Josee Brisson

Josee Brisson
Laval University | ULAVAL · Department of Chemistry

PhD Chemistry, Université de Montréal

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103
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Publications (103)
Article
Full-text available
The dielectric constant (DC) is one of the key properties for detection of threat materials such as Improvised Explosive Devices (IEDs). In the present paper, the density functional theory (DFT) as well as ab-initio approaches are used to explore effective methods to predict dielectric constants of a series of 12 energetic materials (EMs) for which...
Article
In this work, a thiol-ene click reaction was used to graft polystyrene (PS) chains onto the surface of ethylene propylene diene monomer-based ground tire rubber (GTR). A thiol-terminated PS (11 kg mol ⁻¹ ) was selected, due to its commercial availability, to modify a postconsumer GTR. The resulting PS-grafted GTR (GTR- g-PS) particles were analyzed...
Article
The present article reports the synthesis of soluble, propyl‐substituted aromatic ring telechelic polycondensation blocks having molecular weights ranging from 1800 to 6500 g mol−1 and polymolecularities of 1.3 to 1.7. Chain‐growth polycondensation is performed, and the initiator is selected through reactivity studies, using 19F nuclear magnetic re...
Article
Sensitive energetic materials are an issue for military and civilian applications. To prevent undesired explosions, sensitive energetic materials are embedded in a protective polymer, resulting in polymer-bonded explosives (PBX). The appropriate polymer will absorb part of the energy caused by stimuli such as shock, impact, friction, and heat, thus...
Article
Polyetherethersulfones with double bonds inserted along the main polymer chain are synthesized by polycondensation. The glass transition is modulated by increasing the size of aromatic etherethersulfone rigid blocks and decreasing the ratio of flexible allyl segments which contain a double bond. Resulting copolymers have a Mn of up to 60 000 g mol−...
Article
This paper proposes a novel approach to predict Hugoniot properties to characterize explosives materials. The originality and uniqueness of the approach consists in using together quantum mechanics, molecular dynamics calculations combined with known analytical methods. Indeed, four highly experimentally characterized energetic materials, cyclotrim...
Article
The properties of recycled styrene-butadiene rubber (SBR) powder with polystyrene (PS) have been studied as a function of compounding conditions in an internal batch mixer. In particular, the effect of temperature (160-220°C), rotor speed (30-120 rpm), homogenization time (3-9 min), components introduction order, surface treatment of SBR powder wit...
Article
Investigations on ethylene-propylene-diene rubber (EPDM) with varying cross-link densities and carbon black contents, as well as commercial EPDM waste ground rubber (WGR), have been performed to improve characterization. The aim is to provide additional quality-control methods in the field of rubber recycling, as WGR is transformed and reused in th...
Article
Acyclic diene metathesis (ADMET) polymerisation and nucleophilic aromatic substitution polycondensation are used to synthesize alternating copolymers based on polyetherethersulfone (PEES) blocks. ADMET results in incorporation of trans-allyl groups with more than 94 to 98% selectivity. The resulting polymers have a Mw of up to 13600 g mol−1 and low...
Article
Gas–liquid membrane contactors are promising alternatives to conventional absorption technologies. However, in spite of their important advantages, such systems suffer from gradual wetting of porous membranes with liquid absorbents. This review focuses on the wetting phenomenon, which is the main concern for long-term operation of CO2 absorption in...
Article
The synthesis of telechelic poly(ether sulfone)s with methoxy end groups is reported. Molecular weights ranging from 1600 to 2800 g mol(-1) and polydispersities of 1.1-1.2 are synthesized by chain-growth condensation polymerization. The initiator is chosen by using semiempirical calculations and F-19 NMR spectroscopy measurements. The polymers are...
Article
The synthesis of four amphiphilic thieno[3,4-c]pyrrole-4,6-dione (TPD)-based alternating copolymers and their behavior at the air–water interface are reported. Homogeneous and stable monolayers of TPD-based copolymers were prepared. Brewster angle microscopy (BAM) was utilized to characterize the morphology and topography of these Langmuir films. U...
