Izod impact, styrene blends

PPE/PA styrene-butadiene radial copolymer K-Resin ) with citric acid or chloro-epoxytriazine or tapered block copolymer Izod impact strength was improved (in comparison to blends with HIPS) by a factor of three. Gianchandai et al., 1993 Yates, 1993. 

Blends of polycarbonate with other styrenic resins are relatively new and therefore their current market volume is low. They have been developed primarily to upgrade the performance of such styrenic resins as styrenic-maleic anhydride (SMA), styrene-methyl methacrylate (S-MMA), acrylic-sty-rene-acylonitrile (ASA) resins primarily for impact strength and to some extent for DTUL improvement (Tables 15.7, 15.8 and 15.23). These blends uniquely combine high notched Izod impact strengths (ranging from 500 J/m to > 1000 J/m) with better UV resistance or weatherability than ABS. 

In the same manner, blends containing (100% to 90%) polystyrene and (0% to 10%) styrene-butadiene rubber (SBR) exhibited improved impact properties after gamma irradiation at a dose of 100 kGy. FTIR provided evidence that irradiation produced a radical in the benzene ring of PS that could react with the double bond of polybutadiene producing a metasubstituted benzene (Figure 9.5). Hence, this chemical link between the two polymers gave rise to the increase in Izod impact strength parhcularly for 100 kGy y-irradiated 90/10 PS-SBR blend. 

The above blends were modified with styrene-butadiene radial copolymer Threefold increase of the Izod impact strength Gianchandai et al. 1993... 

Commercial impact-modified acrylic resins (Table 19.15) exhibit five- to tenfold improvement in the notched Izod impact strength and the ultimate tensile elongation compared to the neat PMMA resin. These impact-modified acrylics are usually blended captively by the manufacturers of the acrylic resins. The base resin in a typical weatherable grade (Plexiglas DR, Rohm and Haas) could be a methyl methacrylate copolymer with ethylacrylate and styrene, while the rubber additive (ca. 10 %) could be an emulsion-polymerized, PMMA-grafted, cross-linked poly (n-butylacrylate) rubber of controlled particle size (<200 nm). The nonweatherable impact-modified acrylic (XT, CYRO) typically consists of a MMA/S/AN copolymer with MBS (ca. 10 %) rubber particle dispersions. 

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 poly(methyl methacrylate)-grafted butadiene-styrene rubber (MBS) or an all acrylic core-shell rubber such as poly (MMA-g-n-BuA) are used (Nakamura et al. 1975 Chung et al. 1985). ABS (with high polybutadiene content >50 %) or ASA rubber (>50 % aciylate rubber) have also been used. The presence of such a rubber component is definitely needed to obtain high notched Izod impact strengths (>500 J/m) in these blends. 

In the late forties, work began to improve the prcperties of a new thermoplastic blend. It had been revealed [2] in 1948 - 50 that poly(styrene-co-acrylonitrile), or SAN, could be blended with Buna N, a copolymer of butadiene and acrylonitrile, or Buna S, a copolymer of loutadiene and styrene, to get useful thermoplastics. These materials were impact resistant, with Izod impact values of 2 to 3 foot-pounds. The commercial use of these materials was hindered loy the lack of low tenperature impact strength. The rubber technologists of the narbon Division (as the Marsene Corporation had been named on assimilation into Borg-Warner) knew that polybutadiene remained "rubbery" at lower tenperatures than the copolymers cited above. However, blending experiments showed that polybutadiene and SAN were incompatible. The polymerization of SAN could be acconplished in solution, in bulk, or... 

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