References of "Degée, Philippe"
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See detailOxidative degradations of oxodegradable LDPE enhanced with thermoplastic pea starch: thermo-mechanical properties, morphology, and UV-ageing studies
Raquez, Jean-Marie; Bourgeois, Aurore; Jacobs, Heidi et al

in Journal of Applied Polymer Science (2011), 122(1), 489496

The abiotic UV-degradation behavior of oxodegradable LDPE was investigated in the presence of thermoplastic pea starch (TPPS) in this study. Oxodegradable LDPE was first melt-blended with thermoplastic ... [more ▼]

The abiotic UV-degradation behavior of oxodegradable LDPE was investigated in the presence of thermoplastic pea starch (TPPS) in this study. Oxodegradable LDPE was first melt-blended with thermoplastic pea starch (TPPS) using an internal mixing chamber to enhance the abiotic oxidative degradation of oxodegradable LDPE. Because of their different affinity, maleated polyethylene was added as compatibilizer. Tensile properties, thermal properties, and morphology of resulting melt-blends were determined at different content in TPPS. High content in TPPS (40 wt %) could be readily added to oxodegradable LDPE without affecting the tensile properties of resulting melt-blends. UV-ageing studies on compatibilized TPPS/oxodegradable LDPE melt-blends were carried out by Attenuated Total Reflectance infrared spectroscopy (ATR-FTIR), Dynamic Thermomechanical Analyses (DMTA) and Differential Scanning Calorimetry (DSC) under abiotic conditions. These results suggested a synergistic effect on the UV-ageing of TPPS-based melt-blends provided by both components during the first stage of UV-irradiation. [less ▲]

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See detailCopolymerization of vinyl acetate with 1-octene and ethylene by cobalt-mediated radical polymerization
Bryaskova, Rayna ULg; Willet, Nicolas ULg; Degée, Philippe et al

in Journal of Polymer Science. Part A, Polymer Chemistry (2007), 45(12), 2532-2542

The cobalt-mediated radical polymerization of vinyl acetate was extended to copolymerization with I-alkenes (ethylene or 1-octene). In agreement with the low amount of I-alkene that could be incorporated ... [more ▼]

The cobalt-mediated radical polymerization of vinyl acetate was extended to copolymerization with I-alkenes (ethylene or 1-octene). In agreement with the low amount of I-alkene that could be incorporated into the copolymer, a gradient structure was predictable, but a. rather low polydispersity was observed. A poly(vinyl acetate)-b-poly(octene) copolymer was also successfully synthesized, leading to a poly (vinyl alcohol)-b-poly(octene) amphiphilic copolymer upon the methanolysis of the poly (vinyl acetate) block. [less ▲]

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See detail(Plasticized) polylactide/(organo-)clay nanocomposites by in situ intercalative polymerization
Paul, Marie-Amélie; Delcourt, Cécile; Alexandre, Michaël ULg et al

in Macromolecular Chemistry and Physics (2005), 206(4), 484-498

Both intercalated and exfoliated poly(L,L-lactide) (P(L,L-LA)/organomodified montmorillonite nanocomposites were synthesized by in situ ring-opening polymerization Of L,L-lactide, in bulk, directly in the ... [more ▼]

Both intercalated and exfoliated poly(L,L-lactide) (P(L,L-LA)/organomodified montmorillonite nanocomposites were synthesized by in situ ring-opening polymerization Of L,L-lactide, in bulk, directly in the presence of the nanofiller. Intercalation of polyester chains was found to appear even for natural unmodified montmorillonite-Na+, while exfoliation occurred when the aluminosilicate layers were modified by ammonium cations bearing primary hydroxyl groups. Clay delamination was effectively triggered by the grafting reaction of the growing PLA chains onto the hydroxyl groups. Aluminium triisopropoxide, triethylaluminium, and stannous octoate, as initiating or co-initiating species, were compared in terms of polymerization control. The influence of nanoclay content (from 1 to 10 wt.-% in inorganics) on morphology and thermal behavior was also studied. In parallel, a highly filled nanocomposite (called masterbatch), prepared by in situ polymerization, was dispersed into a (plasticized) preformed polylactide matrix in the molten state, to reach a better clay delamination than that obtained by direct melt blending. Finally, L-,L-lactide and alpha,w-dihydroxylated poly(ethylene glycol) (PEG 1000) were copolymerized in presence of clay in order to study the behavior of the resulting triblocks towards nanocomposite formation. [less ▲]

