Pub Date : 1963-07-01Epub Date: 1963-08-01DOI: 10.6028/jres.067A.034
Andrew C Victor, Thomas B Douglas
As a step in developing new standards of high-temperature heat capacity and in determining accurate thermodynamic data for simple substances, the enthalpy (heat content) relative to 273 °K, of high purity fused magnesium oxide, MgO, and of sintered beryllium oxide, BeO, was measured up to 1,173 °K. A Bunsen ice calorimeter and the drop method were used. The two samples of BeO measured had surface-to-volume ratios differing by a factor of 15 or 20, yet agreed with each other closely enough to preclude appreciable error attributable to the considerable surface area. The enthalpies found for MgO are several percent higher than most previously reported values. The values are represented within their uncertainty (estimated to average ± 0.25%) by the following empirical equations (cal mole-1 at T °K) Values of enthalpy, heat capacity, entropy, and Gibbs free-energy function are tabulated from 298.15 to 1,200 °K.
作为制定高温热容量新标准和确定简单物质准确热力学数据的一个步骤，我们测量了高纯度熔融氧化镁（MgO）和烧结氧化铍（BeO）相对于 273 °K 的焓（热含量），最高温度为 1,173 °K。使用的是本生冰量热仪和液滴法。所测量的两个氧化铍样品的表面与体积比相差 15 或 20 倍，但它们之间的结果非常接近，足以排除因表面积较大而产生的明显误差。氧化镁的焓值比之前报告的大多数值都高出几个百分点。这些值在不确定范围内（估计平均 ± 0.25%）用以下经验公式表示（T°K 时的卡摩尔-1） 氧化镁：H T ° - H 273.15 ° = 10.7409 T + 1.2177 ( 10 - 3 ) T 2 - 2.3183 ( 10 - 7 ) T 3 + 2.26151 ( 10 5 ) T - 1 - 3847.94 。 BeO：H T ° - H 273.15 ° = 11.1084 T + 7.1245 ( 10 - 4 ) T 2 + 8.40705 ( 10 5 ) T - 1 - 5.31245 ( 10 7 ) T - 2 - 5453.21 。 焓值、热容量、熵值和吉布斯自由能函数在 298.15 至 1 200 °K 之间以表格形式列出。
{"title":"Thermodynamic Properties of Magnesium Oxide and Beryllium Oxide from 298 to 1,200 °K.","authors":"Andrew C Victor, Thomas B Douglas","doi":"10.6028/jres.067A.034","DOIUrl":"10.6028/jres.067A.034","url":null,"abstract":"<p><p>As a step in developing new standards of high-temperature heat capacity and in determining accurate thermodynamic data for simple substances, the enthalpy (heat content) relative to 273 °K, of high purity fused magnesium oxide, MgO, and of sintered beryllium oxide, BeO, was measured up to 1,173 °K. A Bunsen ice calorimeter and the drop method were used. The two samples of BeO measured had surface-to-volume ratios differing by a factor of 15 or 20, yet agreed with each other closely enough to preclude appreciable error attributable to the considerable surface area. The enthalpies found for MgO are several percent higher than most previously reported values. The values are represented within their uncertainty (estimated to average ± 0.25%) by the following empirical equations (cal mole<sup>-1</sup> at <i>T</i> °K) <dispformula> <math> <mtable> <mtr><mtd><mtext>MgO</mtext> <mo>:</mo> <msubsup><mi>H</mi> <mi>T</mi> <mo>°</mo></msubsup> <mo>-</mo> <msubsup><mi>H</mi> <mrow><mn>273.15</mn></mrow> <mo>°</mo></msubsup> <mo>=</mo> <mn>10.7409</mn> <mi>T</mi> <mo>+</mo> <mn>1.2177</mn> <mrow><mo>(</mo> <mrow> <msup><mrow><mn>10</mn></mrow> <mrow><mo>-</mo> <mn>3</mn></mrow> </msup> </mrow> <mo>)</mo></mrow> <msup><mi>T</mi> <mn>2</mn></msup> <mo>-</mo> <mn>2.3183</mn> <mrow><mo>(</mo> <mrow> <msup><mrow><mn>10</mn></mrow> <mrow><mo>-</mo> <mn>7</mn></mrow> </msup> </mrow> <mo>)</mo></mrow> <msup><mi>T</mi> <mn>3</mn></msup> <mo>+</mo> <mn>2.26151</mn> <mrow><mo>(</mo> <mrow> <msup><mrow><mn>10</mn></mrow> <mn>5</mn></msup> </mrow> <mo>)</mo></mrow> <msup><mi>T</mi> <mrow><mo>-</mo> <mn>1</mn></mrow> </msup> <mo>-</mo> <mn>3847.94</mn> <mo>.</mo></mtd> </mtr> <mtr><mtd><mtext>BeO</mtext> <mo>:</mo> <msubsup><mi>H</mi> <mi>T</mi> <mo>°</mo></msubsup> <mo>-</mo> <msubsup><mi>H</mi> <mrow><mn>273.15</mn></mrow> <mo>°</mo></msubsup> <mo>=</mo> <mn>11.1084</mn> <mi>T</mi> <mo>+</mo> <mn>7.1245</mn> <mrow><mo>(</mo> <mrow> <msup><mrow><mn>10</mn></mrow> <mrow><mo>-</mo> <mn>4</mn></mrow> </msup> </mrow> <mo>)</mo></mrow> <msup><mi>T</mi> <mn>2</mn></msup> <mo>+</mo> <mn>8.40705</mn> <mrow><mo>(</mo> <mrow> <msup><mrow><mn>10</mn></mrow> <mn>5</mn></msup> </mrow> <mo>)</mo></mrow> <msup><mi>T</mi> <mrow><mo>-</mo> <mn>1</mn></mrow> </msup> <mo>-</mo> <mn>5.31245</mn> <mrow><mo>(</mo> <mrow> <msup><mrow><mn>10</mn></mrow> <mn>7</mn></msup> </mrow> <mo>)</mo></mrow> <msup><mi>T</mi> <mrow><mo>-</mo> <mn>2</mn></mrow> </msup> <mo>-</mo> <mn>5453.21</mn> <mo>.</mo></mtd> </mtr> </mtable> </math> </dispformula> Values of enthalpy, heat capacity, entropy, and Gibbs free-energy function are tabulated from 298.15 to 1,200 °K.</p>","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5317226/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82703253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. McCrackin, E. Passaglia, R. Stromberg, H. L. Steinberg
The use of the ellipsometer for the measurement of the thickness and refractive index of very thin films is reviewed. The Poincaré sphere representation of the state of polarization of light is developed and used to describe the reflection process. Details of the operation of the ellipsometer are examined critically. A computational method is presented by which the thickness of a film of known refractive index on a reflecting substrate of known optical constants may be calculated directly from the ellipsometer readings. A method for computing both the refractive index and thickness of an unknown film is also developed. These methods have been applied to the determination of the thickness of an adsorbed water layer on chromium ferrotype plates and on gold surfaces. In the former case the thickness was 23 to 27 Å, and in the latter was 2 to 5 Å. The measurement of the thickness and refractive index of barium fluoride films evaporated on chromium ferrotype surfaces is used as an illustration of the simultaneous determination of these two quantities.
