Positron Lifetimes and Crystallinity of γ-Irradiated Polypropylenes

2012 ◽  
Vol 733 ◽  
pp. 163-166
Author(s):  
Zhe Chen ◽  
Wei Huang ◽  
Peng Fei Fang ◽  
Wen Yu ◽  
Shao Jie Wang
Keyword(s):  
Differential Scanning Calorimetry ◽  
Irradiation Dose ◽  
Gamma Ray ◽  
Positron Lifetime ◽  
Γ Irradiation ◽  
Scanning Calorimetry ◽  
Γ Ray ◽  
Positron Lifetimes ◽  
Dsc Method ◽  
Low Irradiation

The microstructure of the polypropylenes (PP) irradiated by gamma ray was studied by positron lifetime technique and differential scanning calorimetry (DSC). Lifetime measurement shows o-Ps intensity decreases with increasing γ irradiation dose. The crystallinity of irradiated samples was detected by DSC method. The correlation between o-Ps intensity and crystallinity indicates γ-ray can induce higher crystallinity in the polypropylene at low irradiation dose.

scholarly journals A STUDY OF PARAMETERS RELATED TO ANALYSIS OF TRANSITION TEMPERATURES AND ENTHALPIES OF POLYPROPYLENE BY DIFFERENTIAL SCANNING CALORIMETRY (DSC)

2002 ◽  
Vol 10 (11) ◽  
pp. 73-78
Author(s):  
Carlos R. Wolf ◽  
Emir Grave
Keyword(s):  
Differential Scanning Calorimetry ◽  
Material Characterization ◽  
Transition Temperatures ◽  
Nitrogen Flow ◽  
Thermoplastic Polymer ◽  
Scanning Calorimetry ◽  
Know How ◽  
Heating And Cooling ◽  
Polypropylene Material ◽  
Dsc Method

Polypropylene is a thermoplastic polymer, widely employed by converter industries to produce different plastic objects. In order to control and optimize the final properties of the polypropylene material, the evaluation of transition temperatures and enthalpies by Differential Scanning Calorimetry (DSC) has a very important role. Therefore, it is fundamental to know how the analytical conditions influence the results. In this study heating and cooling rates, 10°C/min and 20°C/min, and two different rates of nitrogen flow, 20mL/min and 50mL/min were investigated. It was concluded that thermal properties are influenced by rates of heating and rates of nitrogen flow. The best precision was obtained with the low heating rate, 10°C/min, and high flow rate, 50mL/min. These conditions are being used with the DSC method for polyolefin quality control and material characterization.

Effect of Buffer on the Optical Properties of Irradiated Hydroxyethyl Methacrylate Copolymer

2002 ◽  
Vol 17 (5) ◽  
pp. 1199-1207
Author(s):  
K. F. Chou ◽  
C. C. Han ◽  
Sanboh Lee
Keyword(s):  
Optical Properties ◽  
Irradiation Dose ◽  
Ph Value ◽  
Bathochromic Shift ◽  
Cutoff Wavelength ◽  
Hydroxyethyl Methacrylate ◽  
Γ Irradiation ◽  
Incident Wavelength ◽  
Γ Ray ◽  
Methacrylate Copolymer

The effect of buffer and γ irradiation on the optical properties of hydroxyethyl methacrylate (HEMA) copolymer was investigated. The transmission of HEMA copolymer decreased with the increase of irradiation dose and/or pH value of the buffer. The cutoff wavelength of HEMA copolymer exhibits a bathochromic shift as the γ-ray dose and/or pH value of buffer increases. The influence of atmosphere during γ-ray irradiation on the optical properties of HEMA copolymer was investigated. The change of optical properties of HEMA copolymer irradiated in air was more pronounced than that irradiated in vacuum. Light was scattered by holes in the polymer. The relationship between scattering intensity (Is) and incident wavelength (λ) can be described by the formula Is ∝ λ−n. The span of holes increases with the irradiation dose regardless of radiation atmosphere and pH value in the range of 4.1–6.5. A boundary between the inner and outer layers of HEMA copolymer irradiated in air was observed, separating two differential morphologies of holes.

