Gisela Pompe

Synthesis, electron irradiation modification and characterization of polyethylene/poly(butyl methacrylate-co-methyl methacrylate) interpenetrating polymer network

WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW The present work reports the preparation of a porous structure by electron beam irradiation of interpenetrat- ing polymer network (IPN) based on polyethylene and poly(methyl methacrylate-co-butyl methacrylates). Thin IPN films were synthesized by in situ polymerization. Low-density polyethylene (PE) was used as the first IPN component, and the second IPN component was formed by copolymerization of methyl methacrylate and butyl methacrylate. After the synthesis the methacrylic phase is finely dispersed in a PE matrix. Porous films of these materials were obtained by decomposition of the polymethacrylate phase by means of electron radiation followed by extraction with xylene. The thermal stability in N2 atmosphere of the irradiated and extracted IPN was improved compared with the unirradiated samples. Three temperature regions of weight loss were observed, two of them caused by the copolymer and one by the PE. The lowering of the melting temperature of PE observed by differential scanning calorimetry analysis indicated an increase in crosslinking caused by irradia- tion. Morphology changes were studied by scanning electron microscopy which revealed a porous surface structure of the irradiated and extracted samples. Flux measurements showed that some irradiated samples were permeable to ethanol, demonstrating an interconnected porous structure which may be relevant for membranes.

Studies of interdiffusion in polymer blends by PALS

Abstract It is shown that positron annihilation parameters such as the average positron lifetime τav and the ortho-positronium intensity I3 respond to chemical inhomogeneities in disperse blends and their disappearance due to mutual diffusion of molecules of both phases, when Ps formation is inhibited by one of the constituents. This effect can be used to study mixing in initially demixed compatible blends, demixing in initially mixed incompatible blends, and phase diagrams. With a slow positron beam the concentration-distance profile in thin planar double layer films may be scanned systematically.

Synthesis of oxazoline functionalized polypropene using metallocene catalysts

Using two different zirconocene/MAO catalyst systems, propene was copolymerized with the comonomers 2-(9-decene-1-yl)-1,3-oxazoline and 2-(4 (10-undecene-1-oxo)phenyl)-1,3-oxazoline, respectively. The catalysts used were rac-Et[Ind] 2 ZrCl 2 and rac-Mc 2 Si[2-Me-4, 5-BenzInd] 2 ZrCl 2 . Up to 0.53 mol-% oxazoline could be incorporated into polypropene. Oxazoline ontent, molecular weight, degree of isotacticity and melting behavior were dependent on the catalyst system, comonomer structure and comonomer concentration in the feed.

Synthesis and thermal polymerization of aromatic 2‐oxazolines containing carboxylic groups

2-(4-Carboxyphenyl)-, 2-(3-carboxyphenyl)- and 2-(6-carboxynaphtyl-2-yl)-1,3-oxazoline were synthesized by reaction of monomethyl ester chlorides of aromatic dicarboxylic acids with 2-chloroethylamine hydrochloride in the presence of triethylamine followed by cyclization with methanolic KOH. Thermal bulk polymzerization within a few minutes at 200-220°C resulted in new linear poly(ester amide)s without significant side reactions. The polymerization occurred in the melt phase or in the solid state and the resulting polymers are amorphous or semicrystalline.

Unsaturated 2-oxazoline end capping of liquid crystalline polyester by reactive processing and in a solution

End capping of liquid crystalline poly(ethylene terephthalate-co-oxybenzoate) with a bifunctional 2-oxazoline derivative, 2-(4-allyloxyphenyl)-2-oxazoline, has been performed in melt under the condition of reactive processing and in a solution. The reaction in melt is very fast and, despite some modifier evaporation, it is completed in 2 min at 230°C. The product is a polyester containing unsaturated end groups bonded via esteramide linkage. The presence of unsaturation was proved by 13C-NMR spectroscopy. An increase in temperature and prolongation of the processing time gives raise to thermal-induced reactions on the unsaturated end groups, resulting in an increase of the glass transition temperature. Depending on the processing temperature decomposition, propagation and crosslinking occur in different extent and influence polymer properties.