Charef HARRATS - Academia.edu (original) (raw)

Papers by Charef HARRATS

Research paper thumbnail of Compatibilizer precursors effect on the phase morphology development of PET/LDPE blends

Research paper thumbnail of Features on the Development and Stability of Phase Morphology in Complex Multicomponent Polymeric Systems: Main Focus on Processing Aspects

Research paper thumbnail of Reactive Blending with Immiscible Functional Polymers: Molecular, Morphological, and Interfacial Aspects

Reactive Polymer Blending, 2001

Research paper thumbnail of Cocontinuous Phase Morphologies

Phase Morphology and Interfaces, 2005

Research paper thumbnail of Micro- and Nanostructured Polymer Blends

Micro- and Nanostructured Multiphase Polymer Blend Systems, 2005

Research paper thumbnail of Reactive Processing Of Polymer Blend Using Reactive Compatibilization And Dynamic Crosslinking: Phase Morphology Control And Microstructure – Property Relations

NATO Science Series

This chapter covers the area of polymer blends produced via melt-processing. The blends are first... more This chapter covers the area of polymer blends produced via melt-processing. The blends are first introduced based on their miscible or immiscible nature. Advantages and disadvantages of one class over the other are briefly highlighted. The need to compatibilize immiscible polymer blends is emphasized. The two main strategies of compatibilization, i.e., physical blending which consists of adding a pre-formed copolymer

Research paper thumbnail of Co-continuous and encapsulated three phase morphologies in uncompatibilized and reactively compatibilized polyamide 6/polypropylene/polystyrene ternary blends using two reactive precursors

Polymer, 2005

Phase morphology development in ternary uncompatibilized and reactively compatibilized blends bas... more Phase morphology development in ternary uncompatibilized and reactively compatibilized blends based on polyamide 6 (PA6), polypropylene (PP) and polystyrene (PS) has been investigated. Reactive compatibilization of the blends has been performed using two reactive precursors; maleic anhydride grafted polypropylene (PP-g-MA) and styrene maleic anhydride copolymer (SMA) for PA6/PP and PA6/PS pairs, respectively. For comparison purposes, uncompatibilized and reactively compatibilized PA6/PP

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 c...

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

Research paper thumbnail of Phase continuity detection and phase inversion phenomena in immiscible polypropylene/polystyrene blends with different viscosity ratios

Polymer, 2007

Blends of polypropylene (PP) and polystyrene (PS) were prepared in a twin-screw extruder and stud... more Blends of polypropylene (PP) and polystyrene (PS) were prepared in a twin-screw extruder and studied in a wide range of compositions. Phase continuity was first determined using selective solvent extraction. Subsequently, dynamic stress rheometry and dynamic mechanical analysis were used to detect the co-continuity and phase inversion compositions in the melt and the solid states. It appears that the phase inversion occurs in a domain rather than at a single point. The evaluation of the storage modulus of PP/PS blends in the melt at a constant low frequency gives information about the co-continuity, as far as the onset of co-continuity and phase inversion composition of the PS phase are concerned. The evaluation of the storage modulus and mechanical loss factor at a constant high temperature, or the glass transition temperature intensity allowed to precisely detect the phase inversion composition. The fractionated or bulk crystallization behavior of the crystallizable PP phase in the PP/PS blends can also be used to identify the matrix/dispersed phase or co-continuous phase morphology. Several semi-empirical models using the dynamic viscoelastic properties of blend components have been applied to detect the phase inversion composition. An extensive data set presented, can also be used to guide future modeling.

