Gabriel Groeninckx - Academia.edu (original) (raw)

Papers by Gabriel Groeninckx

Research paper thumbnail of Some aspects of vapor-induced crystallization of polycarbonate of bisphenol A

Journal of Polymer Science Part C: Polymer Symposia, 1967

A ~nelhod is presented t'o crystallize yolycarluonale of bispheriol iZ tirider coiist,aiil vapor ... more A ~nelhod is presented t'o crystallize yolycarluonale of bispheriol iZ tirider coiist,aiil vapor pressure of solvents at near ambient t'emperatures. Methylene chloride arid acetone were used as crystallizing liquids. Acetone is more powerful in iiiducing erystalliration but the final degree of crystallinity does not depend on the nature of the solvent.

Research paper thumbnail of Cure kinetics and morphology of blends of epoxy resin with poly (ether ether ketone) containing pendant tertiary butyl groups

Polymer, 2003

The cure kinetics and morphology of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin modified ... more The cure kinetics and morphology of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin modified with a poly (ether ether ketone) based on tertiary butyl hydroquinone (PEEK-T) cured with diamino diphenyl sulphone (DDS) were investigated using differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and dynamic mechanical thermal analysis (DMTA). The results obtained from DSC were applied to autocatalytic and diffusion controlled kinetic models. The reaction mechanism broadly showed autocatalytic behaviour regardless of the presence of PEEK-T. At higher PEEK-T concentration, more diffusion controlled mechanism was observed. The rate of curing reaction decreased with increase in thermoplastic content and also with the lowering of curing temperature. The activation energies of the blends are higher than that of the neat resin. The blends showed a phase separated morphology. The dispersed phase showed a homogeneous particle size distribution. The T g of the neat resin decreased with the decrease in cure temperature. Two T g 's corresponding to the epoxy rich and thermoplastic rich phases were observed in the dynamic mechanical spectrum. The storage modulus of 10 and 20 phr PEEK-T blends are found to be greater than the neat resin.

Research paper thumbnail of Phase morphology and stability of co-continuous (PPE/PS)/PA6 and PS/PA6 blends: effect of rheology and reactive compatibilization

Polymer, 2004

PPE/PS)/PA6 and PS/PA6 blends were prepared by means of melt-extrusion. They were compatibilized ... more PPE/PS)/PA6 and PS/PA6 blends were prepared by means of melt-extrusion. They were compatibilized using the reactive styrene-maleic anhydride copolymer with 2 wt% maleic anhydride (SMA2). The effect of compatibilization on the phase inversion and the stability of the resulting co-continuous blend structures were investigated using scanning electron microscopy, dissolution and extraction experiments. The onset of co-continuity shifted towards lower PA6 concentrations according to the change in blend viscosity ratio. The melting order of the components inside the extruder could result in a change in the observed co-continuity interval in slowly developing phase morphologies. The unmodified co-continuous blends were not stable and did break-up into a droplet/matrix type of morphology upon annealing in the melt depending on the blend composition. Although the stability of the threads during annealing improved upon compatibilization because of the lower resulting interfacial tension, the decreased possibility for recombination and coalescence during flow reduced the co-continuous region for the compatibilized blends. It is proposed that a dynamic equilibrium between break-up and recombination phenomena after the initial network formation is necessary to maintain the network structure. q

Research paper thumbnail of Influence of shear flow on the preparation of polymer layered silicate nanocomposites

Polymer, 2005

ABSTRACT In this paper the influence of melt-processing on the final polymer/layered silicate nan... more ABSTRACT In this paper the influence of melt-processing on the final polymer/layered silicate nanocomposite morphology is discussed. In particular the role of shear forces on the transformation of the original large clay agglomerates is of interest. Several polymer nanocomposites were prepared by melt-extrusion, involving polycaprolactone, poly(ethylene oxide), polyamide-12 or polyamide-6 as the matrix polymer. The nanocomposite morphology was characterised by X-ray diffraction and transmission electron microscopy and the clay tactoid morphology with polarised optical microscopy and scanning electron microscopy. The development of the tactoid and nanocomposite morphology during melt-mixing under shear was studied time-resolved by optical microscopy in conjunction with a rheometer and synchrotron X-ray scattering together with a Couette type flow cell. The shear forces in the melt-preparation of polymer layered mineral nanocomposites facilitate the break-up of large-sized agglomerates, whereas the extent of further exfoliation of the mineral layers is determined by the compatibility between the polymer matrix and the mineral layers rather than by shear forces.

