The thermoluminescence of irradiated polyethylene and other polymers

1963 ◽  
Vol 271 (1345) ◽  
pp. 170-187 ◽  
Keyword(s):  
Activation Energy ◽  
Glow Curve ◽  
Irradiation Dose ◽  
Visible Region ◽  
Ultra Violet ◽  
Degree Of Crystallinity ◽  
Γ Irradiation ◽  
Chemical Impurities ◽  
Transition Points ◽  
The Degree Of Crystallinity

The thermoluminescence glow curves of various polymers have been observed in the temperature range 77 °K to ice point after 60 Co γ-irradiation, and a number of them are reproduced. A detailed study of polyethylene thermoluminescence was made. The glow curve of this material in the absence of oxygen comprises three glow peaks, the α, β, γ peaks, whose luminescence intensities are proportional to irradiation dose for doses below 50 krads. The α, β, γ peaks all decay exponentially at constant temperature, and a study of the kinetics involved shows that all these peaks have the same activation energy at the lowest temperatures. At higher temperatures the β and γ peaks each show two different transition points, one in the visible region and one in the ultra-violet, which appear to be related to two of the known structural transitions of polyethylene. The glow curves of a variety of different polyethylenes were recorded. By comparison of these it was found that the relative heights of the α, β, γ peaks are dependent on the degree of crystallinity of the materials but that the normal chemical impurities present in commercial polyethylenes have no effect on their glow curves.

scholarly journals The ultra-violet spectrum of magnesium hydride. 1.—The band at λ 2430

1929 ◽  
Vol 122 (790) ◽  
pp. 442-455 ◽  
Keyword(s):  
Fine Structure ◽  
General Structure ◽  
Energy Levels ◽  
Visible Region ◽  
Ultra Violet ◽  
Present Theory ◽  
Magnesium Hydride ◽  
Electronic Energy ◽  
Band Spectra ◽  
Electronic Energy Levels

The system of bands in the visible region of the emission spectrum of magnesium hydride is now well known. The bands with heads at λλ 5622, 5211, 4845 were first measured by Prof. A. Fowler, who arranged many of the strongest lines in empirical series for identification with absorption lines in the spectra of sun-spots. Later, Heurlinger rearranged these series in the now familiar form of P, Q and R branches, and considered them, with the OH group, as typical of doublet systems in his classification of the fine structure of bands. More recently, W. W. Watson and P. Rudnick have remeasured these bands, using the second order of a 21-foot concave grating, and have carried out a further investigation of the fine structure in the light of the present theory of band spectra. Their detection of an isotope effect of the right order of magnitude, considered with the general structure of the system, and the experimental work on the production of the spectrum, seems conclusive in assigning these bands to the diatomic molecule MgH. The ultra-violet spectrum of magnesium hydride is not so well known. The band at λ 2430 and the series of double lines in the region λ 2940 to λ 3100, which were recorded by Prof. Fowler in 1909 as accompanying the group of bands in the visible region, appear to have undergone no further investigation. In view of the important part played by hydride band spectra in the correlation of molecular and atomic electronic energy levels, it was thought that a study of these features might prove of interest in yielding further information on the energy states of the MgH molecule. The present paper deals with observations on the band at λ 2430; details of an investigation of the other features of the ultra-violet spectrum will be given in a later communication.

scholarly journals Estimation of the Age of Architectural Heritage Objects by Microstructural Changes of Calcite in Lime Mortars of Ancient Brickwork and Masonry

Buildings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 240
Author(s):  
Vladimir Kotlyar ◽  
Victoria Pishchulina ◽  
Alexey N. Beskopylny ◽  
Besarion Meskhi ◽  
Yury Popov ◽  
...  
Keyword(s):  
18Th Century ◽  
Degree Of Crystallinity ◽  
Architectural Heritage ◽  
Natural Conditions ◽  
Relative Age ◽  
Lime Mortars ◽  
Powder Samples ◽  
Diffraction Patterns ◽  
Cultural Monuments ◽  
The Degree Of Crystallinity

