Polymer
Motional heterogeneity in acrylate (AA)/laurylmethacrylate (LMA) copolymers was investigated by the two-dimensional 1 H- 1 3 C heteronuclear wideline-separation n.m.r. technique. Qualitative information about molecular dynamics is reflected in the width of the proton wideline. It was found that a decrease of the AA/LMA ratio in the copolymer reduces the packing density.
Stress-strain data have been obtained for poly(vinyl chloride) from drawing experiments in three stretching modes: uniaxial, planar and equibiaxial extension. The experiments were conducted isothermally at 84°C, which is in the glass transition region, and at 90°C, above T g . The stress-strain behaviour is qualitatively different at the two temperatures. At the lower temperature, there...
We have prepared and characterized several trithienylbenzenes. These compounds are used as reticulation points in poly(3-n-octylthiophene). It was necessary to study the reactivity of the reticulation points with regard to 3-n-octylthiophene. That is the reason why we have prepared copolymers starting from very high percentages of deuterated reticulation points (> 10%) and monitored their reactivities...
Interfacial polycondensation of 1,1 -diamino-4,4 -bipyridinium di-iodide, [H 2 N- + NC 5 H 4 -C 5 H 4 N + -NH 2 ]I 2 , with aromatic di- or tri-acyl chlorides, affords a novel class of hydrophilic polymers. These materials are isoelectronic with polyesters but contain ylid linkages [N + -N - -CO] in place of...
A stress-strain equation is studied which uses a non-Gaussian statistical mechanics model for large deformation of crosslinked rubbers. The formulation is based on the work introduced by Doi and Edwards for the description of polymer dynamics in a fixed network. The resulting constitutive equation is applied in the entire network of elastomers. Uniaxial and biaxial tensile and compressive experiments...
A range of hydrogel copolymer membranes of poly(2-hydroxyethyl methacrylate) with 4-vinylpyridine or 4-vinyl-4 -methyl-2,2 -bipyridine have been made and their permeabilities to a series of transition metal salts determined. Ion transport is characterized by an initial induction period prior to the onset of steady-state permeation. This period varies depending on the ion under study and can be...
Amphiphilic polymers with two different alternating functional units along the main chain were synthesized and their monolayer behaviour was investigated. When they have a ligand group adjacent to a carboxylic acid group, two different metal complexes can be introduced into a monolayer: a complex with a free coordination site can be bound via the ligand group, and a cationic complex as counter-ion...
The local dynamics of some model epoxy networks based on various diepoxides and diamines was investigated in the bulk state using high-resolution solid-state 1 3 C nuclear magnetic resonance. The strength of the 1 3 C- 1 H dipolar coupling was determined from the rises of 1 3 C magnetization in cross-polarization experiments using very short contact...
Two non-linear bead and spring models are considered for the Brownian dynamics simulation of the behaviour of polymer chains in a dilute solution under shear or elongational flow. One of them is the HYBRID model whose springs are Hookean at low elongation, and beyond some spring length they follow a Morse potential with a given dissociation energy. This model is suitable for studying polymer fracture...
A general measurement theory for determining the diffusion coefficient D of small molecules in polymer matrices is presented. This theory is applied to an arbitrary geometry of the polymer sample and an arbitrary initial penetrant content in the polymer. It is shown that one does not need to know specifically the dependence of the measured quantity on the concentration of the diffusing species,...
The microvoiding mechanisms and mechanical properties of a blend of poly(vinyl chloride) (PVC) with methyl methacrylate-butadiene-styrene (MBS) graft copolymers are investigated. It is found that the toughening effect is independent of the type of microvoiding mechanism occurring in the blend. Both internal cavitation of the MBS particles and debonding at the PVC/MBS interface relieve the triaxial...
The low-frequency Raman scattering (2-200 cm - 1 range) of poly(methyl methacrylate) (PMMA) specimens plastically deformed in pure shear is compared to that of non-deformed specimens. The main experimental feature is an excess of Raman scattering in the 30-50 cm - 1 spectral range induced by plastic deformation. This excess appears to be strongly anisotropic and is maximum...
Polydimethylsiloxanes (PDMSs) with a narrow molecular weight distribution and fitted at one chain end with a hydrogenodimethylsilyl or a dimethylvinylsilyl function were prepared by the anionic ring-opening reaction of hexamethylcyclotrisiloxane in a 50 vol% benzene-tetrahydrofuran solution, followed by endcapping with chlorodimethylsilane or chlorodimethylvinylsilane. The experimental conditions...
Using dynamic (viscometry) and static (light scattering) measurements we study solutions of polystyrene and poly(methyl methacrylate) fractions ranging from extremely dilute solutions up to the critical concentration c * . When viscometry is used, a crossover phenomenon is observed, separating the dilute solutions into extremely dilute and dilute solutions. The critical concentration c ...
Ubbelohde viscosity measurements were performed on dilute solutions of perfluorosulfonated ionomers (PFSI) in various solvents exhibiting quite different dielectric constants. With aliphatic alcohols as solvents an increase of the reduced viscosity with dilution is evident. This effect is analogous to the so-called polyelectrolyte effect observed for highly charged ionic polymers in polar solvents...
Ultra-high-molecular-weight poly(ethylene terephthalate) (UHMW-PET) with an intrinsic viscosity exceeding 2 dl g - 1 (M n 1.1 10 5 ) was obtained by swollen-state polymerization with hydrogenated terphenyl as the solvent. The rate of swollen-state polymerization was described well by Tomita's kinetics for a melt-phase polycondensation reaction. This suggested that there...
The relaxation behaviour of coextruded linear low-density polyethylene (LLDPE) films, prepared from copolymers of ethylene-1-octene, is reported. The spectra, expressed in terms of loss tan δ, present a γ relaxation of lower intensity than that exhibited for conventional low density polyethylene of the same crystallinity, followed, with increasing temperature, by a β relaxation process that appears...
Changes in the luminescence of poly(ethylene terephthalate) (PET) degraded in the absence and presence of oxygen at melt temperatures has been investigated. On oxidative degradation monomer fluorescence is reduced, with a concurrent increase in dimer fluorescence at long wavelengths. This is consistent with main chain breakdown and aggregation of the terephthalate fragments produced. Longer wavelength...
The fluoropolymer poly[2,3-bis(trifluoromethyl)norbornadiene] (poly(BTFMND)) has been synthesized via ring-opening metathesis polymerization, using initiators based on W, Mo or Ru compounds or via variations of the Schrock-type initiator Mo(CHR)(N-2,6-C 6 H 3 -i-Pr 2 )(OR ) 2 (R = CMe 3 , CMe 2 Ph; R = CMe 3 , CMe(CF 3 ) 2 ...
The viscoelastic properties of polypropylene fibres are investigated in a single-step stress relaxation test for small strains at temperatures between -50 and +30°C, thus well encompassing the glass transition temperature. For the analysis of the curves a formal two-component (TC) model is applied, which comprises an elastic and a viscoelastic component, the time-dependence of which is described...