Temperature memory effect and its stability revealed via differential scanning calorimetry in ethylene-vinyl acetate within glass transition range

2016 ◽  
Vol 54 (17) ◽  
pp. 1731-1737 ◽  
Author(s):  
Tao Xi Wang ◽  
Wei Min Huang ◽  
Hongmei Chen ◽  
Rui Xiao ◽  
Hai Bo Lu ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Vinyl Acetate ◽  
Memory Effect ◽  
Ethylene Vinyl Acetate ◽  
Scanning Calorimetry ◽  
Transition Range ◽  
Glass Transition Range ◽  
Temperature Memory Effect

Recyclable amitraz-ethylene vinyl acetate strips used for beehives treatment against Varroa destructor

2017 ◽  
Vol 50 (5) ◽  
pp. 391-402 ◽  
Author(s):  
Federico Karp ◽  
Julio A Luna ◽  
Luciano N Mengatto
Keyword(s):  
Mass Spectrometry ◽  
Differential Scanning Calorimetry ◽  
Vinyl Acetate ◽  
Varroa Destructor ◽  
Ethylene Vinyl Acetate ◽  
Gas Chromatography Mass Spectrometry ◽  
Recycling Process ◽  
Scanning Calorimetry ◽  
The World ◽  
Natural Pollination

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.

scholarly journals Competition between Structural Relaxation and Crystallization in the Glass Transition Range of Random Copolymers

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1778
Author(s):  
Jürgen E. K. Schawe ◽  
Claus Wrana
Keyword(s):  
Glass Transition ◽  
Structural Relaxation ◽  
Random Sequence ◽  
High Sensitivity ◽  
Random Copolymers ◽  
High Time Resolution ◽  
Scanning Calorimetry ◽  
Transition Range ◽  
Glass Transition Range ◽  
And Control

Structural relaxation in polymers occurs at temperatures in the glass transition range and below. At these temperatures, crystallization is controlled by diffusion and nucleation. A sequential occurrence of structural relaxation, nucleation, and crystallization was observed for several homopolymers during annealing in the range of the glass transition. It is known from the literature that all of these processes are strongly influenced by geometrical confinements. The focus of our work is copolymers, in which the confinements are caused by the random sequence of monomer units in the polymer chain. We characterize the influence of these confinements on structure formation and relaxation in the vicinity of the glass transition. The measurements were performed with a hydrogenated nitrile-butadiene copolymer (HNBR). The kinetics of the structural relaxation and the crystallization was measured using fast differential scanning calorimetry (FDSC). This technique was selected because of the high sensitivity, the fast cooling rates, and the high time resolution. Crystallization in HNBR causes a segregation of non-crystallizable segments in the macromolecule. This yields a reduction in mobility in the vicinity of the formed crystals and as a consequence an increased amount of so-called “rigid amorphous fraction” (RAF). The RAF can be interpreted as self-assembled confinements, which limit and control the crystallization. An analysis of the crystallization and the relaxation shows that the kinetic of both is identical. This means that the Kohlrausch exponent of relaxation and the Avrami exponent of crystallization are identical. Therefore, the crystallization is not controlled by nucleation but by diffusion and is terminated by the formation of RAF.

Influence of Zinc Oxide Addition on Azodicarbonamide Thermal Decomposition in the Polyethylene/Ethylene Vinyl Acetate Foaming Release

2021 ◽  
Vol 1028 ◽  
pp. 234-239
Author(s):  
Bambang Afrinaldi ◽  
David Natanael Vicarneltor ◽  
Reza Pahlevi Rudianto ◽  
Arif Rachman Hakim ◽  
Opa Fajar Muslim
Keyword(s):  
Differential Scanning Calorimetry ◽  
Zinc Oxide ◽  
Thermal Properties ◽  
Vinyl Acetate ◽  
Ethylene Vinyl Acetate ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
Blowing Agent ◽  
Foaming Process ◽  
Oxide Addition

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.

scholarly journals Влияние пероксида на температурные зависимости электропроводности углеродсодержащего полимерного композита

2020 ◽  
Vol 46 (12) ◽  
pp. 3
Author(s):  
А.М. Зюзин ◽  
А.А. Карпеев ◽  
Н.В. Янцен
Keyword(s):  
Differential Scanning Calorimetry ◽  
Temperature Dependence ◽  
Vinyl Acetate ◽  
Polymer Composite ◽  
Ethylene Vinyl Acetate ◽  
Clear Correlation ◽  
Scanning Calorimetry ◽  
Significant Difference ◽  
Temperature Dependences ◽  
Characteristic Points

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.

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