Article
Microporous and highly hydrophobic low-density polyethylene (LDPE) hollow fiber membranes were successfully prepared via a solvent-free method, combining melt-extrusion, and salt-leaching techniques. NaCl particles with particle size of 5–10 µm were mixed with LDPE pellets to produce a blend of 35, 40, 50, 60, 65 and 68 wt% of salt. A microporous s...
Article
Uniaxial deformation of amorphous L-polylactic acid films was performed at two different temperatures at which thermal degradation was minimal, 70 °C or Tg + 10 and 90 °C or Tg + 30. Samples were annealed postdeformation for long times (either 15 or 45 min) to approach equilibrium conditions. Samples deformed and annealed at 70 °C showed low crysta...
Article
Syntheses of symmetrical etherketone rigid blocks containing from four to ten aromatic rings were performed by a succession of Williamson synthesis steps, followed by deprotection by BBr3. Solubility decreased upon an increase in number of aromatic rings. Bis-(p-oxy-(p-hydroxyphenyl))benzophenone, a four-ring block, was soluble in the usual solvent...
Article
Full-text available
Models of plastic-bonded explosives were created with the aim of studying the mechanical properties and sensitivity because the latter is one of the most important problems in relation to energetic materials. Previous models proposed in the literature used short plastic chains, which are appropriate for interaction modeling. In the present work, a...
Article
Soluble organic nanorods were prepared from phenylacetylene macrocycles using the topochemical polymerization of butadiyne moieties placed both inside and outside the macrocycles' skeleton. Macrocycles containing amide groups were self-assembled in a columnar fashion through the formation of an organogel in ethyl acetate. Upon irradiation with UV l...
Article
The gradual deterioration in the morphological and chemical stability of membranes in membrane contactors can extensively influence the membrane wettability, leading to reduction of CO2 absorption efficiency. In the present work, morphological, chemical and thermal stability of microporous low density polyethylene (LDPE) hollow fiber membranes, int...
Article
Full-text available
Crystal forms of polyethersulfones (PES) were investigated by using a model compound and a low molecular weight oligomer. These are amorphous as-synthesized, and can undergo solvent-induced crystallization under the appropriate conditions. The model compound, 4,4'-bis(p-methoxyphenoxy)diphenyl sulfone, yielded monocrystals, and its structure was so...
Article
Full-text available
Molecular dynamics simulations were carried out to study the effects of interface interactions between a crystalline structure and a plastic bonded explosive (PBX) system. In this work, the hydroxyl-terminated polybutadiene (HTPB) represents the polymer, isophorone diisocyanate (IPDI) is the diisocyanate and dioctyl adipate (DOA) is the plasticizer...
Article
Microsingle crystals of poly(para-phenylene terephthalamide), abbreviated PPTA, were obtained by water-vapor induced precipitation of PPTA rigid-flexible copolymers in sulfuric acid solution. Electron diffraction was performed and yielded hk0 patterns. The crystal structure of a model compound, N, N′ para (4-methoxycarbonyl) phenylene dibenzamide,...
Article
The effect of monoethanolamine (MEA) on the surface of non-porous low density polyethylene (LDPE) hollow fibers aimed to be used in membrane contactors was investigated. LDPE hollow fibers were kept in contact with MEA solution (fresh (unloaded) or after CO2 loading) for lengths of time varying from 8 to 45days, at different temperatures and soluti...
Article
Synthesis, X-ray diffraction, and Fourier transform infrared spectroscopy of aliphatic–aromatic aramid oligomers are reported with the aim of shedding light on the effect of end-chain substituent on the morphology and structure of poly(para-phenylene terephthalamide) or PPTA. Three types of X-ray powder diffraction patterns were observed: one simil...
Article
The dibenzamido alcanes, nDBN, for n = 2–10, have been synthesized and characterized by X-ray diffraction and infrared and Raman spectroscopy. From X-ray diffraction it was observed than the dihedral angle ε between the aromatic ring and the amido group averaged 28.3° and did not vary significantly with n. The torsion angle τ between the amide grou...
