Evaluation of Crosslinking in Elastomers Using Thermoporometry, Densimetry and Diffential Scanning Calorimetry Analysis

2002 ◽  
Vol 75 (1) ◽  
pp. 143-154 ◽  
Author(s):  
Mohamed Baba ◽  
Soney C. George ◽  
Jean Luc Gardette ◽  
Jacques Lacoste
Keyword(s):  
Analytical Approach ◽  
Soluble Fraction ◽  
Crosslinking Density ◽  
Insoluble Fraction ◽  
Dicumyl Peroxide ◽  
Scanning Calorimetry ◽  
Photo Oxidation ◽  
Thermal Curves ◽  
Ethylene Propylene Diene Rubber ◽  
Diene Rubber

Abstract The classical methods available for evaluating the degree of crosslinking in elastomers are stress-strain and swelling measurements. In this study, we have adopted a new analytical approach based on thermoporometry, densimetry and DSC for comparing the crosslinking density in elastomers. Crosslinking by chemical reaction or by photo-oxidation has been studied on polymer samples Ethylene-Propylene-Diene rubber (EPDM) and PolyButadiene (PB). Analysis has been done separately for soluble and insoluble fractions. The soluble fraction has been studied by densimetry and the insoluble fraction by thermoporometry and measurement of decomposition of dicumyl peroxide (DCP). The results of both these studies are complementary to each other. The DSC thermal curves of both EPDM and PB are identical in nature, but the density of the photo-oxidized EPDM samples shows a marked increase contrary to that found in PB.

Polyamide Reinforced EPDM Compatibilized with Maleic Anhydride Grafted Ethylene-Propylene-Diene Rubber

2003 ◽  
Vol 11 (3) ◽  
pp. 179-188
Author(s):  
Xin Liu ◽  
Hua Huang ◽  
Yong Zhang ◽  
Yinxi Zhang
Keyword(s):  
Maleic Anhydride ◽  
Thermal Ageing ◽  
Scanning Calorimetry ◽  
Reactive Compatibilization ◽  
Ethylene Propylene ◽  
Ethylene Propylene Diene Rubber ◽  
The Stability ◽  
Diene Rubber ◽  
Crosslinking Agents ◽  
Scanning Electron

Vulcanizates of blends of ethylene-propylene-diene rubber (EPDM) and polyamide (PA) copolymer were prepared by reactive compatibilization. A reactive route was employed to compatibilize these blends by the addition of maleic anhydride EPDM (MAH-g-EPDM). In this paper, the influence of compatibilizers, crosslinking agents, and blend composition on the mechanical properties of the blends were investigated. The morphologies of the blends were determined by scanning electron microscopy. It was found that the addition of MAH-g-EPDM reduced the particle size of the dispersed phase remarkably. The stability of the blend was measured by thermal ageing at high temperature in the presence of compatibilizer. Both dynamic mechanical thermal analysis and differential scanning calorimetry experiments were carried out to investigate the effect of MAH-g-EPDM addition on the Tgs of the blend components. The addition of PA copolymer caused significant improvement in the tensile properties of these blends.

Effect of Bromination on the Properties of Ethylene-Propylene-Diene Rubber in the Presence of Divinylbenzene

1995 ◽  
Vol 68 (5) ◽  
pp. 824-835 ◽  
Author(s):  
J. R. Yoon ◽  
Y. Ikeda ◽  
A. S. Hashim ◽  
S. Kohjiya
Keyword(s):  
Natural Rubber ◽  
Tensile Properties ◽  
Crosslink Density ◽  
Die Swell ◽  
Dicumyl Peroxide ◽  
Peroxide Curing ◽  
Ethylene Propylene Diene Rubber ◽  
Lower Torque ◽  
And Storage ◽  
Diene Rubber

Abstract The curing behavior and vulcanizate properties of EPDM and brominated EPDM (BEPDM) were compared using a dicumyl peroxide curing system. The BEPDM displayed lower torque and crosslink density, but better tensile properties than the EPDM. In the presence of divinylbenzene (DVB) coagent, all vulcanizates, i.e., EPDM, BEPDM, and their blends with natural rubber, had improved tensile properties. At low DVB concentration, the filler effect of DVB on the modulus enhancement was noticed. At high and comparable DVB concentration, both the BEPDM and NR/BEPDM blend showed significantly higher modulus (M100) and tensile strength than their EPDM counterparts. The BEPDM was also found to have higher crosslink density and storage modulus (E′) than the EPDM. This observation could be attributed to the better dispersion of DVB in the BEPDM and NR/BEPDM vulcanizates, as supported by TEM measurements. The TEM data is also consistent with the properties observed on the uncured mixes, in which the NK/BEPDM + DVB mix has favorable viscosity and die swell properties due to the more homogeneous DVB dispersion in the rubber phases. Thus, the bromination of EPDM has resulted in better processing and vulcanizate properties of the rubber and its blend with natural rubber.

