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The mechanical properties of aligned fibres and monofilaments of random copolyesters of 4-hydroxybenzoic acid (HBA) and 2-hydroxy-6-naphthoic acid (HNA) with and without the inclusion of a trifunctional branching monomer have been investigated using both macroscopic and X-ray techniques. Results for unbranched samples are in line with previous work while including the branching monomer reduces both...
A method for the determination and quantification of higher-functional epoxides in liquid diglycidylether of bisphenol-A (DGEBA)-based epoxy resins, and for the determination and quantification of the amount of branching in solid DGEBA-based epoxy resins by 13 C n.m.r. is described. Model compounds were synthesised and their chemical shifts assigned. Examples for both types of resin are...
For in-depth analyses of polyolefin microstructures, we have installed the MW-specific light scattering (LS) and viscosity detectors into a home-built hybrid GPC–TREF instrument. Data processing capabilities were developed for this triple-detector system to determine (1) polymer long chain branching (LCB) distribution across the GPC-determined molecular weight distribution (MWD) curve, (2) the GPC-M...
Recently, a method was presented to model phase separation behaviour of polymer-solvent mixtures around the lower critical solution temperature using dissipative particle dynamics (DPD) [Macromol Theory Simul 9 (2000) 698]. In the current article, a refined version of this method is described, yielding good agreement with the classic Flory-Huggins model. However, the great advantage of DPD, over such...
Binary phase-separation driven by a difference in branch content of the two components has been widely reported in polyolefins. This concept is applied to polysiloxanes in an attempt to control morphology in chemically driven phase separation. It is shown that self-assembled, non-reversible spinodal morphologies (SD) as well as low-polydispersity nucleation and growth morphologies can be controlled...
A method to predict the sequence length distribution (SLD) for homogeneous non-linear irreversible multicomponent polymerizations is described. With more than two monomers, it also predicts chain length distributions of the sub-domains containing a prescribed sub-set of the repeating units, but in all possible orderings. Its goal is the analysis of polymerization systems involving complex kinetic...
A range of comb polymers of poly(n-butyl methacrylate), where the degree of polymerization (DP) of both the backbone and branches was controlled using RAFT-mediated free-radical polymerization, was synthesized using the method of Vosloo et al. [Macromolecules 2004;37: 2371]. Individual architectural parameters (branch length, branch number and DP of the comb backbone) of these relatively monodisperse...
This paper describes a kinetic method to predict the z-average molecular mean square radius of gyration of tree-like polymers formed by irreversible reactions, assuming Gaussian chains. It is based on the population balance equations for the two-sided molecular distributions of pendant chains associated with every chemically distinguishable kind of bonds. An automated method for the solution of those...
Computational studies were carried out to investigate the influence of polymerization procedure on the topology and various macromolecular characteristics of the highly branched polymers formed by the reaction of A 2 and B 3 type monomers through step-growth polymerization reactions. The influence of three different polymerization procedures on the properties of the polymers formed...
In electrospinning, polymer nanofibers are formed by the creation and elongation of an electrified fluid jet. The path of the jet is from a fluid surface that is often, but not necessarily constrained by an orifice, through a straight segment of a tapering cone, then through a series of successively smaller electrically driven bending coils, with each bending coil having turns of increasing radius,...
The interface structure of the poly(ethylene terephthalate) (PET)/silica nanocomposites was characterized by Fourier transform infrared and solid-state nuclear magnetic resonance. Our study reveals that PET chains are grafted onto the surface of silica nanoparticles, and they form branched and lightly crosslinking structures during the polycondensation. Gel permeation chromatography measurements indicate...
Chain branching has been investigated in a homologous series of poly(n-alkyl acrylates) (methyl, ethyl, n-butyl, n-hexyl) obtained by radical polymerization. The total amount of chain branching was quantified using melt-state 13 C nuclear magnetic resonance (NMR) spectroscopy. It gave access to low degrees of branching in both soluble and insoluble polyacrylates, homopolymers and copolymers...
Commercial polyethylene is typically heterogeneous in molecular weight as well as in molecular topology due to variability in catalyst systems and catalyst activity. Further, processing of polyethylene after polymerization may also result in changes to the structure. While quantification of molecular weight is routine using gel permeation chromatography (GPC); quantification of the heterogeneity in...
The pure effects of branching architecture on crystallization and thermal properties were investigated using linear 2-arm and branched 4-arm poly(l-lactide) (2L and 4L, respectively) polymers having a wide range of number-average molecular weight (M n ) values of 5.0 × 10 3 –6.0 × 10 4 g mol −1 . 2L and 4L were synthesized by bulk ring-opening polymerization of l-lactide...
The effect of annealing on the phase composition, molecular mobility and water absorption in linear and branched polyamide 46, poly(tetramethylene adipamide) – PA46, was studied by DSC, 1 H and 2 H solid-state NMR. A series of samples with varying amount of long-chain branches was synthesized for this study. The branches as well as a higher molecular weight of branched PA46 cause a...
Branching has been investigated in poly(acrylic acid) synthesized by conventional radical polymerization with and without chain transfer agent (CTA) at different temperatures and initial monomer concentrations. The average number of branches per monomer unit (i.e. degree of branching) was quantified by solution-state 13C NMR spectroscopy. The heterogeneity of branching (dispersity of the electrophoretic...
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