Article
Full-text available
Three model compounds of poly(tetramethylene terephthalamide) or 4T Nylon have been synthesized and characterized using single crystal X-ray diffractometry, infrared spectroscopy, and 13CCP/MAS nmr spectroscopy. The model compounds are the para-substituted N,N′-tetramethylene dibenzamides, where the substituents are the—OMe, —tBu, —CN, and —CH3 gro...
Article
The effect of uniaxial drawing on orientation of the crystalline fraction of two polymers forming hydrogen bonds, nylon-6 and nylon-11, has been investigated using X-ray diffraction. These two polymers have similar crystal phases, although their hydrogen bond density differs. For both polymers, the deformation occurs in two steps, the first being a...
Conference Paper
Atomistic molecular dynamics simulation was carried out to study interface interactions between a crystal structure and a plastic bonded explosive (PBX) system. In this work, the polymer is hydroxyl-terminated polybutadiene (HTPB), the plasticizer is dioctyl adipate (DOA) and the crystal phase is hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Exper...
Article
Full-text available
High performance propellants and explosives are based on the binding of energetic crystalline solids within a cured elastomeric polymer matrix in order to impart acceptable insensitivity and good mechanical properties to the material. Most plastic-bonded explosives (PBX) used are based on the inert rubbery hydroxyl-terminated polybutadiene polymer...
Article
In this paper, systems for which miscibility (hydroxyl-terminated polybutadiene–dioctyl adipate or HTPB–DOA) or immiscibility (HTPB–diethylene glycol dinitrate or HTPB–DEGDN) have been firmly established were used to test the usefulness of an atomistic molecular mechanics model. Two specific aspects were discussed: miscibility assessment of a plast...
Article
In this article, measurements of glass transition temperature (Tg) changes of two energetic material blend systems were carried out using the differential scanning calorimetry (DSC) technique. On one hand, experimental Tg values were compared to those predicted by the additivity model, Fox and Pochan equations, and, on other hand, to atomistic mole...
Article
Surface crystallinity on films of poly(l-lactide), poly(l/d-lactide) and their blends with poly(d-lactide) was studied. The isothermal spherulitic growth rate and its dependence on temperature were studied using tapping mode atomic force microscopy and ex situ isothermal crystallization. Using this technique, it is possible to extend spherulitic gr...
Article
The molecular orientation distribution of poly(p-dioxanone) (PPDX) uniaxially oriented commercial fibers was determined by polarized Raman spectroscopy and X-ray diffraction. The order parameters 〈P200〉 and 〈P400〉 of the orientation distribution function were determined by polarized Raman spectroscopy. For the CO stretching band, the values of 〈P20...
Article
Orientation relaxation in miscible poly(vinyl phenol) (PVPh)–poly(ethylene oxide) (PEO) blends (from 25 to 40wt% PEO) was investigated using polarization modulation infrared linear dichroism. This blend was selected to study the effect of strong hydrogen bonds on relaxation. The results show that PEO is more oriented than PVPh, and remains so throu...
Article
Nylon-6,6 was grafted at the surface of glass and plasma-treated Kevlar fibers for use in nylon–Kevlar thermoplastic composites. Hydroxyl and, in the case of Kevlar, amine end-groups occur at the fibre surface, either as defects or due to the plasma treatment. These were used as anchor points for nylon-6,6 step polycondensation. Fibers were subject...
Article
Blends of poly-(L-lactide) and poly-(D-lactide) form a triclinic stereocomplex during racemic crystallization while the pure optical isomers crystallize in a pseudo-orthorhombic crystalline form. The triclinic stereocomplex has a high melting point of 503 K compared to 453 K for the other crystalline form. Atomic Force Microscopy (AFM) allows one t...
Article
Crystallization of copolyaramides composed of rigid poly(p-phenylene terephthalamide) segments (containing 3−11 aromatic cycles) and short amine aliphatic chains (5−10 CH2 groups) was studied. Crystallization was induced at room temperature by slow saturation with methanol vapors of sulfuric acid solutions. In electron diffraction, the 3AR6DA, whic...
