Non-isothermal crystallization kinetics and its effect on the mechanical properties of homopolymer isotactic polypropylene

Nouira, S.; Hassine, Tarek; Fitoussi, Joseph; Shirinbayan, Mohammadali; Gamaoun, Fehmi; Tcharkhtchi, Abbas

doi:10.1007/s10965-021-02869-4

Cited by 10 publications

(4 citation statements)

References 48 publications

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“…However, individual examples of the failure are not yet proof of the faulty nature of the method. One can also find examples where the Jeziorny method yields the Avrami exponents that are reasonably consistent with the ones estimated by the Ozawa method [ 8 , 9 , 10 ]. A proper way to understand the faults of the Jeziorny method is via its theoretical analysis.…”

Section: Introductionsupporting

confidence: 64%

Jeziorny Method Should Be Avoided in Avrami Analysis of Nonisothermal Crystallization

Vyazovkin

2022

Polymers

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The Jeziorny method treats nonisothermal crystallization data by replacing the variable temperature (T) values with the corresponding values of time and substituting them into the isothermal Avrami plot, ln[−ln(1 − α)] vs. lnt. For isothermal data, the slope of this plot is the Avrami exponent, n and the intercept is the rate constant, kA. This does not hold for nonisothermal data. Theoretical analysis suggests that in the case of nonisothermal data the intercept cannot be interpreted as kA, and its “correction” by dividing over the temperature change rate β is devoid of any meaning. In turn, the slope cannot be interpreted as n. It is demonstrated that the slope changes with time and its value depends not only on n but also on the temperature, temperature range, and activation energy of crystallization. Generally, the value of the slope is likely to markedly exceed the n value. The theoretical results are confirmed by analysis of simulated data. Overall, the Jeziorny method as well as other techniques that substitute nonisothermal data into the isothermal Avrami plot should be avoided as invalid and useless for any reasonable Avrami analysis. It is noted that n can be estimated from the nonlinear plot of ln[−ln(1 − α)] vs. T.

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Section: Introductionsupporting

confidence: 64%

Jeziorny Method Should Be Avoided in Avrami Analysis of Nonisothermal Crystallization

Vyazovkin

2022

Polymers

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“…Specifically, the response surface methodology (RSM) allows for the obtainment of optimal conditions in many areas of knowledge. In this context, the literature exhibits extensive applications of optimization processes, for example, in the search of the best conditions in the non-isothermal crystallization of isotactic Polypropylene (iPP) [23], in the optimization of annealed HSLA Steel [24], in the search of eco-friendly flame retardant finish for cotton fabric [25], and in the optimization of organophosphorus fire-resistant finish for cotton fabric [26].…”

Section: Introductionmentioning

confidence: 99%

Optimization of Encapsulation by Ionic Gelation Technique of Cryoconcentrated Solution: A Response Surface Methodology and Evaluation of Physicochemical Characteristics Study

2022

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The objective of this study was to evaluate the optimal conditions to encapsulate cryoconcentrate solutions via ionic gelation technique. Hydrogel beads were prepared using alginate (1%, 2% and 3% (w/w)) and cornstarch (0.5%, 1% and 2% (w/w)). Later, a sucrose/acid gallic solution was concentrated through block freeze concentration (BFC) at three cycles. Thus, each solution was a mixture with the respective combination of alginate/cornstarch. The final solution was added drop-wise on a CaCl2 solution, allowing the formation of calcium alginate-cornstarch hydrogel beads filled with sucrose/acid gallic solution or cryoconcentrated solution. The results showed that alginate at 2% (w/w) and cornstarch at 2% (w/w) had the best efficiency to encapsulate any solution, with values close to 63.3%, 90.2%, 97.7%, and 75.1%, and particle sizes of approximately 3.09, 2.82, 2.73, and 2.64 mm, for initial solution, cycle 1, cycle 2, and cycle 3, respectively. Moreover, all the samples presented spherical shape. Therefore, the appropriate content of alginate and cornstarch allows for increasing the amount of model cryoconcentrated solution inside of the hydrogel beads. Furthermore, the physicochemical and morphological characteristics of hydrogel beads can be focused for future food and/or pharmaceutical applications, utilizing juice or extract concentrated by BFC as the solution encapsulated.

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“…A mono‐composite with a fiber gauge length of 20 mm, was held in a micro‐traction machine, designed and fabricated in PIMM laboratory 23 . The micro traction machine, which was developed in the laboratory, is coupled with the microscope.…”

Section: Methodsmentioning

confidence: 99%

“…A mono-composite with a fiber gauge length of 20 mm, was held in a micro-traction machine, designed and fabricated in PIMM laboratory. 23 The micro traction machine, which was developed in the laboratory, is coupled with the microscope. The machine consists of a frame, an electric motor, a 20 dN force cell, one fixed and one movable jaw, gears, a slide and a ball screw.…”

Section: Single Fiber Tensile Strength Testmentioning

confidence: 99%

Effect of processing conditions on morphology and mechanical damage in glass‐reinforced polypropylene composite

Nouira,

Shirinbayan,

Peixinho

et al. 2024

Polymer Composites

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This study aims to analyze the effect of processing parameters, particularly the cooling rate, on the morphology and mechanical properties of reinforced glass fiber polypropylene (GF‐PP) films. To achieve the objective, a multi‐scale analysis was performed to study the different morphology of neat PP and reinforced PP films obtained by controlling the thermal condition during the fabrication process. Films of PP with a thickness of about 100 μm have been prepared to observe the crystalline microstructure's formation and follow its kinetics on the scale of the spherulites. The same procedure was followed using a single glass fiber to obtain the mono‐composite film of PP by controlling the interface/interphase between the fiber and the matrix. Moreover, the dependence of the damage mechanisms on the spherulite diameters and the mechanical test conditions was established. The deformation mechanisms (intra and inter‐spherulitic damage) were analyzed qualitatively and quantitatively according to the controlled morphologies produced for the polymer and the composite, especially at the level of the transcrystalline phase. The results confirm that the processing parameters affect not only the width of the transcrystalline phase but also the morphology of the fiber‐matrix interface. Furthermore, increasing the thickness of the transcrystalline phase exhibited remarkably higher interfacial shear strength, as demonstrated by the single fiber fragmentation test.Highlights Impact of cooling rate on morphology and mechanical properties of glass fiber polypropylene (GF‐PP). Multi‐scale analysis to investigate the distinct morphologies of PP and GF‐PP. Deformation mechanism particularly intra and inter‐spherulitic damage. Attention to the impact on the transcrystalline phase and the fiber‐matrix interface. Influence of transcrystalline phase thickness on interfacial strength.

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Non-isothermal crystallization kinetics and its effect on the mechanical properties of homopolymer isotactic polypropylene

Cited by 10 publications

References 48 publications

Jeziorny Method Should Be Avoided in Avrami Analysis of Nonisothermal Crystallization

Jeziorny Method Should Be Avoided in Avrami Analysis of Nonisothermal Crystallization

Optimization of Encapsulation by Ionic Gelation Technique of Cryoconcentrated Solution: A Response Surface Methodology and Evaluation of Physicochemical Characteristics Study

Effect of processing conditions on morphology and mechanical damage in glass‐reinforced polypropylene composite

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