Rubber compounding development

Rubber Compound Development for FGD (Flue Gas Desulphurizing) Systems [8]... 

Dick. John S., and Pawlowski. Henry. Applications for the curemeter cure rate in rubber compound development and process control. Presented at the Rubber Division. ACS. Philadelphia. May 2 5, 1995. 

The most important rubber application is in tyre compounds, about 70% of the worldwide natural and synthetic rubber consumption. A conventional tyre for passenger cars contain more than ten different rubber compounds, developed as a function of the specific requirements of the various tyre parts and thus based on optimized combinations of rubbers and other ingredients. 

The wear resistance of rubber compounds is of great practical importance for tires, but the mechanisms involved in tire wear are multiple and may vary depending on the vehicle, the driving conditions, and other extraneous variables. Many attempts have been made to develop laboratory test methods to simulate tire wear under various conditions. Whilst none can fully replicate road wear, various laboratory abrasion tests can be used to provide an indicator of wear resistance of tires under certain conditions. 

For the extraction of rubber and rubber compounds a wide variety of solvents (ethyl acetate, acetone, toluene, chloroform, carbon tetrachloride, hexane) have been used [149]. Soxtec extraction has also been used for HDPE/(Tinuvin 770, Chimassorb 944) [114] and has been compared to ultrasonic extraction, room temperature diffusion, dissolution/precipitation and reflux extraction. The relatively poor performance of the Soxtec extraction (50% after 4h in DCM) as compared with the reflux extraction (95% after 2-4 h in toluene at 60 °C) was described to the large difference in temperature between the boiling solvents. Soxtec was also used to extract oil finish from synthetic polymer yam (calibration set range of 0.18-0.33 %, standard error 0.015 %) as reference data for NIRS method development [150]. 

LC-MS is now a nature technology and operation of an LC-MS system is no longer the realm of an MS specialist. The proper choice of the LC-MS mode to be used in a specific situation depends on analyte class, sample type and problem (detection, confirmation, identification). On-line LC-MS is used more for specialised applications than for general polymer or rubber compound analysis. This derives from the fact that LC-MS method development (column, solvent system, solvent programme, ionisation mode) is rather time consuming. LC-MS (in particular with API interface) enables analysis of a wide range of polar and nonvolatile compounds which cannot be analysed by GC (icf. Scheme 7.7). 

The development of rubber compounds which will effectively withstand the conditions under which the products made from them are to be used the mixes so developed must be capable of being processed in the factory without undue difficulty. The term is also applied to the assembling of elastomer and compounding ingredients ready for the mixing proper. 

The rate of vulcanisation of a rubber compound is controllable by the choice of accelerator. The range of products offered to the rubber industry has been categorised historically into recognised classes. New developments have resulted in products that improve compound performance and which overcome dermatological problems, and do not generate nitrosamines and other extractable or volatile decomposition products. 

Resorcinol formaldehyde latex (RFL) cord dips have only a limited application within the general rubber goods industry and for adhesion to be achieved with synthetic fibres it is necessary to use the systems developed by Bayer and Degussa. These systems are based upon a combination of resorcinol, a formaldehyde donor and a hydrated silica filler (commonly called the RFK system). This system is incorporated as dry ingredients into the rubber compound and is activated by the application of heat. 

The feed characteristics of cold rubber compounds differ considerably from those of hot compound to the extruder and a number of devices were developed to overcome this problem. However, the productivity of the early machines was not as high as for the hot-feed machines. 

Compression of the rubber compound as it travels up the barrel is developed in the extruder by either decreasing the thread pitch but maintaining a constant root diameter, or alternatively by increasing root diameter whilst maintaining constant thread pitch. Each of these situations increases the pressure as the rubber compound travels up the barrel. The last portion of the screw prior to the die entry, however, is maintained at a constant pitch or root diameter to enable stock to stabilise in characteristics just prior to entering the die head, to ensure uniformity for extrusion through the die. Conventional extruder screws achieve a compression ratio of 2.5 1. 

The vacuum extruder was developed to eliminate unwanted gases from rubber compounds, so that the profiles produced from rubber stocks could be vulcanised at atmospheric pressure without problems of porosity occurring. Removal of the volatiles is achieved in principle by combining the actions of two individual machines in series, into one machine. The first part of the extruder screw... 

Rubber manufacturers develop their own rubber compounds suitable for constructing chemical plants and equipment possessing the chemical and physical properties to match the functional... 

The commercial significance of the ingredients used in rubber compounding to improve resistance to ageing accelerated work on the discovery, development, use and manufacture of new products. The development efforts were competitive in nature, each manufacturer claiming superiority of their products over the others. Some of the age retardants are listed below. 

The development of silicone elastomer technology has enabled synthetic rubber plants to obtain very convenient and practical rubber compounds. 

These feedstocks were tested in a number of carbon black furnace reactors employing different geometries and different operating conditions. The experiments were designed to develop data for correlation between feedstock composition, yield, production rate, and properties of carbon black produced. The physical properties of the carbon blacks were measured as were the properties of uncured rubber compounds and vulcanizates in standard test recipes. 

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