Research paper thumbnail of Features, Questions and Future Challenges in Layered Silicates Clay Nanocomposites with Semicrystalline Polymer Matrices

Polyamide 6 Polymerisation Epoxy Poly(methyl methacrylate) Poly(e-caprolactone) Polyurethane Poly... more Polyamide 6 Polymerisation Epoxy Poly(methyl methacrylate) Poly(e-caprolactone) Polyurethane Polyimide Polyamide 12 Polyester 93] Melt compounding

Research paper thumbnail of Rheological behaviour of thermoplastic elastomers from polypropylene/ acrylonitrile-butadiene rubber blends: Effect of blend ratio, reactive compatibilization and dynamic vulcanization

The rheological behaviour of polypropylene (PP)/acrylonitrile–butadiene rubber (NBR) blends has b... more The rheological behaviour of polypropylene (PP)/acrylonitrile–butadiene rubber (NBR) blends has been investigated with special reference to the effect of blend ratio, compatibilization and dynamic vulcanization. The morphology of the extrudates and the size and distribution of ...

Research paper thumbnail of Effect of fibre length and chemical modifications on the tensile properties of intimately mixed short sisal/glass hybrid fibre reinforced low density polyethylene composites

Polymer International, 2004

Hybrid composites prepared by the incorporation of two or more different types of fibres into a s... more Hybrid composites prepared by the incorporation of two or more different types of fibres into a single polymer matrix deserve much attention. This method of hybridisation of composites offers a profitable procedure for the fabrication of products while the resulting materials are noted for their high specific strength, modulus and thermal stability. The influence of the relative composition of short sisal/glass fibres, their length and distribution on the tensile properties of short sisal/glass intimately mixed polyethylene composites (SGRP) was examined. Different compositions of sisal and glass such as 70/30, 50/50 and 30/70 have been prepared with varying fibre lengths in the range of 1-10 mm. Emphasis has also been given to the variation of fibre-matrix adhesion with several fibre chemical modifications. Chemical surface modifications such as alkali, acetic anhydride, stearic acid, permanganate, maleic anhydride, silane and peroxides given to the fibres and matrix were found to be successful in improving the interfacial adhesion and compatibility between the fibre and matrix. The nature and extent of chemical modifications were analysed by infrared spectroscopy while improvement in fibre-matrix adhesion was checked by studying the fractography of composite samples using a scanning electron microscope. Assessment of water retention values has been found to be a successful tool to characterize the surface of the stearic acid modified fibres. It was found that the extent of improvement in tensile properties of SGRP varied with respect to the nature of chemical modifications between fibre and matrix. Improved mechanical anchoring and physical and chemical bonding between fibre and polyethylene matrix are supposed to be the reasons for superior tensile strength and Young's modulus in treated composites. Several secondary reasons such as high degree of fibre dispersion and reduced hydrophilicity in chemically modified fibres also are believed to play a role. Among the various chemical modifications, the best tensile strength and modulus was exhibited by the SGRP with benzoyl peroxide treated fibres. This is attributed to the peroxide-initiated grafting of polyethylene on to the fibres.

Research paper thumbnail of Sheet extrusion of in-situ composites: Influence of processing parameters

Polymer Engineering and Science, 1993

Research paper thumbnail of Influence of compatibilizer precursor structure on the phase distribution of low density poly(ethylene) in a poly(ethylene terephthalate) matrix

Polymer Engineering & Science, 2008

In attempt to enhance the compatibility of PET/LDPE blends by using a proper functionalized polym... more 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-b-(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.

Research paper thumbnail of Dynamic mechanical properties of oil palm fiber/phenol formaldehyde and oil palm fiber/glass hybrid phenol formaldehyde composites

Polymer Composites, 2005

... Materials Oil palm empty fruit bunch fibers were collected from local sources and processed b... more ... Materials Oil palm empty fruit bunch fibers were collected from local sources and processed by retting technique. ... The physical and chemical characteristics of the fiber were reported earlier [7]. Phenol formaldehyde (PF) resole type resin was used for composite preparation and ...

