Jan Roda

Thermogravimetric analysis of poly(ε-caprolactam) and poly[(ε-caprolactam)-co-(ε-caprolactone)] polymers

The thermal degradation of poly(e-caprolactam) and its copolymers with e-caprolactone has been studied by high-resolution thermogravimetric analysis (TGA), followed by the analysis of evolved gas via a simultaneous coupling to Fourier transform infrared spectrometry (FTIR) and mass spectrometry (MS). Poly(e-caprolactam) and poly(e-caprolactone) polymers are, respectively, degraded at different temperatures, rendering this study to be particularly useful in determining the structure of their copolymers, i.e. random or blocky-like copolymers. The poly[(e-caprolactam)-co-(e-caprolactone)] polymers have been synthesized in bulk by anionic ring-opening copolymerization promoted by e-caprolactammagnesium bromide in a temperature range from 120 to 180°C. A multi-step degradation was observed by TGA, and characterization of the evolved gas by FTIR and MS gives credit to some blocky-like enchainment of the comonomers. This assignation has been further confirmed by TGA directly performed on blends of poly(e-caprolactam) and poly(e-caprolactone) as obtained by solvent casting.

Study of the conformations of poly(ε-caprolactam) and poly(ε-caprolactam)-polybutadiene block copolymers by FT i.r. spectroscopy with photoacoustic detection and by micro-Raman confocal spectroscopy

The conformations of poly(e-caprolactam) and of poly(e-caprolactam)-block-polybutadiene copolymers were investigated by Fourier Transform infrared spectroscopy with photoacoustic detection (PA-FT i.r.) and by micro-Raman confocal spectroscopy. The lowering of the planar conformation content with increasing concentration of butadiene units was confirmed. In the surface layers formed by rapid saw-cutting and in the islands probably formed by microtome cutting, the content of the planar conformation was reduced. The content of the planar conformation increases on water treatment.

Anionic polymerization of ε-caprolactam in the presence of symmetrically substituted ureas

N,N′-diphenylurea (DPU), N-butyl-N′-phenylurea (BPU), and N,N′-dibutylurea (DBU) were added to the anionic polymerization of e-caprolactam (CL) initiated with sodium salt of CL either as individual activators (150–170°C) or as an additional activator to N-acetyl-e-caprolactam (AcCL) (at 150°C). The activation effect of individual ureas was proved, but it unexpectedly increases in the sequence of their increasing N-acidity, i.e. DBU<BPU<DPU. The ureas produced during polymerization had practically the same number of polyamide chains (∼1.3 chains per molecule) irrespective of their structure and polymerization temperature. From the rates of urea consumption, the different polymerization rates can be explained in terms of the different rates of the primary initiation and first propagation step. The accelerating effect of ureas added to AcCL activator does not correlate with their N-acidities. They act primarily as basicity regulators reducing the side condensation reaction of AcCL and growth centres and produce additional polymer chains by transacylation cleavage and/or formation of new growth centres.

Polymerization of lactams, 92. Non-activated anionic polymerization ofε-caprolactam initiated with the sodium salt ofε-caprolactam

The non-activated polymerization of e-caprolactam initiated with the sodium salt of e-caprolactam (CLNa), which was prepared in situ with sodium methoxide, was studied in the temperature range 170-230°C and at CLNa concentrations from 0.20 to 1.0 mol-%, and at 190°C in the presence of 2.0-10.0 mol-% CLNa. Apparent rate constants and values of apparent activation energy (E a ) were determined for the initial autoaccelerated stage of polymerization (E a = 230 kJ. mol -1 ) as well as for the stage characterized by a zero-order reaction with respect to the monomer (E a = 120 kJ. mol -1 ). Non-integral orders of the polyreaction with respect to the initiator indicate a highly complex polymerization mechanism. Degradation reactions accompany the polymerization at high polymer contents.