Influence of epoxidized ethylene propylene diene rubber on nonisothermal crystallization kinetics and mechanical properties of poly(butylene terephthalate)/polypropylene blend

2019 ◽  
Vol 39 (3) ◽  
pp. 216-227
Author(s):  
Bo Liu ◽  
Wei Wu
Keyword(s):  
Mechanical Properties ◽  
Crystallization Kinetics ◽  
Scanning Calorimetry ◽  
Nonisothermal Crystallization ◽  
Butylene Terephthalate ◽  
Ethylene Propylene ◽  
Uniform Dispersion ◽  
Nonisothermal Crystallization Kinetics ◽  
Ethylene Propylene Diene Rubber ◽  
Diene Rubber

Abstract The epoxidized ethylene propylene diene rubber (eEPDM) was successfully prepared by the epoxidation of ethylene propylene diene rubber (EPDM) using t-butyl hydroperoxide as the oxidant in association with molybdenum oxide as the catalyst and characterized by Fourier-transform infrared (FTIR) spectrometer and 1H-nuclear magnetic resonance analyses. Then the poly(butylene terephthalate) (PBT)/eEPDM/polypropylene (PP) blends with different eEPDM contents were prepared using a twin-screw extruder, and the effect of eEPDM on nonisothermal crystallization kinetics of PBT/PP blend was investigated by differential scanning calorimetry. Meanwhile, morphological features of samples were observed using scanning electron microscopy. Also, the mechanical properties of samples were evaluated. Analyses of the crystallization data by various macro-kinetic models like Jeziorny modified Avrami and Liu-Mo model demonstrated that PP as diluents accelerated the crystallization of PBT in PBT/PP. Moreover, the addition of eEPDM into PBT/PP further facilitated the crystallization of PBT in PBT/eEPDM/PP. The eEPDM was an effective crystallization promoter for PBT/PP blend. And the presence of eEPDM promoted the uniform dispersion of PP in PBT matrix. When the content of eEPDM was 5 phr, the PBT/eEPDM/PP exhibited the highest notched impact strength and Young’s modulus among all the specimens.

Cure and Dynamic-Mechanical Behaviors of Vinyl Ester Resinfilled with Multi-Walled Carbon Nanotubes

2010 ◽  
Vol 150-151 ◽  
pp. 1413-1416 ◽  
Author(s):  
Hong Yan Chen ◽  
Zhen Xing Kong ◽  
Ji Hui Wang
Keyword(s):  
Carbon Nanotubes ◽  
Vinyl Ester ◽  
Mechanical Response ◽  
Cure Kinetics ◽  
Crosslinking Density ◽  
Vinyl Ester Resin ◽  
Scanning Calorimetry ◽  
Dynamic Mechanical ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The cure kinetics of Derakane 411-350, a kind of vinyl ester resin, and its suspensions containing multi-walled carbon nanotubes( MWCNTs) were investigated via non-isothermal dynamic scanning calorimetry (DSC) measurements. The results showed that incorporation of MWCNTs into vinyl ester resin excessively reduces polymerization degree and crosslinking density of vinyl ester resin. For suppressing the negative effect caused by nanotubes, the higher temperature initiator combined with the initiator MEKP was used. Dynamic-mechanical Behavior testing was then carried out on the cured sample in order to relate the curing behavior of MWCNTs modified resin suspensions to mechanical response of their resulting nanocomposites. It was revealed that nanocomposites containing MWCNTs possessed larger storage modulus values as well as higher glass transition temperatures (Tg) as compared to those without MWCNTs after using mixed intiators system to improve the degree of cure.

scholarly journals The radical scavenging activity of 2-2’ diphenyl -1- picrylhydrazil (DPPH) on the methanol extracts and Ethyl acetate fractions of red dragon fruit peel  (Hylocereus polyrhizus (F.A.C.Weber) Britton dan Rose)

2017 ◽  
Vol 9 (1) ◽  
pp. 79
Author(s):  
Sri Wahdaningsih ◽  
Subagus Wahyuono ◽  
Sugeng Riyanto ◽  
Retno Murwanti
Keyword(s):  
Antioxidant Activity ◽  
Ethyl Acetate ◽  
Methanol Extract ◽  
Soluble Fraction ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Insoluble Fraction ◽  
Fruit Peel ◽  
Activity Test ◽  
Dragon Fruit

<p> </p><p>Red dragon fruit (<em>H. Polyrhizus</em>) is one of the the plants that has a great potential as natural antioxidant. This study tested the activity of radical scavenging of 2-2' diphenyl -1- pikril hidrazil (DPPH) in the methanol extract, as well as in the soluble and insoluble fractions of ethyl acetate of red dragon fruit peel. This research is carried out through various stages, such as: extraction and fractionation to obtain both insoluble fraction and soluble fractions of ethyl acetate. Antioxidant activity test is conducted by the method of thin layer chromatography and spectrophotometry.<strong> </strong>Antioxidant activity test, IC<sub>50 </sub>values of methanol extract, ethyl acetate soluble fraction, and insoluble fraction of ethyl acetate had been obtained consecutively as much as 241.19 µg /mL, 8.34  µg/mL, 46.84 µg/mL. The soluble fraction of ethyl acetate had greater antioxidant activity compared to the methanol extract and the insoluble fractions of ethyl acetate.</p>

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