Blend core-shell rubber

Essentially all the literature reviewed in the preceding paragraph emphasized identification rather than control of rubber-phase distribution. Recently, our laboratory conducted a series of investigations to identify and control rubber-phase distribution in several binary blends by using functionalized core-shell rubber. We were able to control butyl acrylate core-shell rubber in PC, PET, or both phases in PC-PET-rubber blends by functionalizing the shell structure of the core-shell rubber with glycidyl methacylate monomer units (16). 

This study demonstrated that the final destination of the added core-shell rubber particles, in PC, PA, or both, in the PC-PA binary blend can be controlled by properly selecting the chemical structure of the shell in the core-shell rubber. The unreactive MBS rubber tends to reside in the PC phase and near the vicinity of the PC-PA interface. The reactive MBS-MA rubber can have a chemical reaction with PA end groups and can therefore be retained within the PA phase. High-molecular-weight bisphenol A epoxy resin has proved to be an efficient compatibilizer for PC-PA blends. Rubber-toughening of the PC-PA blend in which PC is the matrix is much more effective than with blends in which PA is the matrix. 

In order to improve both the thickness sensitivity and low temperature sensitivity of the impact strength, polycarbonate has been blended with a variety of low T, elastomeric impact modifiers. More important among these are the core-shell rubbers like PMMA-g-polybutadiene, PMMA-g-SBR (MBS), PMMA-g-n-butylacrylate (acrylic core-shell), all normally composed of 0.1/core particles. These modifiers improve both the thick-section (6.4 mm) and low temperature notched Izod impact properties of polycarbonate [Witman, 1981 Neuray and Ott, 1981 Bussink et al., 1977] (Figures 15.13 and 15.14). The blends are of course opaque. Impact modified polycarbonate also shows better retention of impact strength with heat-aging. 

All the commercial PBT/PC and PET/PC blends also contain typically 10-20 wt% of an additional elastomeric impact modifier. The exact nature and the content of the impact modifier is kept proprietary and often forms the basis for a particular blend patent. Typically core-shell rubbers such as polymethylmethacrylate grafted butadiene-styrene rubber (MBS) or an all acrylic core-shell rubber such as poly (MMA-g-n-BuA) are used [Nakamura, 1975 Chung, 1985]. ABS (with high polybutadiene content S 50%) or ASA... 

However, the acrylic PVC compositirais commercially used invariably contain an acrylic core-shell rubber (PMMA-g-n-BuA or MBS-type) to get high toughness, with some PMM A, to reduce the cost/impact performance balance. The role of PVC in these blends is primarily to reduce the cost and impart some degree of flame-retardancy to the acryUc resin. The acrylics definitely help in the processability of PVC. These blends have already been discussed under PVC heading. 

Thermoplastic elastomers (TPE), 9 565-566, 24 695-720 applications for, 24 709-717 based on block copolymers, 24 697t based on graft copolymers, ionomers, and structures with core-shell morphologies, 24 699 based on hard polymer/elastomer combinations, 24 699t based on silicone rubber blends, 24 700 commercial production of, 24 705-708 economic aspects of, 24 708-709 elastomer phase in, 24 703 glass-transition and crystal melting temperatures of, 24 702t hard phase in, 24 703-704 health and safety factors related to, 24 717-718... 

Sanchez-Solis, A. Estrada, M.R. Cruz, J. Manero, O. On the properties and processing of polyethylene terephthalate/styrene-butadiene rubber blend. Polym. Eng. Sci. 2000,40 (5), 1216-1225. Luzinov, I. Xi, K. Pagnoulle, C. Huynh-Ba, G. Jerome, R. Composition effect on the core-shell morphology and mechanical properties of ternary polystyrene/styrene butadiene rubber polyethylene blends. Polymer 1999, 40 (10), 2511-2520. 

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