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See detailEnd-grained wood-polyurethane composites, 1 Synthesis, morphology and characterization
Persenaire, Olivier; Alexandre, Michaël ULg; Degée, Philippe et al

in Macromolecular Materials and Engineering (2004), 289(10), 895-902

In order to improve the dimensional stability of end-grained wood upon environmental humidity variations, a two-step procedure was thoroughly Studied which involved the osmotic impregnation of native ... [more ▼]

In order to improve the dimensional stability of end-grained wood upon environmental humidity variations, a two-step procedure was thoroughly Studied which involved the osmotic impregnation of native poplar wood by PEG, followed by the reactive impregnation with HMDI, leading to polymer chain extension and polyurethane formation. It came out that the efficiency of PEG and/or polyurethane grafting within ligno-cellulosic cell walls was intimately related to parameters such as concentration of the PEG impregnation bath, PEG molar mass, time and temperature of impregnation steps. Based on the different sample characterizations, Soxhlet extraction and density measurements, it came out that adequate experimental conditions are to carry out osmotic impreanation at 20degreesC for 24 h starting from an aqueous solution of PEG([PEG] = 0.5mol(.)L(-1) and (M) over bar (nPEG) = 400 or 1000) and reactive impregnation in bulk with a large excess of HMDI at 20degreesC for 2 h. Combining scanning electron microscopy and mercury porosimetry demonstrated the selective impregnation of cell wall and wood rays which were collapsed in native wood and expanded in wood polyurethane composites. [less ▲]

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See detailEnhancement of transfection efficiency through rapid and noncovalent post-PEGylation of poly(dimethylaminoethyl methacrylate)/DNA complexes
Pirotton, S.; Muller, Caroline; Pantoustier, N. et al

in Pharmaceutical Research (2004), 21(8), 1471-1479

Purpose. The aim of this work was to develop a new strategy to introduce poly(ethylene glycol) (PEG) into methacrylate-based polymer/ DNA complexes in order to produce hemocompatible particles able to ... [more ▼]

Purpose. The aim of this work was to develop a new strategy to introduce poly(ethylene glycol) (PEG) into methacrylate-based polymer/ DNA complexes in order to produce hemocompatible particles able to transfect cells in the presence of serum. Methods. Atom transfer radical polymerization was used to synthesize a well-defined poly(2-(dimethylamino) ethyl methacrylate) homopolymer ( PDMAEMA) and a poly( 2-( dimethylamino) ethyl methacrylate-b-poly( ethylene glycol) alpha-methyl ether, omega-methacrylate) palm-tree-like copolymer (P(DMAEMA-b-MAPEG)). The complexes obtained by self assembly of the pCMVbeta plasmid and the polymers were used to transfect Cos-7 cells. Their physical properties - particle size and zeta potential - were characterized respectively by dynamic light scattering and electrophoretic mobility measurements. Ex vivo hemocompatibility was also determined. Results. The PDMAEMA/pCMVbeta complexes transfected Cos-7 cells exclusively in the absence of serum. Although the P(DMAEMA-b-MAPEG) copolymer had no transfection activity per se, the addition of the latter to pre-formed PDMAEMA/DNA complexes significantly enhanced the activity and allowed transfection even in the presence of serum. The presence of palm-tree - like copolymers also improved the hemocompatibility properties of the complexes. No effect on platelet counts was observed for P(DMAEMA-b-MAPEG)/ pCMVbeta complexes, whereas a decrease of platelets was clearly observed when blood cells were incubated with PDMAEMA/pCMVbeta complexes. Conclusions. Such a synergistic effect of noncovalent PEGylation of poly( amino methacrylate)/ DNA complexes allows a new and versatile approach to tune up transfection efficiency. [less ▲]

