Advances in Nitrile Rubber Technology

1978 ◽  
Vol 51 (3) ◽  
pp. 389-405 ◽  
Author(s):  
J. R. Dunn ◽  
D. C. Coulthard ◽  
H. A. Pfisterer
Keyword(s):  
Heat Resistance ◽  
New Product ◽  
Polymer Structure ◽  
Nitrile Rubber ◽  
Product Form ◽  
Polymer Backbone ◽  
End Groups ◽  
Speed Up ◽  
Made In ◽  
Ozone Resistance

Abstract Considerable advances have been made in NBR technology and still more are possible. The heat resistance of NBR has been raised so that it will with-stand 150°C in air for short periods, instead of 120°C. There is potential in the polymer backbone for still greater stability. It has been demonstrated that the ozone resistance of NBR can be improved by blending with EPDM, but the optimum blend has not yet been developed. The use of PVC to improve the ozone resistance of NBR is now much better understood. Crosslinked NBR has been developed as a non-migratory plasticizer which improves embossing characteristics of PVC and PVC-ABS blends. This, in turn, led to the production of NBR powders which may be used to speed up compounding on conventional equipment and permit rubber to be compounded in equipment generally used for fabricating plastics. Powder black masterbatches of NBR are now being evaluated in industry. Another new product form is liquid NBR, generally with reactive end groups. This is already established as an impact modifier for resins and may be a route to castable reinforced elastomers. Polymer structure modifications such as alternating 50:50 copolymers are interesting but do not appear to have found a market. Carboxylated NBR uses are growing in the wake of improvements in scorch resistance. Reprocessible vulcanizates based on amine-modified NBR have been announced, but a true thermoplastic NBR is still awaited.

Network Changes in Nitrile Rubber at Elevated Temperatures

1973 ◽  
Vol 46 (2) ◽  
pp. 483-503 ◽  
Author(s):  
T. C. P. Lee ◽  
S. H. Morrell
Keyword(s):  
Heat Resistance ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
Essential Feature ◽  
Nitrile Rubber ◽  
Polymer Backbone ◽  
Thermal Changes ◽  
Effective Antioxidant ◽  
Cleavage Reactions ◽  
Crosslinking Reactions

Abstract The network analysis of the aged sulfur vulcanizates of nitrile rubber serves to re-emphasize the complexity of the structural changes which can occur at elevated temperatures. Three factors control the rate and degree of crosslinking in these systems. First there is the crosslink structure. An essential feature for heat resistance in sulfur compounds is that they should contain, as near as possible, 100 per cent monosulfide crosslinks. Systems which contain polysulfide crosslinks, and probably to a lesser extent disulfide crosslinks, are prone to purely thermal crosslink shortening or cleavage reactions. The physical effect of these thermal changes would be superimposed on the effects brought about by thermooxidative changes. Despite their thermal stability monosulfide crosslinks can oxidize and cleave, a process which will result in stress relaxation if the sample is held in tension or compression. Hence for truly inert systems one will have to turn to non-sulfur cure in conjunction with a suitable stabilizer. Because the results indicate that scission associated with chemistry at the monosulfide crosslink is reversible, this cleavage does not contribute to the change in modulus or hardening during aging. This brings in the second controlling factor. The degree and rate of hardening depends on the nature of the products of vulcanization, and also possibly on those species intermediate between crosslink and accelerator, the pendent accelerator groups. In acting as an antioxidant ZDMC is apparently oxidized to a new source of sulfur. The more heat resistant cadmate system contains no such products and also a minimum of pendent accelerator groups. This leads to the third factor—the added antioxidant. For its heat resistance the cadmate system relies on an antioxidant. It is this which stops crosslinking reactions through autooxidation of the polymer backbone. The efficiency with which the antioxidant (dioctyldiphenylamine) works suggests that there is a synergistic effect in operation, which in some way involves cadmium. Thus the best heat resistance will be obtained where the compound yields monosulfide crosslinks, an uncomplicated network structure, unreactive vulcanization products, and contains a highly effective antioxidant system. Many facets of the aging of nitrile rubber are still open to explanation. Not the least of these is why crosslinks formed during the aging of the TMTD/S vulcanizate, which, by reason of their reactivity to methyl iodide, are thought to be sulfidic, are not themselves oxidized in a manner similar to the original monosulfide crosslinks. Model compound studies would answer this and other questions.