{"title":"Measurement of the Thickness and Refractive Index of Very Thin Films and the Optical Properties of Surfaces by Ellipsometry1","authors":"F. McCrackin, E. Passaglia, R. Stromberg, H. L. Steinberg","doi":"10.6028/jres.067A.040","DOIUrl":"https://doi.org/10.6028/jres.067A.040","url":null,"abstract":"The use of the ellipsometer for the measurement of the thickness and refractive index of very thin films is reviewed. The Poincaré sphere representation of the state of polarization of light is developed and used to describe the reflection process. Details of the operation of the ellipsometer are examined critically. A computational method is presented by which the thickness of a film of known refractive index on a reflecting substrate of known optical constants may be calculated directly from the ellipsometer readings. A method for computing both the refractive index and thickness of an unknown film is also developed. These methods have been applied to the determination of the thickness of an adsorbed water layer on chromium ferrotype plates and on gold surfaces. In the former case the thickness was 23 to 27 Å, and in the latter was 2 to 5 Å. The measurement of the thickness and refractive index of barium fluoride films evaporated on chromium ferrotype surfaces is used as an illustration of the simultaneous determination of these two quantities.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82706802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1963-07-01Epub Date: 1963-08-01DOI: 10.6028/jres.067A.033
Stanley Ruthberg, Mary W Barnes, Ralph H Noyce
A detailed experimental study of color, apparent optic angle, and absorption spectrum (0.3 to 16μ of λ) indicates that there are basic chemical and structural differences in muscovite micas. Color identification is based upon spectrophotometer measurements. A method for quantitative evaluation of absorption band activity is defined so that single and multiple band intensities within the spectrum of an individual specimen and within spectra of different specimens can be compared. Three basic spectral types exist for the 0.3 to 1μ λ region which are comprised of various weak lines and absorption regions lying along the base of a deep absorption edge near 0.32μ. Of the three spectral types, one is associated with ruby micas, while the other two are associated with dark green and light green micas. The activities of numerous lines and bands are reported. It is shown that apparent optic axial angle is related to the position of the deep band edge except for a certain class of ruby specimens which show anomalous values. A definitive characterization of muscovite sheet is formulated in terms of the absorption coefficients at 0.44, 0.49, and 0.58μ. Direct associations are shown between certain lines in the visible λ range and certain bands in the near infrared, while the activities of a number of bands in the middle infrared are correlated to color.
{"title":"Correlation of Muscovite Sheet Mica on the Basis of Color, Apparent Optic Angle, and Absorption Spectrum.","authors":"Stanley Ruthberg, Mary W Barnes, Ralph H Noyce","doi":"10.6028/jres.067A.033","DOIUrl":"10.6028/jres.067A.033","url":null,"abstract":"<p><p>A detailed experimental study of color, apparent optic angle, and absorption spectrum (0.3 to 16<i>μ</i> of <i>λ</i>) indicates that there are basic chemical and structural differences in muscovite micas. Color identification is based upon spectrophotometer measurements. A method for quantitative evaluation of absorption band activity is defined so that single and multiple band intensities within the spectrum of an individual specimen and within spectra of different specimens can be compared. Three basic spectral types exist for the 0.3 to 1<i>μ λ</i> region which are comprised of various weak lines and absorption regions lying along the base of a deep absorption edge near 0.32<i>μ.</i> Of the three spectral types, one is associated with ruby micas, while the other two are associated with dark green and light green micas. The activities of numerous lines and bands are reported. It is shown that apparent optic axial angle is related to the position of the deep band edge except for a certain class of ruby specimens which show anomalous values. A definitive characterization of muscovite sheet is formulated in terms of the absorption coefficients at 0.44, 0.49, and 0.58<i>μ</i>. Direct associations are shown between certain lines in the visible λ range and certain bands in the near infrared, while the activities of a number of bands in the middle infrared are correlated to color.</p>","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5317225/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76356897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The fourth order Hamiltonian of an asymmetric rotor molecule of orthorhombic symmetry given recently has been considerably reduced in complexity through the use of equations derived from the basic relationship among the angular momentum operators. The reduced Hamiltonian obtained provides a most convenient starting point for the calculation of rotational energy levels from a solution of the complete secular equation, for a perturbation theory solution to the problem of centrifugal distortion, and for the deduction of sum rules among the energy levels.