Research paper thumbnail of Reaction induced phase separation in semicrystalline thermoplastic/epoxy resin blends

Polymer, 2005

The phase separation behaviour and phase morphology of blends of 4,4′-diaminodiphenyl sulphone cu... more The phase separation behaviour and phase morphology of blends of 4,4′-diaminodiphenyl sulphone cured diglycidyl ether of bisphenol-A with poly(ε-caprolactone) were investigated by means of scanning electron microscopy, small angle light scattering and optical microscopy. The components are miscible prior to curing. High-temperature isothermal curing induces phase separation. Blends with near to critical concentrations demix via spinodal decomposition. The associated co-continuous morphology is only preserved in the actual critical compositions whereas for off-critical compositions it rapidly breaks up into spherical particles. The proceeding reaction in the separated phases induces a secondary phase separation. Occasionally, tertiary phase separation is observed as well. Off-critical compositions that are further away on either side from the critical point, phase separate via the direct formation of spherical particles, most likely as a result of the dynamic asymmetry of these blends. The influence of the amount, the molar mass of PCL and the cure temperature is discussed.

Research paper thumbnail of Anisotropy and instability of the co-continuous phase morphology in uncompatibilized and reactively compatibilized polypropylene/polystyrene blends

Polymer, 2007

The present work describes the anisotropy and instability observed upon the formation of co-conti... more The present work describes the anisotropy and instability observed upon the formation of co-continuous phase morphologies in model polystyrene/polypropylene melt-extruded blends. Uncompatibilized and reactively compatibilized blends using amino-terminated polystyrene, PSeNH 2 , and maleic anhydride grafted polypropylene, PPeMAh, reactive precursors were investigated. Differences in phase morphology are discussed based on the viscoelastic properties of the components used, the blend composition and, the type and content of the compatibilizer precursor employed. As expected, for the same polystyrene grade at a concentration in the blend below 20 wt%, a polypropylene matrix having a higher viscosity enables the formation of a more co-continuous phase morphology than a less viscous one, as quantified by solvent extraction. The co-continuous phase morphology developed was found to exhibit a highly elongated structure upon melt flow through the die of the extruder. Isotropic co-continuity, observed inside the barrel of extruder, was transformed into anisotropic phase co-continuity in the form of interconnected infinite strands of the minor phase highly oriented in the extrusion direction.

Research paper thumbnail of Crystallization behavior of polymer/montmorillonite nanocomposites. Part II. Intercalated poly(ε-caprolactone)/montmorillonite nanocomposites

Polymer, 2006

The combination of surfactant modified montmorillonite (MMT) silicate layers, poly(3-caprolactone... more The combination of surfactant modified montmorillonite (MMT) silicate layers, poly(3-caprolactone) (PCL) and the adopted melt processing procedure results in intercalated nanocomposites in which the silicate layers act as nucleating agents for the crystallization of the PCL matrix and by which in turn the overall crystallization rate increases. At a sufficiently high MMT concentration and degree of supercooling the polymerswollen silicate layer stacks disturb crystal growth, resulting in a decrease in the overall crystallization rate. Simultaneous, time resolved, synchrotron small and wide angle X-ray scattering experiments reveal that-when the retarding effect is absent at a sufficiently high temperature-the final semicrystalline structures of pure PCL and its nanocomposites are identical. The poorer nucleation in the case of pure PCL, however, results in a time wise smearing of primary and secondary crystallization whereas in the nanocomposites these events are well separated due to a nucleation induced, efficient and rapid primary crystallization. Secondary crystallization involves the insertion of new lamellar crystals in between the already existing ones. q

Research paper thumbnail of Immiscible polymer blends of semicrystalline biocompatible components: thermal properties and phase morphology analysis of PLLA/PCL blends

Polymer, 2001

... Ramiro Dell'Erba a , Gabriel Groeninckx b , Giovanni Maglio Corresponding Author Contact... more ... Ramiro Dell'Erba a , Gabriel Groeninckx b , Giovanni Maglio Corresponding Author Contact Information , E-mail The Corresponding Author , c , Mario ... Thin samples between glass-slides were observed by an Olympus optical microscope equipped with a Mettler hot stage. ...

