Crystallization kinetics of polymer–diluent mixtures. Influence of benzophenone on the spherulitic growth rate of isotactic polystyrene

Boon, J.; Azcue, J. M.

doi:10.1002/pol.1968.160060508

Cited by 141 publications

(70 citation statements)

References 12 publications

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“…increases from 0.07 to 0.28 with a decrease in chain length. 5 7,5 8 This may suggest that TcmaxfTm changes from 0.84 to 0.56. 4° Further discussion in many other crystalline materials, such as metals, molecular liquids, organic compounds and inorganic materials, will be reported elsewhere.…”

Section: Ratio Of Tcmax!tmmentioning

confidence: 99%

Theoretical Aspect of Crystallization Temperature at Maximum Crystal Growth Rate

Okui

1987

Polym J

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ABSTRACT:The ratio of the temperature at which the nucleation rate or the crystal growth rate is maximum (Tcmax) to the melting temperature (Tm) was predicted theoretically as a function of two parameters: one is the ratio of the activation energy of migration through the nucleus-melt interface to the heat of fusion and the other is the ratio of the mean surface energy of a mole of repeat unit to the heat of fusion. The ratios of TcmaxiTm were evaluated from the above two parameters.KEY It has been well-known that a ratio of crystallization temperature at which crystallization rate is maximum (Tcmax) to melting temperature (Tm) is nearly a constant in most crystalline polymers 30 -32 in analogous with an empirical relationship between melting temperature and glass transition temperature (T 8 ). 33 · 34 In an extensive study on the relationship between Tm and Tg for 138 polymers, the ratio Tg/Tm varies widely. 35 There is no sharp division between the ratios of T 8 /Tm observed for symmetrical and that for unsymmetrical polymers: about 80% of polymers have values in the range 0.5--0.8. The relation of TcmaxfTm is found not only in polymers but also in most metals 36 and organic compounds.37·38In a crystallization theory/· 36 the temperature dependence of homogeneous crystal nucleation rate and 'that of crystal growth rate from melt are generally described with the following exponential equation, where the crystal growth is based on the formation of a two-dimensional surface nucleus.(1) G=G 0 exp( -AE/RT-K2Tm/RTAT) (2)where I and G are the rate of nucleation and the rate of-crystal growth, respectively. AE is the energy of activation for migration through the nucleus-melt interface. K 1 and K2 are a function of the free energy of the interface, the heat of fusion and the shape of nucleus or crystal. AT is the degree of supercooling (Tm-T), where T is the crystallization temperature. / 0 and G 0 are constant and R is the gas constant.If / 0 , G 0 , AE, and K (Kl and K2) are assumed to be independent of temperature, the crystallization temperature (Tcmax) at the maximum rate of nucleation Umax) or that of crystal growth (Gmax) is observed by equating to zero the derivative of eq 1 or 2 with respect to the temperature. The relations so found are for the maximum nucleation rate: TcmaxfTm=(D 2 -D+ l)/(D 2 +D+ 1) (3)/max=/oexp 1309

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Section: Ratio Of Tcmax!tmmentioning

confidence: 99%

Theoretical Aspect of Crystallization Temperature at Maximum Crystal Growth Rate

Okui

1987

Polym J

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“…6 At low concentrations, these materials can aid processing by increasing the crystal growth rate. 4,7 The addition of fillers can affect crystallization in a variety of ways, depending on the surface area of the filler particles and the interaction between the filler and the polymer. 8 -11 Filler particles with low surface areas increase the crystallization rate by acting as nucleation agents, 10 whereas particles with high surface areas retard crystallization through increased adsorption of polymer.…”

Section: Introductionmentioning

confidence: 99%

Crystallization of tethered polyethylene in confined geometries

Weimann

Hajduk

Chu

et al. 1999

J. Polym. Sci. B Polym. Phys.

105

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“…14 HIGHLIGHT blending. 82,103 Since the T g 's of the components are almost equal, and T c (1) is far from these T g 's, the deceleration is mainly due to change of the entropic conditions. 82 It has been shown above that the transition from regime I to regime III (i.e., regime II) is linked with the development of composition inhomogeneities, which in their turn unveil among others by distinct nonlinear spherulite growth.…”

Section: Crystallization and Growth Of Pvdfmentioning

confidence: 99%

Crystallization kinetical and morphological peculiarities in binary crystalline/crystalline polymer blends

Liu

Jungnickel

2007

J Polym Sci B Polym Phys

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A survey is presented on the crystallization kinetics and the morphology of miscible crystalline/crystalline polymer blends. There are only few corresponding systems. In them, however, a number of strange kinetic and structural phenomena can be observed: (i) spherulitic crystallization of the components side‐by‐side, (ii) “interpenetrating crystallization,” (iii) “interlocking spherulitic crystallization,” and (iv) “interfilling crystallization.” Cocrystallization is forbidden for crystallographic reasons. The blend partners grow instead in their own lamellar stacks, and mixed lamellar stacks are a seldom and questionable exception. They crystallize also usually stepwise and not simultaneously. Upon step crystallization, the crystallization of the second component is determined by its redistribution with crystallization of the former. Those composition inhomogeneities are an independent issue that arises also with the development of the morphology in crystalline/amorphous blends, and a corresponding survey is yielded, too. The blend poly (vinylidene fluoride)/poly‐β‐hydroxybutyrate is a convenient model system as it can show all of these morphological and kinetic features after suitable thermal treatment. Some of them are demonstrated in the present publication. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1917–1931, 2007

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Crystallization kinetics of polymer–diluent mixtures. Influence of benzophenone on the spherulitic growth rate of isotactic polystyrene

Cited by 141 publications

References 12 publications

Theoretical Aspect of Crystallization Temperature at Maximum Crystal Growth Rate

Theoretical Aspect of Crystallization Temperature at Maximum Crystal Growth Rate

Crystallization of tethered polyethylene in confined geometries

Crystallization kinetical and morphological peculiarities in binary crystalline/crystalline polymer blends

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