Some Problems Involved in the Grading and Testing of Natural Rubber. A Progress Report

1950 ◽  
Vol 23 (1) ◽  
pp. 107-116 ◽  
Author(s):  
W. P. Fletcher
Keyword(s):  
Natural Rubber ◽  
Maximum Modulus ◽  
American Chemical Society ◽  
Chemical Society ◽  
Standard Test ◽  
Great Sensitivity ◽  
National Bureau ◽  
Testing Procedures ◽  
Cure Time

Abstract In the establishment of grading and testing procedures for natural rubber based on the properties of vulcanizates, four main questions arise. First it is necessary to decide on the property to be measured, and reasons are given for the choice of elongation at a fixed load for the purpose, elongations being below 250 per cent. Secondly the method of test had to be decided, and a simple version of the National Bureau of Standards' strain tester has been developed and is in use. Thirdly a standard test mix, into which the raw rubber samples are compounded, must be selected; the well known No. 1 compound of the Crude Rubber Committee of the American Chemical Society has been found to be defective because of its great sensitivity to moisture, whereas a mixed mercaptobenzothiazole-diphenylguanidine stock and a stock accelerated with N-cyclohexyl-2-benzothiazole sulfenamide appear suitable. Finally the interpretation of results is discussed. The use of a single cure for classification of rubbers is felt to be inadequate, and to determine both the maximum modulus of which the rubber is capable in the compound and also the cure time to obtain this condition, it is proposed to define the property with tolerance limits at three cures. Incidental problems arising include mixing error, and some investigation of this is described.

Fun and Frustrations with Synthetic Rubber

1977 ◽  
Vol 50 (3) ◽  
pp. 67-77
Author(s):  
James D. D'Ianni
Keyword(s):  
World War Ii ◽  
Natural Rubber ◽  
Korean War ◽  
American Chemical Society ◽  
Chemical Society ◽  
World War ◽  
Great Pleasure ◽  
The Past ◽  
Synthetic Rubber ◽  
The Korean War

Abstract It is a great pleasure and honor to have this opportunity to share with you some of my experiences in synthetic rubber over the past forty years. I am deeply appreciative of my selection as the thirty-fourth recipient of the Charles Goodyear Medal by the Rubber Division of the American Chemical Society and accept it only as a representative of my many associates at Goodyear who have participated with me in significant developments in synthetic rubber during this period. As the title of this talk indicates, we had both successes and disappointments in our endeavors to develop improved synthetic rubbers. These efforts were greatly stimulated by shortages of natural rubber which occurred in times of national emergencies such as World War II and the Korean War. When we successfully met these challenges it was fun, but to the extent that we were not able to achieve all of our objectives, we suffered a number of frustrations.

People Make the Difference

1990 ◽  
Vol 63 (5) ◽  
pp. 81-95
Author(s):  
Benjamin Kastein
Keyword(s):  
Technical Information ◽  
American Chemical Society ◽  
Chemical Society ◽  
Early Years ◽  
Neutral Position ◽  
National Bureau ◽  
Chief Chemist ◽  
The Subject ◽  
The Difference

