Synthesis of High Molecular Weight Polycarbonate by Solid-State Polymerization
TL;DR: The solid-state polymerization (SSP) of small particles (20 μm) of poly(bisphenol A carbonate) resulted in high molecular weight material (Mw of 36 000 g/mol) as discussed by the authors.
Abstract: The solid-state polymerization (SSP) of small particles (20 μm) of poly(bisphenol A carbonate) resulted in high molecular weight material (Mw of 36 000 g/mol). Molecular weight distribution broaden...
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TL;DR: Asahi Kasei as discussed by the authors developed a new green process for producing an aromatic polycarbonate based on bisphenol-A without using phosgene and methylene chloride.
371 citations
TL;DR: The conventional solution to melt polymerization techniques stop at a low or medium molecular weight product, due to problems arising from severe increase of the melt viscosity and operating temperatures as discussed by the authors.
150 citations
TL;DR: In this article, the authors focused on the world's first process succeeded in development and industrialization by Asahi Kasei Corp. for producing an aromatic polycarbonate (PC) using CO2 as starting material.
Abstract: This review focuses on the world’s first process succeeded in development and industrialization by Asahi Kasei Corp. for producing an aromatic polycarbonate (PC) using CO2 as starting material.1 The carbonate group of PC links directly to the residual aromatic groups of the bisphenol. Until Asahi Kasei’s new process is revealed, all of carbonate groups of PC in the world were derived from CO as starting material. Furthermore, more than about 90% of PC has been produced by so-called “phosgene process”, and the PC contains Cl-impurities. It needs to use not only highly toxic and corrosive phosgene made from CO and Cl2 as a monomer, but also very large amounts of CH2Cl2 and water, and needs to clean a large amount of waste water. The new process enables high-yield production of the two products, Cl-free and high-quality PC and high-purity monoethylene glycol (MEG), starting from ethylene oxide (EO), by-produced CO2 and bisphenol-A. PC produced by the new process has many excellent properties compared with conventional PCs. The new process not only overcomes drawbacks in the conventional processes, but also achieves resource and energy conservation. The reduction of CO2 emissions (0.173 t/PC 1 t) is also achieved in the new process, because all CO2 is utilized as the component consisting main chains of the products. The newly constructed commercial plant of Chimei-Asahi Corp. (Taiwan), a joint venture between Asahi Kasei Corp. and Chi Mei Corp., has been successfully operating at full-production since June 2002. The initial capacity (PC:50,000 t/y) is now increased to 150,000 t/y. A typical example of the Green and Sustainable Chemistry (GSC) contributing to society and mankind has been realized.
113 citations
TL;DR: In this article, the benefits of the main polymerization processes in supercritical carbon dioxide (scCO 2 ) including homogeneous, precipitation, dispersion, suspension and emulsion systems are discussed.
81 citations
Patent•
27 Feb 1987TL;DR: In this article, an improved process for solid state polymerizing a polyester prepolymer into a high molecular weight polyester resin was proposed, in which the vapor of at least one member selected from the group consisting of volatile chlorinated hydrocarbons, volatile ketones, tetrahydrofuran, ethylene oxide, and propylene oxide was used.
Abstract: High molecular weight polyester resins are sometimes produced from low molecular weight polyester prepolymers having the same composition by solid state polymerization. Polyester prepolymers are generally converted from the amorphous state to the crystalline state prior to solid state polymerization in order to raise their sticking temperature. This is done in order to keep the polyester prepolymer from sticking together as a solid mass in the solid state polymerization reactor. Such polyester prepolymers have traditionally been crystallized by heating them to elevated temperatures. It has been found that polyester prepolymers can be crystallized by exposing them to the vapors of certain volatile organic compounds. By utilizing such vapors to crystallize polyester prepolymers the need for a thermal crystallization step can be eliminated. The present invention specifically relates to an improved process for solid state polymerizing a polyester prepolymer into a high molecular weight polyester resin comprising (1) crystallizing said polyester prepolymer in the presence of the vapor of at least one member selected from the group consisting of volatile chlorinated hydrocarbons, volatile ketones, tetrahydrofuran, ethylene oxide, and propylene oxide; and (2) subsequently heating the crystallized polyester prepolymer to a temperature of from about 1° C. to about 50° C. below its sticking temperature for a period of time sufficient to produce a high molecular weight polyester resin.