Determining the age of ancient architectural and cultural monuments is a significant scientific problem. An approach based on the transformation of portlandite into calcite and subsequent recrystallization of calcite is considered, which allows for estimating the relative age of ancient brickworks for local groups of historic buildings based on the results of diffraction studies of powder samples of carbonate mortars and measurements of samples with a known age. This article presents the results of the study of lime mortars of ancient brickwork. Under natural conditions, the process of transformation of portlandite into calcite takes from 100 to 200 years. The rate of this process is influenced by temperature, humidity, peculiarities of interaction with carbon dioxide contained in the air, etc. Examples show that portlandite is completely transformed into calcite in masonry mortars of the 18th century and that portlandite is not found in older mortars. It was determined that after the transformation of portlandite into calcite, an increase in the degree of recrystallization of calcite is observed, which manifests itself in powder diffraction patterns in the relative broadening of the diffraction peak of calcite hkl 104. In a detailed study, an estimate of the peak width at half maximum (FWHM) associated with the degree of crystallinity is effective. The actual data are given, which show that in older lime mortars the degree of recrystallization of calcite is higher than in younger ones. This fact makes it possible to indirectly determine the relative age of brickwork and masonry of various buildings of architectural heritage, which is especially relevant for the objects with the use of lime mortars of the northern provinces of the Byzantine Oecumene and other periods of various cultures.

Cr-Substituted Mesoporous Aluminophosphate Molecular Sieve: Synthesis, Characterization, Crystallization Kinetics and Catalytic Activity

2013 ◽  
Vol 316-317 ◽  
pp. 1018-1023
Author(s):  
Xin Zhu Li ◽  
Ji Shi Zhang
Keyword(s):  
Activation Energy ◽  
Catalytic Activity ◽  
Crystal Growth ◽  
Crystallization Kinetics ◽  
Molecular Sieve ◽  
Arrhenius Equation ◽  
Degree Of Crystallinity ◽  
Tert Butylhydroperoxide ◽  
Growth Activation ◽  
Cr Map

Cr-substituted mesoporous aluminophosphate molecular sieve (Cr-MAP) was synthesized and characterized. Crystallization kinetics curves measured as an index to the relative degree of crystallinity, according to the Arrhenius equation to calculate the apparent nucleation activation energy and crystal growth activation energy of Cr-MAP, which was 63.7 and 14.7 kJ• mol-1, respectively. Cr-MAP had highly catalytic activity for fabricating acetophenone by selectively oxizing ethylbenzene. Using tert-butylhydroperoxide as oxidant and chlorobenzene as solvent at 100 °C for 8 h, acetophenone selectivity, acetophenone yield and ethylbenzene conversion reaches 85.4, 62.2 and 72.8 %, respectively.

scholarly journals Preparation and Characterization of Talc Filled Thermoplastic Polyurethane/Polypropylene Blends

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Emi Govorčin Bajsić ◽  
Vesna Rek ◽  
Ivana Ćosić
Keyword(s):  
Thermal Properties ◽  
Thermoplastic Polyurethane ◽  
Mechanical Analysis ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Polypropylene Blends ◽  
Pp Blends ◽  
The Degree Of Crystallinity ◽  
Better Than

The effect of the addition of talc on the morphology and thermal properties of blends of thermoplastic polyurethane (TPU) and polypropylene (PP) was investigated. The blends of TPU and PP are incompatible because of large differences in polarities between the nonpolar crystalline PP and polar TPU and high interfacial tensions. The interaction between TPU and PP can be improved by using talc as reinforcing filler. The morphology was observed by means of scanning electron microscopy (SEM). The thermal properties of the neat polymers and unfilled and talc filled TPU/PP blends were studied by using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The addition of talc in TPU/PP blends improved miscibility in all investigated TPU/T/PP blends. The DSC results for talc filled TPU/PP blends show that the degree of crystallinity increased, which is due to the nucleating effect induced by talc particles. The reason for the increased storage modulus of blends with the incorporation of talc is due to the improved interface between polymers and filler. According to TGA results, the addition of talc enhanced thermal stability. The homogeneity of the talc filled TPU/PP blends is better than unfilled TPU/PP blends.

The Influence of the Degree of Crystallinity on the Glass Transition Temperature of Polymers

2013 ◽  
Vol 864-867 ◽  
pp. 751-754 ◽  
Author(s):  
Andrey Askadskii ◽  
Marina Popova ◽  
Tatyana Matseevich ◽  
Elena Kurskaya
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Degree Of Crystallinity ◽  
Low Degrees ◽  
The Degree Of Crystallinity

The influence of the degree of crystallinity of polymers on the glass transition temperature Tg of their amorphous domains is quantitatively analyzed. The analysis is made based on the Mandelkerns ideas [ concerning the restrictive effect of crystallization on the mobility of macromolecules within the amorphous domains. At low degrees of crystallinity, Tg of amorphous domains slowly increases, and then increases much faster at high degrees of crystallinity.