Research paper thumbnail of Reactive compatibilization of A/(B/C) polymer blends. Part 3. Quantitative analysis of the interfacial thickness and the interfacial reaction

Polymer, 1998

... t 3 Haslam, J., Willis, HA and Squirrel, DCM, Identification and Analysis of Plastics, 2nd ed... more ... t 3 Haslam, J., Willis, HA and Squirrel, DCM, Identification and Analysis of Plastics, 2nd edn. Heyden and Son, London, 1980, p. 292. 14 Lawson, DF, Hergenrother, WL and Matlock, MG, Polym. Pr7m, 1988, 29(2), 193. ... DF, Hergenrother. WL and Matlock, MG, ,I. Appl. Polym. ...

Research paper thumbnail of Nanocomposites based on layered silicate and miscible PVDF/PMMA blends: melt preparation, nanophase morphology and rheological behaviour

Polymer, 2003

Polyvinylidene fluoride (PVDF) -organoclay nanocomposites were prepared by melt-extrusion using p... more Polyvinylidene fluoride (PVDF) -organoclay nanocomposites were prepared by melt-extrusion using polymethylmethacrylate (PMMA) as an interfacial agent. These nanocomposite materials were analysed with respect to their morphological and rheological properties. The nanophase morphology development and nanophase dispersion were studied using TEM. A fine dispersion of partially to nearly fully exfoliated silicate layers in miscible PVDF/PMMA blend matrices was observed when organophilic montmorillonite was used. Increasing the amount of PMMA in the PVDF/PMMA blend leads to high degree of exfoliation.

Research paper thumbnail of Characterization of the dual crystal population in an isothermally crystallized homogeneous ethylene-1-octene copolymer

Polymer, 2004

The melting of a homogeneous ethylene-1-octene copolymer after isothermal crystallization is disc... more The melting of a homogeneous ethylene-1-octene copolymer after isothermal crystallization is discussed based on DSC and time-resolved SALS, SAXS and WAXD data. Two melting peaks appear in DSC suggesting the presence of two crystal fractions. All crystals grow in a lamellar habit and there is no evidence for fringed micellar or isolated block-like crystals. The high melting fraction crystallizes while segregating comonomer-rich parts into separate regions where in a later stage the low melting fraction crystallizes. The data support the view of lamellae that grow via the secondary nucleation of crystalline blocks from a preexisting layer-like mesomorphic phase with preservation of the mesomorphic layer thickness. The stability of these blocks increases due to sintering, forming lamellae that melt slightly above the crystallization temperature. The high melting fraction is generated from those lamellae that are able to reduce the crystalline-amorphous interfacial tension. q

Research paper thumbnail of Ternary blends of PCL, SAN15 and SMA14: miscibility, crystallization and melting behaviour, and semicrystalline morphology

Polymer, 1995

The miscibility and phase behaviour of the ternary blend consisting of poly(ε-caprolactone) (PCL)... more The miscibility and phase behaviour of the ternary blend consisting of poly(ε-caprolactone) (PCL), poly(styrene-co-acrylonitrile) with 15 wt% acrylonitrile (SAN15) and poly(styrene-co-maleic anhydride) with 14 wt% maleic anhydride (SMA14) have been investigated by means of visual observations, light transmission measurements, differential scanning calorimetry (d.s.c.) and dynamic mechanical thermal analysis. The influence of the molecular weight of the components and of the

Research paper thumbnail of Quantitative evaluation of fractionated and homogeneous nucleation of polydisperse distributions of water-dispersed maleic anhydride-grafted-polypropylene micro- and nano-sized droplets

Polymer, 2009

The nucleation processes in waterborne Maleic Anhydride-grafted-Polypropylene micro-and nanodropl... more The nucleation processes in waterborne Maleic Anhydride-grafted-Polypropylene micro-and nanodroplet 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.

Research paper thumbnail of Miscibility, crystallization and melting behaviour, and morphology of binary blends of polycaprolactone with styrene-co-maleic anhydride copolymers

Polymer, 1989

ABSTRACT The semicrystalline morphology of pure PCL and of some of its miscible binary and ternar... more ABSTRACT The semicrystalline morphology of pure PCL and of some of its miscible binary and ternary blends with Phenoxy and SAN15 has been investigated by small angle X-ray scattering. Morphological parameters have been obtained from the analysis of the one-dimensional correlation function. The influence of the crystallization temperature on the semicrystalline morphology has been investigated and is compared with the melting behaviour as studied with differential scanning calorimetry. (C) 1997 Elsevier Science Ltd.