{"title":"On the Fourth Order Hamiltonian of an Asymmetric Rotor Molecule of Orthorhombic Symmetry","authors":"W. Olson, H. Allen","doi":"10.6028/jres.067A.039","DOIUrl":"https://doi.org/10.6028/jres.067A.039","url":null,"abstract":"The fourth order Hamiltonian of an asymmetric rotor molecule of orthorhombic symmetry given recently has been considerably reduced in complexity through the use of equations derived from the basic relationship among the angular momentum operators. The reduced Hamiltonian obtained provides a most convenient starting point for the calculation of rotational energy levels from a solution of the complete secular equation, for a perturbation theory solution to the problem of centrifugal distortion, and for the deduction of sum rules among the energy levels.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80967329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Heat flow in adiabatic calorimeters of various shapes and materials is described in terms of linear partial differential equations. From these equations it is deduced that in the intermittent heating method the heat exchange between the calorimeter and the adiabatic shield due to transients at the beginning and end of the heating period can be made to cancel. The remaining heat exchange is the same for intermittent or continuous heating methods and can be treated as the sum of effects due to gradients set up by heat flow (1) from the shield to the environment and (2) from the shield and calorimeter heaters to raise the temperatures of the shield and calorimeter, respectively. The first effect can be accounted for by measurements during fore and after periods in intermittent calorimetry and by varying the heating rate in continuous calorimetry. Under certain conditions the second effect can be accounted for by measurements with the empty calorimeter. Variation in heating rate fails as a test for the magnitude of the second effect.
{"title":"Heat Exchange in Adiabatic Calorimeters","authors":"E. D. West","doi":"10.6028/jres.067A.035","DOIUrl":"https://doi.org/10.6028/jres.067A.035","url":null,"abstract":"Heat flow in adiabatic calorimeters of various shapes and materials is described in terms of linear partial differential equations. From these equations it is deduced that in the intermittent heating method the heat exchange between the calorimeter and the adiabatic shield due to transients at the beginning and end of the heating period can be made to cancel. The remaining heat exchange is the same for intermittent or continuous heating methods and can be treated as the sum of effects due to gradients set up by heat flow (1) from the shield to the environment and (2) from the shield and calorimeter heaters to raise the temperatures of the shield and calorimeter, respectively. The first effect can be accounted for by measurements during fore and after periods in intermittent calorimetry and by varying the heating rate in continuous calorimetry. Under certain conditions the second effect can be accounted for by measurements with the empty calorimeter. Variation in heating rate fails as a test for the magnitude of the second effect.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90065541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Reactions involving reactive species produced in electric discharges are frequently characterized by the emission of visible light of many different colors. Some typical afterglows and atomic flames have been photographed, and the observed colors (or spectral distributions) are discussed with regard to the reactions from which they arise. Laboratory studies of this sort are helpful for the understanding of the energy transfer processes which occur in flames, in electrical discharges, and in the upper atmosphere.
{"title":"Color Phenomena Associated With Energy Transfer in Afterglows and Atomic Flames","authors":"A. Bass, H. Broida","doi":"10.6028/jres.067A.041","DOIUrl":"https://doi.org/10.6028/jres.067A.041","url":null,"abstract":"Reactions involving reactive species produced in electric discharges are frequently characterized by the emission of visible light of many different colors. Some typical afterglows and atomic flames have been photographed, and the observed colors (or spectral distributions) are discussed with regard to the reactions from which they arise. Laboratory studies of this sort are helpful for the understanding of the energy transfer processes which occur in flames, in electrical discharges, and in the upper atmosphere.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90409443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The infrared spectrum of the v2+v6 band of C13C12H6 has been analyzed and a value of B0= 0.64865 ±0.00005 cm−1 determined. When this value is combined with that found in recent work on isotopically normal ethane, a “rs” value of 1.527±0.004 A for the carboncarbon bond distance is obtained. (Uncertainties are probable errors.)