Research paper thumbnail of Synthesis and compatibilization ability of hydrogenated polybutadiene-b-polyamide 6 diblock copolymer in low density polyethylene and polyamide 6 blends

Research paper thumbnail of Phase morphology development and stabilization in polycyclohexylmethacrylate/polypropylene blends: uncompatibilized and reactively compatibilized blends using two reactive precursors

Polymer, 2004

The phase morphology developed in immiscible polypropylene (PP)/polycyclohexylmethacrylate (PCHMA... more The phase morphology developed in immiscible polypropylene (PP)/polycyclohexylmethacrylate (PCHMA) blends has been studied using an in situ reactively generated polystyrene-graft-polypropylene compatibilizer from maleic anhydride grafted polypropylene (MA-g-PP) and amine end-capped polystyrene (PS-NH2) reactive precursors during melt-blending. The imidation reaction responsible for the formation of the compatibilizer is similar to the reaction occurring in polyamide/MA-PP (MA-EPR or MA-EPDM) blends which are industrially important. In the present blend PP/PCHMA/(PP-MAPS -NH2), no undesired reaction occurs between the maleic anhydride groups and the backbone of the PCHMA chain, as is usually the case with polyamide homopolymer. This type of reaction, although considered non significant, has consequences on the phase morphology development as it affects the viscosity of the polyamide matrix when chain scission takes place. PP/PCHMA blends covering the whole range of compositions were prepared. The composition window at which the blends exhibit a droplet-in-matrix phase morphology and that where the two phases are co-continuous were determined using a selective phase extraction in combination with scanning electron microscopy. The generation in situ of the PP-g-PS compatibilizer substantially changed the state of the phase morphology developed. In the blends having a droplet-in-matrix type of morphology, the particle sizes were significantly reduced (by a factor of more than 10). Two types of MA-g-PP reactive copolymers differing in maleic anhydride content (1 and 8 wt%) have been separately employed with the same grade of PS-NH2. Emphasis was put on a detailed investigation of the behaviour and structural stability of the blends exhibiting a co-continuous phase morphology when the compatibilizer is generated. Significant differences were found in relation to the maleic anhydride content of the MA-PP reactive compatibilizer precursor.

Research paper thumbnail of Reactively and physically compatibilized immiscible polymer blends: stability of the copolymer at the interface

Macromolecular Symposia, 2003

This paper reports on the interfacial behaviour of block and graft copolymers used as compatibili... more This paper reports on the interfacial behaviour of block and graft copolymers used as compatibilizers in immiscible polymer blends. A limited residence time of the copolymer at the interface has been shown in both reactive blending and blend compatibilization by preformed copolymers. Polystyrene (PS)/polyamide6 (PA6), polyphenylene oxide (PPO)/PA6 and polymethylmethacrylate (PMMA)/PA6 blends have been reactively compatibilized by a styrene‐maleic anhydride copolymer SMA. The extent of miscibility of SMA with PS, PPO and PMMA is a key criterion for the stability of the graft copolymer at the interface. For the first 10 to 15 minutes of mixing, the in situ formed copolymer is able to decrease the particle size of the dispersed phase and to prevent it from coalescencing. However, upon increasing mixing time, the copolymer leaves the interface which results in phase coalescence.In PS/LDPE blends compatibilized by preformed PS/hydrogenated polybutadiene (hPB) block copolymers, a tapered ...

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

Macromolecular Rapid Communications, 2008

Research paper thumbnail of Block balance in hydrogenated polybutadiene-b-polymethylmethacrylate diblock copolymer for efficient interfacial activity in low-density polyethylene/polymethylmethacrylate blend: Phase morphology development

Journal of Polymer Science Part B: Polymer Physics, 2005

The objective of the present study was to determine the best molecular balance between the two hy... more The objective of the present study was to determine the best molecular balance between the two hydrogenated polybutadiene (HPB) and polymethylmethacrylate (PMMA) blocks that promotes an HPB-b-PMMA diblock copolymer with efficient compatibilization activity in a low-density polyethylene (LDPE)/PMMA immiscible blend. The model blend selected, LDPE/PMMA, is more immiscible than the LDPE/ polystyrene pair largely reported in open literature. The blends having a composition of 80LDPE/20PMMA exhibit a droplet-in-matrix phase morphology whereas in 20LDPE/ 80PMMA a co-continuous phase morphology was developed. In the droplet-in-matrix phase morphology, the emulsifying efficiency of the copolymer was evaluated based on the maximum reduction of the PMMA droplet size it is able to promote. Whereas, in the co-continuous phase morphology, the copolymer was evaluated based on its ability to stabilize the maximum phase co-continuity. The sequences of the best emulsifying copolymer revealed are not symmetrical. An HPB-b-PMMA where the ratio of molar mass of the blocks, M n HPB /M n PMMA, is within 1.8-1.95 exhibits a much better interfacial activity in LDPE/PMMA blends than a copolymer of much lower ratio (longer PMMA block). This is ascribed to the much higher interactions (cohesive energy density) encountered in PMMA (PMMA of the copolymer and PMMA phase of the blend) compared with the LDPE side (HPB of the copolymer and LDPE phase of the blend).

