Patents improvements

Nitrocellulose or gun cotton was discovered by Braconnot (France, 1833) and patented by Schonbein (1846) (Fig. 1). It is speculated that in order to determine whether the action of nitric acid was a reaction or merely a sorption into fibrous material, Sobrero (1846) treated glycerin, a liquid, with nitric acid and found a true reaction took place. Hence, nitrocellulose and nitroglycerin were discovered within a decade of each other, but neither found widespread use until the 1860 s when methods of stabilizing them were devised. Between 1865 and 1868, Abel patented improved preparations of nitrocellulose. He found that pulping allowed impurities, such as residual acid, to be more easily washed out by "poaching" and resulted in improved stability. The Abel stability test is named after him[5]. 

Thus the net energy utilization is about 1 5 times the fuel value of ethylene, indicative of significant inefficiency in the overall process. (As an alternative to cracking. Union Carbide have patented improved catalysts for the selective oxidation of ethane to ethylene, which may ultimately prove more energetically and economically favourable.)... 

First polyethylene-polyethylene, PE/PE, blends were patented both cross-linked (using electron accelerators) and uncross-linked components were disclosed. In Phillips patent, low-density polyethylene, LDPE, was blended with linear low-density polyethylene, LLDPE, for unproved stiffiiess and abrasion resistance and reduced water vapor permeability, fir the Celanese patent, improvement of processability was particularly stressed. In the DuPont patent, 10-50 wt% LLDPE was used with LDPE or its copolymers for generating heat-shrinkable films... 

Table XIX. A Survey of Patented Improvements For Cyanoacrylate Adhesives...

The metal-catalyzed conversion of amino-alcohols to amino acid salts has been known since 1945. Commercial application, however, was not known until Monsanto developed a series of proprietary catalysts that made the chemistry commercially feasible. Monsanto s patented improvements on metallic copper catalysts afford an active, easily recoverable, highly selective, and physically durable catalyst that has proven itself in large-scale use. 

No attempt has been made to define the ownership or patent status of the processes described. Many of the basic patents on well-known processes have expired however, patented improvements may be critical to commercial application. In fact, a number of iirqportant propti ary systems ate based primarily on the inctxpotalion of spedal additives or flow system modificatimis into previously existing processes. 

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