TY - THES

T1 - Spherulite Growth and Crystallization Kinetics of Polypropylene and its blends

AU - Jacobs, Anna

N1 - no embargo

PY - 2024

Y1 - 2024

N2 - Crystallization kinetics in polymers is a very important topic in the field of plastics technology since crystallization is correlated with the properties of polymers. Crystallization deals with the orientation and arrangement of polymer crystals in their microstructure and this in turn dictates the degree of crystallinity of polymer affecting their thermal properties, optical properties, mechanical properties and the general application of polymers. In terms of applications, polypropylene (PP) is one of the most utilized polymers in the plastic industry hence it is imperative to recycle them and maintain them in the circular economy loop. Blending of Polypropylene is a sustainable and material efficient way of polymer recycling and to successfully engineer blended recycled PP, it is important to understand the crystallization kinetics of individual types of polypropylene and their blends. In this work, crystallization growth kinetics of the different types of polypropylenes and their blends were investigated via two distinct routes using isothermal analysis. Both Differential Scanning Calorimetry and Polarized Light Optical Microscopy using a Heating stage at various isothermal crystallization temperatures were employed to investigate the nucleation rate, growth rate and overall crystallization kinetics of polypropylene and its blends. In analysis the results gained from the experiments, the Avrami´s Law which is the basis for understanding crystallization kinetics of polymers was used in evaluating the growth rate of Polypropylene Homo, Polypropylene Block, and Polypropylene Random polymers, as well as blends consisting of Polypropylene Random and Block, Polypropylene Homo and Random and Polypropylene Homo and Block types. This was done to investigate and understand the effects the samples had on each other in terms of crystallization kinetics. The Avrami numbers and exponentials were used in the prediction of nucleation rate and crystal geometry of PP and its blends. The obtained values were between 2 and 4 which meant the geometry was spheres or disc-like. The nucleation constants and pre-exponential constants obtained from Lauritzen-Hoffman analysis using both PLOM and DSC were compared to each other and with literature values to help identify the similarities and differences between them. Based on the results, different types of PP especially Polypropylene Block copolymer and Polypropylene Homopolymer can be blended to obtain a single interpenetrating phase with no obvious separation and may undergo co-crystallization during processing for recycling.

AB - Crystallization kinetics in polymers is a very important topic in the field of plastics technology since crystallization is correlated with the properties of polymers. Crystallization deals with the orientation and arrangement of polymer crystals in their microstructure and this in turn dictates the degree of crystallinity of polymer affecting their thermal properties, optical properties, mechanical properties and the general application of polymers. In terms of applications, polypropylene (PP) is one of the most utilized polymers in the plastic industry hence it is imperative to recycle them and maintain them in the circular economy loop. Blending of Polypropylene is a sustainable and material efficient way of polymer recycling and to successfully engineer blended recycled PP, it is important to understand the crystallization kinetics of individual types of polypropylene and their blends. In this work, crystallization growth kinetics of the different types of polypropylenes and their blends were investigated via two distinct routes using isothermal analysis. Both Differential Scanning Calorimetry and Polarized Light Optical Microscopy using a Heating stage at various isothermal crystallization temperatures were employed to investigate the nucleation rate, growth rate and overall crystallization kinetics of polypropylene and its blends. In analysis the results gained from the experiments, the Avrami´s Law which is the basis for understanding crystallization kinetics of polymers was used in evaluating the growth rate of Polypropylene Homo, Polypropylene Block, and Polypropylene Random polymers, as well as blends consisting of Polypropylene Random and Block, Polypropylene Homo and Random and Polypropylene Homo and Block types. This was done to investigate and understand the effects the samples had on each other in terms of crystallization kinetics. The Avrami numbers and exponentials were used in the prediction of nucleation rate and crystal geometry of PP and its blends. The obtained values were between 2 and 4 which meant the geometry was spheres or disc-like. The nucleation constants and pre-exponential constants obtained from Lauritzen-Hoffman analysis using both PLOM and DSC were compared to each other and with literature values to help identify the similarities and differences between them. Based on the results, different types of PP especially Polypropylene Block copolymer and Polypropylene Homopolymer can be blended to obtain a single interpenetrating phase with no obvious separation and may undergo co-crystallization during processing for recycling.

KW - Polypropylene

KW - Polypropylene blends

KW - Crystallization Kinetics

KW - Relative Crystallinity

KW - Avrami exponent

KW - Avrami number

KW - Isothermal Crystallization

KW - Lauritzen-Hoffman equation

KW - Activation energy

KW - Polypropylen

KW - Polypropylenmischungen

KW - Kristallisationskinetik

KW - Relative Kristallinität

KW - Avrami-Exponent

KW - Avrami-Nummer

KW - Isotherme Kristallisation

KW - Lauritzen-Hoffman-Gleichung

KW - Aktivierungsenergie

U2 - 10.34901/mul.pub.2024.225

DO - 10.34901/mul.pub.2024.225

M3 - Master's Thesis

ER -