Can rheometry measure crystallization kinetics? A comparative study using block copolymers

Kelarakis, Antonios; Mai, Sebastian; Booth, Colin; Ryan, Anthony J.

doi:10.1016/j.polymer.2005.01.068

Cited by 18 publications

(12 citation statements)

References 22 publications

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“…The spherical, lamellar and cylindrical micro-domains formed by microphase separation and/or the forgoing crystallization conne the crystallization of the second crystalline component. It should be noted that, although the morphology of the crystallized block copolymer is the same before and aer conned crystallization, the properties, such as optical, mechanical, rheological and biodegradable properties, 69,[86][87][88] are indeed altered due to the crystallization.…”

Section: Conned Crystallization Of Bbcpsmentioning

confidence: 99%

Structures and morphologies of biocompatible and biodegradable block copolymers

Huang

Jiang

2014

RSC Adv.

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Section: Conned Crystallization Of Bbcpsmentioning

confidence: 99%

Structures and morphologies of biocompatible and biodegradable block copolymers

Huang

Jiang

2014

RSC Adv.

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“…However, these experiments considered only single component thermoplastics, and did not consider how the relationships might be changed by nanofillers. Furthermore, the experimental endeavor suffers from uncertainties because of the difficulty in maintaining identical thermal histories, geometries and surface properties between the rheological measurement and that of the crystallinity [32–35]. Recently, Kotula and coworkers developed a hybrid instrument – a rheo-Raman microscope - that simultaneously measures the kinetics of crystallinity via Raman spectroscopy and measures the kinetics of moduli growth through mechanical rheometry [36].…”

Section: Introductionmentioning

confidence: 99%

Effect of cellulose nanocrystals on crystallization kinetics of polycaprolactone as probed by Rheo-Raman

Roy

Kotula

Natarajan

et al. 2018

Polymer

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The development of biocompatible polymer nano-composites that enhance mechanical properties while maintaining thermoplastic processability is a longstanding goal in sustainable materials. When the matrix is semi-crystalline, the nanoparticles may induce significant changes to crystallization kinetics and morphology due to their ability to act as nucleating agents. To fully model this behavior in a process line, an understanding of the relationship between crystallinity and modulus is required. Here, we introduce a scalable model system consisting of surface-compatibilized cellulose nanocrystals (CNC) dispersed into poly(ε-caprolactone) (PCL) and study the effects of nanoparticle concentration on isothermal crystallization kinetics. The dispersion is accomplished by exchange of the Na+ of sulfated cellulose nanocrystals by tetra-butyl ammonium cations (Bu4N+) followed by melt mixing via twin-screw extrusion. Crystallization kinetics are measured through the recently developed rheo-Raman instrument which extracts the relationship between the growth of the transient mechanical modulus and that of crystallinity. With extrusion and increasing CNC content, we find the expected enhancement of crystallization rate, but we moreover find a significant change in the relative kinetics of increase in modulus versus crystallinity. We analyze this via generalized effective medium theory which allows computation of a critical percolation threshold ξc and discuss the results in terms of a change in nucleation density and a change in the anisotropy of crystallization.

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“…Khanna1 used a simple equation to relate the storage modulus to the crystallized volume ϕ( t ): where G

_{′}^{0}

and G

_{′}^{∞}

are initial and final plateau of storage modulus, respectively. By studying a range of polymers, Kelarakis et al2 found that the rates of crystallization from calorimetry and rheometry cannot be described by such a simple relation. The authors showed that at low crystallite volume fraction, the storage modulus of some polymers is directly proportional to the degree of crystallinity but at high crystalline volume fractions, the proportionality is lost.…”

Section: Introductionmentioning

confidence: 99%

Rheological properties of crystallizing polylactide: Detection of induction time and modeling the evolving structure and properties

Yuryev

Wood‐Adams

2010

J Polym Sci B Polym Phys

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Linear viscoelastic properties of polymer melts are highly sensitive to any structural changes, including molecular weight changes and the formation and growth of crystallites. Here, we make use of this sensitivity to study the homogeneous crystallization of polylactide. As this polymer is rather quickly susceptible to thermal degradation even at moderate temperatures, it is essentially impossible to study homogeneous crystallization in the absence of degradation. Thus, the evolution of complex viscosity of a polylactide due to thermal degradation in the absence of crystallization was studied. A simple empirical model is used to characterize the variation of complex viscosity due to thermal degradation and to determine the induction time of homogeneous crystallization at wide range of degrees of supercooling. Next, the evolution of complex viscosity due to crystallization was measured at several temperatures. Based on the results, a phenomenological model describing the viscosity evolution during homogeneous crystallization is proposed and validated. Finally, the linear viscoselastic data in the early stages of crystallization are shown to be consistent with gelation due to the formation of a network of tie molecules between spherulites. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 812-822, 2010

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Can rheometry measure crystallization kinetics? A comparative study using block copolymers

Cited by 18 publications

References 22 publications

Structures and morphologies of biocompatible and biodegradable block copolymers

Structures and morphologies of biocompatible and biodegradable block copolymers

Effect of cellulose nanocrystals on crystallization kinetics of polycaprolactone as probed by Rheo-Raman

Rheological properties of crystallizing polylactide: Detection of induction time and modeling the evolving structure and properties

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