On distribution of molecular weight in anionic polymerizates of caprolactam

Abstract Measurement has been made of the dependence of the molecular weight distribution on the ratio of the catalytic system components and on the polymerization time for polycaprolactam obtained by anionic polymerization. A bimodal character of the curves was observed for products made using molar ratios of activator ( N -benzoylcaprolactam) to initiator (sodium dihydro-bis(methoxyethoxy)aluminate) of 1:1 and 1:3, when the polymerization times were less than 1 hr. This course is explained by the influence of fast side-reactions, mainly condensations. For a ratio of 3:1 of the components of the catalytic system, smooth integral distribution curves are obtained, accounting for a very fast decrease in the strong base concentration in the initial stages of the polymerization.

Polymerization of lactams

SummaryThe anionic polymerization of 2-pyrrolidone is markedly affected by 1-(1-pyrrolin-2-yl)-2-pyrrolidone which probably influences the propagation reaction. A kinetic analysis of the polymerization process demonstrates its distinct similarity with non-activated polymerization. The polymers thus obtained possess a satisfactory thermal stability.

Effects of the reaction conditions on the anionic polymerization of 2-pyrrolidone

Abstract The effects of temperature and initiator and activator concentrations on the anionic polymerization of 2-pyrrolidone were studied. Potassium tert, butanolate and γ-butyrolactone served as initiator and activator respectively. The polymer yield and intrinsic viscosity of the polymer were employed as criteria for evaluating the polymerization process. The orthogonal central composition planning of the experiment was used as an approach to studying the problem; the results were processed to yield explicit mathematical equations by using a digital computer. In the region measured, the polymer yield as well as the intrinsic viscosity were found to increase with increasing temperature. initiator concentration and polymerization time.

Polymerization of lactams, 94. Formation of cyclic oligomers in anionic polymerization of 6-hexanelactam

HPLC analysis of the methanol-extractable fractions of polymers was used to study the formation of cyclic oligomers during the non-activated anionic polymerization of 6-hexanelactam initiated by sodium or magnesium salt of 6-hexanelactam and ethylmagnesium bromide at 190°C. It was demonstrated that the nature of the counterion of the substance which initiates the anionic polymerization has a crucial effect on the mechanism of the formation of the cyclic oligomers. It was proved that in the course of the 6-hexanelactam polymerization in presence of magnesium compounds, the cyclic oligomer formation is distinctly slower, as compared to the sodium 6-hexanelactam-initiated polymerization. Das Aufkommen von cyclischen Oligomeren wahrend der nichtaktivierten, durch das Natrium- oder Magnesiumsalz von 6-Hexanlactam oder Ethylmagnesiumbromid initiierten anionischen Polymerisation von 6-Hexanlactam bei 190°C wurde mittels HPLC Analyse der mit Methanol extrahierbaren Anteile der Polymerisationsprodukte bestimmt. Es wurde gezeigt, das die Art des Gegenions der initiierenden Spezies den Mechanismus des Entstehens der cyclischen Oligomeren grundlegend beeinflust. Im Vergleich mit der durch das Natriumsalz von 6-Hexanlactam initiierten Polymerisation entstehen die cyclischen Oligomeren bei der mit Magnesiumverbindungen initiierten Polymerisation wesentlich langsamer.

Polymerization of lactams: 70. Anionic polymerization of 2-pyrrolidone accelerated with N-iminolactams

SummaryA pronounced acceleration of the anionic polymerization of 2-pyrrolidone (PD) occurs with the following N-iminolactams: 1-(1-pyrrolin-2-yl)-2-pyrrolidone (PDPD), 1-(1-azacyclohept-1-en-2-yl)-2-pyrrolidone (CLPD), and 1-(1-azacyclohept-1--en-2-yl)-1-aza-2-oxocycloheptane (CLCL). This acceleration effect on the anionic polymerization of PD initiated with 2-oxo-1-pyrrolidinylpotassium decreases in the sequence CLPD> PDPD > CLCL. The possible role of N-iminolactams in the system is discussed.

POLYAMIDE/POLYESTERAMIDE BASED NANOFIBERS

The formation of novel high aspect ratio nanofibers from polyesteramides based on e-caprolactam and e-caprolactone is reported. Nanofibers were prepared by the electrospinning method from polymer solution. Scanning electron microscopy images of nanofiber layers revealed that the diameter of fibers depended on the nature of the solvent or the mixture of solvents used and especially on the composition of polyesteramides.