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See detailExfoliated polylactide/clay nanocomposites by in-situ coordination-insertion polymerization
Paul, Marie-Amélie; Alexandre, Michaël ULg; Degée, Philippe et al

in Macromolecular Rapid Communications (2003), 24(9), 561-566

Poly(L-lactide)/layered aluminosilicate nanocomposites were synthesized in bulk by ring-opening polymerization in the presence of two organo-modified montmorillonites. When the organo-modifier consisted ... [more ▼]

Poly(L-lactide)/layered aluminosilicate nanocomposites were synthesized in bulk by ring-opening polymerization in the presence of two organo-modified montmorillonites. When the organo-modifier consisted of an ammonium cation bearing primary hydroxyl groups, polymerization was initiated by the alcohol functions after adequate activation. The growing polymer chains were directly "grafted" onto the clay surface through the hydroxyl-functionalized ammonium cations yielding exfoliated nano-composites with enhanced thermal stability. [less ▲]

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See detailNew nanocomposite materials based on plasticized poly(L-lactide) and organo-modified montmorillonites: thermal and morphological study
Paul, Marie-Amélie; Degée, Philippe; Henrist, Catherine ULg et al

in Polymer (2003), 44(2), 443-450

Plasticized poly(L-lactide) (PLA) based nanocomposites were prepared by melt blending of the matrix with 20 wt% of poly(ethyleneglycol) 1000 (PEG 1000) and different amounts of montmorillonite, organo ... [more ▼]

Plasticized poly(L-lactide) (PLA) based nanocomposites were prepared by melt blending of the matrix with 20 wt% of poly(ethyleneglycol) 1000 (PEG 1000) and different amounts of montmorillonite, organo-modified or not. The intercalation of the polymer chains between the aluminosilicates layers and morphological structure of the filled PLAs were analysed by wide-angle X-ray scattering (WAXS). Thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC) were performed to study the thermal behaviour of the prepared composites. At constant filler level, it appears that from all the clays studied, the montmorillonite organo-modified by bis-(2-hydroxyethyl)methyl (hydrogenated tallowalkyl) ammonium cations brings the greater effect in terms of thermal stability. Increasing the amount of clay allows to delay the onset of thermal degradation of the plasticized polymer matrix. It was also pointed out, by WAXS and DSC analyses, that it exists a real competition between PEG 1000 and PLA for the intercalation into the interlayer spacing of the clay. (C) 2002 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailIntercalative polymerization of cyclic esters in layered silicates : thermal vs. catalytic activation
Pantoustier, Nadège; Alexandre, Michaël ULg; Degée, Philippe et al

in Composite Interfaces (2003), 10(4-5), 423-433

Poly(ε-caprolactone) layered silicate nanocomposites were synthesized by in situ inter-calative ring-opening polymerization (ROP) of ε-caprolactone. The polymerization was promoted by thermal or catalytic ... [more ▼]

Poly(ε-caprolactone) layered silicate nanocomposites were synthesized by in situ inter-calative ring-opening polymerization (ROP) of ε-caprolactone. The polymerization was promoted by thermal or catalytic initiation starting from either non-modified natural sodium-montmorillonite (MMT-Na) or montmorillonite modified by different ammonium cations bearing either non-functional alkyl chains or chains terminated by carboxylic acid or hydroxyl functions. The resulting compositions were analyzed by small-angle X-ray diffraction and transmission electron microscopy. The clay dispersion depended on the structure of the alkyl ammonium. Exfoliated nanocomposites were formed when hydroxyl-containing alkyl-ammonium was used; otherwise, partially intercalated/partially exfoliated structures were observed. Moreover, caving to the inherent catalytic properties of the montmo-rillomte surface, it was also possible to prepare intercalated nanocomposites by in situ polymerization of ε-caprolactone in presence of non-modified montmorillonite-Na (MMT-Na) without any added catalyst. [less ▲]

