Titel Deelnemers "Korte inhoud" "Features on the development and stability of phase morphology in complex multicomponent polymeric systems: Main focus on processing aspects" "Gabriël Groeninckx" "© 2016 John Wiley & Sons, Inc. The present chapter discusses crucial aspects of the phase morphologies developed in polymer-based multicomponent systems. Focus is on complex phase morphology as the co-continuous one in binary and ternary thermoplastic blends both uncompatible and reactively compatibilized. Away from reviewing all the work reported in literature, some important and recent developments on the effects of the processing parameters used to generate these morphologies during melt compounding process are highlighted. New approaches of compatibilization as the use of organoclay are discussed, too. The review includes also a significant part on the various routes of intermediate chemistry involved in the development of multicomponent polymer blends." "Crystallization, micro- and nano-structure, and melting behavior of polymer blends" "Gabriël Groeninckx" "© Springer Science+Business Media Dordrecht 2014. All rights reserved. When the melt of a crystalline polymer is cooled to a temperature between the glass transition and the equilibrium melting point, the thermodynamic requirement for crystallization is fulfilled. In a crystallizable miscible blend, however, the presence of an amorphous component, either thermoplastic or thermosetting, can either increase or decrease the tendency to crystallize depending on the effect of the composition of the blend on its glass transition and on the equilibrium melting point of the crystallizable component and also on the curing extent and conditions in case of thermosetting amorphous component. The type of segregation of the amorphous component, influenced by parameters such as crystallization conditions, chain microstructure, molecular weight, blend composition, and curing extent, determines to a large extent the crystalline morphology of a crystallizable binary blend. Separate crystallization, concurrent crystallization, or cocrystallization can occur in a blend of two crystallizable components. The spherulite growth of the crystallizable component in miscible blends is influenced by the type and molecular weight of the amorphous component, the former affecting the intermolecular interactions between both components and the latter the diffusion of the amorphous component. The blend composition, the crystallization conditions, the degree of miscibility and the mobility of both blend components, and the nucleation activity of the amorphous component are important factors with respect to the crystallization kinetics. The melting behavior of crystallizable miscible blends often reveals multiple DSC endotherms, which can be ascribed to recrystallization, secondary crystallization, or liquid-liquid phase separation. Complex crystallization behavior develops in miscible blends containing a crystallizable thermoplastic and a curable thermosetting component. That depends on the temperature and time of curing the thermosetting and also on whether crystallization is initiated before, during, or after the curing process. For the discussion of the crystallization and melting behavior in immiscible polymer blends, a division into three main classes is proposed. In blends with a crystallizable matrix and an amorphous dispersed phase, both the nucleation behavior and the spherulite growth rate of the matrix can be affected. Nucleation of the matrix always remains heterogeneous; however, the amount of nuclei can be altered due to migration of heterogeneous nuclei during melt-mixing. Blending can also influence the spherulite growth rate of the matrix. During their growth, the spherulites can have to reject, occlude, or deform the dispersed droplets. In general, the major influence of blending is a change in the spherulite size and semicrystalline morphology of the matrix. A completely different behavior is reported for blends in which the crystallizable phase is dispersed. Fractionated crystallization of the dispersed droplets, associated with different degrees of undercooling and types of nuclei, is the rule. The most important reason is a lack of primary heterogeneous nuclei within each crystallizable droplet. An important consequence of fractionated crystallization may be a drastic reduction in the degree of crystallinity. When two crystallizable components are blended, a more complex behavior due to the influence of both phases on each other is expected. In general, the discussion for matrix crystallization and droplet crystallization can be combined. However, crystallization of one of the phases can sometimes directly induce crystallization in the second phase. As a consequence, the discussion of blends of this type has been subdivided with respect to the physical state of the second phase during crystallization. The special case of “coincident crystallization,” in which the two phases crystallize at the same time, is discussed. Finally, the effect of compatibilization of crystalline/crystalline polymer blends is briefly reviewed. A new section has been added, introduced to deal with crystallization phenomena in immiscible polymer blends containing nanoparticles. Recent reports, although few, discuss the effect of nanoparticles on crystallization and melting in immiscible polymer blends." "Treatment of water-induced curvature of the DSC heat flow rate signal Applied to fractionated nucleation of polypropylene dispersed in water" "Gabriël Groeninckx, Vincent Mathot" "In samples containing a volatile phase, quite often the evaporation of the volatile substance during heating causes appreciable curvature of the DSC heat flow rate signal as function of temperature, making it difficult to quantify thermal transitions and reorganization phenomena occurring in the same temperature range. This is the case for e.g. polyamide-water, polyamide-alcohol, and polypropylene-water systems, thus complicating the study of polymer crystallization, melting, and