Crystallization and fusion of self-seeded polymers

Kovacs, A. J.; Gonthier, A.

doi:10.1007/bf01507524

Cited by 201 publications

(118 citation statements)

References 12 publications

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“…Even though in crystallization state different morphologies are obtainable from concentrated solutions or from polymer melts, ranging from axialites, dendrites to spherulites, crystallization into somehow well-defined single crystals is delimited to supercooled dilute solutions [1]. An ample range of empirical works were dedicated to study the diffraction effects, lateral habits, lamellar structures, and crystal orientation of poly(ethylene oxide) (PEO) single crystals [1][2][3][4][5][6][7][8][9][10][11][12][13]. In a frontier step, Lin and his coworker studied semicrystalline diblock copolymer platelets of PEO-bpolystyrene (PS) in dilute solution by means of small-angle neutron scattering (SANS) [14].…”

Section: Introductionmentioning

confidence: 99%

Fine fibrillar and rectangular/hexagonal ordered grains of poly(3-hexyl thiophene) and poly(ethylene glycol) developed by seeding technique

et al. 2016

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The fibrillar poly(3-hexyl thiophene) single crystals were prepared from dilute solutions of toluene, xylene, and anisole (0.01 wt%), and were investigated from the perspective of structural properties. Next, the rectangular and hexagonal poly(ethylene glycol) single crystals were developed from the dilute solutions and molten thin polymer films. The developing methodology used for all growth systems was self-seeding. The dimensions of fibrillar and rectangular/hexagonal single crystals ranged from several nanometers to some microns. Random single-co-crystals were also grown from dilute solution (0.018 wt% in amyl acetate) of crystalline-amorphous diblock copolymers and homopolymers. The small-angle X-ray scattering, grazing incidence wide-angle X-ray scattering, and atomic force microscopy analyses were employed to characterize prepared grained samples. The incident X-ray experiments demonstrated highly ordered and lamellar crystalline structures.

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Section: Introductionmentioning

confidence: 99%

Fine fibrillar and rectangular/hexagonal ordered grains of poly(3-hexyl thiophene) and poly(ethylene glycol) developed by seeding technique

et al. 2016

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“…It was reported that the crystal growth rate of poly(ethyleneoxide) showed the clear dependence on the number of folds. 10 In conclusion we suggest that the mechanism of the formation of extended-chain crystallization at atmospheric pressure is different from that at high pressures. It is considered that the formation of extended-chain crystals for high molecular weight at atmospheric pressure is difficult, mostly because of the high free energy in nucleation events due to the large lamellar thickness.…”