Research paper thumbnail of Stabilization of a cocontinuous phase morphology by a tapered diblock or triblock copolymer in polystyrene‐rich low‐density polyethylene/polystyrene blends

Journal of Polymer Science Part B: Polymer Physics, 2002

The stability against the thermal annealing of a cocontinuous two‐phase morphology developed in p... more The stability against the thermal annealing of a cocontinuous two‐phase morphology developed in polystyrene (PS)/low‐density polyethylene (LDPE) blends containing 80 wt % PS was investigated. Blends containing 1, 5, and 10 wt % of a tapered diblock poly(styrene‐block‐hydrogenated butadiene) (P(S‐b‐hB)) or triblock poly(styrene‐block‐hydrogenated butadiene‐block‐styrene) (P(S‐hB‐S)) copolymer were melt‐blended with roll‐mill mixing equipment. The efficiency of each of the two copolymers in stabilizing against coalescence the cocontinuous morphology was examined. The tensile properties of the resulting blends, annealed and nonannealed, were also examined in relation to the morphology induced by thermal annealing. The phase morphology was studied by optical and scanning electron microscopy. With computer‐aided image analysis, it was possible to obtain a measurable characteristic parameter to quantify the cocontinuous phase morphology. When it was necessary, the extraction of one phase ...

Research paper thumbnail of Stress-strain behavior of low-density polyethylene/poly(methyl methacrylate) blends with modulated interfaces with a hydrogenated polybutadiene-block-poly(methyl methacrylate) diblock copolymer

Journal of Polymer Science Part B: Polymer Physics, 2004

ABSTRACT

Research paper thumbnail of Molecular design of multicomponent polymer systems, XI, emulsifying effect of poly(hydrogenated diene-b-methyl methacrylate) in poly(vinylidene fluoride)/polyolefins blends

Journal of Applied Polymer Science, 1986

Research paper thumbnail of Design and characterisation of microfibrillar reinforced composite materials based on PET/PA12 blends

Composites Part A: Applied Science and Manufacturing, 2004

Microfibrillar reinforced composites (MFCs) have been prepared by reactive melt-extrusion of poly... more Microfibrillar reinforced composites (MFCs) have been prepared by reactive melt-extrusion of poly(ethylene terephthalate) (PET) and polyamide 12 (PA12) in the presence of a catalyst. These composites have been generated by a series of processes, which include reactive extrusion in a mini twin-screw extruder, followed by drawing (fibrillation) and finally the isotropisation of the lower-melting PA12 phase. During the preparation of

Research paper thumbnail of Adsorption of polyampholyte copolymers at the solid/liquid interface: the influence of pH and salt on the adsorption behaviour

Physical Chemistry Chemical Physics, 1999

Polyampholytes are macromolecules that contain oppositely charged groups. We have studied the ads... more Polyampholytes are macromolecules that contain oppositely charged groups. We have studied the adsorption of the polyampholyte diblock copolymer poly(methacrylic acid)-block-poly((dimethylamino)ethyl methacrylate), PMAA-b-PDMAEMA, on oxidized silicon surfaces. The amount of polymer adsorbed from aqueous solution of different pH and salt concentration was measured by ellipsometry. The influence of the added salts NaCl, Na 2 SO 4 and CaCl 2 was determined. In every case adsorption took place, although the polyampholyte and the substrate exhibit the same sign of net charge. For all types of salt, the adsorbed amount shows two maxima close to the isoelectric point (IEP) of the polymer as a function of pH. Directly at the IEP of the polyampholyte, no adsorption was found. The measured dependences can be explained by the adsorption of one or the other of the two blocks depending on acidity and ionic strength. Furthermore, the lateral structure of the dried films was investigated by scanning force microscopy (SFM).

