Polymer blends polystyrene

In polymers such as polystyrene that do not readily undergo charring, phosphoms-based flame retardants tend to be less effective, and such polymers are often flame retarded by antimony—halogen combinations (see Styrene). However, even in such noncharring polymers, phosphoms additives exhibit some activity that suggests at least one other mode of action. Phosphoms compounds may produce a barrier layer of polyphosphoric acid on the burning polymer (4,5). Phosphoms-based flame retardants are more effective in styrenic polymers blended with a char-forming polymer such as polyphenylene oxide or polycarbonate. 

Noryl. Noryl engineering thermoplastics are polymer blends formed by melt-blending DMPPO and HIPS or other polymers such as nylon with proprietary stabilizers, flame retardants, impact modifiers, and other additives (69). Because the mbber characteristics that are required for optimum performance in DMPPO—polystyrene blends are not the same as for polystyrene alone, most of the HIPS that is used in DMPPO blends is designed specifically for this use (70). Noryl is produced as sheet and for vacuum forming, but by far the greatest use is in pellets for injection mol ding. 

In situ preparation of polymer blends of 1,4-polybutadiene with polystyrene, or poly(l-butene) has been achieved by using the heterogeneous Ziegler-Natta type catalyst (C2H )2A1C1—Ti(OC4H )4 in the host polymers (217). Homogeneous catalysts can also be used to catalyze these reactions (218). 

Two commercially significant graft copolymers are acrylonitrile—butadiene—styrene (ABS) resins and impact polystyrene (IPS) plastics. Both of these families of materials were once simple mechanical polymer blends, but today such compositions are generally graft copolymers or blends of graft copolymers and homopolymers. 

The relative U.S. production of styrene homopolymer and copolymer resins is also noteworthy (103) (Fig. 6). The impact polystyrene (graft and polymer blend) copolymers are produced in nearly the same quantities as styrene homopolymers. The ABS resins are synthesized in lesser, yet significant, quantities. 

Transparent toughened polystyrene polymers are produced by blending polystyrene with SBS block copolymers (see Section 11.8). During the 1970s and 1980s most development was with block copolymers with a radial (or star) shape. Two types were developed block copolymers with a central butadiene block, and block copolymers with a central polystyrene block. 

The advances in polymer blending and alloying technology have occurred through three routes (1) similar-rheology polymer pairs, (2) miscible polymers such as polyphenylene oxide and polystyrene, or (3) interpenetrating polymer networks (IPNs). All these systems were limited to specific polymer combinations that have an inherent physical affinity for each other. However with... 

The heat distortion temperature of impact-resistant polystyrene may also be improved by polymer blends. Those of impact-resistant polystyrene with poly-2,5-dimethylphenylene-1,4-oxide (PPO) are particularly interesting (90). Polystyrene and PPO are molecularly compatible and mixtures of them have glass transition temperatures which vary virtually linearly with composition. A further advantage of these compositions which should not be under-estimated is their better flame resistance. 

New Orleans, La., August 1999, p.752-3 POLYSTYRENE/POLYPROPYLENE POLYMER BLEND COMPATIBILISATION WITHOUT ADDITION OF PREMADE BLOCK OR GRAFT COPOLYMERS OR FUNCTIONALISATION Furgiuele N Khait K Torkelson J M (ACS,Div.of Polymer Chemistry)... 

Fig. 14 Creation of a single specimen polymer blend phase diagram from orthogonal polymer composition and temperature gradients. The polymers are polystyrene and poly(vinyl methyl ether) (PVME) a composition library placed orthogonal to a temperature gradient b completed gradient library polymer blend phase diagram. White points are data derived from traditional measurement for comparison. See text for details, (b reproduced with permission from [3])...

Figure 5.19 Homogenous polymer blend of 2,7-diamido-l,8-naphthyridine (DAN) functionalized polystyrene and urea of guanosine (UG) functionalized poly(butyl methacrylate) (14), based on the four-point complementary complex formation between DAN and UG.

---