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Industrial polymerisation processe

Although the polymerisation rate increases with increasing temperature, ethylene and 7-olefin polymerisations in the presence of most Ziegler-Natta catalysts are carried out at moderately elevated temperature, usually not exceeding 100 °C. This is due to destabilisation of the system, which occurs when temperature is raised beyond a certain critical value. There are, however, few catalysts that operate in industrial polymerisation processes at temperatures above 200 °C [51,240]. [Pg.97]

Industrial polymerisation processes with the use of titanium-, cobalt- and nickel-based aluminium alkyl-activated Ziegler-Natta catalysts, which are employed for the manufacture of cis- 1,4-poly butadiene, involve a solution polymerisation in low-boiling aromatic hydrocarbons such as toluene or in a mixture of aromatic and aliphatic hydrocarbons such as n-heptane or cyclohexane. The polymerisation is carried out in an anhydrous hydrocarbon solvent system. The proper ratio of butadiene monomer and solvent is blended and then completely dried in the tower, followed by molecular sieves. The alkyla-luminium activator is added, the mixture is agitated and then the transition metal precatalyst is introduced. This blend then passes through a series of reactors in a cascade system in which highly exothermic polymerisation occurs. Therefore, the reaction vessels are cooled to slightly below room temperature. [Pg.319]

PoIysuIfonyIa.tlon, The polysulfonylation route to aromatic sulfone polymers was developed independendy by Minnesota Mining and Manufacturing (3M) and by Imperial Chemical Industries (ICI) at about the same time (81). In the polymerisation step, sulfone links are formed by reaction of an aromatic sulfonyl chloride with a second aromatic ring. The reaction is similar to the Friedel-Crafts acylation reaction. The key to development of sulfonylation as a polymerisation process was the discovery that, unlike the acylation reaction which requires equimolar amounts of aluminum chloride or other strong Lewis acids, sulfonylation can be accompHshed with only catalytic amounts of certain haUdes, eg, FeCl, SbCl, and InCl. The reaction is a typical electrophilic substitution by an arylsulfonium cation (eq. 13). [Pg.332]

So far we have been discussing the processes that are carried out in liquid phase and are very popular and widely used for industrial preparation of polymers. However, the polymerisation process can also be carried out in solid and gaseous phases. [Pg.20]

New Views on Cationic Polymerisation, A. Gandini and P.H. Plesch, The Chemistry of Polymerisation Processes, Society of Chemical Industry Monograph No. 20,1966, 107-114. [Pg.774]

Imperial Chemical Industries Ltd. Acrylonitrile Polymerisation Products, Brit. Pat. 715,194 (September 8, 1954). Polymerisation Process, Brit. Pat. 733,093 (July 6, 1955). [Pg.149]

Accident statistics formerly showed nitration as the most widespread and powerfully destructive industrial unit process operation (it has been overtaken by polymerisation). This is because nitric acid can, under certain conditions, effect complete and highly exothermal conversion of organic molecules to gases, the reactions often being capable of acceleration to deflagration or detonation. Case histories are described and safety aspects of continuous nitration processes are discussed in detail [1]. Of the 25 chapters of the book [2], each a paper presented at the symposium on Advances in Industrial and Laboratory Nitrations at Philadelphia in 1975, 3 deal with safety aspects of nitration Ch. 8, Hanson, C. etal., Side Reactions during Aromatic Nitration, Ch. 22, Biasutti, G. S.,... [Pg.2458]

The development of Nd-based catalysts has permitted the industrial realisation of a polymerisation process for cis- 1,4-polybutadiene in which temperature varies in the range 20-50 °C. In such a process, the polymerisation proceeds relatively fast the average residence time of the monomer varies in the range 0.5-4 h to achieve 90% butadiene conversion. [Pg.320]

Nevertheless, they may be present as impurities in the substances used, as reaction intermediates formed during polymerisation processes or as decomposition or reaction products. As stated before, these NIAS (Not Intentionally Added Substances) can be a particular challenge to the industry and authorities alike. [Pg.11]

