Structure and properties of abs polymers. X. Influence of particle size and graft structure on loss modulus temperature dependence and deformation behavior

Abstract

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...

Effects of the polybutadiene/poly(styrene‐co‐acrylonitrile) ratio in a polybutadiene‐g‐poly(styrene‐co‐acrylonitrile) impact modifier on the morphology and mechanical behavior of acrylonitrile–butadiene–styrene blends

“…Similar results were obtained by Morbitzer et al, 13 who ascribed the peak shift to the thermal expansion mismatch between the rubber and the surrounding matrix. When the material is cooled below T g of SAN, the rubber, which has the higher thermal expansion coefficient, undergoes a hydrostatic dilation stress.…”

“…Figure 3(b) shows that tan ␦ increases and then decreases with an increase in the PB/SAN ratio in the PB-g-SAN copolymer. Because the maximum tan ␦ value [(tan ␦) max ] increases with an increasing rubber volume fraction, 3,13 the increase in (tan ␦) max of the ABS-60 blend, compared with that of the ABS-80 blend, can be explained by the increase in the effective volume fraction of the rubber particles, which results from the subocclusions. Another explanation for the result is that more energy is transferred to the rubber chains for the material having a higher grafting degree through the chains grafted to the rubber surface.…”

On the Reversible Nature of Rubber Particle Cavitation in Toughened Thermoplastics

“…The low temperature peak (depending mainly on the rubber level and hence on the modulus of the composite material) with lower intensity can be attributed to intact rubber particles under thermally induced hydrostatic tension. The higher intensity peak at -80 8C has been attributed by Morbitzer et al [8] to rubber particles without thermally induced hydrostatic tension due to debonding of intact particles from the surrounding matrix. It should be noticed that this result has been reinterpreted by Booij [9] later on in terms of internal particle rupture, i. e., in terms of particle cavitation rather than debonding of internally intact particles.…”

Rubber–Plastic Blends: Structure–Property Relationship

“…Impact strength increases with increasing rubber content. In a series with a constant particle size and a constant degree of grafting, impact strength increases with the rubber-plastic volume ratio [203,204]. Unlike HIPS, the rubber particles contain little or no matrix material occlusions.…”