Infrared Examination of Various Polyisoprenes

1954 ◽  
Vol 27 (2) ◽  
pp. 348-362
Author(s):  
W. S. Richardson ◽  
A. Sacher
Keyword(s):  
Quantitative Analysis ◽  
Natural Rubber ◽  
Rheological Properties ◽  
General Problem ◽  
Naturally Occurring ◽  
High Polymers ◽  
Effect Of Microstructure

Abstract It is well known that, in general, the laboratory polymerization of diene monomers leads to materials which are intramolecular mixtures of various types of addition products. Thus, synthetic polyisoprene has been shown to contain chemical groupings arising from 1,2, 3,4, and 1,4 addition of the isoprene units. This is in contrast to the naturally occurring high polymers of isoprene, the rubbers and guttas, which appear to be exclusively cis-1,4 and trans-1,4 adducts, respectively. An exception to this last statement is the polyisoprene derived from chicle, which is a mixture of cis-1,4 and trans-1,4 addition. In this case, however, the mixture is an intermolecular one, and fractionation of the material leads to components which are all cis-1,4 and all trans-1,4. The general problem of diene polymerization is, of course, of great importance, and the synthetic polyisoprenes are of particular interest because of their relationship to natural rubber. The following attempt to obtain a quantitative analysis for the various types of addition occurring in synthetic polyisoprenes may lead to a better understanding of the nature of these materials and may be of help in elucidating the effect of microstructure on rheological properties.

Characterizing the naturally occurring sacrificial bond within natural rubber

Polymer ◽  
2019 ◽  
Vol 161 ◽  
pp. 41-48 ◽  
Author(s):  
Xuan Fu ◽  
Cheng Huang ◽  
Yong Zhu ◽  
Guangsu Huang ◽  
Jinrong Wu
Keyword(s):  
Natural Rubber ◽  
Naturally Occurring

Physical and rheological properties of epoxidized natural rubber modified bitumens

2014 ◽  
Vol 63 ◽  
pp. 242-248 ◽  
Author(s):  
Ramez A. Al-Mansob ◽  
Amiruddin Ismail ◽  
Aows N. Alduri ◽  
Che Husna Azhari ◽  
Mohamed Rehan Karim ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Rheological Properties ◽  
Epoxidized Natural Rubber

“You’re absolutely right!!”

2010 ◽  
Vol 10 (2) ◽  
pp. 194-222 ◽  
Author(s):  
Marta Carretero
Keyword(s):  
Quantitative Analysis ◽  
Written Language ◽  
Propositional Content ◽  
Main Function ◽  
Maximal Strength ◽  
Linguistic Data ◽  
Naturally Occurring ◽  
Semantic Difference ◽  
Verbal Group ◽  
Discourse Functions

The English degree adverb absolutely and its Spanish equivalent absolutamente may function as modifiers of words of different kinds, as Adjuncts and as (parts of) minor clauses. This article sets forth a quantitative analysis, based on naturally-occurring linguistic data, of the distribution of these functions for both adverbs. Apart from distributional differences between the two adverbs and between their occurrences in spoken and written language, the results show that when they are modifiers of words or Verbal Group-oriented Adjuncts, their main function is to qualify (part of) the propositional content of the utterance; however, when they are clausal Adjuncts or (parts of) minor clauses, they are often geared to the performance of discourse functions such as contrast, concession or agreement. These functions are shared with some adverbs of certainty such as ‘certainly’ or ‘definitely’, which suggests that the semantic difference between degree and certainty tends to be blurred when adverbs of maximal strength of both types are used for performing discourse functions that enhance assertiveness.

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.