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See detailPoly(e-caprolactone) layered silicate nanocomposites: effect of clay surface modifiers on the melt intercalation process
Pantoustier, Nadège; Alexandre, Michaël ULg; Degée, Philippe et al

in e-Polymers (2001), (9), 1-9

Nanocomposites based on biodegradable poly(e-caprolactone) (PCL) and layered silicates (montmorillonite) modified by various alkylammonium cations were prepared by melt intercalation. Depending on whether ... [more ▼]

Nanocomposites based on biodegradable poly(e-caprolactone) (PCL) and layered silicates (montmorillonite) modified by various alkylammonium cations were prepared by melt intercalation. Depending on whether the ammonium cations contain non-functional alkyl chains or chains terminated by carboxylic acid or hydroxyl functions, microcomposites or nanocomposites were recovered as shown by X-ray diffraction and transmission electron microscopy. Mechanical and thermal properties were examined by tensile testing and thermogravimetric analysis. The layered silicate PCL nanocomposites exhibited some improvement of the mechanical properties (higher Young's modulus) and increased thermal stability as well as enhanced flame retardant characteristics as result of a charring effect. This communication aims at reporting that the formation of PCL-based nanocomposites strictly depends on the nature of the ammonium cation and its functionality, but also on the selected synthetic route, i.e. melt intercalation vs. in situ intercalative polymerization. Typically, protonated w-aminododecanoic acid exchanged montmorillonite allowed to intercalate e-caprolactone monomer and yielded nanocomposites upon in situ polymerization, whereas they exclusively formed microcomposites when blended with preformed PCL chains. In other words, it is shown that the formation of polymer layered silicate nanocomposites is not straightforward and cannot be predicted since it strongly depends on parameters such as ammonium cation type and functionality together with the production procedure, i.e., melt intercalation, solvent evaporation or in situ polymerization [less ▲]

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See detailSingle-step reactive extrusion of PLLA in a corotating twin-screw extruder promoted by 2-ethylhexanoic acid tin(II) salt and triphenylphosphine
Jacobsen, S.; Fritz, H. G.; Degée, Philippe et al

in Polymer (2000), 41(9), 3395-3403

The ring opening polymerisation of L,L-lactide using an equimolar complex of 2-ethylhexanoic acid tin(II) salt Sn(Oct)2 and triphenylphosphine P( )3 as catalyst shows for the first time a reactivity ... [more ▼]

The ring opening polymerisation of L,L-lactide using an equimolar complex of 2-ethylhexanoic acid tin(II) salt Sn(Oct)2 and triphenylphosphine P( )3 as catalyst shows for the first time a reactivity providing a polymerisation propagation rate fast enough to imagine a continuous single-step reactive extrusion process for bulk polymerisation. The ring opening polymerisation has been realised on a corotating closely intermeshing twin-screw extruder, using a specially designed screw concept to provide sufficient energy input and mixing for further enhancement of the propagation rate, without detrimentally enhancing depolymerisation or transesterification reactions. Using one chosen screw and processing concept on a twin-screw extruder with 25 mm diameter and a L/D-ratio of 48, the influence of different processing parameters on the resulting molecular parameters of the Polylactide (PLA) has been determined. Furthermore, the mechanical property profile of the generated PLA-polymers is discussed and related to the molecular parameters. [less ▲]

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See detailContinuous reactive extrusion polymerization of L-lactide - an engineering view
Jacobsen, Sven; Fritz, Hans-Gerhard; Degée, Philippe et al

in Macromolecular Symposia (2000), 153

Polylactides (PLA), biodegradable aliphatic polyesters, produced from renewable resources might substitute petrochemically based polymers in a broad range of applications in the near future, if we manage ... [more ▼]