The industrial manufacturing process for cyanoacrylate monomers is designed to generate pure organic compounds free of metals. The prepared monomer is functionally very reactive and is polymerised by several mechanisms of which the most common is by anionic methods. In most applications the initiation is usually carried out by the nucleophilic contaminant (water or moisture) found on most surfaces. These adhesives differ from other adhesives in that they are monofunctional and can homopolymerise rapidly at room temperature. A number of modifiers have been added to impart a range of desired properties and these include stabilisers, inhibitors, thickeners, plasticisers, tracers, colorants and preservatives. [Pg.169]

The above gas-phase reaction is a polymerisation process which causes deviation from linear kinetics. Long residence-time performance is essential in large industrial reactions for forming hard coatings, where the residence time of the feed precursor is measured in minutes, whereas typical residence times for small tubular reactions is on the order of 1 s or less. [Pg.234]

The case study presented in the last subsection can also be taken to summarize the characteristics of industrial design processes. This subsection abstracts from the concrete example. The reader, however, may also relate the following general statements to the polymerisation case study. [Pg.11]

The formation of relatively high yield (15-25%) cylic oligomers, means that the cationic polymerisation of alkylene oxides cannot be used for high MW polyether polyol synthesis on an industrial scale [38, 56]. The cationic polymerisation process is only used industrially for producing PTHF- and THF-alkylene oxide copolymers [2, 3, 7, 35, 36, 54, 57, 58]. The cyclic oligomers are totally inert in the chemistry of PU formation because they do not have hydroxyl groups (are simple diluents) and confer a very unpleasant odour to the synthesised polyether polyols. [Pg.247]

Alkylbenzene sulfonates are the main surfactants used in household cleaners, detergents and sanitary formulations, as well as in industrial and institutional cleaners. They are used in the production of fabrics. They are also used as emulsifiers, in many technical processes as wetting agents and dispersants, e.g. in polymerisation processes and in the formulation of plant protection products. [Pg.279]

The choice is high purity industrial hexane, a stable material with a boiling range 65-70°C, low benzene and lead content, low and neutral evaporation residue and low content of corrosive sulphur compounds. The same solvent is, for similar reasons, often used in polymerisation processes for the manufacture of certain polyethylene, polypropylene or rubber grades. [Pg.49]

In addition to the above, there are other industrially modified or pretreated vegetable oils. These are blown oil, boiled oil and stand oU. Blown oils are made by blowing air through the oU at a temperature between 95 and 120°C, depending on the iodine value of the oil. As the durability of films of such oils is poor, they are mainly used in oiled fabrics, lithographic varnishes, pigment grinding aids, and so on. Boiled oils are not actually boiled, rather they are dried (cross-linked) by an oxidative polymerisation process in the presence of an appropriate type and dose of drier at a specified temperature for 8-16 hours. They are mainly used in oil paints, enamels and oil-based primers. Stand oils are the heat bodied or polymerised oils... [Pg.56]

Recovery of solid polymer can be obtained by coagulation of the latex. As the size of the particles is submicronic, recovery by filtration without precipitation is not possible. Separation without precipitation cannot be obtained by usual centrifugation but requires ultracentrifugation. The emulsion polymerisation process is very well adapted for production of large amounts of polymeric colloids used in the paint industry by polymerisation of acrylic and methacrylic monomers, i.e. acrylic paints. Similarly, poly(alkylcyanoacrylate) nanoparticles can be obtained by such a process. [Pg.79]


See other pages where Industrial polymerisation processe is mentioned: [Pg.56]    [Pg.208]    [Pg.291]    [Pg.318]    [Pg.368]    [Pg.193]    [Pg.56]    [Pg.208]    [Pg.291]    [Pg.318]    [Pg.368]    [Pg.193]    [Pg.514]    [Pg.219]    [Pg.56]    [Pg.4]    [Pg.4]    [Pg.29]    [Pg.32]    [Pg.54]    [Pg.55]    [Pg.61]    [Pg.86]    [Pg.94]    [Pg.214]    [Pg.537]    [Pg.112]    [Pg.245]    [Pg.49]    [Pg.53]    [Pg.147]    [Pg.67]    [Pg.3]    [Pg.105]    [Pg.152]    [Pg.16]   
See also in sourсe #XX -- [ Pg.208 , Pg.209 , Pg.210 , Pg.211 , Pg.212 , Pg.213 , Pg.214 , Pg.215 ]




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