Effect of alignment of magnetic particles on the rheological properties of natural rubber composite

2021 ◽  
Vol 28 (10) ◽  
Author(s):  
Jeong-Hwan Yoon ◽  
Seung-Won Lee ◽  
Seok-Hu Bae ◽  
Nam-Il Kim ◽  
Ju-Ho Yun ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Rheological Properties ◽  
Magnetic Particles ◽  
Rubber Composite

Relative Contributions of Viscoelasticity and Aging to the Relaxation of Rubber Vulcanizates

1963 ◽  
Vol 36 (1) ◽  
pp. 50-58 ◽  
Author(s):  
P. Thirion ◽  
R. Chasset
Keyword(s):  
Quantitative Analysis ◽  
Natural Rubber ◽  
Time Interval ◽  
Dicumyl Peroxide ◽  
Infinite Time ◽  
Negative Power ◽  
Theoretical Assumptions ◽  
The Difference ◽  
Natural Rubber Vulcanizates ◽  
Actual Stress

Abstract Relaxation in relatively stable, gum natural rubber vulcanizates has been studied to determine the effects of viscoelasticity and aging, respectively, using a dark, air-oven. A quantitative analysis of experimental results shows that, in the case of a dicumyl peroxide vulcanizate at 100° C, relaxation is caused by aging, except in its initial stages. Stress decreases as a linear function of time, in agreement with theoretical assumptions. Conversely, at 30° C, the effect of aging is negligible. At this temperature the difference between actual stress and stress extrapolated to infinite time, is proportional to a negative power of time. At intermediate temperatures, both phenomena occur simultaneously over a time interval ranging from. 3 minutes to 150 hours.

Quantitative Analysis of Total Phenolic Contents and Antioxidant Activity of Fresh Field Natural Rubber Latex

2015 ◽  
Vol 354 (1) ◽  
pp. 265-272 ◽  
Author(s):  
Suwimon Siriwong ◽  
Adisai Rungvichaniwat ◽  
Pairote Klinpituksa ◽  
Khalid Hamid Musa ◽  
Aminah Abdullah
Keyword(s):  
Antioxidant Activity ◽  
Quantitative Analysis ◽  
Natural Rubber ◽  
Natural Rubber Latex ◽  
Total Phenolic ◽  
Rubber Latex ◽  
Phenolic Contents ◽  
Total Phenolic Contents

Quantitative Analysis of Abnormal Groups on Molecular Chain of Natural Rubber

2019 ◽  
Vol 61 (6) ◽  
pp. 856-864 ◽  
Author(s):  
Yanchan Wei ◽  
Aiwu Ding ◽  
Linhe Jin ◽  
Huifeng Zhang ◽  
Shuangquan Liao
Keyword(s):  
Quantitative Analysis ◽  
Natural Rubber ◽  
Molecular Chain

scholarly journals Thermal Stability and Rheological Properties of Epoxidized Natural Rubber-Based Magnetorheological Elastomer

2019 ◽  
Vol 20 (3) ◽  
pp. 746 ◽  
Author(s):  
Nurul Yunus ◽  
Saiful Mazlan ◽  
Ubaidillah ◽  
Siti Abdul Aziz ◽  
Salihah Tan Shilan ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Natural Rubber ◽  
Rheological Properties ◽  
Strain Amplitude ◽  
Thermal Analyses ◽  
Thermal Characteristics ◽  
Epoxidized Natural Rubber ◽  
Effect Of Temperature ◽  
Temperature Dependent ◽  
Roll Mill

Determination of the thermal characteristics and temperature-dependent rheological properties of the magnetorheological elastomers (MREs) is of paramount importance particularly with regards to MRE applications. Hitherto, a paucity of temperature dependent analysis has been conducted by MRE researchers. In this study, an investigation on the thermal and rheological properties of epoxidized natural rubber (ENR)-based MREs was performed. Various percentages of carbonyl iron particles (CIPs) were blended with the ENR compound using a two roll-mill for the preparation of the ENR-based MRE samples. The morphological, elemental, and thermal analyses were performed before the rheological test. Several characterizations, as well as the effects of the strain amplitude, temperature, and magnetic field on the rheological properties of ENR-based MRE samples, were evaluated. The micrographs and elemental results were well-correlated regarding the CIP and Fe contents, and a uniform distribution of CIPs was achieved. The results of the thermal test indicated that the incorporation of CIPs enhanced the thermal stability of the ENR-based MREs. Based on the rheological analysis, the storage modulus and loss factor were dependent on the CIP content and strain amplitude. The effect of temperature on the rheological properties revealed that the stiffness of the ENR-based MREs was considered stable, and they were appropriate to be employed in the MRE devices exposed to high temperatures above 45 °C.

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