On the Degree of Crystallinity in Natural Rubber. I. An Improved Method to Determine the Degree of Crystallization in Rubber

1948 ◽  
Vol 21 (4) ◽  
pp. 773-783 ◽  
Author(s):  
J. M. Goppel
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Present Article ◽  
Degree Of Crystallinity ◽  
Improved Method ◽  
Ray Method ◽  
X Ray ◽  
Degree Of Crystallization ◽  
The Degree Of Crystallinity

Abstract There are indications that the degree of crystallization in high polymeric substances is of importance in studying mechanical properties. With regard to the crystallization of rubber, few measurements have been made, mainly by Field. The results, however, are in contradiction to estimates of an earlier date, and therefore the necessity was felt to have them checked. An x-ray method, in some respecta differing from that of Field, was developed, the results of which diverged considerably from the figures reported by Field. The present article deals with a description of the method.

The Degree of Crystallinity in Natural Rubber. IV. The Degree of Crystallization in Frozen Raw Rubber and Stretched Vulcanized Rubber

1950 ◽  
Vol 23 (2) ◽  
pp. 310-319 ◽  
Author(s):  
J. M. Goppel ◽  
J. J. Arlman
Keyword(s):  
Natural Rubber ◽  
Experimental Evidence ◽  
Theoretical Investigation ◽  
Degree Of Crystallinity ◽  
X Ray ◽  
Crystallization Point ◽  
Vulcanized Rubber ◽  
Degree Of Crystallization ◽  
The Degree Of Crystallinity

Abstract An improved x-ray technique has been worked out to determine the degree of crystallinity in natural rubber. Inaccuracies which sometimes occur in quantitative x-ray measurements were eliminated, and it has been shown that the amount of crystalline rubber, both in frozen samples of raw rubber and in stretched vulcanized rubber, could be determined fairly accurately. More experiments were carried out and the results are described. These results, which confirm the current views on the problem of crystallization, point to relatively low degress of crystallization, even in highly stretched rubber, and they agree with some other experimental evidence and with a recent theoretical investigation.

The Degree of Crystallinity in Natural Rubber. III. Correlation between X-Ray and Density Measurements

1950 ◽  
Vol 23 (2) ◽  
pp. 306-310 ◽  
Author(s):  
J. J. Arlman
Keyword(s):  
Natural Rubber ◽  
Unit Cell ◽  
Degree Of Crystallinity ◽  
X Rays ◽  
Density Measurements ◽  
X Ray ◽  
Degree Of Crystallization ◽  
The Degree Of Crystallinity

Abstract In 1925 Katz discovered the crystallization of stretched rubber. In the following years several investigators tried to determine the structure of rubber crystallites. The densities of the rubber crystallites calculated from the results of these investigations varied strongly. The results of x-ray and density measurements on crude rubber carried out by the author can be made to correspond only when the latter are based on the unit cell of Bunn. It is shown by experiment that, to measure the correct degree of crystallization, it is necessary to use monochromatic x-rays.

The Degree of Crystallinity in Natural Rubber. V. A Discussion of the X-Ray Results on Natural Rubber in Connection with the Work of Flory, Gee and Wildschut

1950 ◽  
Vol 23 (2) ◽  
pp. 319-325 ◽  
Author(s):  
J. J. Arlman ◽  
J. M. Goppel
Keyword(s):  
Natural Rubber ◽  
Physical Meaning ◽  
Average Length ◽  
Degree Of Crystallinity ◽  
Recent Theory ◽  
X Ray ◽  
Degree Of Crystallization ◽  
The Degree Of Crystallinity

Abstract A recent theory, developed by Flory, makes it possible to calculate the degree of crystallization from thermodynamical measurements if certain parameters are properly evaluated. Such evaluation is possible by combining Wildschut's thermodynamical measurements with the x-ray results presented in previous papers. Thus the average length of molecule chains between cross-linkages can be derived; it closely corresponds to the results of swelling measurements carried out by Gee. Other parameters are also evaluated in agreement with their physical meaning.

On the Degree of Crystallinity in Natural Rubber. II. The Orientation of Rubber Crystallites in Stretched Samples

1948 ◽  
Vol 21 (4) ◽  
pp. 783-789
Author(s):  
J. M. Goppel
Keyword(s):  
Natural Rubber ◽  
Rapid Determination ◽  
Simple Relation ◽  
Degree Of Crystallinity ◽  
Crystallite Orientation ◽  
Empirical Constant ◽  
Degree Of Orientation ◽  
Degree Of Crystallization ◽  
The Degree Of Crystallinity

Abstract In the foregoing article a method for determining the proportion of crystalline rubber in stretched samples has been described. A complication due to varying crystallite orientation in different samples appeared to interfere with the application. A simple relation is given between the degree of orientation and an empirical constant which makes possible a rapid determination of the degree of crystallization, regardless of the orientation in the sample under investigation.