Research paper thumbnail of Some aspects of vapor-induced crystallization of polycarbonate of bisphenol A

Journal of Polymer Science Part C: Polymer Symposia, 1967

A ~nelhod is presented t'o crystallize yolycarluonale of bispheriol iZ tirider coiist,aiil vapor ... more A ~nelhod is presented t'o crystallize yolycarluonale of bispheriol iZ tirider coiist,aiil vapor pressure of solvents at near ambient t'emperatures. Methylene chloride arid acetone were used as crystallizing liquids. Acetone is more powerful in iiiducing erystalliration but the final degree of crystallinity does not depend on the nature of the solvent.

Research paper thumbnail of Cure kinetics and morphology of blends of epoxy resin with poly (ether ether ketone) containing pendant tertiary butyl groups

Polymer, 2003

The cure kinetics and morphology of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin modified ... more The cure kinetics and morphology of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin modified with a poly (ether ether ketone) based on tertiary butyl hydroquinone (PEEK-T) cured with diamino diphenyl sulphone (DDS) were investigated using differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and dynamic mechanical thermal analysis (DMTA). The results obtained from DSC were applied to autocatalytic and diffusion controlled kinetic models. The reaction mechanism broadly showed autocatalytic behaviour regardless of the presence of PEEK-T. At higher PEEK-T concentration, more diffusion controlled mechanism was observed. The rate of curing reaction decreased with increase in thermoplastic content and also with the lowering of curing temperature. The activation energies of the blends are higher than that of the neat resin. The blends showed a phase separated morphology. The dispersed phase showed a homogeneous particle size distribution. The T g of the neat resin decreased with the decrease in cure temperature. Two T g 's corresponding to the epoxy rich and thermoplastic rich phases were observed in the dynamic mechanical spectrum. The storage modulus of 10 and 20 phr PEEK-T blends are found to be greater than the neat resin.

Research paper thumbnail of Phase morphology and stability of co-continuous (PPE/PS)/PA6 and PS/PA6 blends: effect of rheology and reactive compatibilization

Polymer, 2004

PPE/PS)/PA6 and PS/PA6 blends were prepared by means of melt-extrusion. They were compatibilized ... more PPE/PS)/PA6 and PS/PA6 blends were prepared by means of melt-extrusion. They were compatibilized using the reactive styrene-maleic anhydride copolymer with 2 wt% maleic anhydride (SMA2). The effect of compatibilization on the phase inversion and the stability of the resulting co-continuous blend structures were investigated using scanning electron microscopy, dissolution and extraction experiments. The onset of co-continuity shifted towards lower PA6 concentrations according to the change in blend viscosity ratio. The melting order of the components inside the extruder could result in a change in the observed co-continuity interval in slowly developing phase morphologies. The unmodified co-continuous blends were not stable and did break-up into a droplet/matrix type of morphology upon annealing in the melt depending on the blend composition. Although the stability of the threads during annealing improved upon compatibilization because of the lower resulting interfacial tension, the decreased possibility for recombination and coalescence during flow reduced the co-continuous region for the compatibilized blends. It is proposed that a dynamic equilibrium between break-up and recombination phenomena after the initial network formation is necessary to maintain the network structure. q

Research paper thumbnail of Influence of shear flow on the preparation of polymer layered silicate nanocomposites

Polymer, 2005

ABSTRACT In this paper the influence of melt-processing on the final polymer/layered silicate nan... more ABSTRACT In this paper the influence of melt-processing on the final polymer/layered silicate nanocomposite morphology is discussed. In particular the role of shear forces on the transformation of the original large clay agglomerates is of interest. Several polymer nanocomposites were prepared by melt-extrusion, involving polycaprolactone, poly(ethylene oxide), polyamide-12 or polyamide-6 as the matrix polymer. The nanocomposite morphology was characterised by X-ray diffraction and transmission electron microscopy and the clay tactoid morphology with polarised optical microscopy and scanning electron microscopy. The development of the tactoid and nanocomposite morphology during melt-mixing under shear was studied time-resolved by optical microscopy in conjunction with a rheometer and synchrotron X-ray scattering together with a Couette type flow cell. The shear forces in the melt-preparation of polymer layered mineral nanocomposites facilitate the break-up of large-sized agglomerates, whereas the extent of further exfoliation of the mineral layers is determined by the compatibility between the polymer matrix and the mineral layers rather than by shear forces.

