
T. A. Nenasheva ◽  
...  

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2232 ◽  
Author(s):  
Piotr Krawiec ◽  
Łukasz Warguła ◽  
Daniel Małozięć ◽  
Piotr Kaczmarzyk ◽  
Anna Dziechciarz ◽  
...  

The article presents the potential impact of flat drive and transport belts on people’s safety during a fire. The analysis distinguished belts made of classically used fabric–rubber composite materials reinforced with cord and currently used multilayer polymer composites. Moreover, the products’ multilayers during the thermal decomposition and combustion can be a source of emissions for unpredictable and toxic substances with different concentrations and compositions. In the evaluation of the compared belts, a testing methodology was used to determine the toxicometric indicators (WLC50SM) on the basis of which it was possible to determine the toxicity of thermal decomposition and combustion products in agreement with the standards in force in several countries of the EU and Russia. The analysis was carried out on the basis of the registration of emissions of chemical compounds during the thermal decomposition and combustion of polymer materials at three different temperatures. Moreover, the degradation kinetics of the polymeric belts by using the thermogravimetric (TGA) technique was evaluated. Test results have shown that products of thermal decomposition resulting from the neoprene (NE22), leder leder (LL2), thermoplastic connection (TC), and extra high top cower (XH) belts can be characterized as moderately toxic or toxic. Their toxicity significantly increases with the increasing temperature of thermal decomposition or combustion, especially above 450 °C. The results showed that the belts made of several layers of polyamide can be considered the least toxic in fire conditions. The TGA results showed that NBR/PA/PA/NBR belt made with two layers of polyamide and the acrylonitrile–butadiene rubber has the highest thermal stability in comparison to other belts.


2021 ◽  
Vol 273 ◽  
pp. 04014
Author(s):  
Irina Zhukova ◽  
Evgeniya Flik ◽  
Elena Shubina ◽  
Vladimir Mishurov ◽  
Ivan Kashparov

The process of thermal-oxidative degradation of polymer materials has been studied on the example of polyethylene in the presence of quinones and / or nitroxyl radicals. The synergistic effect of the positive action of a mixture of stabilisers from a number of quinones and nitroxyl radicals on the destructive process of polyethylene has been established. It has been shown that the rate of degradation has significantly slowed down when an equimolecular mixture of 4-acetylamino-2,2,6,6-tetramethylhexahydropyridine-1-oxyl and 2,6-di-tert-amyl-1,4-cyclohexadienone inhibitors has been introduced into the polymer. The kinetics of the initiated thermo-destructive process of polyethylene oxidation in the presence and absence of stabilisers has been studied. A mechanism of joint action of stabilisers based on their interaction with radicals and the breakage of radical chains, as well as a mechanism for the regeneration of stabilisers, has been proposed.


Author(s):  
В. П. Селяев ◽  
Д. Р. Низин ◽  
Н. С. Канаева

Постановка задачи. Изучено изменение упруго-прочностных показателей и кинетики накопления повреждений в эпоксидных полимерах под действием растягивающих нагрузок в контрольном состоянии и после натурного климатического воздействия в течение одного календарного года. Расчет кинетики накопления повреждений осуществлялся на основе авторской методики, основанной на использовании методов фрактального анализа кривых деформирования образцов полимерных материалов при растяжении. Результаты. Предложен удельный показатель θ, позволяющий количественно оценивать суммарное число повреждений на единицу прочности, накопление которого приводит к разрушению полимеров. Получены аппроксимирующие зависимости, описывающие взаимосвязь между удельным показателем θ и пределом прочности эпоксидных полимеров при растяжении. Выводы. Установлено, что наибольшей стабильностью свойств под действием натурного климатического воздействия обладает полимер на основе эпоксидной смолы «Этал-247». Statement of the problem. In the current study we look at the change in the elastic-strength performance and kinetics of damage accumulation in epoxy polymers under tensile loads in the control state and after full-scale climatic exposure during one calendar year were studied. Damage accumulation kinetics was calculated based on the author's method using methods of fractal analysis of deformation curves for polymer materials samples under tension. Results. We proposed specific index θ to quantify the total number of damages per unit of strength where its accumulation leads to the destruction of polymers. The dependences have been obtained that describe the relationship between specific index θ and tensile strength of epoxy polymers. Consclusion. The study has shown that the Etal-247 epoxy resin-based polymer cured with Etal-1440 amine hardener has the most stable properties under the full-scale climatic exposure.


Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 304
Author(s):  
Jun Xu ◽  
Günter Reiter ◽  
Rufina G. Alamo

Nucleation plays a vital role in polymer crystallization, in which chain connectivity and thus the multiple length and time scales make crystal nucleation of polymer chains an interesting but complex subject. Though the topic has been intensively studied in the past decades, there are still many open questions to answer. The final properties of semicrystalline polymer materials are affected by all of the following: the starting melt, paths of nucleation, organization of lamellar crystals and evolution of the final crystalline structures. In this viewpoint, we attempt to discuss some of the remaining open questions and corresponding concepts: non-equilibrated polymers, self-induced nucleation, microscopic kinetics of different processes, metastability of polymer lamellar crystals, hierarchical order and cooperativity involved in nucleation, etc. Addressing these open questions through a combination of novel concepts, new theories and advanced approaches provides a deeper understanding of the multifaceted process of crystal nucleation of polymers.


Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6000
Author(s):  
Dagmara Słota ◽  
Wioletta Florkiewicz ◽  
Karina Piętak ◽  
Aleksandra Szwed ◽  
Marcin Włodarczyk ◽  
...  

In the present work, hydroxyapatite-polymer materials were developed. The preparation, as well as characterization of the ceramic-polymer composites based on polyvinylpyrrolidone, sodium alginate, and gelatin were described. The system was enriched with the addition of common sage extract (Salvia officinalis). The antioxidant potential of sage aqueous extract and total polyphenol content was determined. The antioxidant capacity and total phenolic content of extract were equal to 86.06 ± 0,49% and 16.21 ± 0,58 mg gallic acid equivalents per gram of dry weight, respectively. Incubation studies in selected biological liquids were carried out to determine the biomineralization capacity on the surface of the composites and to examine the kinetics of release of the active substances from within the material. As a result of the incubation, a gradual release of the extract over time from the polymer matrix was observed; moreover, the appearance of new apatite layers on the composite surface was recorded as early as after 14 days, which was also confirmed by energy-dispersive X-ray spectroscopy (EDS) microanalysis. The composites were analyzed with Fourier transform infrared spectroscopy (FTIR) spectroscopy, and the morphology was recorded by scanning electron microscope (SEM) imaging. The in vitro biological studies allowed their cytotoxic effect on the reference L929 fibroblasts to be excluded. Further analysis of the biomaterials showed that enrichment with polyphenols does not support the adhesion of L929 cells to the surface of the material. However, the addition of these natural components stimulates human monocytes that constitute the first step of tissue regeneration.


2021 ◽  
pp. 46-48
Author(s):  
D. V. Kolotilin ◽  
A. V. Dedov ◽  
R. I. Kunnap

The analysis of methods for assessing the diffusion permeability of polymer materials is carried out. The limitations of the methods for determining the tightness time and the rate of fuel bleeding from elastic tanks based on thermoplastic polyurethanes are shown. To solve the set tasks, an approach is proposed related to establishing dependencies of the kinetics of diesel fuel bleeding in the coordinate system of the conditional time, which was calculated as the square root of the process time. The tightness time and rate of fuel bleeding depends on the degree of filling of the tank during testing.


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