{"title":"Infrared Spectrum of the v2+ v6 Band of C13C12H6*","authors":"W. J. Lafferty, E. K. Plyler","doi":"10.6028/jres.067A.021","DOIUrl":"https://doi.org/10.6028/jres.067A.021","url":null,"abstract":"The infrared spectrum of the v2+v6 band of C13C12H6 has been analyzed and a value of B0= 0.64865 ±0.00005 cm−1 determined. When this value is combined with that found in recent work on isotopically normal ethane, a “rs” value of 1.527±0.004 A for the carboncarbon bond distance is obtained. (Uncertainties are probable errors.)","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87433280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The self-broadening of carbon monoxide has been measured for the 2 v and 3 v bands with pressures up to 3.5 atmospheres. A grating spectrometer of high resolving power was used for the measurements and the correction for finite slits was small. The corrections varied from 3 to 20 percent for the different conditions of measurement. The half-widths per atmosphere, γ°, decreased from 0.089 cm−1 for |m| = 1 to 0.053 cm−1 for |m| = 21. The half-widths are compared with those obtained by other investigators and it is shown that the results reported in this work fall in between the self-broadening values previously obtained.
{"title":"Self-Broadening of Carbon Monoxide in the 2 v and 3 v Bands *","authors":"E. K. Plyler, R. J. Thibault","doi":"10.6028/jres.067A.022","DOIUrl":"https://doi.org/10.6028/jres.067A.022","url":null,"abstract":"The self-broadening of carbon monoxide has been measured for the 2 v and 3 v bands with pressures up to 3.5 atmospheres. A grating spectrometer of high resolving power was used for the measurements and the correction for finite slits was small. The corrections varied from 3 to 20 percent for the different conditions of measurement. The half-widths per atmosphere, γ°, decreased from 0.089 cm−1 for |m| = 1 to 0.053 cm−1 for |m| = 21. The half-widths are compared with those obtained by other investigators and it is shown that the results reported in this work fall in between the self-broadening values previously obtained.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83769653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The NBS Thermal Neutron Flux has been calibrated in terms of the gold thermal neutron capture cross section. The effective thermal neutron (below cadmium cutoff energy) flux density is estimated to be 4307 ± 2 percent n/cm2 sec in September 1961. This figure is in agreement with a recent value quoted by the NBS.
{"title":"An Absolute Calibration of the National Bureau of Standards Thermal Neutron Flux","authors":"E. Axton","doi":"10.6028/jres.067A.019","DOIUrl":"https://doi.org/10.6028/jres.067A.019","url":null,"abstract":"The NBS Thermal Neutron Flux has been calibrated in terms of the gold thermal neutron capture cross section. The effective thermal neutron (below cadmium cutoff energy) flux density is estimated to be 4307 ± 2 percent n/cm2 sec in September 1961. This figure is in agreement with a recent value quoted by the NBS.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80438355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1963-05-01Epub Date: 1963-06-01DOI: 10.6028/jres.067A.023
Martin G Broadhurst
Thermodynamic data on the n-paraffins from n-C6H14 through n-C18H38 have been used to obtain values for the specific heat, entropy, enthalpy, and Gibbs free energy of a large, ideal CH2-chain crystal from 0 to 420 °K and of the liquid above 200 °K. Analytical expressions are given for the properties of the crystal and liquid above 200 °K. For the crystal, a modified Einstein function was used to adjust the melting temperature to 414.3 °K. Values between 975 and 1025 cal/mole for the heat of fusion were found to be the ones most consistent with the data. Comparison of the results with polyethylene data shows reasonable agreement.
{"title":"Thermodynamic Properties of Polyethylene Predicted from Paraffin Data.","authors":"Martin G Broadhurst","doi":"10.6028/jres.067A.023","DOIUrl":"10.6028/jres.067A.023","url":null,"abstract":"<p><p>Thermodynamic data on the <i>n</i>-paraffins from <i>n</i>-C<sub>6</sub>H<sub>14</sub> through <i>n</i>-C<sub>18</sub>H<sub>38</sub> have been used to obtain values for the specific heat, entropy, enthalpy, and Gibbs free energy of a large, ideal CH<sub>2</sub>-chain crystal from 0 to 420 °K and of the liquid above 200 °K. Analytical expressions are given for the properties of the crystal and liquid above 200 °K. For the crystal, a modified Einstein function was used to adjust the melting temperature to 414.3 °K. Values between 975 and 1025 cal/mole for the heat of fusion were found to be the ones most consistent with the data. Comparison of the results with polyethylene data shows reasonable agreement.</p>","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5319452/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85427209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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