End-grained wood-polyurethane composites, 1 Synthesis, morphology and characterization

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 ▲]

Effects of temperature on the chemistry of the echinoderm skeleton

Poster (2004)

2-oxepane-1,5-dione: a precursor of a novel class of versatile semicrystalline biodegradable (co)-polyesters

Poster (2003, July 01)

2-oxepane-1,5-dione (OPD) was synthesized by Baeyer-Villiger oxidation of 1,4-cyclohexanedione and ring-opening polymerized by 1-phenyl-2-propanol / tin octoate with formation of a semicrystalline ... [more ▼]

2-oxepane-1,5-dione (OPD) was synthesized by Baeyer-Villiger oxidation of 1,4-cyclohexanedione and ring-opening polymerized by 1-phenyl-2-propanol / tin octoate with formation of a semicrystalline polyester of high melting temperature (Tm: 147°C). A crystallographic study showed that the polyester is orthorombic in the P212121 space with two molecules extended along the c-axis as is the case for poly(ε-caprolactone) (PCL). Dibutyltin dimethoxide and 2,2-dibutyl-2-stanna-1,3-dioxepane (DSDOP) proved to be efficient initiators for the random copolymerization of ε-caprolactone (εCL) and OPD. Random distribution of the comonomer units was confirmed by DSC, 1H and 13C NMR analyses. A single Tm was observed, which varies regularly and monotonically with the OPD content as result of a cocrystallisation phenomenon. The single glass transition temperature (Tg) obeys the Fox equation. It is noteworthy that a copolymer containing 30 mol % OPD exhibits a Tm of 90°C. It is stable up to 140°C under nitrogen for one hour, such that processing by extrusion is quite possible. The OPD decomposition is maximum at 223°C for a heating rate of 10°C/min. The mechanism of thermal degradation was investigated and cleared up. The ketone increases the copolymer hydrophilicity and thus sensitivity to hydrolysis. The mechanical properties are quite reminiscent of PCL of comparable molecular weight. Quite interestingly, OPD imparts sensitivity to photo-cross-linking to this novel class of materials. [less ▲]

Layered silicate/polyester nanohybrids by controlled ring-opening polymerization

in Macromolecular Symposia (2002), 183

In this study, layered silicate/aliphatic polyester nanohybrids were synthesized by ring-opening polymerization of c-caprolactone as promoted by the so-called coordination-insertion mechanism. These ... [more ▼]

In this study, layered silicate/aliphatic polyester nanohybrids were synthesized by ring-opening polymerization of c-caprolactone as promoted by the so-called coordination-insertion mechanism. These nanocomposites were formed in presence of montmorillortite surface-modified by ammonium cations bearing hydroxyl group(s), such as bis(2-hydroxyethyl)methyl (hydrogenated tallow alkyl) ammonium. The lactone polymerization could in initiated by all the hydroxyl functions available at the clay surface, after activation into either tin(II) or AI(III) alkoxide active species. Hybrid nanocomposites were accordingly generated through the covalent grafting of every polyester chain onto the filler surface. Surface-grafted polycaprolactone (PCL) chains were untied and isolated by ionic exchange reaction with LiCl in THF solution and molar masses were measured by size exclusion chromatography. The PCL molar masses could be controlled and readily tuned by the content of hydroxyl groups available at the clay surface. Interestingly, initiation reaction by aluminum trialkoxide active species yielded grafted PCL chains characterized by very narrow molecular weight distribution (M-w/M(n)similar to1.2). These polyester-grafted layered silicate nanohybrids displayed complete exfoliation of silicate sheets as shown by X-ray diffraction (XRD) and transmission electron microscopy (TEM). [less ▲]

Cyclic esterketone compounds, processes for the synthesis thereof and process for the preparation of poly (esterketone) polymers

Patent (2002)

Unsubstituted oxepane-diones useful as monomers for the production of polymers, process for the synthesis thereof by oxidation of unsubstituted cyclohexanediones, process for the preparation of ... [more ▼]