Polylactides (PLA), biodegradable aliphatic polyesters, produced from renewable resources might substitute petrochemically based polymers in a broad range of applications in the near future, if we manage to produce them at lower cost and higher efficiency than nowadays. Possible applications include food packaging for meat and soft drinks, films for agro-industry and non-wovens in hygienic products. The authors developed, based on a new catalytic system, a reactive extrusion polymerisation process, which can be used to produce PLA continuously in larger quantities and at lower costs than before. This extrusion polymerisation process has been developed and tested with laboratory scale machines and has to be transferred to industrial processing equipment. This paper aims to address the problems attached with this transfer and to discuss the chances to finally achieve low cost PLA at industrial scale. [less ▲]

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See detailNew developments on the ring opening polymerisation of polylactide
Jacobsen, Sven; Fritz, Hans-Gerhard; Degée, Philippe et al

in Industrial Crops & Products (2000), 11

Polylactides (PLA), biodegradable aliphatic polyesters, produced solely from renewable resources may substitute petrochemically based polymers in a broad range of applications in the near future, if we ... [more ▼]

Polylactides (PLA), biodegradable aliphatic polyesters, produced solely from renewable resources may substitute petrochemically based polymers in a broad range of applications in the near future, if we manage to produce them at lower cost and higher efficiency as nowadays. Possible applications include food packaging for meat and soft drinks, films for agro-industry and non-wovens in hygienic products. The authors developed, based on a new catalytic system, a reactive extrusion polymerisation process, which can be used to produce PLA continuously in larger quantities and at lower costs than before. This extrusion polymerisation process has been developed and tested with laboratory scale machines and the possibilities to extend this polymerisation process to lactide based blockcopolymers have been investigated. [less ▲]

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See detailNew catalysis for fast bulk ring-opening polymerization of lactide monomers
Degée, Philippe; Dubois, Philippe ULg; Jérôme, Robert ULg et al

in Macromolecular Symposia (1999), 144

The ring-opening polymerization of lactides has been studied in bulk using either 2-ethylhexanoic acid tin(II) salt, Sn(Oct)2, or aluminum triisopropoxide, Al(OiPr)3, as the initiator over a wide range of ... [more ▼]

The ring-opening polymerization of lactides has been studied in bulk using either 2-ethylhexanoic acid tin(II) salt, Sn(Oct)2, or aluminum triisopropoxide, Al(OiPr)3, as the initiator over a wide range of temperature and monomer-to-initiator molar ratio, A high increase in the bulk polymerization rate has been observed when the initiator was added with an equimolar amount of a Lewis base, such as triphenylphosphine and 4-picoline (C6H7N) added to Sn(Oct)2 and Al(OiPr)3, respectively Melt stable polylactides of high molecular weight and reasonably narrow molecular weight distribution have been accordingly prepared. The use of the Sn(Oct)2. equimolar combination has allowed for reaching an acceptable balance between propagation and depolymerization rates, so that the polymerization is fast enough to be performed through a continuous single-stage process in a twin-screw extruder A global activation mechanism is proposed and discussed by comparison with both investigated initiation systems. [less ▲]

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See detailBeneficial effect of triphenylphosphine on the bulk polymerization of L,L-lactide promoted by 2-ethylhexanoic acid tin (II) salt
Degée, Philippe; Dubois, Philippe ULg; Jacobsen, S. et al

in Journal of Polymer Science. Part A, Polymer Chemistry (1999), 37(14), 2413-2420

The ring-opening polymerization of L,L-lactide has been studied in bulk using 2-ethylhexanoic acid tin (II) salt, Sn(Oct)2, as a catalyst over a wide range of temperature and monomer to Sn(Oct)2 molar ... [more ▼]

The ring-opening polymerization of L,L-lactide has been studied in bulk using 2-ethylhexanoic acid tin (II) salt, Sn(Oct)2, as a catalyst over a wide range of temperature and monomer to Sn(Oct)2 molar ratio. Although Sn(Oct)2 was known to initiate a fast polymerization, it is reported now that some Lewis bases, particularly triphenylphosphine (P()3), can increase further the polymerization rate, without any detrimental effect on the polylactide thermal stability. In order to optimize the balance between propagation and competing depolymerization reactions, the experimental conditions, i.e., temperature and concentration of Sn(Oct)2 and P()3 have been optimized. The up-scaling of the laboratory experiments to reactive extrusion has proved to be feasible, which demonstrates the efficiency of this catalytic system to produce polylactide in a continuous one-stage polymerization process. [less ▲]