Abstract The Las Vegas meeting of the Rubber Division, ACS, provided attendees the opportunity to hear the interview of Mr. Arnold H. Smith, by Mr. Herbert A. Endres, recorded April 7, 1966. Mr. Smith, as Secretary-Treasurer of the Division from 1919 to 1928, and as Chairman in 1929, was the person most responsible for laying the foundation which supported the growth of the Division to its present status. The India Rubber Section was sanctioned by the American Chemical Society on December 30, 1909. The 28 chemists from the rubber industry who were the organizing members, had the objective of meeting together to solve mutual problems. The major problem for everyone in 1909 was the variable quality of the 36 varieties of wild rubber from the jungles of Central and South America and Africa. Para rubber from the Hevea Brasiliensis tree was considered to be the best type available, but there were at least 13 variations, identified by source of the Para rubber. Charles C. Goodrich, as first chairman of the India Rubber Section, moved immediately to resolve the problem and appointed a committee, chaired by Dr. Charles Knight of Buchtel College, to develop standard methods of testing and evaluation. The committee diligently addressed the subject and reported to the Section at each meeting for 10 years, but progress was slow. Members attending had been instructed by their superiors, “Listen—but don't talk!” Not a very satisfactory format for conducting a meeting. Several key individuals helping to organize the India Rubber Section were W. C. Geer, Chief Chemist at the B. F. Goodrich Co. and George Oenslager, of the Diamond Rubber Co. Geer invented the air oven used to accelerate heat aging of rubber samples, and Oenslager is famous for discovering the effect on vulcanization of organic accelerators in 1906 and for the use of carbon blacks in treads in 1911. Although the sharing of technical information was tantalizing slow during the early years, the American Chemical Society, at their meeting in Buffalo, April 7, 1919, approved the formation of the Division of Rubber Chemistry. John B. Tuttle, first chairman of the Division in 1919, with Arnold H. Smith as secretary-treasurer, determined to bring to the members technical information less restricted in content, and from their neutral position of employment at the National Bureau of Standards, thought results could be obtained.

Rubber Fracture Characterization Using J-Integral

1988 ◽  
Vol 16 (1) ◽  
pp. 44-60 ◽  
Author(s):  
C. L. Chow ◽  
J. Wang ◽  
P. N. Tse
Keyword(s):  
Crack Initiation ◽  
Carbon Black ◽  
Natural Rubber ◽  
Fracture Parameter ◽  
J Integral ◽  
Specimen Length ◽  
Fracture Characterization ◽  
Premature Failure ◽  
Testing Procedures ◽  
Material Evaluation

Abstract The use of the J-integral to investigate fracture characterization in a carbon black reinforced natural rubber is described. Three applications to crack initiation are included: two based on the use of a hypothetical zero specimen length and one on conventional testing procedures for metals. While the validity of the zero-length methods is questionable, the conventional method yielded a consistent Jc value of 1.01 N/mm for a typical tire compound. This value was obtained from 24 combinations of varying specimen geometries and pre-crack lengths. The J-integral is revealed as a valid fracture parameter that is applicable not only for material evaluation but also for designing tire structures to resist premature failure. These conclusions disagree with those from an earlier investigation, so the causes for the discrepancies are examined and discussed.

Polysaccharide Structures in the Outer Mucilage of Arabidopsis Seeds Visualized by AFM

2020 ◽  
Author(s):  
MAK Williams ◽  
V Cornuault ◽  
AH Irani ◽  
VV Symonds ◽  
J Malmström ◽  
...  
Keyword(s):  
Average Length ◽  
American Chemical Society ◽  
Md Simulations ◽  
Chemical Society ◽  
Side Chains ◽  
Rhamnogalacturonan I ◽  
Afm Imaging ◽  
Minor Population ◽  
The Stability ◽  
A Minor

© 2020 American Chemical Society. Evidence is presented that the polysaccharide rhamnogalacturonan I (RGI) can be biosynthesized in remarkably organized branched configurations and surprisingly long versions and can self-assemble into a plethora of structures. AFM imaging has been applied to study the outer mucilage obtained from wild-type (WT) and mutant (bxl1-3 and cesa5-1) Arabidopsis thaliana seeds. For WT mucilage, ordered, multichain structures of the polysaccharide RGI were observed, with a helical twist visible in favorable circumstances. Molecular dynamics (MD) simulations demonstrated the stability of several possible multichain complexes and the possibility of twisted fibril formation. For bxl1-3 seeds, the imaged polymers clearly showed the presence of side chains. These were surprisingly regular and well organized with an average length of ∼100 nm and a spacing of ∼50 nm. The heights of the side chains imaged were suggestive of single polysaccharide chains, while the backbone was on average 4 times this height and showed regular height variations along its length consistent with models of multichain fibrils examined in MD. Finally, in mucilage extracts from cesa5-1 seeds, a minor population of chains in excess of 30 μm long was observed.

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