Article
Polycondensation of nylon-6,6 onto Kevlar and glass fibers has been previously proposed by our group as a surface treatment for composite fabrication. The present article reports the optimisation of this procedure for glass fibers via a study of the first two steps of the polymerisation, the esterification of pendant OH groups at the glass fiber su...
Article
Regular rigid-flexible copolymers composed of aramid segments and aliphatic chains formed of 5 to 10 CH2 groups were synthesized using a two-stage procedure. A first stage consisted of synthesizing, under Yamasaki–Higashi phosphorylation conditions, poly(paraphenylene terephthalamide) blocks or macromonomers of different lengths by using an excess...
Article
The component dynamics and molecular parameters were investigated for miscible poly(4-vinyl phenol)/poly(ethylene oxide) (PVPh/PEO) blends. Global values of molecular weight between entanglements (Me) were first estimated for the blends and were compared with existing athermal model predictions. Global interchain friction coefficients (ξ) of the bl...
Article
Interfacial polymerization to polyamide 6, 6 followed by introduction of ionic groups was performed on the surface of short glass fibers. The ionic interphase-modified fibers were used with poly(ethylene-co-methacrylic acid) (DuPont Surlyn) to prepare composites with specific fiber-matrix interactions. Fiber treatment increased composite tensile an...
Article
A review of past and present studies on orientation, rheology, and FTIR investigations on a hydrogen bond–forming polymer, poly(vinyl phenol) (PVPh), and its blends with polyethylene oxide (PEO), poly(methyl methacrylate) (PMMA), and poly(vinyl methyl ether) (PVME) is presented. Orientation is analyzed on the basis of deformation-induced orientatio...
Article
We have studied the hydrolytic degradation of high molecular weight poly(p-dioxanone), PPDX, sutures. The samples were degraded either in distilled water or in a phosphate buffer at 37 degrees C, and the starting viscosity-average molecular weight was 130 kg/mol. The hydrolytic degradation of PPDX occurs in an approximate two stage process where th...
Article
Deformation of polyethylene terephthalate, PET, was simulated using atomistic molecular dynamics using a Parrinello–Rahman constant-stress constant-temperature algorithm under periodic boundary conditions. The evolution in trans and gauche populations is in good agreement with experimental data reported in the literature: In the isotropic model, ap...
Article
Orientation of amorphous, miscible poly(vinyl phenol) (PVPh)-poly(ethylene terephthalate) (PET) blends is studied using experimental and modelling techniques. Up to 50 wt% PVPh, the blends are semi-crystalline and were therefore not studied. At 60 wt% PVPh, no crystallisation was observed using either differential scanning calorimetry or X-ray diff...
Article
Nylon-6,6 was grafted onto the surface of short glass fibers through the sequential reaction of adipoyl chloride and hexamethylenediamine onto the fiber surface. Grafted and unsized short glass fibers (USGF) were used to prepare composites with nylon-6,6 via melt blending. The glass fibers were found to act as nucleating agents for the nylon-6,6 ma...
Article
Quantitative evaluation of hydrogen bonding of poly(4-vinyl phenol)/poly(ethylene oxide) PVPh/PEO blends was conducted using Fourier transform near infrared (FT-NIR) spectroscopy. Absorption coefficients of the free (aF), intra- (PVPh-PVPh) (aA) and inter-associated (PVPh-PEO) hydroxyl groups (aI) were estimated. Two sets of approximations were tes...
Article
Molecular simulations of poly(vinyl phenol)/poly(vinyl methyl ether) (PVPh/PVME) blends were performed and their degree of miscibility evaluated as a preliminary step before orientation simulations. A minimum of three periodic boundary condition amorphous models was constructed and analysed in terms of solubility parameter, X-ray pattern, pair corr...
Article
The rheological behavior of miscible blends was studied through oscillatory shear measurements. Two miscible blends were selected to compare with athermal blending cases, i.e. the hydrogen bonding poly(4-vinyl phenol)/poly(ethylene oxide) (PVPh/PEO) blend and the weakly interacting polystyrene/poly(2,6-dimethyl-1,4-phenylene oxide) (PS/PPO) blend....
