scholarly journals Влияние пероксида на температурные зависимости электропроводности углеродсодержащего полимерного композита

Author(s):  
А.М. Зюзин ◽  
А.А. Карпеев ◽  
Н.В. Янцен

A significant difference was found in the temperature dependences of the resistivity of a carbon-containing polymer composite based on ethylene-vinyl acetate and the same composite saturated with peroxide. The presence of a sufficiently clear correlation between the characteristic points on the temperature dependence of the resistivity and on the curves of the differential scanning calorimetry was established.

2017 ◽  
Vol 50 (5) ◽  
pp. 391-402 ◽  
Author(s):  
Federico Karp ◽  
Julio A Luna ◽  
Luciano N Mengatto

In this work, a new recyclable ethylene-vinyl acetate (EVA)-based strip impregnated with amitraz (AMZ) was prepared, characterized, and evaluated for the treatment of Apis mellifera against Varroa destructor. Bees are important for natural pollination, honey, and related goods production. Varroa destructor is currently considered one of the major pests and important efforts around the world are focused on methods for varroasis treatment. The procedure of strips preparation presented in this work consisted of two steps: impregnation and molding of impregnated pellets. Differential scanning calorimetry and gas chromatography–mass spectrometry analyses confirmed that AMZ molecule resisted the impregnation and molding conditions. The strips were sufficiently strong to resist destruction by the bees. The final infestation was lower in the hives treated with AMZ/EVA strips than in those treated with commercial strips. In order to check the possibility of recycling, strips were cut into little pieces and were subjected to total AMZ extraction. Finally, the fragments were exposed to re-impregnation and molding. The strips prepared after the recycling process presented the same shape and AMZ load than fresh strips.


2021 ◽  
Vol 1028 ◽  
pp. 234-239
Author(s):  
Bambang Afrinaldi ◽  
David Natanael Vicarneltor ◽  
Reza Pahlevi Rudianto ◽  
Arif Rachman Hakim ◽  
Opa Fajar Muslim

Thermal properties, i.e. melting point and decomposition temperature of polymers, azodicarbonamide (ADC), and other additives mixture, are the most important information to determine the appropriate foaming process parameters. ADC has been widely used as a blowing agent for foam fabrication. Here, ADC will decompose and release gas which will be trapped in the melting polymer to make a foamed product. Originally, ADC has a decomposition temperature at around 220°C. In this study, the effect of Zinc Oxide (ZnO) addition on the thermal properties of intermediate product and Polyethylene/Ethylene Vinyl Acetate (PE/EVA) foam with ADC as the blowing agent was investigated. ZnO addition decreased the decomposition temperature of ADC. The thermal properties were characterized by Differential Scanning Calorimetry (DSC). The result showed that the decomposition temperature of ADC significantly decreased from the temperature of 220°C to 170°C with the increment of the ZnO.


Author(s):  
А.М. Зюзин ◽  
А.А. Карпеев ◽  
Н.В. Янцен

It was found that in the region of the percolation threshold, depending on the dominance of one or another conduction mechanism, the temperature dependence of the specific volume resistivity ρ(Т) of the polymer composite based on a matrix of ethylene vinyl acetate is significantly transformed. With an increase in the CB content, there is a decrease by several orders of magnitude in the maximum value of the relative resistivity ρ(Т)max/ρ20 in its temperature dependence. Peroxide crosslinking of matrix macromolecules leads to a change in the nature of the temperature dependence of resistivity.


2021 ◽  
Vol 66 (11) ◽  
pp. 983
Author(s):  
S.S. Ragimov ◽  
M.A. Musayev ◽  
N.N. Hashimova

The transport properties of (AgSbTe2)0.9(PbTe)0.1, namely, the electrical conductivity and the Seebeck (S) and Hall (RH) coefficients, are studied in the temperature interval 80–560 K. An endothermic peak at 410 K is found by the differential scanning calorimetry (DSC). Sharp changes in the temperature dependences of the electrical conductivity and thermoelectric power in the region near 410 K are observed. The temperature dependence of Hall coefficient passes through maximum at ∼200 K and has negative sign. It is shown that, these peculiarities are due to the presence of the Ag2Te phase. The thermoelectric Z-factor has the maximum value of 2.7 × 10−3 K−1 at 400 K.


Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1383
Author(s):  
Jerzy Korol ◽  
Aleksander Hejna ◽  
Klaudiusz Wypiór ◽  
Krzysztof Mijalski ◽  
Ewelina Chmielnicka

The recycling of plastics is currently one of the most significant industrial challenges. Due to the enormous amounts of plastic wastes generated by various industry branches, it is essential to look for potential methods for their utilization. In the presented work, we investigated the recycling potential of wastes originated from the agricultural films recycling line. Their structure and properties were analyzed, and they were modified with 2.5 wt % of commercially available compatibilizers. The mechanical and thermal performance of modified wastes were evaluated by tensile tests, thermogravimetric analysis, and differential scanning calorimetry. It was found that incorporation of such a small amount of modifiers may overcome the drawbacks caused by the presence of impurities. The incorporation of maleic anhydride-grafted compounds enhanced the tensile strength of wastes by 13–25%. The use of more ductile compatibilizers—ethylene-vinyl acetate and paraffin increased the elongation at break by 55–64%. The presence of compatibilizers also reduced the stiffness of materials resulting from the presence of solid particles. It was particularly emphasized for styrene-ethylene-butadiene-styrene and ethylene-vinyl acetate copolymers, which caused up to a 20% drop of Young’s modulus. Such effects may facilitate the further applications of analyzed wastes, e.g., in polymer film production. Thermal performance was only slightly affected by compatibilization. It caused a slight reduction in polyethylene melting temperatures (up to 2.8 °C) and crystallinity degree (up to 16%). For more contaminated materials, the addition of compatibilizers caused a minor reduction in the decomposition onset (up to 6 °C). At the same time, for the waste after three washing cycles, thermal stability was improved. Moreover, depending on the desired properties and application, materials do not have to go through the whole recycling line, simplifying the process, reducing energy and water consumption. The presented results indicate that it is possible to efficiently use the materials, which do not have to undergo the whole recycling process. Despite the presence of impurities, they could be applied in the manufacturing of products which do not require exceptional mechanical performance.


2017 ◽  
Vol 751 ◽  
pp. 657-662
Author(s):  
Phakphum Srinuan ◽  
Jeerapatr O. Baiyokvichit ◽  
Rasana Boonpeng ◽  
Tanapol Wongwisatekit ◽  
Pacharaporn Pattanasukwasan ◽  
...  

The effect of thermoforming on the tear strength of ethylene vinyl acetate (EVA) mouthguard material (Bioplast®) has not been widely investigated. The present study compared the tear strengths of non-processed and processed EVA specimens in various thicknesses. Two groups of EVA sheet (non-processed and processed) in three different thicknesses of 3, 4 and 5 mm were used in specimen fabrication. The processed EVA sheets were achieved by forming the EVA sheet on the cylindrical stone model with the pressure-molding device (Biostar®). Twelve of tear strength specimens of non-processed and processed group in each thickness were prepared following the modified ASTM D 624-00 guideline. The tear strength test was conducted using universal testing machine (Lloyd® 1K series) with the speed of 500 mm/min. The mean thickness and tear strength of the non-processed and processed specimens in each thickness were compared using independent T-test. The differences in the mean tear strength for each thickness of non-processed and process specimens were determined using one-way ANOVA. The mean tear strength and mean thickness of processed EVA specimens was significantly lower than the non-processed EVA specimens for every thickness (P ≤ 0.05). There was no significant difference in the mean tear strength of EVA specimens among each thickness in both non-processed and processed groups. It can be concluded that the thermoforming process has the significant effect on the tear strength of the EVA mouthguard material formed by pressure molding device in every thicknesses. The tear strength of processed specimens were significant lower than the non-processed. Thus, it is more relevant for testing properties of the processed mouthguard material that the mouthguard material before processing.


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