Research paper thumbnail of Features, Questions and Future Challenges in Layered Silicates Clay Nanocomposites with Semicrystalline Polymer Matrices

Polyamide 6 Polymerisation Epoxy Poly(methyl methacrylate) Poly(e-caprolactone) Polyurethane Poly... more Polyamide 6 Polymerisation Epoxy Poly(methyl methacrylate) Poly(e-caprolactone) Polyurethane Polyimide Polyamide 12 Polyester 93] Melt compounding

Research paper thumbnail of Rheological behaviour of thermoplastic elastomers from polypropylene/ acrylonitrile-butadiene rubber blends: Effect of blend ratio, reactive compatibilization and dynamic vulcanization

The rheological behaviour of polypropylene (PP)/acrylonitrile–butadiene rubber (NBR) blends has b... more The rheological behaviour of polypropylene (PP)/acrylonitrile–butadiene rubber (NBR) blends has been investigated with special reference to the effect of blend ratio, compatibilization and dynamic vulcanization. The morphology of the extrudates and the size and distribution of ...

Research paper thumbnail of Effect of fibre length and chemical modifications on the tensile properties of intimately mixed short sisal/glass hybrid fibre reinforced low density polyethylene composites

Polymer International, 2004

Hybrid composites prepared by the incorporation of two or more different types of fibres into a s... more Hybrid composites prepared by the incorporation of two or more different types of fibres into a single polymer matrix deserve much attention. This method of hybridisation of composites offers a profitable procedure for the fabrication of products while the resulting materials are noted for their high specific strength, modulus and thermal stability. The influence of the relative composition of short sisal/glass fibres, their length and distribution on the tensile properties of short sisal/glass intimately mixed polyethylene composites (SGRP) was examined. Different compositions of sisal and glass such as 70/30, 50/50 and 30/70 have been prepared with varying fibre lengths in the range of 1-10 mm. Emphasis has also been given to the variation of fibre-matrix adhesion with several fibre chemical modifications. Chemical surface modifications such as alkali, acetic anhydride, stearic acid, permanganate, maleic anhydride, silane and peroxides given to the fibres and matrix were found to be successful in improving the interfacial adhesion and compatibility between the fibre and matrix. The nature and extent of chemical modifications were analysed by infrared spectroscopy while improvement in fibre-matrix adhesion was checked by studying the fractography of composite samples using a scanning electron microscope. Assessment of water retention values has been found to be a successful tool to characterize the surface of the stearic acid modified fibres. It was found that the extent of improvement in tensile properties of SGRP varied with respect to the nature of chemical modifications between fibre and matrix. Improved mechanical anchoring and physical and chemical bonding between fibre and polyethylene matrix are supposed to be the reasons for superior tensile strength and Young's modulus in treated composites. Several secondary reasons such as high degree of fibre dispersion and reduced hydrophilicity in chemically modified fibres also are believed to play a role. Among the various chemical modifications, the best tensile strength and modulus was exhibited by the SGRP with benzoyl peroxide treated fibres. This is attributed to the peroxide-initiated grafting of polyethylene on to the fibres.

Research paper thumbnail of Sheet extrusion of in-situ composites: Influence of processing parameters

Polymer Engineering and Science, 1993

Research paper thumbnail of Influence of compatibilizer precursor structure on the phase distribution of low density poly(ethylene) in a poly(ethylene terephthalate) matrix

Polymer Engineering & Science, 2008

In attempt to enhance the compatibility of PET/LDPE blends by using a proper functionalized polym... more 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-b-(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.

Research paper thumbnail of Dynamic mechanical properties of oil palm fiber/phenol formaldehyde and oil palm fiber/glass hybrid phenol formaldehyde composites

Polymer Composites, 2005

... Materials Oil palm empty fruit bunch fibers were collected from local sources and processed b... more ... Materials Oil palm empty fruit bunch fibers were collected from local sources and processed by retting technique. ... The physical and chemical characteristics of the fiber were reported earlier [7]. Phenol formaldehyde (PF) resole type resin was used for composite preparation and ...