Research paper thumbnail of Compatibilizer precursors effect on the phase morphology development of PET/LDPE blends

Research paper thumbnail of Features on the Development and Stability of Phase Morphology in Complex Multicomponent Polymeric Systems: Main Focus on Processing Aspects

Research paper thumbnail of Reactive Blending with Immiscible Functional Polymers: Molecular, Morphological, and Interfacial Aspects

Reactive Polymer Blending, 2001

Research paper thumbnail of Cocontinuous Phase Morphologies

Phase Morphology and Interfaces, 2005

Research paper thumbnail of Micro- and Nanostructured Polymer Blends

Micro- and Nanostructured Multiphase Polymer Blend Systems, 2005

Research paper thumbnail of Reactive Processing Of Polymer Blend Using Reactive Compatibilization And Dynamic Crosslinking: Phase Morphology Control And Microstructure – Property Relations

NATO Science Series

This chapter covers the area of polymer blends produced via melt-processing. The blends are first... more This chapter covers the area of polymer blends produced via melt-processing. The blends are first introduced based on their miscible or immiscible nature. Advantages and disadvantages of one class over the other are briefly highlighted. The need to compatibilize immiscible polymer blends is emphasized. The two main strategies of compatibilization, i.e., physical blending which consists of adding a pre-formed copolymer

Research paper thumbnail of Co-continuous and encapsulated three phase morphologies in uncompatibilized and reactively compatibilized polyamide 6/polypropylene/polystyrene ternary blends using two reactive precursors

Polymer, 2005

Phase morphology development in ternary uncompatibilized and reactively compatibilized blends bas... more Phase morphology development in ternary uncompatibilized and reactively compatibilized blends based on polyamide 6 (PA6), polypropylene (PP) and polystyrene (PS) has been investigated. Reactive compatibilization of the blends has been performed using two reactive precursors; maleic anhydride grafted polypropylene (PP-g-MA) and styrene maleic anhydride copolymer (SMA) for PA6/PP and PA6/PS pairs, respectively. For comparison purposes, uncompatibilized and reactively compatibilized PA6/PP

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 c...

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

Research paper thumbnail of Phase continuity detection and phase inversion phenomena in immiscible polypropylene/polystyrene blends with different viscosity ratios

Polymer, 2007

Blends of polypropylene (PP) and polystyrene (PS) were prepared in a twin-screw extruder and stud... more Blends of polypropylene (PP) and polystyrene (PS) were prepared in a twin-screw extruder and studied in a wide range of compositions. Phase continuity was first determined using selective solvent extraction. Subsequently, dynamic stress rheometry and dynamic mechanical analysis were used to detect the co-continuity and phase inversion compositions in the melt and the solid states. It appears that the phase inversion occurs in a domain rather than at a single point. The evaluation of the storage modulus of PP/PS blends in the melt at a constant low frequency gives information about the co-continuity, as far as the onset of co-continuity and phase inversion composition of the PS phase are concerned. The evaluation of the storage modulus and mechanical loss factor at a constant high temperature, or the glass transition temperature intensity allowed to precisely detect the phase inversion composition. The fractionated or bulk crystallization behavior of the crystallizable PP phase in the PP/PS blends can also be used to identify the matrix/dispersed phase or co-continuous phase morphology. Several semi-empirical models using the dynamic viscoelastic properties of blend components have been applied to detect the phase inversion composition. An extensive data set presented, can also be used to guide future modeling.

Research paper thumbnail of Synthesis and compatibilization ability of hydrogenated polybutadiene-b-polyamide 6 diblock copolymer in low density polyethylene and polyamide 6 blends

Research paper thumbnail of Phase morphology development and stabilization in polycyclohexylmethacrylate/polypropylene blends: uncompatibilized and reactively compatibilized blends using two reactive precursors