Article
Full-text available
Adhesion measurements performed on a polyethylene (PE)-grafted-glass interface showed that the structure of the PE free chains (matrix) was an important parameter. The fracture energy was higher for interfaces prepared from a linear matrix, such as high-density polyethylene (HDPE), than for those from a branched PE [low-density polyethylene (LDPE)]...
Article
Molecular orientation and relaxation of the trans and gauche conformers of poly(ethylene terephthalate), during and after an uniaxial deformation above the glass transition temperature, between 85 and 100 °C, were investigated using polarization modulation infrared linear dichroism. At all temperatures, it was found that the trans conformers orient...
Article
Molecular dynamics were performed for the simulation of the uniaxial deformation of poly(vinyl phenol) under periodic boundary conditions with the Parrinello–Rahman scheme followed by relaxation under NVT conditions (constant number of atoms, volume, and temperature). Changes in the orientation of the main chain, benzene segments, and hydrogen bond...
Article
Poly(ethylene terephthalate) (PET) has been uniaxially stretched at different draw ratios and draw rates above its glass transition temperature, in the 80–105°C temperature range. Molecular orientation and relaxation have been followed by birefringence. A decrease in temperature reduces the mobility of the oriented chains resulting in a slow relaxa...
Article
Orientation of poly(vinyl phenol) (PVPh)–poly(vinyl methyl ether) (PVME) amorphous miscible blends has been studied using FTIR spectroscopy. Blends of 33, 42, 53 and 66% (mol/mol) in PVPh were uniaxially stretched at 0.1s−1 and Tg+15. Both polymers showed similar orientation values in the blend. Whereas, at high PVPh concentration, the orientation...
Article
Molecular simulations of poly(vinyl phenol) were performed to study the effect of hydrogen bonds. Three conformations were constructed and their structure was validated in terms of the solubility parameter and gyration radius. Amorphousness was confirmed by calculating the X-ray pattern and pair correlation function. Isotropy of the structure was v...
Article
Monodisperse oligomers of poly(hexamethylene isophthalamide) (nylon-6I) with degrees of polymerization of one and two were prepared by solid-state synthesis on a Merrifield-type hydroxymethyl polystyrene resin using symmetrical diamines and diacid chlorides as starting materials.
Article
The orientation of miscible poly(vinylphenol) (PVPh)−poly(ethylene oxide) (PEO) blends for compositions of 20−35 wt % PEO and from Tg + 10 to Tg + 18 was studied using FTIR spectroscopy. In uniaxially deformed samples, both polymers were oriented for all compositions studied. For the POE component, a nonlinear relationship was observed between the...
Article
The optically active and crystalline poly(alpha-methyl-alpha-ethyl-beta-propiolactone) (PMEPL) shows conformational changes and polymorphic behavior depending on the preparation method of the sample. The melt-crystallized isotactic PMEPL exhibits a monoclinic lattice and an extended planar zigzag conformation. Using computational modeling, we have...
Article
The effect of uniaxial drawing on orientation of the crystalline fraction of two polymers forming hydrogen bonds, nylon-6 and nylon-11, has been investigated using X-ray diffraction. These two polymers have similar crystal phases, although their hydrogen bond density differs. For both polymers, the deformation occurs in two steps, the first being a...
Article
The kinetically controlled thermal isomerization of the nadimide endo to exo configuration was investigated in the solid state. Experiments were conducted on 4,4‘-methylene dianiline bis-5-norbornene-2,3-dicarboximide, which is the lowest molar mass compound common to two nadimide end-capped thermosets (the well-known commercially available PMR-15...
Article
FTi.r. was used to investigate quantitatively hydrogen bonds in poly(methyl methacrylate) (PMMA) and poly(4-vinyl phenol) (PVPh) blends. An absorption coefficient of free (or non-hydrogen bonded) carbonyl vibration of 750 ± 40 cm−1 m2 mol−1 was determined from pure PMMA using the Beer-Lambert law, along with precise measurements of film thickness a...