Research paper thumbnail of Reaction induced phase separation in semicrystalline thermoplastic/epoxy resin blends

Polymer, 2005

The phase separation behaviour and phase morphology of blends of 4,4′-diaminodiphenyl sulphone cu... more The phase separation behaviour and phase morphology of blends of 4,4′-diaminodiphenyl sulphone cured diglycidyl ether of bisphenol-A with poly(ε-caprolactone) were investigated by means of scanning electron microscopy, small angle light scattering and optical microscopy. The components are miscible prior to curing. High-temperature isothermal curing induces phase separation. Blends with near to critical concentrations demix via spinodal decomposition. The associated co-continuous morphology is only preserved in the actual critical compositions whereas for off-critical compositions it rapidly breaks up into spherical particles. The proceeding reaction in the separated phases induces a secondary phase separation. Occasionally, tertiary phase separation is observed as well. Off-critical compositions that are further away on either side from the critical point, phase separate via the direct formation of spherical particles, most likely as a result of the dynamic asymmetry of these blends. The influence of the amount, the molar mass of PCL and the cure temperature is discussed.

Research paper thumbnail of Anisotropy and instability of the co-continuous phase morphology in uncompatibilized and reactively compatibilized polypropylene/polystyrene blends

Polymer, 2007

The present work describes the anisotropy and instability observed upon the formation of co-conti... more The present work describes the anisotropy and instability observed upon the formation of co-continuous phase morphologies in model polystyrene/polypropylene melt-extruded blends. Uncompatibilized and reactively compatibilized blends using amino-terminated polystyrene, PSeNH 2 , and maleic anhydride grafted polypropylene, PPeMAh, reactive precursors were investigated. Differences in phase morphology are discussed based on the viscoelastic properties of the components used, the blend composition and, the type and content of the compatibilizer precursor employed. As expected, for the same polystyrene grade at a concentration in the blend below 20 wt%, a polypropylene matrix having a higher viscosity enables the formation of a more co-continuous phase morphology than a less viscous one, as quantified by solvent extraction. The co-continuous phase morphology developed was found to exhibit a highly elongated structure upon melt flow through the die of the extruder. Isotropic co-continuity, observed inside the barrel of extruder, was transformed into anisotropic phase co-continuity in the form of interconnected infinite strands of the minor phase highly oriented in the extrusion direction.

Research paper thumbnail of Crystallization behavior of polymer/montmorillonite nanocomposites. Part II. Intercalated poly(ε-caprolactone)/montmorillonite nanocomposites

Polymer, 2006

The combination of surfactant modified montmorillonite (MMT) silicate layers, poly(3-caprolactone... more The combination of surfactant modified montmorillonite (MMT) silicate layers, poly(3-caprolactone) (PCL) and the adopted melt processing procedure results in intercalated nanocomposites in which the silicate layers act as nucleating agents for the crystallization of the PCL matrix and by which in turn the overall crystallization rate increases. At a sufficiently high MMT concentration and degree of supercooling the polymerswollen silicate layer stacks disturb crystal growth, resulting in a decrease in the overall crystallization rate. Simultaneous, time resolved, synchrotron small and wide angle X-ray scattering experiments reveal that-when the retarding effect is absent at a sufficiently high temperature-the final semicrystalline structures of pure PCL and its nanocomposites are identical. The poorer nucleation in the case of pure PCL, however, results in a time wise smearing of primary and secondary crystallization whereas in the nanocomposites these events are well separated due to a nucleation induced, efficient and rapid primary crystallization. Secondary crystallization involves the insertion of new lamellar crystals in between the already existing ones. q

Research paper thumbnail of Immiscible polymer blends of semicrystalline biocompatible components: thermal properties and phase morphology analysis of PLLA/PCL blends

Polymer, 2001

... Ramiro Dell'Erba a , Gabriel Groeninckx b , Giovanni Maglio Corresponding Author Contact... more ... Ramiro Dell'Erba a , Gabriel Groeninckx b , Giovanni Maglio Corresponding Author Contact Information , E-mail The Corresponding Author , c , Mario ... Thin samples between glass-slides were observed by an Olympus optical microscope equipped with a Mettler hot stage. ...