scholarly journals Product forms based on backward traffic equations

1995 ◽  
Vol 32 (02) ◽  
pp. 508-518
Author(s):  
Richard J. Boucherie
Keyword(s):  
Queueing Networks ◽  
Queueing Network ◽  
New Product ◽  
Capacity Constraints ◽  
Product Form ◽  
New Form ◽  
Product Forms ◽  
Exact Product

This paper introduces a new form of local balance and the corresponding product-form results. It is shown that these new product-form results allow capacity constraints at the stations of a queueing network without reversibility assumptions and without special blocking protocols. In particular, exact product-form results for heavily loaded queueing networks are obtained.

scholarly journals Breeding for higher productivity in mulberry

2012 ◽  
Vol 48 (No. 4) ◽  
pp. 147-156 ◽  
Author(s):  
K. Vijayan ◽  
P.P. Srivastava ◽  
P.J. Raju ◽  
B. Saratchandra
Keyword(s):  
Molecular Biology ◽  
Reproductive System ◽  
Considerable Improvement ◽  
Breeding Methods ◽  
Leaf Quality ◽  
Conventional Breeding ◽  
Leaf Yield ◽  
Speed Up ◽  
Silkworm Bombyx Mori ◽  
Made In

Mulberry (Morus L.) is an economically important tree being cultivated for its leaves to rear the silkworm Bombyx mori. Rearing of silkworm is an art and science popularly known as sericulture; an agrobased cottage industry provides employment to millions in China, India, Korea, Vietnam, etc. Mulberry is a perennial tree that maintains high heterozygosity due to the outbreeding reproductive system. It is recalcitrant to most of the conventional breeding methods, yet considerable improvement has been made in leaf yield and leaf quality. Conventional breeding in mulberry is a tedious, labour intensive and time taking process, which needs to be complemented with modern biotechnological methods to speed up the process. This article enumerates the problems, challenges, constraints and achievements in mulberry breeding along with recent advances in biotechnology and molecular biology to enable mulberry breeders to tackle specific problems more systematically and effectively.

Study on Application of the Blends of Nitrile Rubber with Acrylate Rubber in the Coat-Metal Sealing Gasket

2011 ◽  
Vol 393-395 ◽  
pp. 1438-1442 ◽  
Author(s):  
Zu Min Qiu ◽  
Chao Yan Qin ◽  
Jun Ming Qiu
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Heat Resistance ◽  
Nitrile Rubber ◽  
Temperature Resistance ◽  
Oil Resistance ◽  
Comprehensive Properties ◽  
The Cost ◽  
Low Temperature Resistance

This paper discussed the effect of different blending ratio with BNR and ACM on the mechanical properties, heat resistance, low temperature resistance and oil resistance of coat-metal sealing gasket. The result showed that the comprehensive properties of the NBR/ACM blends at the ratio of 85/15 were preferable to the NBR and ACM, the low temperature resistance and oil resistance of NBR are taken into account. The cost of the blends were lower than the ACM. The blends can be used for coat-metal sealing gasket instead of NBR.

Practical implementations for improving the throughput in a manual crystallization setup

2005 ◽  
Vol 38 (3) ◽  
pp. 568-570 ◽  
Author(s):  
Christian Biertümpfel ◽  
Jérôme Basquin ◽  
Dietrich Suck
Keyword(s):  
High Throughput ◽  
Structural Genomics ◽  
Basic Research ◽  
Financial Resources ◽  
The Past ◽  
Financial Investments ◽  
Simple Question ◽  
Speed Up ◽  
Reduction Of Costs ◽  
Made In

For the past few years, the number of structural genomics projects has been growing enormously worldwide. All these projects are supported by substantial financial resources and therefore are able to employ robotics for setting up high-throughput platforms. This paper addresses a simple question: how can basic research laboratories draw profit from the efforts and innovations that have been made to establish high-throughput facilities? To answer this question, the implementations that have been made in the authors' laboratory to improve manual crystallization setup with very limited financial investments are presented. In combination with 96-well microplates, an advanced protocol has been introduced and several simple devices have been designed to speed up different aspects of the manual crystallization setup, from storage of solutions to the setting of drops. These implementations lead to the reduction of costs in terms of time and money without any loss of quality. In addition, the crystallization throughput in the manual setup has been significantly increased.