Article
Changes in the proportion of hydrogen bonds of poly(4-vinyl phenol) (PVPh) and poly(methyl methacrylate) (PMMA) blends have been investigated by FTi.r. spectroscopy both above and below the glass transition temperature Tg. Changes in three spectral regions, namely the carbonyl, hydroxyl and aromatic ring vibration regions, are attributed to variati...
Article
Infrared spectroscopy has been used to investigate the orientation behavior of poly(methyl methacrylate) (PMMA)−poly(4-vinylphenol) (PVPh) blends in uniaxially stretched films, for 0−54.5 wt % PVPh blend content. The orientation of PVPh chains increases upon addition of the lower Tg PMMA component, whereas the orientation of PMMA chains decreases u...
Article
Copolyamides based on poly(m-phenylene isophthalamide) and poly-(p-phenylene terephthalamide), to which 1,6-diaminohexane units were regularly inserted every 3 or 5 phenylene monomer units, were synthesized. The copolymers were obtained by condensation of individually prepared diamino- and dicarboxylic-building blocks via the Yamazaki–;Higashi reac...
Article
Copolyamides based on poly(m-phenylene isophthalamide) (PMIA) and poly(p-phenylene terephthalamide) (PPTA), to which 1,6-diaminohexane units were regularly inserted every 7 or 9 phenylene monomer units were synthesized. Solubility of the copolyamides was found to be similar to the parent homopolymers PMIA or PPTA.
Article
The surface of glass fibres was modified using chemical treatments to improve fibre–matrix interface properties. Interfacial polycondensation was performed with the fibre acting as the interface, and nylon-6,6 chains were grafted on the free hydroxyl groups located at the fibre surface. Grafted nylon was observed through the scanning electron micro...
Article
Wide-angle X-ray diffraction measurements of the orientation distribution of (hkl) crystal planes give values of some of the 〈Pn(cosχ)〉c coefficients, characterizing the orientation of the molecular chains, which disagree with those obtained from hk0 or 00l reflections. In this present article, a calculation method is proposed for obtaining reliabl...
Article
Chemical modifications of the surface of Kevlar fiber were investigated as a means of improving fiber-matrix adhesion. The fiber surface was used as a polymerization support for interfacial polycondensation. Nylon-6,6 was successfully polymerized in this way. The grafted nylon was characterized by ESCA (electron spectroscopy for chemical analysis),...
Article
The phase behavior of poly(methyl methacrylate) (PMMA)/poly(4-vinylphenol) (PVPh) blends was investigated using differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), small-angle X-ray scattering (SAXS), and Fourier transform infrared (FTIR) spectroscopy. Only one glass transition was observed by DSC in both pure state...
Article
Drawing of poly(ethylene terephthalate) (PET) films was performed from the amorphous state using different drawing rates at a temperature of 80°C. The crystallinity of the films was determined by thermal analysis and orientation of the different phases by specular reflection Fourier transform infra-red (FTi.r.) spectroscopy and wide-angle X-ray dif...
Article
The ability of various hydrogen bond-forming solvents to induce crystallinity in nylon-6I was studied using DSC, FTIR spectroscopy, and x-ray diffraction. Comparison was made with predictions using the solubility parameter, which is related to possibilities of interaction formation. General predicted tendencies agreed with experimental results, in...
Article
Miscibility of a series of nylons-6,m with poly(hexamethylene isophthalamide), abbreviated 6I nylon, was investigated. Four polyamides (nylon-6,5, nylon-6,7, nylon-6,8, and nylon-6,9) were found miscible, on a DSC scale, with 6I nylon. A series of nylon-n,m which had the same number of CH2 groups as nylon-6,7 was also studied; no miscible blend wit...
Article
Fourier transform infra-red (FTi.r.) spectroscopy was used to investigate the orientation of uniaxially stretched films of poly(vinyl phenol) (PVPh). The alpha angles of the various vibrations were determined with respect to the CH2...CH2 axis. No evidence was found for any influence of the hydrogen bonds on the orientation of PVPh when compared to...
