Polymer blends with 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. 

More recently Fina Chemicals have introduced linear SBS materials (Finaclear) in which the butadiene is present both in block form and in a mixed butadiene-styrene block. Thus comparing typical materials with a total styrene content of about 75% by weight, the amount of rubbery segment in the total molecule is somewhat higher. As a result it is claimed that when blended with polystyrene the linear block copolymers give polymers with a higher impact strength but without loss of clarity. 

Styrene-butadiene block polymers also find applications in blends with polystyrene and ABS plastics. When minor amounts of rubbery SBS or (SB)n- X block polymers are blended with high molecular weight polystyrene such that the polystyrene forms the... 

The rather unexpected properties described above seem to be peculiar to PVN, for none of the blends with polystyrene, poIy-4-vinylbiphenyl, and polyacenaphthylene contained significant amounts of amorphous PEO. The modulus curves for these systems are characteristic of blends of incompatible polymers. The photomicrograph in Figure 12 illustrates the different morphologies of PVB and PEO blends. The reason for the apparently different behavior for these polymers as compared with PVN is not yet understood. But there is strong evidence from dilute solution-studies that the conformational properties for these polymers differ markedly. 

Because the components must initially form miscible solutions or swollen networks a degree of affinity between the reacting components is needed. Therefore, most of the investigations into epoxy IPNs have involved the use of partially miscible components such as thermoplastic urethanes (TPU) with polystyrenes [57], acrylates [58-61] or esters which form loose hydrogen-bound mixtures during fabrication [62-71 ]. Epoxy has also been modified with polyetherketones [72],polyether sulfones [5] and even polyetherimides [66] to help improve fracture behavior. These systems, due to immiscibility, tend to be polymer blends with distinct macromolecular phase morphologies and not molecularly mixed compounds. 

Halogenated styrenes can form a number of copolymers, some used in blends with polystyrenes or other polymers. Examples of such copolymers are poly(o-chloro-styrene-co-p-chlorostyrene), polystyrene-co-poly(2-chlorostyrene) [14], poly(methyl acrylate-co-4-chlorostyrene), etc. A few studies on thermal behavior of these polymers are available [15, 16]. 

These polymers can be blended either in solutions or in the melt. A blend of up to 2% of polymer 3 with polystyrene appeared clear, but turbid blends resulted from higher percentages of polymer 3. The Tg s of blended polymers containing up to 30% of polymer 3 did not change from that of pure polystyrene. Transmission electron microscope (TEM) analysis of the 5% blend showed that there are bimodal distributions of polymer 3 domains, a small amount of approximately 10 nm domains, and a large portion of approximately 1 l domains. 

Oxidative coupling of phenols was first reported by Hay and coworkers in 1959" and has since been developed to produce commercially useful polymers. In these reactions the parent compound, phenol, has a potential functionality of four, that is the two ortho and the one para position of the aromatic ring and the phenolic group. Not surprisingly, the commercially useful polymers are made from substituted phenols in which the potential functionality is reduced to two. Of these phenols 2,6-dimethylphenol or orf/zo-xylenol has been developed to a commercial polymer, poly(2,6-dimethyl-1,4-phenylene oxide) (54). The General Electric Company sells this as a blend with polystyrene under the trade name Noryl. 

Wang H. L., Toppare L., and Fernandez J. E., Conducting polymer blends polythiophene and polypyrrole blends with polystyrene and poly (bisphenol A carbonate). 

In order to meet increasing performance demands for electret applications, polymer electret blends are being explored. Lovera et al. have recently reported on tailored polymer electrets based on poly(2,6-dimethyl-l,4-phenylene ether) (PPE) and its blends with polystyrene (PS) [98]. They obtained good electret performance with neat PPE and showed that it could be improved by blending with PS. 

Lovera D, Ruckdaschel H, Goldel A, Behrendt N, Frese T, Sandler JKW, Altstadt B, Giesa R, Schmidt HW (2007) Tailored polymer electrets based on poly(2,6-dimethy 1-1,4-phenylene ether) and its blends with polystyrene. Eur Polym J 43 1195... 

Figure 6.2 demonstrates the role the substrate can play. In this example, the same polymer blend solution (polystyrene and polythiophene dissolved in a chlorobenzene solution) was deposited with the same procedure (spin coating) [6]. The only difference between samples was a modification of the surface chemistry... 

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