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See detailPolylactide (PLA) – A new way of production
Jacobsen, Sven; Degée, Philippe; Fritz, Hans-Gerhard et al

in Polymer Engineering & Science (1999), 39(7), 1311-1319

Poly(lactide) (PLA), a biodegradable aliphatic polyester with excellent properties for different polymer applications, has been used mostly in the biomedical field, mainly because of its high price ... [more ▼]

Poly(lactide) (PLA), a biodegradable aliphatic polyester with excellent properties for different polymer applications, has been used mostly in the biomedical field, mainly because of its high price, resulting from expensive polymerization and purification techniques. Although this polymer can play a major role in future markets for biodegradable polymers, the current high price has to be reduced significantly to at least $4 US/kg. Therefore, this paper aims to partially review the polymerization techniques traditionally used in PLA synthesis and to propose new developments that enable us to produce these polymers by an innovative process for just a portion of the costs traditionally charged, using reactive extrusion techniques in a closely intermeshing co-rotating twin screw extruder. This paper gives an overview of attainable mechanical properties and future markets. [less ▲]

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See detailBulk polymerization of lactides initiated by aluminum isopropoxide. 1. Mechanism and kinetics
Degée, Philippe; Dubois, Philippe ULg; Jérôme, Robert ULg

in Macromolecular Symposia (1997), 123

Commercially available Al isopiopoxide (Al(OiPr)3) has proved to be an efficient initiator for the bulk polymerization of lactide. The ring-opening polymerization proceeds through a "coordination ... [more ▼]

Commercially available Al isopiopoxide (Al(OiPr)3) has proved to be an efficient initiator for the bulk polymerization of lactide. The ring-opening polymerization proceeds through a "coordination-insertion" mechanism and the selective rupture of the acyl-oxygen bond of the monomer Polyester chains are selectively end-capped with an aluminum alkoxide and an isopropoxy group. Therefore, substitution of Al tris(4-penten-1-olate) for Al(OiPr)3 leads to the formation of macromonomers In the temperature range from 110 to 150°C, polymerization is "living", i.e. the molecular weight can be predicted by the initial monomer-to-Al molar ratio and the monomer conversion. The narrower polydispetsity of poly(L,L-lactide) compared to the amorphous poly(D,L-lactide) ( 1.3 compared to 1.9, respectively), both prepared in the bulk, is thought to result from the restricted mobility of the crystallized isotactic polyester chains. When the temperature is increased up to 180°C, inter- and intramolecular transesterification reactions interfere with chain propagation. [less ▲]

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See detailDesign of polymer blend rheology: 4. Effect of polymethacrylic ionomers on the melt viscosity of polyamide m x D,6
Degée, Philippe; Vankan, R.; Teyssié, Philippe et al

in Polymer (1997), 38(15), 3861-3867

Rheological properties of blends of polyamide m x D,6 (PA) with random copolymers of methyl methacrylate and methacrylic acid (P(MMA-co-MAA)) and the related ionomers (P(MMA-co-metal MA)), respectively ... [more ▼]

Rheological properties of blends of polyamide m x D,6 (PA) with random copolymers of methyl methacrylate and methacrylic acid (P(MMA-co-MAA)) and the related ionomers (P(MMA-co-metal MA)), respectively, have been investigated at 260°C. Addition of small amounts of suitable ionomers (up to 5 wt%) remarkably increases the melt viscosity of PA. At low shear rates and depending on the metal cation of the ionomer, the rheofluidity of PA is reduced by at least two orders of magnitude. The PA melt viscosity increases with the cation as follows: Ni2+ < Ba2+ < Mg2+ < Li+ < Na+ < K+ < Cs+. The major effect is believed to occur when the polymer compatibility is improved to the point where a finely dispersed two-phase system with a low interfacial tension is reached, as a result of strong ion-dipole interactions. Polyblends show a rheothinning behaviour which agrees with the reversibility of H-bonding and dipolar interactions. [less ▲]