Article
In this work, nylon-6,6/Kevlar short fibre composites have been processed by injection moulding. Their microstructure, and fibre and matrix orientation, measured by wide-angle X-ray diffraction (WAXD), have been studied as a function of two major processing variables, i.e. the injection speed and the mould temperature. At low mould temperatures, sk...
Article
Injection molded short Kevlar (DuPont) fiber/nylon-6,6 composites have been studied. Fiber length and length distribution were measured as a function of processing variables. Critical fiber length was measured by an embedded single-fiber method. Tensile modulus of the molded composites was predicted by an adapted classical lamination analogy. Fiber...
Article
Nematic solutions of PPTA and nylon 3T were prepared in H2SO4 Optical microscopy was used to ascertain the phase behaviour of the blends. In the studied concentration range, no phase separation was observed. The solutions were shear-oriented and coagulated, and the resulting samples were studied by x-ray and electron diffraction. Nylon 3T crystalli...
Article
A procedure is proposed for the preparation of blends of cellulose with poly(n-methylene isophthalamides) (abbreviated as nylons nI) in N-methyl morpholine N-oxide (MMNO). Nylons nI blends with n = 3–7 were characterized by DSC and found to be immiscible at all concentrations. Reprecipitation from MMNO solutions was found to affect considerably the...
Article
Crystal lattices for various polymorphs of poly(alpha-methyl-alpha-ethyl-beta-propiolactone) (PMEPL) and poly(alpha-methyl-alpha-n-propyl-beta-propiolactone) (PMPPL) are proposed on the basis of combined electron and X-ray diffraction data. Single-crystal-like electron diffraction is observed from melt-crystallized thin films of isotactic PMPPL, is...
Article
Blends of poly (butylene terephthalate) (PBT) and a liquid-crystalline copolyester (60 mol % poly(p-hydroxy benzoic acid)/40 mol % polyethylene terephthalate) (LCP) were prepared in the melt state. The investigation of mechanical properties indicated that, for the processing conditions used, neither the addition of up to 30 wt % LCP to PBT nor the...
Article
This paper deals with the characterization of the mechanical properties of Kevlar/nylon composites. It has been shown that addition of up to 5 % Kevlar to nylon matrices (nylon-6, nylon- 11, and nylon-6,6) is possible by melt blending, and results in improved mechanical properties as compared to the pure matrix. In order to increase the interfacial...
Article
The aim of this article was the investigation of the fiber-matrix interface of nylon/Kevlar composites. Both washed fibers and chemically treated fibers were used as reinforcements for nylon-6 and nylon-l1. Improvements of the mechanical properties were related to the increase in the nucleating abilities of the fibers, which was modified considerab...
Article
The crystal and molecular structures of VH amylose were determined by a constrained linked-atom least-squares refinement, utilizing intensities measured from electron diffraction patterns and stereochemical restraints. Hexagonal platelet single crystals were grown from dilute aqueous ethanol solution and their electron diffraction diagrams analysed...
Article
The miscibility of blends of two polyamides, poly(n-methyleneisophthalamide), or nI nylons, for n = 3-9 and poly(m-phenyleneisophthalamide), or mpI, has been investigated by using differential scanning calorimetry. For the polymers studied, only the blends with n = 6 and n = 7 were found completely miscible at all concentrations. Partial miscibilit...
Article
Single crystals of amylose complexed with isopropanol or acetone were prepared by adding these precipitants to a metastable aqueous solution of amylose. With both precipitants, similar micrometre sized platelet crystals were obtained. They gave indistinguishable electron diffraction diagrams which could be indexed in an orthorhombic unit cell, with...
Article
High resolution TEM lattice images can be recorded from beam sensitive (i.e., cellulose, amylose and chitin) crystalline biopolymers. Images showing information to 0.3–0.4 nm resolution are achieved with electron doses of 100–1000 elec/nm2, at magnifications of 20000–40000 X and accelerating voltages of 100–200 kV. Lattice images are very noisy, bu...