Structure and morphology of polycarbonate synthesized by solid state polycondensation

Crystallization and Solid-State Polymerization of Poly(bisphenol A carbonate) Facilitated by Supercritical CO2

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...

Synthesis of High Molecular Weight Polycarbonate by Solid-State Polymerization

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...

Melt processing of cellulose nanocrystal reinforced polycarbonate from a masterbatch process

Abstract: Cellulose nanocrystal (CNC) reinforced polycarbonate (PC) nanocomposites were obtained by melt extrusion Highly concentrated CNC/PC masterbatch was first prepared using a dissolution/precipitation process which was then diluted by extrusion Water from the CNC aqueous dispersion was exchanged to pyridine PC was dissolved in this suspension and the mixture was precipitated in water Two different methodologies were adopted for the PC matrix In the first one, PC was submitted to the same dissolution/precipitation process than masterbatch, whereas in the second approach, the PC pellets were directly mixed with the solid masterbatch capsules The structural, thermal and mechanical properties of ensuing nanocomposite materials were investigated

Solid-State Polymerization of Polycarbonates Using Supercritical CO2

Abstract: We report the extension of the crystallization process with supercritical CO 2 to granules or beads of low molecular weight polycarbonate in an effort to create a material that can undergo slid-state polymerization without using toxic organic solvents

Polymer Crystallization By Chemical Nucleation

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.

Zur kristallstruktur der polycarbonate aus 4,4′-dihydroxydiphenyl-2,2-propan, 4,4′-dihydroxydiphenylsulfid und 4,4′-dihydroxydiphenylmethan†

Abstract: Es wird gezeigt, das das Polycarbonat aus 4,4′-Dihydroxydiphenyl-2,2-propan monoklin in der Raumgruppe Cs2 mit je 4 Ketten in der Gitterzelle, das Polycarbonat aus 4,4′-Dihydroxydiphenylsulfid und das aus 4,4′-Dihydroxydiphenylmethan dagegen rhombisch in der Raumgrupe C2v9 mit je 2 Ketten in der Gitterzelle kristallisiert. Die Faseridentitatsperiode umfast in allen drei Substanzen jeweils zwei monomere Einheiten, so das je 8 bzw. je 4 monomere Einheiten in der Gitterzelle liegen. Die Kristalldichten sind 1,315 g/ccm fur das Polycarbonat aus 4,4′-Dihydroxydiphenyl-2,2-propan, 1,50 g/ccm fur das Polycarbonat aus 4,4′-Dihydroxydiphenylsulfid und 1,303 g/ccm fur das Polycarbonat aus 4,4′-Dihydroxydiphenylmethan. Die Faseridentitatsperioden der drei betrachteten Polycarbonate sind um ca. 15% bis 20% gegenuber ihrer theoretischen Maximallange bei voll ausgestreckten Ketten verkurzt. Dementsprechend betragt der Kristall-Elastizitatsmodul in Kettenrichtung ca. 450 bis 600 kp/mm2. Die betrachteten Kristallstrukturen enthalten keinerlei Gleitebenen, so das die Kristallbereiche eine hohe Scherfestigkeit besitzen. Die geringe Kristallisationstendenz des Polycarbonates aus 4,4′-Dihydroxydiphenyl-2,2-propan findet durch die Kristallstruktur eine plausible, zwanglose Erklarung. The polycarbonate from 4,4′-dihydroxydiphenyl-2,2-propane crystallizes monoclinically in the space group Cs2 with four chains each in the lattice cell, but the polycarbonate from 4,4′-dihydroxydiphenyl sulfide and from 4,4′-dihydroxydiphenyl methane crystallizes orthorhombically in the space group C2v9 with two chains each in the lattice cell. In all three substances, the fibre identity period always comprises two monomeric units, so that always eight and always four monomeric units, respectively, are located in the lattice cell. The crystal densities are 1.315 g./ccm. for the polycarbonate from 4,4′-dihydroxydiphenyl-2,2-propane, 1.50 g./ccm. for the polycarbonate from 4,4′-dihydroxydiphenyl sulfide, and 1.303 g./ccm. for the polycarbonate from 4,4′-dihydroxydiphenyl methane. The fibre identity period of the three substances, as compared with their theoretical maximum length in the case of fully stretched chains, has been shortened by 15 per cent to 20 per cent. Accordingly, the crystal elasticity modulus in the direction of the chain only amounts to about 450 to 600 kp./mm2. The crystal structures considered do not contain any glide planes, so that the crystal domains possess a high shear strength. The low crystallization tendency of the polycarbonate from 4,4′-dihydroxydiphenyl-2,2-propane is easily and plausibly accounted for by its crystal structure.

Kristallisation von Polycarbonaten. I. Lichtmikroskopische Untersuchungen

Abstract: Polycarbonate auf der Basis 4,4′-Dioxy-diphenyl-2,2-propan, 4,4′-Dioxy-diphenylmethan und 4,4′-Dioxy-diphenyl-sulfid kristallisieren mit athermischer Keimbildung aus der Schmelze spharolithisch. Es wurden verschiedene morphologische Strukturen beobachtet. Die lichtmikroskopische Bestimmung der Spharolith-Wachstumsgeschwindigkeit last eine unterschiedliche Kristallisationsneigung der betrachteten aromatischen Polycarbonate erkennen. Danach zeigt das Polycarbonat auf Basis 4,4′-Dioxy-diphenyl-2,2-propan ein stark gehemmtes und verzogertes Kristallisationsverhalten, wahrend die Polycarbonate auf Basis 4,4′-Dioxy-diphenyl-methan und 4,4′-Dioxy-diphenylsulfid als relative kristallisationsfreudig zu bezeichnen sind. Als Ursache fur das unterschiedliche Kristallisationsverhalten wird der verschiedenartige molekular Aufbau diskutiert. Polycarbonates from 4,4′-Dioxy-diphenyl-2,2-propan, 4,4′-Dioxy-diphenylmethan, and 4,4′-Dioxy-diphenyl-sulfid crystallize from the melt with spherulitic structure and athermal nucleation. Depending on crystallization conditions different morphological textures were observed. The rate of spherulite growth, measured by means of polarisation microscope, depends on the chemical structure of the polycarbonate. The crystallization of polycarbonates from 4,4′-Dioxy-diphenyl-2,2-propan is hindered by the spacefilling isopropyl-group. On the other hand, polycarbonates from 4,4′-Dioxy-diphenyl-methan and 4,4′-Dioxy-diphenyl-sulfid have a relatively high tendency to crystallisation.

Polymer-induced crystallization of inorganic salts: PEO-CuCl2

Abstract: Crystallization in polyethylene oxide containing high concentrations of Cu(ll) chloride has been studied as a function of temperature. As concentrations above 1 : 4 mole/monomer ratio, highly crystalline acicular morphology is observed which can be attributed to precipitation of the inorganic component. The crystalline structure and morphology of these deposites is strongly influenced by the polymer matrix. The crystallites are seen to grow along the radical direction of the spherulitic domains of the polymer. A new hexagonal type structure with unit cell dimensions of a = 6.52and c = 19is seen to occur for high concentrations of the copper chloride, while an orthorhombic phase is observed at high temperatures. These various findings have been explained on the basis of complex formation at low concentrations with Cu 2+ ions being bound within the polymer matrix which acts as the template for subsequent crystallization of the excess salt.