Unsubstituted oxepane-diones useful as monomers for the production of polymers, process for the synthesis thereof by oxidation of unsubstituted cyclohexanediones, process for the preparation of polyesterketone polymers by polymerization of cyclic esterketones and polyesterketone polymers so obtained. [less ▲]

Cyclic esterketone compounds, processes for the synthesis thereof and process for the preparation of poly (esterketone) polymers

Patent (2001)

PROBLEM TO BE SOLVED: To provide a monomer compound, which is improved to be useful as the novel monomer for forming a poly(ester ketone)polymer by polymerization, and can be directly synthesized in high ... [more ▼]

PROBLEM TO BE SOLVED: To provide a monomer compound, which is improved to be useful as the novel monomer for forming a poly(ester ketone)polymer by polymerization, and can be directly synthesized in high yield in a one-stage process from the stock material. SOLUTION: This compound is a novel cyclic ester compound, in particular 2-oxepane-1,5-dione (KCL), synthesized in one-stage process involving oxidation of the stock material (cyclic diketone, e.g. 1,4-cyclohexane-dione) and useful for simply and easily producing a poly(ester ketone)polymer, in particular poly(2- oxepane-1,5-dione) (PKCL) in high yield. [less ▲]

Cyclic esterketone compounds, processes for the synthesis thereof and process for the preparation of poly(esterketone)polymers

Patent (2000)

Unsubstituted oxepane-diones useful as monomers for the production of polymers, process for the synthesis thereof by oxidation of unsubstituted cyclohexanediones, process for the preparation of ... [more ▼]

Unsubstituted oxepane-diones useful as monomers for the production of polymers, process for the synthesis thereof by oxidation of unsubstituted cyclohexanediones, process for the preparation of polyesterketone polymers by polymerisation of cyclic esterketones and polyesterketone polymers so obtained. [less ▲]

Synthesis of polynorbornene grafted with poly(ε-caprolactone) by sequential controlled ring opening polymerization

Poster (1999, April 12)

Analysis of living tert-butyl methacrylate oligoanions in tetrahydrofuran by NMR spectroscopy, viscosity and light scattering

in Macromolecular Chemistry and Physics (1999), 200(3), 562-573

Previous kinetic studies concluded on the aggregation of the anionic chain ends of living tert-butyl methacrylate oligomers [PtBMA-, Li+] in THF at low temperature. This aggregation has been confirmed by ... [more ▼]

Previous kinetic studies concluded on the aggregation of the anionic chain ends of living tert-butyl methacrylate oligomers [PtBMA-, Li+] in THF at low temperature. This aggregation has been confirmed by viscosimetry, light scattering and gradient field NMR techniques in a range of temperature from 253 K to 298 K. These techniques have been systematically used for the analysis of both the living oligomers and the same chains recovered after hydrolysis of the anionic end groups. The structure of the growing anionic species was analyzed by means of 13C and 7Li NMR spectroscopy. 13C NMR required the selective labeling of the last monomer units by 13C atoms. [less ▲]

Process for radical controlled polymerization or copolymerization of (meth)acryl and vinyl monomers and thus prepared (co)polymers

Patent (1998)

This process is characterized by the fact that at least one of the said monomers is polymerized or copolymerized in bulk, solution, emulsion or suspension, at a temperature that can be as low as 0 DEG C ... [more ▼]

This process is characterized by the fact that at least one of the said monomers is polymerized or copolymerized in bulk, solution, emulsion or suspension, at a temperature that can be as low as 0 DEG C., in the presence of an initiation system including: at least one compound generating radicals, other than bromofluorene, and at least one catalyst consisting of a complex of palladium in the 0 oxidation state, denoted by the following formula (I): Pd(0)L1L2L3L4 in which each of L1, L2, L3 and L4, which are identical or different, denotes a ligand which may be a chiral ligand, which is chosen from PRR'R'', P(OR)(OR')(OR''), NRR'R'', ORR', SRR', SeRR', AsRR'R'', SbRR'R'', where each of R, R' and R'' independently denotes a C1-C14 alkyl group, optionally substituted, or an optionally substituted aromatic group, it being possible for at least two of these ligands to be joined to one another by one or more divalent radicals. [less ▲]