Characterization of Main-Chain Liquid Crystal Elastomers by Using Differential Scanning Calorimetry (DSC) Method

2015 ◽  
Vol 1123 ◽  
pp. 69-72 ◽  
Author(s):  
Supardi ◽  
Y. Yusuf ◽  
Harsoyo
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Basic Principle ◽  
Main Chain ◽  
Scanning Calorimetry ◽  
Mechanical Effects ◽  
Liquid Crystal Elastomers ◽  
Dsc Method

We performed an experiment to characterize the four samples of main chain liquid crystal elastomers (MCLCEs) by using differential scanning calorimetry (DSC) method. Basic principle of this method is that difference in the amount of heat required to increase the temperature of the sample and reference is measured as a function of temperature. The temperature between the sample and reference is maintained nearly the same throughout the experiment. There were four samples with different concentrations of crosslinker we have taken, namely 8%, 12%, 14%, and 16%. The results showed that the phase transition from nematic to isotropic obtained by this method had correlation with their thermo-mechanical effects.

Novel isochoric measurement of the onset of vapor–liquid phase transition using differential scanning calorimetry

2018 ◽  
Vol 20 (41) ◽  
pp. 26241-26248 ◽  
Author(s):  
Xingdong Qiu ◽  
Sugata P. Tan ◽  
Morteza Dejam ◽  
Hertanto Adidharma
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Liquid Phase ◽  
Dew Point ◽  
Gas Mixture ◽  
Scanning Calorimetry ◽  
Liquid Phase Transition ◽  
Dsc Method ◽  
Vapor Liquid

Dew point measurements of methane/ethane gas mixture using isochoric DSC method.

scholarly journals Thermal Properties of Lignocellulose Pellets

2017 ◽  
Vol 25 (40) ◽  
pp. 83-90
Author(s):  
Igor Wachter ◽  
Siegfried Hirle ◽  
Karol Balog
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Reaction Enthalpy ◽  
Wood Pellets ◽  
Scanning Calorimetry ◽  
Wood Pellet ◽  
Exothermic Reactions ◽  
Enthalpy Changes ◽  
Dsc Method

Abstract This article deals with the characterization of biomass pellets using Differential Scanning Calorimetry. We used three types of industrially produced and commercially available pellets as samples: wood pellets containing grass, wood pellet containing bark and wood pellets without bark. Each of the samples were examined using the DSC method. Based on the measurements in atmosphere of air and nitrogen temperature, the changes caused by thermal degradation of various kinds of test fuels were observed. Subsequently, limits of exothermic processes, reaction enthalpy changes and the temperature at which exothermic reactions reached peaks were determined.

MEASUREMENT THE EFFECT OF γ-IRRADIATION DOSES ON AlCu8.5 BY POSITRON ANNIHILATION DOPPLER-BROADENING SPECTROSCOPY

2007 ◽  
Vol 21 (22) ◽  
pp. 3901-3907
Author(s):  
M. A. ABDEL-RAHMAN ◽  
M. ABDEL-RAHMAN ◽  
M. ABO-ELSOUD ◽  
M. F. EISSA ◽  
YAHIA A. LOTFY ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Irradiation Dose ◽  
Room Temperature ◽  
Doppler Broadening ◽  
Γ Irradiation ◽  
Second Stage ◽  
S Parameter ◽  
Controlling Mechanism ◽  
Γ Ray ◽  
Two Stages

The effect of irradiation dose (kGy) on a set of AlCu 8.5 samples has been studied. The samples were irradiated to doses of 10, 30, 50, 70, 100, 300, 500, 700 and 1000 kGy of 60 Co γ-source at room temperature. The effect of γ-ray irradiation on the values of the S- and W-parameters reveals two stages. In the first stage, the S-parameter increases, while the W-parameter decreases up to 70 kGy. In the second stage, the S- and W-parameters decrease and increase respectively in the dose region from 100 to 1000 kGy. The dominant controlling mechanism of the S- and W-parameters was observed.

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