摘要:
A polymer composite prepared by melt blending, comprising an amorphous polymer; and a crystallizable polymer; wherein upon cooling the polymer composite, the amorphous polymer forms a continuous phase and the crystallizable polymer forms a dispersed phase, and wherein the dispersed phase is less than 200 nanometers in size.
摘要:
A polyester block terpolymer comprising an amorphous block comprising a polystyrene dicarboxylate; a crystallizable block comprising a polyethylene glycol; and an aliphatic diol block; wherein the amorphous block is a continuous phase and the crystallizable block is a dispersed phase, and wherein the dispersed phase is less than about 200 nanometers in size.
摘要:
Polycarbonates containing low or undetectable levels of Fries rearrangement products and comprising repeat units derived from one or more of resorcinol, hydroquinone, methylhydroquinone, bisphenol A, and 4,4′-biphenol have been prepared by the melt reaction of one or more of the aforementioned dihydroxy aromatic compounds with an ester-substituted diaryl carbonate such as bis-methyl salicyl carbonate. Low, or in many instances undetectable, levels of Fries rearrangement products are found in the product polycarbonates obtained as the combined result of a highly effective catalyst system which suppresses the Fries reaction and the use of lower melt polymerization temperatures relative to temperatures required for the analogous polymerization reactions using diphenyl carbonate.
摘要:
The present invention provides a method of preparing polycarbonate, said method comprising (A) oligomerising in the presence of a catalyst at least one dihydroxyaromatic compound at a temperature in a range between about 220-280° C. and a pressure in a range between 180 mbar and 20 mbar, said catalyst comprising a tetraarylphosphonium compound and optionally a co-catalyst, to provide an oligomeric polycarbonate having a number average molecular weight, Mn, in a range between about 1000 and about 6000 daltons; and (B) in a second step heating the oligomeric polycarbonate formed in step (A) at a temperature range between about 280 and about 310° C. and a pressure in a range between about 15 mbar and about 0.1 mbar, to provide a polycarbonate having a weight average molecular weight, in a range between about 15,000 and about 50,000 daltons, said product polycarbonate comprising less than 1000 parts per million Fries product.
摘要:
Mixed alkali metal salts of phosphoric acid in combination with a co-catalyst such as tetramethylammonium hydroxide (TMAH) are excellent transesterification catalysts for use in the preparation of polycarbonate from bisphenol A and diphenyl carbonate. The mixed alkali metal phosphate salts were shown by kinetic measurements made on a model system composed of p-tert-octylphenol and bis(p-cumylphenyl) carbonate to be inherently more potent catalysts than salts of phosphoric acid comprising a single alkali metal ion. In addition to providing higher rates of polymerization, the new catalysts were shown to provide polycarbonates containing reduced levels of Fries rearrangement product relative to polymerization reactions catalyzed by conventional catalyst systems such as sodium hydroxide together with TMAH co-catalyst.
摘要:
A melt method of preparing polycarbonate having a predetermined number average molecular weight and percent endcapping is described. A computerized process model is used to determine the reaction parameters to be employed in order to furnish the product polycarbonate possessing the desired Mn and %EC. Reaction parameters of importance include a suitable starting molar ratio of diaryl carbonate to dihydroxy aromatic compound, the most appropriate reaction time, reaction temperature and pressure ranges. The target polycarbonate is then prepared using reaction parameters indicated by the process model in a reactor which forms an element of the process model. Characteristics of the reactor which may be included in the process model include agitation rate and reflux ratio during the distillative removal of hydroxy aromatic compound formed as a by-product during the polymerization.
摘要:
A polymer composite prepared by melt blending, comprising an amorphous polymer; and a crystallizable polymer; wherein upon cooling the polymer composite, the amorphous polymer forms a continuous phase and the crystallizable polymer forms a dispersed phase, and wherein the dispersed phase is less than 200 nanometers in size.
摘要:
Polycarbonates containing low or undetectable levels of Fries rearrangement products and comprising repeat units derived from one or more of resorcinol, hydroquinone, methylhydroquinone, bisphenol A, and 4,4′-biphenol have been prepared by the melt reaction of one or more of the aforementioned dihydroxy aromatic compounds with an ester-substituted diaryl carbonate such as bis-methyl salicyl carbonate. Low, or in many instances undetectable, levels of Fries rearrangement products are found in the product polycarbonates obtained as the combined result of a highly effective catalyst system which suppresses the Fries reaction and the use of lower melt polymerization temperatures relative to temperatures required for the analogous polymerization reactions using diphenyl carbonate.
摘要:
A polyester block terpolymer comprising an amorphous block comprising a polystyrene dicarboxylate; a crystallizable block comprising a polyethylene glycol; and an aliphatic diol block; wherein the amorphous block is a continuous phase and the crystallizable block is a dispersed phase, and wherein the dispersed phase is less than about 200 nanometers in size.
摘要:
Polycarbonates having a high level of endcapping and containing a low level of Fries rearrangement product are prepared from dihydroxy aromatic compounds, such as bisphenol A, and diaryl carbonates such as diphenyl carbonate in a two stage process involving a tetraalkyl phosphonium carboxylate catalyzed oligomerization of the reactants in a first reaction stage followed by the addition of an alkali metal hydroxide co-catalyst in the second stage of the polymerization reaction. The late addition of the co-catalyst provides improved polymerization reaction rates as judged by higher polycarbonate molecular weights. The amount of alkali metal hydroxide co-catalyst is small thus avoiding the formation of excessive amounts of Fries product. The method has been used to provide Fries product levels between 200 and 800 parts per million in polycarbonates having Mn values between 7,500 and 8,500 Daltons.