High‐melting bisphenol‐A polycarbonate from annealing of vapor‐induced crystals

Abstract

Polycarbonate is known to crystallize thermally, but only slowly and to a limited (25%) extent. The melting points reported exhibit a wide variation. We have found that the melting temperature of polycarbonate may be drastically increased by employing a sequence of vapor‐induced crystallization and annealing treatments. The crystals formed by the treatment with organic vapor act as a nucleation or precursor state for further crystallization into larger, more perfect lamellae. An initial peak melting temperature of 195°C has been annealed up to 239°C, and then to 295°C by a double‐heat treatment. This sample is 60% crystalline, based on heat‐of‐fusion calculations. An equilibrium melting point of 335°C has been obtained for PC from an extrapolation of reciprocal lamellar thickness.

Enhanced crystallization of bisphenol-A polycarbonate by nano-scale clays in the presence of supercritical carbon dioxide

“…These changes in X-ray patterns also indicate the increase in crystallinity. In every case, reflection peaks are at the same position, which match those of Bonart's result [9,16]. This indicates that, although the melting temperatures are different with variant processing conditions, the unit cell of crystal phase in all samples is the same.…”

“…The half-time of crystallization, t 1=2 ; of PC with a molecular weight higher than 17,000 is more than a week [4,5]. Both solvents [6,7] and vapors [8,9] have been used to induce crystallization in PC. However, due to the high residue of solvents in the crystallized materials as well as the associated environmental considerations, this method is only used in the basic research.…”

A direct method of beam-height correction in small-angle X-ray scattering

“…A number of correction schemes have been suggested (Guinier & Fournet, 1955, ch. 3;Lake, 1967;Strobl, 1970;Schelten & Hossfeld, 1971;Vonk, 1971;Glatter, 1974;SSler & Baldrian, 1974;Deutsch & Luban, 1978a,b;Schmidt & Fedorov, 1978;Moore, 1980;Schmidt, 1988;Svergun, 1991) and implemented (Barnes et al, 1988;Phillips, Stevenson, Nagarajan & Cooper, 1988;Stuhn & Rennie, 1989;Rigby & Roe, 1986;North, Dore, Mackie, Howe & Harries, 1990;Jonza & Porter, 1986;Plestil, Hlavata, Hrouz & Tuzar, 1990;Fujisawa, Ueki, Inoko & Kataoka, 1987) with varying degrees of success.…”

Growth of Spatial Dendrites in Bisphenol-A Polycarbonate Induced by Dioctyl Phthalate at High Pressure

“…Many studies on the crystallization behaviors of BAPC have been reported, including bulk crystallization [3], solvent-induced and vapor-induced crystallization [2,4], effects of nucleating agents [5][6][7][8] and supercritical carbon dioxide [9,10] on crystallinity and crystallizability in polymer blends [11]. However, to the best of our knowledge, no investigation was performed on the morphology of high-pressure crystallized BAPC samples.…”