SynopsisABS systems which differ distinctly in particle size and degree of grafting were prepared and investigated by dynamic mechanical measurements as function of temperature in the glass transition region of the rubber phase. Variation of rubber content within different sample series results in effects which were majnly referred to thermal stresses as consequence of phase interactions. Basic aspects of the deformation behavior of some of these ABS systems are studied by mechanical and morphological methods, and the operation modes of the component of a bimodal/bigraft-system concerning toughness are discussed. INTRODUCTIONMany investigations in the field of ABS have shown that particle size and graft structure are dominating factors controlling many important properRecent developments describe ABS systems using combinations of rubbers with different particle ~i z e .~a Beyond this, mixtures of grafts with different particle size and additionally changed degrees of grafting can result in improved properties, i.e., impact, gloss, and processing, compared with standard ABS types. These bimodalbigraft systems exhibit a number of problems which demand further physical investigations.The importance of good interfacial bonding between rubber particle and SAN surrounding is always emphasized, but in the literature there is a lack of experimental evidence for describing these effects in bulk material.The first part of the present paper deals with some aspects concerning interfacial bonding using the well-known fact that thermal stresses arise in ABS systems when samples are cooled down from the melt or from ambient temperatures influencing thereby the glass transition of the rubber phase by volume dilatations of the rubber p a r t i~l e s . 6~ In the second part, remarks are made about the resulting deformation behavior comparing notched impact values and the morphology of the fracture surfaces gained a t high and low strain rates. In addition, fracture phenomena from slow penetration tests and transmission electron micrographs from the notched impact material are presented.* Presented at IUPAC Symposium, Madrid, Spain, 1974. 2692MORBITZER E T AL. MATERIALSDifferent series of samples were prepared by mixing emulsion-grafted rubber with SAN resin: the first with small particles and a high degree of grafting (SPHG), the second with large particles and also with a high degree of grafting (LPHG), the third with large particles but a lower degree of grafting (LPLG), and the fourth a mixture of SPHG and LPLG with a S / L ratio of 1:l. In each of these series, the rubber content was varied up to a maximum content of 30%. The grafting degree of the SPHG and LPHG series was about 0.5-0.8, and of the LPLG series less than 0.5. The S/AN ratio was usually 75/25. Only for the LPLG'series was the AN content of the graft somewhat lower than that of the matrix. The fifth series contained samples of constant rubber level but different S / L ratios. Finally, the sixth series was built up with small particles but different degrees o...

Analysis—requiring no pretreatment—of the core‐shell morphology of polymer latices is achieved by X‐ray small‐angle scattering in combination with ultra‐centrifuge sedimentation. The latter technique is required for the determination of the particle size distribution. For larger scattering angles (g > 0.1 nm−1), the measured and calculated scattering intensities agree quantitatively; the differences for the smallest g values may be attributed to interparticle interferences and give information on the interaction of the particles.

Schema 2. Umsetrung von 3.3-Dimethylcyclopropen mil 2 zu 3 samt Vorschlag eines Mechanismus.

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ZUSAMMENFASSUNG :Zwischen Elastomerteilchen und Matrix eines ABS-Pfropfpolymerisates konnen mechanische Wechselwirkungen auftreten, die wegen der unterschiedlichen thermischen Ausdehnungskoeffizienten der beiden Phasen beim Abkuhlen zu thermischen Spannungen f a r e n und dadurch den Glasubergang der Elastomerphase beeinflussen. Da bei einem ungepfropften Material ein solcher Effekt nicht auftritt, wird in Ubereinstimmung mit verschiedenen Angaben in der Literatur geschlossen, daf3 diese Wechselwirkungen durch die Pfropfhulle verursacht werden. Die vorliegenden Untersuchungen zeigen aber daruber hinaus, daf3 je nach Herstellungsbedingungen auch bei einem ungepfropften Material eine ausreichende Adhasion zwischen Teilchen und Matrix erreicht werden kann, um hinsichtlich der thermischen Spannungen ahnliche Effekte wie bei einem gepfropften Material zu ergeben. In einem solchen Fall kann naturlich die thermische Spannung nicht zum makroskopischen Nachweis der Pfropfung herangezogen werden. Eine Pfropfhulle ist demnach keine notwendige Bedingung fur das Auftreten dieser mechanischen Wechselwirkungen. Nach einer Abschatzung der' Volumendilatation der Elastomerphase beim Abkuhlen wird anhand von Schubmoduluntersuchungen auf den EinfluB von Quellung, unterschiedlicher thermischer Vorbehandlung und unterschiedlichem Elastomergehalt eingegangen. AbschlieBend werden Kraft-Dehnungsuntersuchungen und Anisotropieerscheinungen in der thermischen Ausdehnung an gepfropften und ungepfropften Proben diskutiert. Das Zahigkeitsverhalten der untersuchten ABS-Polymerisate kann nicht ohne zusatzliche Angaben nach der GroBe der thermischen Spannungen zwischen Teilchen und Matrix beurteilt werden. SUMMARY:The differences in thermal expansion between rubber-particle and matrix-resin in graft polymers (ABS) cause thermal stresses which influence the glass transition of the rubber phase. Such effects were observed hitherto only in grafted material so that the graft-adhesion between the two phases is hold responsible for this mechanical interaction. The present investigations show that thermal stresses may also arise in ungrafted material if the samples are properly prepared. I n such 57 L. MORBITZER, K. H. Om, H. SCHUSTER und D. KRANZ special cases it is obviously not reasonable t o use the thermal stresses as a proof of grafting. After estimating the volume dilatation of the rubber phase during cooling the influence of swelling, thermal pretreatment and rubber content on the temperature dependence of the shear modulus is investigated. In addition stress-strain measurements and anisotropic thermal expansion of grafted and ungrafted samples are discussed. Toughness behaviour cannot be derived in a direct manner from the size of the thermal stresses; additional data must be considered.