Rudolf Puffr

Thermooxidation of lactam-based polyamides with amino end-groups. thermooxidation of hexano-6-lactam and decomposition of 6-hydroperoxyhexano-6-lactam in the presence of primary amines*

Oxygen consumption, reaction products and chemiluminescence in the course of the thermooxidation of hexano-6-lactam melt in the presence of primary amines as well as thermooxidation of lactam-based polyamides with amino end-groups were studied. Amines induce the homolysis of amide hydroperoxides, primary products of the chain oxidation of lactams, and react with aldehydes originating from hydroperoxide homolysis. By condensation of amines with aldehydes, aldimines are produced together with singlet oxygen, the initiator of N-alkylamide oxidation. In polylactams prepared by hydrolytic polymerization, the carboxylic and amino end-groups are associated and their effect on polymer thermooxidation is thus suppressed.

Vibrational and n.m.r. study of poly(N-methyllaurolactam) and of poly(N-methyllaurolactam)-poly(4-vinylphenol) blends

Poly(N-methyllaurolactam) (PNMLL) and its blends with poly(4-vinylphenol) (PVPh) were studied by a combination of infra-red, Raman and n.m.r. spectroscopic methods. In the crystalline phase of semicrystalline PNMLL, the amide bond was shown to be present in the cis form, and the polymethylene chain to contain long trans sequences, with a rans conformation on the -CH2CO- bond. In the blends, the content of the crystalline phase, and also of the polymethylene trans sequences, is strongly suppressed. Analysis of the OH stretching vibrations shows that in the blends the hydrogen bonds between the OH groups of PVPh and PNMLL carbonyls are stronger than the hydrogen bonds in pure PVPh. The values of T1ρH relaxation times indicate intimate mixing of the blend components on a scale of <3 nm.

New soluble polyimides prepared from 4,4'-(alkylenediyldioxy) dianilines

Abstract New soluble aromatic polyimides have been prepared from 4,4′-(hexafluoroisopropylidene)bis(phthalic anhydride) (6FDA) and 4,4′-(alkylenediyldioxy)dianilines. Their structures were determined by i.r., 1 H n.m.r. and 13 C n.m.r. spectroscopic measurements, based on model compounds prepared by reacting 6FDA with p -anisidine. These polymers show low glass transition temperatures and good solubility in various solvents, and are stable up to 440°C in a nitrogen atmosphere.

Nylon 6 with a short rigid central block

Block copolymers of the general structure nylon 6-short aramid block-nylon 6 were prepared by anionic polymerization of 6-hexanelactam using as precursors of the central rigid block bifunctional initiators having three aromatic rings connected with amide groups in the para-meta-para or para-para-para positions. The effects of the type and concentration of the central block on the crystallization of nylon 6 component were studied by WAXS, SAXS, DSC and optical microscopy.

Low‐filled toughened composites of poly(hexano‐6‐lactam)‐block‐polybutadiene‐block‐poly(hexano‐6‐lactam)/wollastonite by polymerization casting

Composites consisting of 10–15 wt % wollastonite as an acicular filler and poly(hexano-6-lactam)-block-polybutadiene-block-poly(hexano-6-lactam) matrix (5–15 wt % polybutadiene blocks) were prepared by anionic polymerization of hexano-6-lactam. Hydroxyterminated polybutadiene in situ functionalized with toluene-2,4-diyl diisocyanate (TDI) was used as an initiator and sodium salt of hexano-6-lactam as a catalyst. To achieve a good dispergation and high adhesion to the matrix, the filler was modified with (3-aminopropyl)triethoxysilane and then functionalized either separately with N,N′-benzene-1,3-dicarbonylbis(hexano-6-lactam) or N-benzoyl-hexano-6-lactam or in situ functionalized with TDI. The increase in Youngs modulus and decrease in elongation were achieved along with a moderate decrease in impact resistance.

Block copolymers of 6-hexanelactam and 12-dodecanelactam

Abstract Poly(6-hexanelactam)- block -poly(12-dodecanelactam) (polyamide-6- block -polyamide-12) diblock copolymers containing a small portion of the corresponding homopolymers were prepared by the anionic polymerization of 6-hexanelactam using poly(12-dodecanelactam)s with diacylamine branching sites as precursors of polymeric initiators (PPI). The PPI were prepared by the acidolytic copolymerization of 12-dodecanelactam with N -benzoyl-12-dodecanelactam. The effect of PPI molecular structure on the composition and properties of the block copolymers was followed.

Properties of aliphatic block copolyamides and homopolyamide blends prepared by combined polymerization

Poly(6-hexanelactam)-block-poly(12-dodecanelactam) copolymers containing a minor part of poly-(6-hexanelactam) (PA6) and poly(12-dodecanelactam) (PA12) were compared with PA6-PA12 blends as regards their crystallization behaviour, thermal properties, sorption of water vapour, morphology and mechanical properties. All blends were prepared by the combined polymerization procedures described earlier. The differences found are ascribed to the different composition of amorphous phases, specifically to the compatibilization effect of the diblock copolymer.