A new self‐nucleation phenomenon and its application to the growing of polymer crystals from solution

Blundell, D.J.; Keller, A.; Kovacs, A. J.

doi:10.1002/pol.1966.110040709

Cited by 420 publications

(231 citation statements)

References 7 publications

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“…planes in each sector might be regularly staggered in a 10 It is noteworthy that this feature is exhibited by the monolayered crystals from both filtered and unfiltered preparations. In short.…”

Section: Crystals Formed At Tc= 140°c (I) Preliminary Commentsmentioning

confidence: 87%

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The formation of curved polymer crystals: Polyoxymethylene

Khoury¹,

Barnes²

1974

J. RES. NATL. BUR. STAN. SECT. A.

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An opti cal and electron microsco pi cal study is PJese nte d of th e habits exhibited by chain·folded polyoxymethylene crys tals grow n from hot 0.02 percent solutions of th e polymer in orthodi chlorobe nzene when th ese solutions are cooled to temperatures (Te) between 140 and 80°C inclus ive . In co ntras t with the lam ellar crystals formed in the Te= 140 and 120°C preparations, whi ch crystals were six-sectored and nearly planar, the crystals formed below Tc= 120°C exhibited multisectored dendriti c habits and were all the more pronouncedly curved the lower the temperature at whic h they grew. The most pronouncedly c urved crystals which were observed were hollow bow! shaped dendrites having a radiu s of c urvature of -2 /-tm which were formed in th e 80°C preparations. The possible origins of why the lam ellar crys tals of polyoxymethylene were all the more pronouncedly curved th e lower the cryst allization temperature are co nside red in th e light of conjectures which hav e been previously advanced concerning th e formation of curved crystals of poly(4-methylpente ne-l). Among the features which are di sc ussed is th e role played by th e bulkiness of the chain folds.

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Section: Crystals Formed At Tc= 140°c (I) Preliminary Commentsmentioning

confidence: 87%

“…Table 1 summarizes the crystallization conditions adopted in this study. This crystallization procedure is akin in principle to the self-seeding procedure used by Blundell et al in the case of polyethylene [10]. All the bath temperatures"were controlled to within ± 0.1 °C.…”

Section: Materials and Preparation Methodsmentioning

confidence: 99%

The formation of curved polymer crystals: Polyoxymethylene

Khoury¹,

Barnes²

1974

J. RES. NATL. BUR. STAN. SECT. A.

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“…In order to confirm the origin behind fractionated crystallization, the following self-nucleation procedure 18 is applied in the investigation: erasing thermal history and creating a initial standard state. The samples were first heated to 250 C and kept there for 5 min.…”

Section: Differential Scanning Calorimetry (Dsc)mentioning

confidence: 99%

Crystallization Behaviors of Polypropylene/Polyamide-6 Blends Modified by a Maleated Thermoplastic Elastomer

Liu

Xie²,

Zhang

et al. 2006

Polym J

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ABSTRACT:In this paper, with the maleated thermoplastic elastomer (TPEg) as a compatibilizer of polypropylene (PP)/polyamide-6 (PA6) blends, the effects of interfacial compatibilization on the crystallization behaviors of the blends were investigated by differential scanning calorimetry (DSC). Compared with the binary blend, the addition of TPEg significantly affected the crystallization behaviors of the individual component in the blends, especially those of PA6. The presence of TPEg weakened the nucleating role of the PA6 on the PP matrix. The increasing concentration of the compatibilizer caused a decrease in crystallization temperature (T c ) and crystallization enthalpy (ÁH c ) associated with PA6. When TPEg amount was added up to 24 wt %, the crystallization of PA6 at its bulk T c was almost completely suppressed and the complete concurrent crystallization of PA6 and PP matrix took place. In the case of PP/PA6/TPEg blend containing 24 wt % TPEg, it was found that the disappearance of bulk PA6 crystallization peak was independent of the cooling rate and annealing time, but can be introduced by self-nucleation experiments. The above fractionated crystallization phenomenon was attributed to the reduction in PA6 particle size due to compatibilization role of added TPEg, which leads to the lack of the active heterogeneities. The crystalline morphologies under isothermal conditions were also observed by polarized optical microscopy (POM). [DOI 10.1295/polymj.38.21] KEY WORDS Polypropylene (PP) / Polyamide-6 / Crystallization / Compatibilization / Morphology / Compatibilization strongly affects the blend phase morphology and as such, it may also influence the crystallization behaviors of the blend. Both morphology and crystallization behaviors are closely related with the final properties of the blend, a profound understanding of the crystallization behavior and the resulting semicrystalline structure in polymer blends is necessary for effective manipulation and control of their properties from both scientific and industrial point of view. However, the general influence of a compatibilizer on the crystallization behavior of an immiscible polymer blend system is still far from being well understood, especially for crystalline polymer/crystalline polymer.

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“…[35] Due to very slow PFDMS crystallization, and in order to realize its crystallization at as high temperatures T c as possible, the so-called self-seeding technique was applied for the preparation of isothermally crystallized samples. [32,36] This technique is known to tremendously reduce the time required for nucleation, especially for slowly nucleating polymers at moderate super-coolings. For self-seeding crystallization, a pre-crystallized sample is initially needed which can be prepared by long-term isothermal annealing of the material.…”

Section: Introductionmentioning

confidence: 99%

Equilibrium Melting Temperature of Poly(ferrocenyl dimethylsilane) in Homopolymers and Lamellar Diblock Copolymers with Polystyrene

Bellas

Jungnickel

et al. 2010

Macro Chemistry & Physics

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The equilibrium melting temperature, Tm,0, of poly(ferrocenyl dimethylsilane) (PFDMS) is re‐investigated using two PFDMS homopolymers and a PS‐b‐PFDMS copolymer (PS: polystyrene). The melting temperatures of samples crystallized at different crystallization temperatures, Tc, were found to depend in a nonlinear fashion on Tc. Consequently, the Hoffmann–Weeks approach fails in determining Tm,0. The more reliable Gibbs–Thomson approach results in a Tm,0 = (215 ± 11) °C for the PFDMS homopolymers, and a Tm,0 = (179 ± 5) °C for the PFDMS microphases in the lamellar PS‐b‐PFDMS diblock copolymer.magnified image

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A new self‐nucleation phenomenon and its application to the growing of polymer crystals from solution

Cited by 420 publications

References 7 publications

The formation of curved polymer crystals: Polyoxymethylene

The formation of curved polymer crystals: Polyoxymethylene

Crystallization Behaviors of Polypropylene/Polyamide-6 Blends Modified by a Maleated Thermoplastic Elastomer

Equilibrium Melting Temperature of Poly(ferrocenyl dimethylsilane) in Homopolymers and Lamellar Diblock Copolymers with Polystyrene

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