Polymer, 2004

The phase morphology developed in immiscible polypropylene (PP)/polycyclohexylmethacrylate (PCHMA... more The phase morphology developed in immiscible polypropylene (PP)/polycyclohexylmethacrylate (PCHMA) blends has been studied using an in situ reactively generated polystyrene-graft-polypropylene compatibilizer from maleic anhydride grafted polypropylene (MA-g-PP) and amine end-capped polystyrene (PS-NH2) reactive precursors during melt-blending. The imidation reaction responsible for the formation of the compatibilizer is similar to the reaction occurring in polyamide/MA-PP (MA-EPR or MA-EPDM) blends which are industrially important. In the present blend PP/PCHMA/(PP-MAPS -NH2), no undesired reaction occurs between the maleic anhydride groups and the backbone of the PCHMA chain, as is usually the case with polyamide homopolymer. This type of reaction, although considered non significant, has consequences on the phase morphology development as it affects the viscosity of the polyamide matrix when chain scission takes place. PP/PCHMA blends covering the whole range of compositions were prepared. The composition window at which the blends exhibit a droplet-in-matrix phase morphology and that where the two phases are co-continuous were determined using a selective phase extraction in combination with scanning electron microscopy. The generation in situ of the PP-g-PS compatibilizer substantially changed the state of the phase morphology developed. In the blends having a droplet-in-matrix type of morphology, the particle sizes were significantly reduced (by a factor of more than 10). Two types of MA-g-PP reactive copolymers differing in maleic anhydride content (1 and 8 wt%) have been separately employed with the same grade of PS-NH2. Emphasis was put on a detailed investigation of the behaviour and structural stability of the blends exhibiting a co-continuous phase morphology when the compatibilizer is generated. Significant differences were found in relation to the maleic anhydride content of the MA-PP reactive compatibilizer precursor.

Research paper thumbnail of Reactively and physically compatibilized immiscible polymer blends: stability of the copolymer at the interface

Macromolecular Symposia, 2003

This paper reports on the interfacial behaviour of block and graft copolymers used as compatibili... more This paper reports on the interfacial behaviour of block and graft copolymers used as compatibilizers in immiscible polymer blends. A limited residence time of the copolymer at the interface has been shown in both reactive blending and blend compatibilization by preformed copolymers. Polystyrene (PS)/polyamide6 (PA6), polyphenylene oxide (PPO)/PA6 and polymethylmethacrylate (PMMA)/PA6 blends have been reactively compatibilized by a styrene‐maleic anhydride copolymer SMA. The extent of miscibility of SMA with PS, PPO and PMMA is a key criterion for the stability of the graft copolymer at the interface. For the first 10 to 15 minutes of mixing, the in situ formed copolymer is able to decrease the particle size of the dispersed phase and to prevent it from coalescencing. However, upon increasing mixing time, the copolymer leaves the interface which results in phase coalescence.In PS/LDPE blends compatibilized by preformed PS/hydrogenated polybutadiene (hPB) block copolymers, a tapered ...

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

Macromolecular Rapid Communications, 2008

Research paper thumbnail of Block balance in hydrogenated polybutadiene-b-polymethylmethacrylate diblock copolymer for efficient interfacial activity in low-density polyethylene/polymethylmethacrylate blend: Phase morphology development

Journal of Polymer Science Part B: Polymer Physics, 2005

The objective of the present study was to determine the best molecular balance between the two hy... more The objective of the present study was to determine the best molecular balance between the two hydrogenated polybutadiene (HPB) and polymethylmethacrylate (PMMA) blocks that promotes an HPB-b-PMMA diblock copolymer with efficient compatibilization activity in a low-density polyethylene (LDPE)/PMMA immiscible blend. The model blend selected, LDPE/PMMA, is more immiscible than the LDPE/ polystyrene pair largely reported in open literature. The blends having a composition of 80LDPE/20PMMA exhibit a droplet-in-matrix phase morphology whereas in 20LDPE/ 80PMMA a co-continuous phase morphology was developed. In the droplet-in-matrix phase morphology, the emulsifying efficiency of the copolymer was evaluated based on the maximum reduction of the PMMA droplet size it is able to promote. Whereas, in the co-continuous phase morphology, the copolymer was evaluated based on its ability to stabilize the maximum phase co-continuity. The sequences of the best emulsifying copolymer revealed are not symmetrical. An HPB-b-PMMA where the ratio of molar mass of the blocks, M n HPB /M n PMMA, is within 1.8-1.95 exhibits a much better interfacial activity in LDPE/PMMA blends than a copolymer of much lower ratio (longer PMMA block). This is ascribed to the much higher interactions (cohesive energy density) encountered in PMMA (PMMA of the copolymer and PMMA phase of the blend) compared with the LDPE side (HPB of the copolymer and LDPE phase of the blend).