Study of the Activated Charcoal Structure from Water Hyacinth Based on Carbonization Temperature Variations and Activators

2021 ◽  
Vol 1028 ◽  
pp. 326-330
Author(s):  
Otong Nurhilal ◽  
Sahrul Hidayat ◽  
Dadan Sumiarsa ◽  
Maykel Manawan ◽  
Risdiana
Keyword(s):  
Carbon Material ◽  
Activated Charcoal ◽  
Water Hyacinth ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Lithium Sulfur Batteries ◽  
Amorphous Structures ◽  
Degree Of Graphitization ◽  
The Degree Of Crystallinity

The quality of the carbon material for application of electrodes in the battery is indicated by its ability to intercalate ions, atoms or molecules. Graphite is a carbon material with good intercalation capability. In this research, a carbon material in the form of activated charcoal produced from biomass of water hyacinth has been prepared, which is carbonized at various temperatures of 400, 500, and 600 °C with three different activators of ZnCl2, KOH and H3PO4. The activated charcoal will be used as a cathode composite in lithium sulfur batteries. To determine the quality of the activated charcoal, the structure properties of activated charcoal were characterized using X-ray diffraction (XRD). Several parameters that are determined from XRD data included the degree of crystallinity, and the degree of graphitization (Y). The degree of crystallinity was found in the ranges between 5.56 and 12.6%, where activated charcoal was dominated by amorphous structures. The value of the degree of graphitization was about 36%.

Study of structural and morphological changes during acсelerated oxidative degradation of mixtures of polyoxybutyrate with polycaprolactane

2021 ◽  
Vol 5 ◽  
pp. 60-69
Author(s):  
V. N. Vasilets ◽  
◽  
A. P. Pankina ◽  
E. A. Nemets ◽  
V. Yu. Belov ◽  
...  
Keyword(s):  
Morphological Changes ◽  
Oxidative Degradation ◽  
Initial Mixture ◽  
Polymer Composite Material ◽  
Degree Of Crystallinity ◽  
Fenton Reagent ◽  
Dsc Method ◽  
The Degree Of Crystallinity ◽  
Composite Samples ◽  
Scanning Electron

Structural and morphological changes in the films of poly(oxybirutyrate-co-oxyvalerate) (P(OB-OV)) with poly-e-caprolactone (PCL) were studied by IR spectroscopy, DSC, and scanning electron microscopy during accelerated oxidative degradation under tests in Fenton reagent. It is shown by the DSC method that the phase separation of the P(OB-OV) and PCL components is observed in the initial mixture. The melting of various phases of P(OB-OV) is observed at temperatures of 147 °C and 157 °C, and PCL melts at a temperature of 61 °C. The degree of crystallinity of P(OB-OV) and PCL in the mixture is 67 % and 50 %, respectively. It was found that the degradation of poly(oxybirutyrate-co-oxyvalerate) prevails during incubation of composite samples in Fenton solution for 2 to 12 weeks. By changing the ratio of the components, it is possible to significantly change the rate of oxidative degradation, the molecular weight and the degree of crystallinity of the polymer composite material P(OB-OV):PCL.

Preparation of Chitin Whisker and Effect to Crystallization of Polylactide

2018 ◽  
Vol 773 ◽  
pp. 82-87
Author(s):  
Nichaphat Passornraprasit ◽  
Wanpen Tachaboonyakiat
Keyword(s):  
Phase Separation ◽  
Transition Temperature ◽  
Nanocomposite Films ◽  
Degree Of Crystallinity ◽  
Thermal Transition ◽  
Hydrolysis Time ◽  
Film Extrusion ◽  
Agglomeration Of Nanoparticles ◽  
Acidolysis Reaction ◽  
The Degree Of Crystallinity

The aim of this study was to investigate the effect of chitin whisker (CW) to the crystallization of polylactide (PLA) nanocomposite films. CW which obtained from acidolysis reaction was compounded with PLA pellets into nanocomposite films by cast film extrusion. The morphology and crystallinity of CW were observed by TEM and XRD, illustrated that the dimension of whisker was affected by hydrolysis time. Increasing of hydrolysis time, the length of whisker was more regular with narrower distribution. Moreover, the crystallinity of whisker was obviously increased after acid hydrolysis. The nanocomposite film showed rough surface compared to pure PLA film due to some agglomeration of nanoparticles. However, CW and PLA were well-mixed with no phase separation. The introduction of 0.1 phr of CW decrease cold-crystallization temperature (Tcc) from about 121 °C to 118 °C and also increase the degree of crystallinity around 10%. There was no difference of thermal transition temperature between pure PLA and nanocomposite films with the addition of CW more than 0.1 phr which inspected by DSC. Despite the transition temperature express insignificantly different, the degree of crystallinity of nanocomposite was increase, indicating that chitin whisker would induce the crystallinity of PLA.

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