Section: (4)mentioning

confidence: 74%

Transition in Crystallization Rates of Fractionated Polyethylenes

Sawada

Nose

1979

Polym J

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ABSTRACT:The kinetics of fractionated polyethylenes was investigated by the method of dilatometry. A discontinuous change in crystallization rates was observed for molecular weights 4300 and 17300. This discontinuity is shown to be an important factor in clarifying the mechanism of the formation of extended-chain crystals. Extended-chain crystals were obtained within the region where folded-chain crystals were prohibited. Extended-chain crystallization had a mode of three-dimensional growth. It is suggested that the formation of extended-chain crystals at atmospheric pressure is distinct from that under high pressure. A theory of polymer crystallization is proposed in order to explain the transition in crystalJization rates.KEY WORDS Polyethylene I Crystallization Rates I Extended-Chain Crystals I Avrami Exponent I Stochastic Process I Surface Nucleation Rate I Extended-chain crystals can be produced at atmospheric pressure, depending on the crystallization conditions. 1 It was shown, however, that it became harder to give rise to extendedchain crystals as the molecular weight of polymers was increased. In extended-chain crystallization under high pressure, the situation is completely reversed, that is, extended-chain crystals are easily produced with increasing molecular weight. 2 -4 As regards this inconsistency, we consider that it is necessary to clear up whether the mechanism of the formation of extended-chain crystals at atmospheric pressure and at high pressures is the same or not. Under high pressure, extended and folded-chain crystallization are considered to be rival processes from the kinetical point of view. Meanwhile, little is known about the mechanism of the formation of extended-chain crystals at atmospheric pressure, because the kinetics of extended-chain crystals has not been fully investigated.In this study the crystallization rates of three kinds of fractionated linear polyethylenes with different molecular weights were measured in order to get information about the mechanism of the formation of extended-chain crystals at atmoPolymer J., Vol. 11, No.3, 1979 spheric pressure, and the growth mode of extendedchain crystallization was compared with that at high pressures.We also present a theory of the growth rates of m-times folded-chain crystals with finite molecular weight for the purpose of explaining the transition in crystallization rates observed in this experiment. EXPERIMENTALThe materials used in this work were the viscosity-average molecular weights M. =4300, 17300. and 150000 of linear polyethylene fractions (Mw! M, was in the range 1.2-1.3) that were obtained from Sholex 6000C by the column fractionation method.We studied crystallization kinetics by using dilatometric techniques. The materials which were originally in the form of powder were melted and cooled to room temperature under vacuum. About 300 mg of the materials were put into the dilatometer, whose diameter was 0.8 mm; after being filled with fresh mercury, the dilatometer was evacuated overnight. The dilatometer was p...

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“…In those investigations with PEO, the untypical thermal behavior is known as the integral folding (IF) and nonintegral folding (NIF) structure. Kovacs et al pioneered this issue and studied the relationship between linear growth rate, single crystal morphology and the IF structure [41][42][43][44][45]. Cheng et al demonstrated the existence of the NIF structure using time resolved small-angle X-ray scattering (SAXS) [46][47][48][49][50][51][52][53][54][55][56].…”

Section: Dsc Measurements Of Pdmsb Homopolymersmentioning

confidence: 99%

Immobilization of Poly(1,1-dimethysilacyclobutane) by Means of Anionic Ring-Opening Polymerization on Organic Nanoparticles and Reinvestigation of Crystallization

Gallei

Elbert

et al. 2013

Polymers

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Abstract:In the present study, the synthesis of poly(1,1-dimethylsilacyclobutane) (PDMSB) by anionic ring opening polymerization (ROP) is reinvestigated, leading to narrowly distributed molar masses (polydispersities 1.04-1.15) in the range of 2.3 to 60 kg mol −1. Investigations of thermal behavior for low molar mass PDMSB revealed an untypical multiple peaks melting phenomenon, which at first glance, seems to be of the same origin as low molar mass poly(ethylene oxide)s. Small angle X-ray scattering (SAXS) and X-ray diffraction (XRD) measurements are done, proving the fast crystallization and subsequent recrystallization for investigated low molar mass samples. Synthetic attempts are expanded to the surface-initiated anionic ROP of 1,1-dimethylsilacyclobutane (DMSB) monomer from the surface of cross-linked polystyrene (PS) nanoparticles. Novel polycarbosilanes (PCS)/organic core/shell particles are obtained, which are investigated by using transmission electron microscopy (TEM) and dynamic light scattering (DLS) experiments. First insights into the crystallization behavior OPEN ACCESSPolymers 2013, 5 285 of surface-attached PDMSB chains reveal that crystallization seems to be hindered.

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Crystallization and fusion of self-seeded polymers

Cited by 201 publications

References 12 publications

Fine fibrillar and rectangular/hexagonal ordered grains of poly(3-hexyl thiophene) and poly(ethylene glycol) developed by seeding technique

Fine fibrillar and rectangular/hexagonal ordered grains of poly(3-hexyl thiophene) and poly(ethylene glycol) developed by seeding technique

Transition in Crystallization Rates of Fractionated Polyethylenes

Immobilization of Poly(1,1-dimethysilacyclobutane) by Means of Anionic Ring-Opening Polymerization on Organic Nanoparticles and Reinvestigation of Crystallization

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