Crystallization kinetics of isotactic polystyrene. I. Spherulitic growth rate

Boon, J.; Challa, G.; Krevelen, D.W. Van

doi:10.1002/pol.1968.160061009

Cited by 101 publications

(60 citation statements)

References 18 publications

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“…:PLLA [9,10], ✷:cis-PIP [11,12], :i-PS [15][16][17], :PESU [18] maximum molecular weight dependence is found in poly(3,3-diethyl oxetane) [27] crystallized at the constant super cooling. The molecular weight dependence of the linear growth rate and the overall crystallization rate of poly(ethylene oxide) (PEO) [25] show a complex behavior.…”

Section: Molecular Weight Dependence Of Crystal Growth Ratementioning

confidence: 99%

Maximum Crystal Growth Rate and Its Corresponding State in Polymeric Materials

Okui

Umemoto

2003

Polymer Crystallization

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Abstract. The temperature dependence of crystal growth rate (G) shows a bell shape with the maximum growth rate G max. The activation energy for the molecular transport in G could be expressed in terms of equation of either Arrhenius or WLF. The G max showed remarkable molecular weight dependence. The plots of G/Gmax against T /Tcmax showed a single master curve without molecular weight dependence. The ratio of Go/Gmax gave a constant value for each polymer. Plots of ln(G/Gmax)/ ln(Go/Gmax) against T /Tcmax for various polymers showed the universal curve. The molecular weight dependence of Gmax was expressed as Gmax ∝ MW α , α was a constant but depending on the morphological features on the crystallization. The value of α was a function of the adsorption mechanism of polymer molecules on the crystal growth front and its diffusion mechanism. The ratio of T cmax/T o m was formulated. Tcmax was also correlated to many other thermodynamic transition temperatures. IntroductionAccording to a classical crystallization theory, a temperature dependence of linear crystal growth rate (G) can be expressed by two exponent factors, such as the molecular transport term (∆E) and the nucleation term (∆F ) [1][2][3]. These two terms have opposing temperature dependence thereby bring about a maximum growth rate (G max ). In fact, many polymeric materials show a bell shape temperature dependence of crystal growth rate, showing the maximum growth rate at T cmax [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. This equation has been applied frequently to data of spherulitic growth rate. Application to the polymer crystallization leads to that the molecular transport term is considerably important in the lower temperature ranges. The transport term can be expressed by either WLF or Arrhenius type. In analyzing the crystallization data in bulk polymers, the WLF expression has been used much familiar than the Arrhenius type, since it has been believed that the former expression fits the data better than the later one. However, the transport term could be sufficiently expressed by the Arrhenius type in polymer crystallization [18][19][20][21]. It is worth to recheck which transport term equation is better describing the temperature dependence of the linear crystal growth rate.On the basis of G max for many crystalline materials, a universal master curve of temperature dependence of crystal growth rate has been proposed by Magill et al. [22,23]. This universal curve comes from a phenomenological basis. The universal master curve is derived from the corresponding state in the growth rate

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Section: Molecular Weight Dependence Of Crystal Growth Ratementioning

confidence: 99%

Maximum Crystal Growth Rate and Its Corresponding State in Polymeric Materials

Okui

Umemoto

2003

Polymer Crystallization

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“…in which C1 and C2 are constant, respectively equal to 4120 cal/mol and 51.6 ~ although this relationship has been used with adjustable parameters [24,25].…”

Section: Temperature Coefficient Of the Overall Crystallization Ratementioning

confidence: 99%

Effect of molecular weight and temperature on the isothermal crystallization of poly(oxetane)

Pérez¹,

Bello²,

Fatou³

1984

Colloid & Polymer Sci

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Poly(oxetane) fractions ranging in number-average molecular weights from 7800 to 157000 have been isothermally crystallized in the temperature range from-50 to 19 ~ using dilatometric and calorimetric techniques. In both cases, reproducible isotherms were obtained with an Avrami exponent equal to three. The crystallization rate against crystallization temperature presents a maximum at -30 ~ The level of crystallinity changes with molecular weight and the influence of this parameter on the rate of crystallization is pronounced. The crystallization temperature coefficient was studied using nucleation theory and it was found an slight increase in the basal interfacial free energy for the lowest molecular weight fraction. For the analysis of the temperature coefficient at the higher undercoolings, different approximations for the free energy of fusion and the transport term have been considered. The conclusion of this analysis is that, independently of these approximations, the obtained temperature coefficients are the same.

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“…24,25 As for PBS, which is one of the flexible polymers, there are few works about its melting behavior. 26 The interpretation of melting endotherms, particularly of the double melting peaks, has been dependent upon researcher and polymer as a sample.…”

Section: Introductionmentioning

confidence: 99%