OVERVIEW OF 3D PRINTING TECHNOLOGIES IN DENTISTRY

2020 ◽  
pp. 15-18
Author(s):  
Ertesyan A.R. ◽  
Sadykov M.I. ◽  
Nesterov A.M.
Keyword(s):  
3D Printing ◽  
New Product ◽  
Layer By Layer ◽  
High Speeds ◽  
Qualified Personnel ◽  
Speed Up ◽  
Typing Technique

Today, in an age of high speeds and scientific discov-eries, people are trying with all their might to speed up the process of developing and publishing a new product. One of these ways is the use of rapid proto-typing technique (rapid creation of a prototype of the equipment being developed to conduct a series of tests on it or to refine it to the final product). In the begin-ning, classical methods (turning, milling, stamping) were used to make prototypes, but this was inconven-ient for a number of reasons (such production of blanks generates a large amount of waste, the work must be performed by qualified personnel). Therefore, in the 80s of the last century, an alternative appeared - the object is not made "at once" (from a workpiece by changing its shape), but layer by layer (moreover, rather unusual materials are used - metal and plastic powders, various types of clay, polymers sensitive to light), after which the layers are held together. This review focuses on common 3D printing technologies used in dentistry. Technologies and schemes of 3D printing are presented.

Stereo Vision Based Distance Measurement and its Application

2014 ◽  
Vol 926-930 ◽  
pp. 3258-3261
Author(s):  
Gan Le Hu ◽  
Yan Chen ◽  
Zheng Guo Gu
Keyword(s):  
Computer Graphics ◽  
Stereo Vision ◽  
Stereo Matching ◽  
High Accuracy ◽  
Good Combination ◽  
Practical Applications ◽  
Time Performance ◽  
Speed Up ◽  
Left And Right ◽  
Made In

In computer graphics, Stereo Vision has been a research hotspot for many years, and it is been widely used in many areas. Stereo Vision is a technique which utilizes computer to simulate human eye system. In order to achieve this simulation, two main problems need to be solved: camera calibration and stereo matching. We focus on stereo matching in this paper. After years of development some achievements have been made in stereo matching, but some problems remain unsolved. The two most important things concerned in stereo vision trend to be contradictory: accuracy and efficiency. This paper presents a method called Advanced-Census which is a good combination of SAD and Census. When finding corresponding pixel in left and right image, SAD can get high accuracy with low speed and Census have the opposite result. Advanced-Census has advantages of both SAD and Census. It retains the speed of Census while having the accuracy of SAD. Although it has the speed of Census but not enough for practical applications, so we speed up Advanced-Census using multi-thread technique and edge detection. After speeding up, Advanced-Census gets nearly real-time performance.

The experience of the SJ X2000 tilting train and its effect on the market

1998 ◽  
Vol 212 (1) ◽  
pp. 103-108 ◽  
Author(s):  
B-L Nelldal
Keyword(s):  
Market Share ◽  
New Product ◽  
Speed Up ◽  
Tilting Train

X2000 is a tilting train that was introduced as a new product by the Swedish State Railways (SJ) on the 450 km line between Stockholm and Gothenburg in 1991. Travelling times have been reduced from 4 to 3 h or 25 per cent by the tilting device and increased top speed up to 200 km/h. Now rail can really compete with air. The rail market share of the rail-air market between the Stockholm and Gothenburg regions increased from 42 to 57 per cent between 1990 and 1996. The success of X2000 can, in addition to the travelling times, also be explained by higher comfort, service and quality as well as by the image of X2000 as a new product.

Sign in / Sign up

Export Citation Format

Share Document