metastability by DSC. In this study, maleic anhydride-grafted polypropylene particles of sub-micrometer diameters dispersed in water are discussed. These samples show, upon cooling from the melt, different degrees of extra supercooling in crystallization and several phenomena in the subsequent heating, like reorganization of a crystalline phase into another one, perfecting of crystallites, and melting. All these phenomena are difficult to analyze quantitatively due to the mentioned curvature of the DSC trace. In this article two methods, the ""Reference"" and ""Extrapolation from the melt"" methods, are described to correct for the influence of evaporation on the DSC heat flow rate signal and for the baseline signal, enabling the discussion of the transitions by way of the excess heat flow rate as function of temperature. © 2011 Akadémiai Kiadó, Budapest, Hungary." "Quantitative evaluation of fractionated and homogeneous nucleation of polydisperse distributions of water-dispersed maleic anhydride-grafted-polypropylene micro- and nano-sized droplets" "Gabriël Groeninckx, Vincent Mathot" "The nucleation processes in waterborne Maleic Anhydride-grafted-Polypropylene micro- and nano-droplet suspensions have been studied. Compared to a previous report on this topic, an extended set of samples in combination with improved particle size distribution data of the samples have been used, which are both essential for the advancement of the analysis. Self-nucleation was utilized to ensure that the observed lowered fractionated crystallization (peak) temperatures - down to the extremely low value of 34 °C - are due to a lack of seeds in the droplets, which seeds for the polypropylene system used are normally active at the heterogeneous crystallization temperature of approximately 110 °C. An unusual self-nucleation behavior was observed in case of samples having a large amount of small droplets, requiring an extremely low self-nucleation temperature in order to suppress all crystallization at the lowest temperatures. Such behavior was observed for block copolymers but has not been reported so far for droplets dispersed in an immiscible matrix, polymeric or not. Another unusual behavior was observed for some self-nucleation temperatures for which apparently two different populations of self-nuclei are created that are suggestive of the α1 and α2 crystal structures of isotactic polypropylene. Next, two new methods are presented to quantify various crucial parameters of the nucleation process: one estimates the density of nucleants acting at different temperatures from the combination of dynamic DSC data and particle size distribution (PSD) data, and the other one focuses on the nature of the nucleation mechanism using both isothermal DSC data and PSD data, quantifying the nucleation rate at different temperatures. For the present MA-g-PP dispersions the latter method leads to the conclusion that the lowest crystallization temperatures reflect sporadic nucleation, probably by way of volume (homogeneous) nucleation. In the field of polymer crystallization, polymer dispersions are usually treated as being monodisperse, even though that is rarely the case. This simplification is inadequate for the present calculations, which is why polydispersity has been taken into account in order to quantify the density of nucleants and the kinetics of nucleation. Though in the present study DSC data are used for the calculations, the methods developed can be easily adapted to other techniques like time-resolved X-ray, rheometry and dilatometry. © 2009 Elsevier Ltd. All rights reserved." "Influence of compatibilizer precursor structure on the phase distribution of low density poly(ethylene) in a poly(ethylene terephthalate) matrix" "Gabriël Groeninckx" "In attempt to enhance the compatibility of PET/LDPE blends by using a proper functionalized polymer as third component, diethyl maleate (DEM)-functionalized ultralow density poly(ethylene) (ULDPE-g-DEM) and styrene-/j-(ethylene-co-1 -butene)-b-styrene triblock copolymer (SEBS-g-DEM) were prepared by radical functionalization in the melt. Immiscible PET/LDPE blends having compositions of 70/30 and 80/20 by weight were then extruded in the presence of 1-10% by weight of ULDPE-g-DEM and SEBS-g-DEM as compatibilizer precursors and ZnO (0.3% by weight) as transesterification catalyst. In both cases, evidences about the occurring of compatibilization between the two immiscible phases, thanks to the studied reactive processes, were obtained. Moreover, the phase distribution and particle size of blends were deeply investigated. Completely different kinds of phase morphology were achieved, as ULDPE-g-DEM stabilized a dispersed phase morphology, whereas SEBS-g-DEM favored the development of a cocontinuous phase morphology. The observed differences are tentatively explained on the basis of reactivity and physical features of polymers. ©2008 Society of Plastics Engineers." "Features, questions and future challenges in layered silicates clay nanocomposites with semicrystalline polymer matrices" "Gabriël Groeninckx" "The present features review article discusses the crystallisation of the polymer matrix when containing silicate layers. The accent is put on nylons (polyamides) and polyethylene oxide) as typical hydrophilic polymers and, poly(propylene) from the hydrophobic group. The effects of the clay, either intercalated or exfoliated, on the crystallisation behaviour of the matrix are highlighted. In addition, the crucial aspects of the semicrystalline morphology of the matrix in the presence of the clay platelets are also debated. The overall crystallisation rate is reported to slow down for most of the crystallisable polymer matrices on account of a retarding growth effect exerted by the clay platelets. As far as the location of the exfoliated clay platelets in the polymer matrix is concerned, they are assumed to be rejected from the crystalline phase in the interspherulitic space. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA."