Graft blends

Graft Blends. The properties of ABS-type polymers involving mixtures of terpolymer resins and graft rubbers are shown in Table IV. As with the nitrile rubber types, there is a pronounced gain in impact strength at a given rubber level when DBPF is present in both phases (Blends 1 vs. 3 and 2 vs. 4). 

Flame Resistance. Blends with nitrile rubbers (Table III) containing at least 10% bromine passed the comparatively stringent Underwriters Subject 94 test. Graft blends having 7-10% bromine failed the Underwriter s test only because of dripping. They passed the ASTM D-635 test, as did all the nitrile rubber blend types. 

Graft/Blend Polymers. These polymers were prepared by dissolving PVC in either methyl ethyl ketone or tetrahydrofuran, followed by the appropriate 2-ethylhexyl acrylate/acrylonitrile monomer charge and the free radial initiator, e.g., Lupersol 11 (tert-butyl peroxypivalate). This solution was then heated to 50°-70°C in 4-oz bottles, 2-1. glass reactors, or larger glass-lined autoclaves. Polymerization times were normally 12-16 hrs a conversion check was then made, and, if conversion was complete, films were cast from the polymer solution. 

Unexpectedly, when films were cast from these poly (vinyl chloride-g-2-ethylhexyl acrylate/acrylonitrile) solutions, they were crystal clear with very low haze values. Table IV lists some of the physical properties of these poly (vinyl chloride-g-2-ethylhexyl acrylate/acrylonitrile) cast films values for a solution blend of the acrylic copolymer and PVC are also included. While tensile strengths of the 1.0/1.5 and 1.0/4.0 acrylic copolymer/PVC-graft/blend films were about 80-90% that of the homopolymer PVC film, they were significantly higher than that of the blend polymer. Furthermore, the crescent tear strengths were higher than those of the blend and the PVC film. Most importantly, the haze values of the graft blend films were much improved over that of the blend polymer, and they more nearly approached that of the homopolymer PVC. 

Furthermore, a GPC curve (Figure 3), obtained on this 1.5/1.0-PVC/ acrylic copolymer (1.5/1.0-2EHA/AN) graft/blend showed only a single peak, although it was considerably broader than that of the parent homopolymer PVC which had an MWD of 2.1. 

Figure 2. DTA thermogram of 1.5/1.0-PVC/acrylic copolymer graft/blend...

Figure 5. Electron photomicrograph of 1.0/4.0-acrylic copolymer (1.5/1.0 2-EHA/AN)/PVC-graft/blend...

Table V. Controls for Oxygen Content of Graft/Blend Polymers"...

It was observed that these transparent 1.5/1.0-PVC/acrylic copolymer (1.5/ 1.0-2EHA/AN)-graft/blend films were somewhat more resistant to degradation from UV exposure than unstabilized homopolymer PVC (see Table VI). The graft/blend films retained clarity and were noticeably less prone to shrinkage in the Fadeometer where the service life was extended from 500 hrs for the control to 2000 hrs for the graft/blend films. 

The transparent PVC-acrylic graft/blend products are somewhat more resistant to UV degradation than the parent PVC polymer and have physical properties which are of interest in film applications. These properties include improved tear strength over the PVC parent polymer and somewhat higher tensiles than are obtainable with the acrylic copolymer. 

They found that the grafted blends do not suffer degradation because of electron beam irradiation. The grafted blends maintained their stmctural integrity, with the advantage of improved surface properties. 

Somewhat similar results were obtained with cellulose graft/blend systems with PMA, PMMA and poly(2-hydroxyethyl methacrylate) [Nishioka and Yoshida, 1992] and could be correlated with the degree of compatibility. In one case the thermal stability of blends containing grafted cellulose was 100°C less than those without grafted product [Nishioka et al., 1993]. 

Rheological anomalies in maleic anhydride-PE graft blends with polyamide-6, PA-6, have been noted. These were explained on the basis of chemical reactions occurring at the interface of the biphasic melt [Kim et al, 1991]. 

The PA/PE grafted blend was offered commercially as a concentrate (Selar RB) to be melt blended with HDPE to a final PA/HDPE ratio = 15/85 for subsequent blow molding into containers such as gasoline tanks, solvent containers, etc. This laminar barrier blend of HDPE and PA was reported to provide up to 100 fold improvement in the barrier to permeation of such organic solvents as toluene, relative to pure HDPE, or a similar blend composition containing PA as a uniform spherical dispersion. 

GRT particles have an ability to adsorb hydrocarbons. However, their adsorption capacity is low in comparison with adsorbent materials currently in use. To improve its adsorption capacity various methods for manufacturing of adsorbents and their various uses were proposed, as discussed in this section. An oil absorptive material of lower cost can be obtained by graft copolymerization through blending of various proportions of GRT of particle size of 100 mesh with 4-tert-butylstyrene (tBS), as a monomer in the presence of divinylbenzene, as a crosslinker, and benzoylperoxide, as an initiator (Wu and Zhou, 2009). Oil absorbency of the grafted blends reached a maximum of 24.0 g/g at a feed ratio GRT/tBS of 60/40 and a divinylbenzene concentration of 1 wt.%. 

Macro-moiecular modifiers improve impact wide range resistance, wear, etc. grafting, blends, two-phase sy stems... 

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