A core-shell latex built up of polybutadiene as a mobile component and polystyrene as a rigid component is investigated. Solid-state NMR spectroscopy and transmission electron microscopy are used to characterize the morphology and possible heterogeneities of the latex particles (average particles sizes 70-100 nm). NMR spectroscopy allows the determination of average domain distances much below the particle size due to standard electron microscopy. These differences are explained by an additional microstructure of the core-shell particles. Indeed, electron micrographs at high resolution confirm the existence of heterogeneities within the polybutadiene core of the latex. The presented investigations demonstrate the power of a combined application of solid-state NMR spectroscopy and transmission electron microscopy for the characterization of core-shell latexes.

A B S TRA C T:Poly(vinylch1oride) (PVC)was mixed with various poly(methacry1ate)s. poly(carb0nate)s and polymers containing nitrile groups (poly(acrylonitrile), poly(styreneco-acrylonit r i l e ) , nitrile rubber, hydrogenated nitrile rubber) a n d / o r C -C double bonds ( n i t r i l e rubber, high-impact poly(styrene)). The thermal stability was measured a t 180 OC in nitrogen, and the evolved HC1 was d e t e c t e d by conductometry.I t is shown that t h e n a t u r e of the e s t e r group and the content of nitrile groups and C-C double bonds a r e t h e dominating f a c t o r s for the thermal stability of poly(vinylchloride) in these blends. An influence of t h e miscibility of PVC with the various blend components on t h e t h e r m a l stability can not b e c l e a r l y detected.Differential scanning calorimetry (DSC) was used a s a powerful method to study the stabilizer distribution of heterogeneous PVC/poly(styrene-co-acrylonitrile) and PVC/poly(methylacrylate) blends. It is shown that the stabilizer can be solubilized either in t h e PVC phase (PVC/poly(methylacrylate)) or in both phases of t h e blends PVC/poly(styrene-co-acrylonitrile)).

Poly(viny1 chloride) was mixed with various poly(methacry1ate)s and polycarbonates by combined precipitation from common solutions. The thermal stability of the samples was measured at 180 "C under nitrogen, the HCI evolved was detected by conductometry.UV-Vis-spectra of degraded samples were measured to investigate the influence of the poly(methacry1ate)s on the lengths of polyenes formed during the degradation of poly(viny1 chloride).The experiments show that the nature of the ester group is the dominating factor for the thermal stability of poly(viny1 chloride) in these blends. Poly(n-butylmethacrylate) exhibits the best stabilization for poly(viny1 chloride) in this series. Polycarbonates with a higher glass transition temperature than the temperature of degradation destabilize poly(viny1 chloride).Stabilization experiments with dibutyltin-bis(isooctylthioglyco1ate) show a costabilizing effect of the poly(methacry1ate)s and polycarbonates. ZUSAMMENFASSUNG:Polyvinylchlorid wurde mit verschiedenen Polymethacrylaten und Polycarbonaten durch Ausfallen gemeinsamer Liisungen gemischt. Die thermische Stabilitat der Proben wurde bei 180 "C in einer Stickstoffatmosphare mittels konduktometrischer Messung der abgespaltenen Salzsaure bestimmt. Um den EinfluB der Polymethacrylate auf die Unge der entstandenen Polyensequenzen zu ermitteln, wurden die abgebauten Proben UV-spektroskopisch untersucht.Wie die Experimente zeigen, ist die Estergruppe von dominierendem EinfluB auf die thermische Stabilitat von Polyvinylchlorid in diesen Blends. Poly-n-butylmethacrylat stabilisiert dabei Polyvinylchlorid am besten. Die eingesetzten Polycarbonate haben Glastemperaturen, die iiber der Abbautemperatur liegen; sie vermindern die thermische Stabilitat von Polyvinylchlorid.Stabilisierungsversuche mit Dibutylzinn-bis(isooctylthioglykolat) zeigen einen costabilisierenden Effekt der Polymethacrylate und Polycarbonate.

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The distribution of a liquid organotin stabilizer between the phases of heterogeneous poly(viny1 chloride) (PVC) blends has been studied by differential scanning calorimetry (DSC). This method can be used even at low stabilizer concentrations. At concentrations > 1 wt.4'0 the stabilizer can be detected in both phases of a PVCISAN (poly(viny1 chloride)/poly(styrene-co-acrylonitrile)) blend. At lower concentrations no stabilizer could be found in the SAN phase. Determination of the induction period of thermal degradation at 180°C under nitrogen atmosphere showed no loss of thermal stability for blends containing the stabilizer partly in the SAN phase. Kinetic measurements with the DSC indicate a migration of the stabilizer out of the SAN phase. PVC/PMA (poly(viny1 chloride)/poly(methyl acrylate)) blends showed no solubility of the stabilizer in the soft PMA phase. ZUSAMMENFASSUNG:Es wurde die Verteilung eines flussigen Organozinnstabilisators zwischen den Phasen zweiphasiger Blends aus PVC/SAN sowie PVC/PMA mittels DSC untersucht. Die angewandte Methode erwies sich als geeignet, die Verteilung auch in niedrigen Konzentrationsbereichen zu messen. In PVC/SAN-Blends befindet sich der Stabilisator bei Konzentrationen > 1 Gew.-qo in beiden Phasen, bei niedrigeren Konzentrationen nur im PVC. Messungen der Induktionszeiten des thermischen Abbaus bei 180 "C unter Stickstoff zeigen keine Verschlechterung der stabilisierenden Eigenschaften fur die Blends, bei denen ein Teil des Stabilisators in der SAN-Phase vorlag. Kinetische Messungen mit der DSC-Methode sprechen fur eine Migration des Stabilisators aus dem SAN. In PVC/PMA-Blends wurde dagegen eine vollstandige Unlaslichkeit des Stabilisators in der weichen Polyacrylatphase nachgewiesen.