Research paper thumbnail of Stabilization of a cocontinuous phase morphology by a tapered diblock or triblock copolymer in polystyrene‐rich low‐density polyethylene/polystyrene blends

Journal of Polymer Science Part B: Polymer Physics, 2002

The stability against the thermal annealing of a cocontinuous two‐phase morphology developed in p... more The stability against the thermal annealing of a cocontinuous two‐phase morphology developed in polystyrene (PS)/low‐density polyethylene (LDPE) blends containing 80 wt % PS was investigated. Blends containing 1, 5, and 10 wt % of a tapered diblock poly(styrene‐block‐hydrogenated butadiene) (P(S‐b‐hB)) or triblock poly(styrene‐block‐hydrogenated butadiene‐block‐styrene) (P(S‐hB‐S)) copolymer were melt‐blended with roll‐mill mixing equipment. The efficiency of each of the two copolymers in stabilizing against coalescence the cocontinuous morphology was examined. The tensile properties of the resulting blends, annealed and nonannealed, were also examined in relation to the morphology induced by thermal annealing. The phase morphology was studied by optical and scanning electron microscopy. With computer‐aided image analysis, it was possible to obtain a measurable characteristic parameter to quantify the cocontinuous phase morphology. When it was necessary, the extraction of one phase ...

Research paper thumbnail of Stress-strain behavior of low-density polyethylene/poly(methyl methacrylate) blends with modulated interfaces with a hydrogenated polybutadiene-block-poly(methyl methacrylate) diblock copolymer

Journal of Polymer Science Part B: Polymer Physics, 2004

ABSTRACT

Research paper thumbnail of Molecular design of multicomponent polymer systems, XI, emulsifying effect of poly(hydrogenated diene-b-methyl methacrylate) in poly(vinylidene fluoride)/polyolefins blends

Journal of Applied Polymer Science, 1986

Research paper thumbnail of Design and characterisation of microfibrillar reinforced composite materials based on PET/PA12 blends

Composites Part A: Applied Science and Manufacturing, 2004

Microfibrillar reinforced composites (MFCs) have been prepared by reactive melt-extrusion of poly... more Microfibrillar reinforced composites (MFCs) have been prepared by reactive melt-extrusion of poly(ethylene terephthalate) (PET) and polyamide 12 (PA12) in the presence of a catalyst. These composites have been generated by a series of processes, which include reactive extrusion in a mini twin-screw extruder, followed by drawing (fibrillation) and finally the isotropisation of the lower-melting PA12 phase. During the preparation of

Research paper thumbnail of Adsorption of polyampholyte copolymers at the solid/liquid interface: the influence of pH and salt on the adsorption behaviour

Physical Chemistry Chemical Physics, 1999

Polyampholytes are macromolecules that contain oppositely charged groups. We have studied the ads... more Polyampholytes are macromolecules that contain oppositely charged groups. We have studied the adsorption of the polyampholyte diblock copolymer poly(methacrylic acid)-block-poly((dimethylamino)ethyl methacrylate), PMAA-b-PDMAEMA, on oxidized silicon surfaces. The amount of polymer adsorbed from aqueous solution of different pH and salt concentration was measured by ellipsometry. The influence of the added salts NaCl, Na 2 SO 4 and CaCl 2 was determined. In every case adsorption took place, although the polyampholyte and the substrate exhibit the same sign of net charge. For all types of salt, the adsorbed amount shows two maxima close to the isoelectric point (IEP) of the polymer as a function of pH. Directly at the IEP of the polyampholyte, no adsorption was found. The measured dependences can be explained by the adsorption of one or the other of the two blocks depending on acidity and ionic strength. Furthermore, the lateral structure of the dried films was investigated by scanning force microscopy (SFM).