Research paper thumbnail of Reactive compatibilization of A/(B/C) polymer blends. Part 3. Quantitative analysis of the interfacial thickness and the interfacial reaction

Polymer, 1998

... t 3 Haslam, J., Willis, HA and Squirrel, DCM, Identification and Analysis of Plastics, 2nd ed... more ... t 3 Haslam, J., Willis, HA and Squirrel, DCM, Identification and Analysis of Plastics, 2nd edn. Heyden and Son, London, 1980, p. 292. 14 Lawson, DF, Hergenrother, WL and Matlock, MG, Polym. Pr7m, 1988, 29(2), 193. ... DF, Hergenrother. WL and Matlock, MG, ,I. Appl. Polym. ...

Research paper thumbnail of Nanocomposites based on layered silicate and miscible PVDF/PMMA blends: melt preparation, nanophase morphology and rheological behaviour

Polymer, 2003

Polyvinylidene fluoride (PVDF) -organoclay nanocomposites were prepared by melt-extrusion using p... more Polyvinylidene fluoride (PVDF) -organoclay nanocomposites were prepared by melt-extrusion using polymethylmethacrylate (PMMA) as an interfacial agent. These nanocomposite materials were analysed with respect to their morphological and rheological properties. The nanophase morphology development and nanophase dispersion were studied using TEM. A fine dispersion of partially to nearly fully exfoliated silicate layers in miscible PVDF/PMMA blend matrices was observed when organophilic montmorillonite was used. Increasing the amount of PMMA in the PVDF/PMMA blend leads to high degree of exfoliation.

Research paper thumbnail of Characterization of the dual crystal population in an isothermally crystallized homogeneous ethylene-1-octene copolymer

Polymer, 2004

The melting of a homogeneous ethylene-1-octene copolymer after isothermal crystallization is disc... more The melting of a homogeneous ethylene-1-octene copolymer after isothermal crystallization is discussed based on DSC and time-resolved SALS, SAXS and WAXD data. Two melting peaks appear in DSC suggesting the presence of two crystal fractions. All crystals grow in a lamellar habit and there is no evidence for fringed micellar or isolated block-like crystals. The high melting fraction crystallizes while segregating comonomer-rich parts into separate regions where in a later stage the low melting fraction crystallizes. The data support the view of lamellae that grow via the secondary nucleation of crystalline blocks from a preexisting layer-like mesomorphic phase with preservation of the mesomorphic layer thickness. The stability of these blocks increases due to sintering, forming lamellae that melt slightly above the crystallization temperature. The high melting fraction is generated from those lamellae that are able to reduce the crystalline-amorphous interfacial tension. q

Research paper thumbnail of Ternary blends of PCL, SAN15 and SMA14: miscibility, crystallization and melting behaviour, and semicrystalline morphology

Polymer, 1995

The miscibility and phase behaviour of the ternary blend consisting of poly(ε-caprolactone) (PCL)... more The miscibility and phase behaviour of the ternary blend consisting of poly(ε-caprolactone) (PCL), poly(styrene-co-acrylonitrile) with 15 wt% acrylonitrile (SAN15) and poly(styrene-co-maleic anhydride) with 14 wt% maleic anhydride (SMA14) have been investigated by means of visual observations, light transmission measurements, differential scanning calorimetry (d.s.c.) and dynamic mechanical thermal analysis. The influence of the molecular weight of the components and of the

Research paper thumbnail of Quantitative evaluation of fractionated and homogeneous nucleation of polydisperse distributions of water-dispersed maleic anhydride-grafted-polypropylene micro- and nano-sized droplets

Polymer, 2009

The nucleation processes in waterborne Maleic Anhydride-grafted-Polypropylene micro-and nanodropl... more The nucleation processes in waterborne Maleic Anhydride-grafted-Polypropylene micro-and nanodroplet 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.

Research paper thumbnail of Miscibility, crystallization and melting behaviour, and morphology of binary blends of polycaprolactone with styrene-co-maleic anhydride copolymers

Polymer, 1989

ABSTRACT The semicrystalline morphology of pure PCL and of some of its miscible binary and ternar... more ABSTRACT The semicrystalline morphology of pure PCL and of some of its miscible binary and ternary blends with Phenoxy and SAN15 has been investigated by small angle X-ray scattering. Morphological parameters have been obtained from the analysis of the one-dimensional correlation function. The influence of the crystallization temperature on the semicrystalline morphology has been investigated and is compared with the melting behaviour as studied with differential scanning calorimetry. (C) 1997 Elsevier Science Ltd.