54 citations
References
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TL;DR: In this article, the mechanism of action of organic nucleating agents such as sodium benzoate and its derived salts completely differs from the generally accepted model, at least in the case of polyesters.
Abstract: Several attempts1–5 have been made to control the rate of crystallization and the morphology by the addition of very finely-divided substances which promote abundant nucleation. However, these studies have mostly been carried out on an empirical basis and, except in a few cases (self-seeding6, epitaxy2–5), the mechanism of action of these nucleating agents is poorly understood despite several attempts at modelling1,2. This is particularly so in the case of most technical nucleating agents such as mica, talc and organic salts. We report here that the mechanism of action of organic nucleating agents such as sodium benzoate and its derived salts completely differs from the generally accepted model, at least in the case of polyesters. The nucleating agent reacts as a true chemical reagent with the molten macromolecules and produces ionic end groups which constitute the true nucleating species.
122 citations
TL;DR: In this paper, supercritical carbon dioxide readily induces crystallization in bisphenol A polycarbonate and the degree of crystallinity increases sharply as the CO2 pressure is raised from 100 to 300 atm but levels off thereafter.
Abstract: Supercritical carbon dioxide readily induces crystallization in bisphenol A polycarbonate. Crystallization begins within one h of exposure to the CO2 at temperatures and pressures as low as 75°C and 100 atm. The degree of crystallinity increases sharply as the CO2 pressure is raised from 100 to 300 atm but levels off thereafter. This behavior is likely due to a minimum in the Tg of the polycarbonate/CO2 mixture owing to the opposite effects of the pressure on the Tg of the polymer and on the equilibrium weight fraction of CO2 absorbed. Percent crystallinities of over 20%, comparable to that achieved using acetone or other organic liquids, have been obtained after 2 h exposure to supercritical CO2. Since polycarbonate degasses quickly and quantitatively at ambient temperature and pressure, the high Tg of bisphenol A polycarbonate can be regained in the crystallized material without further vacuum treatment.
116 citations
TL;DR: In this paper, a poly(bisphenol A carbonate) was synthesized by solid-state polymerization (SSP) using supercritical CO2 to induce crystallinity in low molecular weight polycarbonate beads.
Abstract: Poly(bisphenol A carbonate) was synthesized by solid-state polymerization (SSP) using supercritical CO2 to induce crystallinity in low molecular weight polycarbonate beads. The CO2-induced crystallization was studied as a function of time, temperature, molecular weight, and pressure. There was an optimum temperature for crystallization which depended on the molecular weight of the polymer. The molecular weight and percent crystallinity of the polymer produced by SSP were determined as a function of time and radial position in the bead. The molecular weight and percent crystallinity were strong functions of the particle radius, probably because of the slow diffusion of phenol out of the polymer particles. Nitrogen and supercritical CO2 were used as sweep fluids for the SSP process. The polymerization rate was always higher in supercritical CO2 at otherwise comparable conditions. We hypothesize that supercritical CO2 plasticizes the amorphous regions of the polymer, thereby increasing chain mobility and the...
97 citations
TL;DR: It has been reported that a number of organic liquids will induce crystallization in amorphous polyethylene terephthalate as discussed by the authors, which occurs readily at ambient temperatures, that is, at much lower temperatures than those at which the normal 'thermal' process is observed.
Abstract: IT has been reported that a number of organic liquids will induce crystallization in amorphous polyethylene terephthalate1. This occurs readily at ambient temperatures, that is, at much lower temperatures than those at which the normal ‘thermal’ process is observed. It has been further suggested that the phenomenon of liquid-induced crystallization is probably common to other polymers which are crystallizable but which may be obtained in the amorphous state2.
40 citations
TL;DR: In this article, a linear correlation was established between these two physical variables and from this an enthalpy of fusion for the polycarbonate crystal of 26 Kcal was deduced.
Abstract: Several measurements of the heat of fusion and of specific volume were carried out on bisphenol A-polycarbonate of varying degrees of crystallinity. A linear correlation was established between these two physical variables and from this an enthalpy of fusion for the polycarbonate crystal of 26 Kcal. was deduced.
39 citations