Crystallization kinetics of polypropylene composites filled with nano calcium carbonate modified with maleic anhydride

Abstract

The subject of this study was the crystallization behavior and thermal properties of polypropylene (PP)/maleic anhydride (MAH) modified nano calcium carbonate (nano-CaCO 3 ) composites. In this study, 5 wt % nano-CaCO 3 modified with different contents of MAH was filled into a PP matrix. X-ray diffraction and differential scanning calorimetry were used to characterize the crystal morphology and crystallization kinetics of a series of composites. The results demonstrate that the nanoCaCO 3 modified with MAH had an important effect on the thermal and morphological properties of the nanocomposites. The Avrami exponent of the pure PP was an integer, but those of the composites were not integers, but the crystallization rate constant decreased as the content of MAH in the nano-CaCO 3 filler increased in isothermal crystallization. In nonisothermal crystallization, the kinetic parameter F(T) and the degree of crystallinity of pure PP were compared with those of the PP composites filled with nano-CaCO 3 . We suggest that heterogeneous nucleation existed in the PP composites and that the transformation and retention of the b-form crystal into the a-form crystal took place in the composite system and the b-form crystal had a higher nucleation rate and growth process than the a-form crystal in the PP composites.

Isothermal crystallization kinetics and morphology of PP/TiO2 nanocomposites using titanium n‐butoxide precursor

“…Both the induction time and the width of the exotherms increased, indicating progressively slower crystallization rate . These data indicate that longer elapsed times were required to complete the crystallization in the Neat PP and PP/TiO 2 nanocomposites in the isothermal crystallization . PP/TiO 2 b1 and PP/TiO 2 b5 had a significant effect, which showed higher rate of crystallization than pure PP and the samples PP/TiO 2 b2.…”

Impact modification of polypropylene‐based composites using surface‐coated waste rubber crumbs

“…Nevertheless, to improve its mechanical performance, a wide range of materials have been proposed to produce PP‐based composites. Initially, inorganic particles like talc, glass, calcium carbonate, carbon black, and mica were used . Recently, organic fillers such as hemp, flax, cotton, and wood flour attracted a great deal of attention.…”

Nonisothermal crystallization of highly‐filled polyolefin/calcium carbonate composites

“…DSC investigations were used to determine stearic acid influence on the polyolefin‐calcium carbonate composites crystallization behavior. After converting DSC crystallization curves at different cooling rates (Φ = 5, 10, 20, 30°C/min), relative crystallinity as a function of time and temperature was determined . Calculations were based on the following equations: where X t ( t ), X T ( T ), and X t (∞), X T (∞) indicated relative crystallinity at time t and temperature T and at the end of the crystallization process, whereas dH(t)/dt and dH(T)/dT were the heat flow rates.…”

“…To analyze the mechanism of crystallization at its early stage, crystallization kinetics analysis was undertaken by applying Avrami theory modified by Jeziorny . The model of crystallization that was used allowed to determine crystallization kinetics parameters during nonisothermal crystallization after an adequate correction of the crystallization rate: …”

“…In case of highly‐filled composites (that contain between 30 and 50 wt % of the filler) designated for cast film production, the evaluation of crystallization kinetics, especially during primary crystallization, is necessary. Various papers present the application of the modified Avrami theory with regards to nonisothermal crystallization of several polymers . It should be mentioned that only few papers focused on crystallization kinetics behavior of highly‐filled composites .…”