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See detailBulk polymerization of lactides initiated by aluminium isopropoxide, 3a). Thermal stability and viscoelastic properties
Degée, Philippe; Dubois, Philippe ULg; Jérôme, Robert ULg

in Macromolecular Chemistry and Physics (1997), 198(6), 1985-1995

The thermal stability of poly(L-lactide) and L/D-lactide stereocopolymers polymerized in bulk with aluminium isopropoxide as initiator was investigated by thermogravimetric analysis, and time and ... [more ▼]

The thermal stability of poly(L-lactide) and L/D-lactide stereocopolymers polymerized in bulk with aluminium isopropoxide as initiator was investigated by thermogravimetric analysis, and time and température dependence of molecular weight and polydispersity. Compared to poly(L-lactide) prepared with stannous octoate as catalyst, the thermal stability of polylactides is remarkably enhanced when the ring-opening polymerization is initiated by aluminium alkoxide. Ultimate mechanical properties and viscoelasticity of these melt-stable thermoplastics have also been studied in relation to the polyester enan-tiomeric composition. [less ▲]

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See detailBulk polymerization of lactides initiated by aluminium isopropoxide, 2a). Beneficial effect of Lewis bases and transfer agents
Degée, Philippe; Dubois, Philippe ULg; Jérôme, Robert ULg

in Macromolecular Chemistry and Physics (1997), 198(6), 1973-1984

A high increase in the bulk polymerization rate of L,L-lactide and racemic D,L-lactide is observed when aluminium isopropoxide is added with an equimolar amount of a Lewis base, such as triphenylphosphine ... [more ▼]

A high increase in the bulk polymerization rate of L,L-lactide and racemic D,L-lactide is observed when aluminium isopropoxide is added with an equimolar amount of a Lewis base, such as triphenylphosphine (P(Φ)3) and better 4-picoline (C6H7N). Polylactide of high molecular weight and narrow molecular weight distribution is accordingly prepared in a controlled manner when the Al(OiPr)3 ; C6H7N combination is used as an initiator over a large temperature range from 110 to 180°C. A secondary alcohol, such as 2-propa-nol, has proved to be an efficient transfer agent, which allows the amount of Al per kg of polylactide to be advantageously reduced. All the alcohol molecules participate in the ring-opening polymerization even at an [iPrOH]0/[Al] ratio as high as 103. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 11. Synthesis and use of alkylaluminium dialkoxides and dithiolates as promoters of hydroxy telechelic poly(epsilon-capprolactone) and alph,omega-dihydroxy triblock copolymers containing outer polyester blocks
Dubois, Philippe; Degée, Philippe; Jérôme, Robert ULg et al

in Macromolecules (1993), 26(11), 2730-2735

Diethylaluminum dialkoxides (Et2AlOXOAlEt2, where X is either an aliphatic radical or a polymer chain) and related dithiolates have been investigated as potential initiators for the ring-opening ... [more ▼]

Diethylaluminum dialkoxides (Et2AlOXOAlEt2, where X is either an aliphatic radical or a polymer chain) and related dithiolates have been investigated as potential initiators for the ring-opening polymerization of ε-caprolactone. Hydroxy telechelic poly(ε-caprolactone) and alpha,omega-dihydroxypoly(ε-caprolactone-b-X-b-ε-caprolactone) have been accordingly prepared and characterized. A hydroxy group is selectively attached at both ends as demonstrated by IR and H-1 NMR spectroscopies and confirmed by titration of the derivatized alpha,omega-dicarboxylic acid (co)polymers. Polymerization of epsilon-caprolactone is living and yields linear polyester chains of a predictable molecular weight and of quite a narrow molecular weight distribution. [less ▲]

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