Effect of Crystalline Morphology on Mechanical Properties of PPB Polymer Nanofiber Composite

2012 ◽  
Vol 506 ◽  
pp. 262-265
Author(s):  
S. Sangthaiyarak ◽  
N. Tawichai ◽  
Kamonpan Pengpat ◽  
Gobwute Rujijanagul ◽  
Tawee Tunkasiri ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Applied Voltage ◽  
Degree Of Crystallinity ◽  
Crystalline Morphology ◽  
X Ray Diffraction ◽  
Electrospinning Technique ◽  
Nanofiber Composite ◽  
X Ray ◽  
Polymer Nanofiber ◽  
The Degree Of Crystallinity

In this work, the effects of crystalline morphology on the mechanical properties of polycaprolactone/polyvinyl alcohol/ butterfly pea extract (PPB) nanofiber composite were investigated. Biopolymer nanofiber composite of PPB was fabricated by electrospinning technique using polycaprolactone concentration and distance of nozzle to ground collector of 7 wt% and 20 cm, respectively. The influence of applied voltage (vary from 15-25 kV) on the stress-strain curves was also observed. The structure and morphology of electrospun PPB nanofibers were investigated by x-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that, the degree of crystallinity increased with applied voltage and the mechanical properties was affected by the morphology of PPB nanofiber.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

Mechanism of the Crystallization of High Polymers

1954 ◽  
Vol 27 (2) ◽  
pp. 374-384 ◽  
Author(s):  
G. Schuur
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Amorphous Material ◽  
Crystalline Polymer ◽  
Longitudinal Direction ◽  
Crystalline Material ◽  
Current View ◽  
X Ray ◽  
Made In ◽  
High Polymers

Abstract The crystallization of higher polymers is a phenomenon which is not yet fully understood, one of the main difficulties being to explain how the spherulites arise. An attempt will be made in this paper to draw a clearer picture of the mechanism of crystallization and thus to account for the origin of spherulites. It will then be seen how several other phenomena involved in the crystallization of natural rubber can be shown to be logically interrelated. The current view is that a crystalline polymer consists of a continuous amorphous phase containing small crystalline regions, the crystallites. The evidence as to the size of these crystallites, however, is at present inconclusive, because only the lower limit of their size can be measured by means of x-ray examination. The reason is that, owing to the absence of reflections of a higher order, the effect of irregularities in the crystallites and of the heat motion of the molecules cannot be measured separately. Another doubtful question is whether the small angle interference maxima are to be interpreted as a measure of mean distances between the crystallites. To do this, Wallner has to resort to the assumption that the crystallites are unstable, whereas it is presumed, on the evidence of the mechanical properties of the high polymers, that a crystallite is stable and permanent. Hoffmann found 82 ± 7 per cent of crystalline material in polychlorotrifluoroethylene and Buckley, Cross, and Ray found as much as 95 per cent in polymethylene. Such high percentages make it doubtful whether the crystalline phase can be discontinuous at all. In this article any volume of material in which the molecules lie parallel is called a crystallite. The direction in which the molecules are oriented is termed the longitudinal direction of the crystallite. It is immaterial to the argument whether a crystallite consists of several crystallites, aligned in parallel separated by a small amount of amorphous material, or of a single crystallite containing large irregularities.

scholarly journals Impact of environmental agents on non-woven polylactide/natural rubber agrofiber

2021 ◽  
Vol 285 ◽  
pp. 07034
Author(s):  
Yulia Tertyshnaya ◽  
Maksim Zakharov ◽  
Alina Ivanitskikh ◽  
Anatoliy Popov
Keyword(s):  
Natural Rubber ◽  
Uv Irradiation ◽  
Thermal Characteristics ◽  
Degree Of Crystallinity ◽  
Distilled Water ◽  
Fibrous Materials ◽  
Scanning Calorimetry ◽  
Melting Temperatures ◽  
Environmental Agents ◽  
The Degree Of Crystallinity

In the work an eco-friendly non-woven fiber made of polylactide and natural rubber with a rubber content from 0 to 15 wt.% was obtained by electrospinning. The influence of distilled water and UV irradiation on the agrofibers has been investigated. The water sorption test showed that the addition of natural rubber into the polylactide matrix does not significantly affect the degree of water absorption of the fibrous materials, which is in the range of 49-50.6%. Thermal characteristics after 180 days of degradation in distilled water at 22±2 oC and UV irradiation at a wavelength of 365 nm during 100 hours were determined using the differential scanning calorimetry. Changes in the values for glass transition and melting temperatures, and the degree of crystallinity were determined.

scholarly journals Selectively Etched Halloysite Nanotubes as Performance Booster of Epoxidized Natural Rubber Composites

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3536
Author(s):  
Indra Surya ◽  
Kamaruddin Waesateh ◽  
Abdulhakim Masa ◽  
Nabil Hayeemasae
Keyword(s):  
Natural Rubber ◽  
Treatment Time ◽  
Halloysite Nanotubes ◽  
Epoxidized Natural Rubber ◽  
Degree Of Crystallinity ◽  
X Ray Scattering ◽  
Natural Rubber Composites ◽  
Matrix Interactions ◽  
Strain Induced Crystallization ◽  
The Degree Of Crystallinity

Halloysite Nanotubes (HNT) are chemically similar to clay, which makes them incompatible with non-polar rubbers such as natural rubber (NR). Modification of NR into a polar rubber is of interest. In this work, Epoxidized Natural Rubber (ENR) was prepared in order to obtain a composite that could assure filler–matrix compatibility. However, the performance of this composite was still not satisfactory, so an alternative to the basic HNT filler was pursued. The surface area of HNT was further increased by etching with acid; the specific surface increased with treatment time. The FTIR spectra confirmed selective etching on the Al–OH surface of HNT with reduction in peak intensity in the regions 3750–3600 cm−1 and 825–725 cm−1, indicating decrease in Al–OH structures. The use of acid-treated HNT improved modulus, tensile strength, and tear strength of the filled composites. This was attributed to the filler–matrix interactions of acid-treated HNT with ENR. Further evidence was found from the Payne effect being reduced to 44.2% through acid treatment of the filler. As for the strain-induced crystallization (SIC) in the composites, the stress–strain curves correlated well with the degree of crystallinity observed from synchrotron wide-angle X-ray scattering.

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