Poly styrene, role

The reaction is reversible and therefore the products should be removed from the reaction zone to improve conversion. The process was catalyzed by a commercially available poly(styrene-divinyl benzene) support, which played the dual role of catalyst and selective sorbent. The affinity of this resin was the highest for water, followed by ethanol, acetic acid, and finally ethyl acetate. The mathematical analysis was based on an equilibrium dispersive model where mass transfer resistances were neglected. Although many experiments were performed at different fed compositions, we will focus here on the one exhibiting the most complex behavior see Fig. 5. 

Kanemitsu and Einami (1990) investigated the role of the polymer on hole transport in a series of 2-(p-dipropylaminophenyl)-4-(p-dimethylaminophenyl)-5-(o-chlorophenyl)-l,3-oxazole (OX) doped polymers. The polymers were a polyarylate (PA), bisphenol-A polycarbonate (PC), poly(methyl methacrylate) (PMMA), poly(styrene) PS, poly(vinyl chloride) (PVC), polyethylene terephthalate) (PET), and poly(vinyl butyral) (PVB). The glass transition temperatures of the polymers range from 322 (PVB) to 448 K (PA). The temporal features of the photocurrent transients were strongly dependent on the polymer. Figure 76 shows the results. The field was 4.0 x H)5 V/cm and the temperature 295 K. The transients were near rectangular for PS, PET, PA, and PMMA, and highly dispersive for PVC land PVB. This was attributed to the fact... 

The results showed that the -factor proposal alone is too simplistic, and other processes during the radical formation and transfer may play a more important role than termination alone. The rate of degradation of the host poly(styrene) was found to be enhanced and not diminished. However, the degradation rates of the added blend polymer (the acrylates) were reduced by a factor of about eight. Several other studies using the kinetics information on the pyrolysis process were used for the elucidation of the structure of polymeric samples [32-34]. 

Poly(styrene-co-chloromethylstyrene) crosslinked with divinylbenzene, which is immobilized with quaternary ammonium salts, was investigated for the synthesis of the fine chemicals in our previous studies [161-166]. The microenvironment of the polymer support played a crucial role in enhancing the reaction rate. More information about characterization of the polymer structure, the interaction between organic solvent, resin, and aqueous solution, and the reuse of the catalyst is required to encourage application. 

Metal/polymer hybrid particles displaying an eccentric structure were very recently reported [327, 328]. The key parameter for the formation of such morphologies was the addition of the metal nanoparticles after the polymerization was started. The reaction was performed in a water/ethanol mixture (40/60 by weight), ethanol playing a key role in the reduction of charge effects. Each hybrid particle contained only one metal nanoparticle anchored on the poly(styrene-co-DVB-ct)-NaSS) polymer particle. The strategy proved to be successful for gold, palladium, and platinum. 

Sato et al. [752] did a similar study on poly(styrene/methyl methacrylate) copolymer (PMMA). A 100/0-> 60/40 acetonitrile/DCM gradient was used with a polystyrene column. As pore size decreased, significant band broadening occurred as the retention mechanism became less dominated by adsorption while size exclusion began to play an equally important role in the separation process. 

Syndiotactic poly(styrene) displays a complex polymorphic behavior that reflects the specific role played by solvents. Four crystalline forms have been reported.(289,290) The a and p forms can be obtained from the melt (or glass), depending on the crystallization conditions.(291) Both structures comprise planar zigzag chains that have the same identity period of 5.1 A. The a form has a trigonal unit cell while the p form is orthorhombic. The P form can also be produced by crys-taflization from solution.(292,293) The y and 8 structures develop after interaction with solvent. In contrast to the all trans bond orientation of the a and p structures, the chains in the y and 8 crystals adopt a ttggttgg sequence of bond orientation. Thus a helical ordered structure evolves. This structure is similar to the crystalline chain conformation of syndiotactic poly(propylene).(294) The difference between the y and the 8 polymorphs is that in the former the sample is completely dried, while the solvent is included in the 8 form. It therefore represents a clathrate type structure. The formation of these structures is, thus, solvent specific.(292,293,295,296) The... 

The organic-inorganic hybrid materials have shown significant increases in properties compared to the conventional composites or neat polymers. The degree of dispersion of nanofiUers in a polymer matrix and the processing method play a key role on the final properties of the materials. Key objectives of researches are to design nanocomposites with enhanced properties at low filler contents. Different modified clays have been used in view of these objectives [31,52], There are reports on the use of ammonium-treated layered silicates [52,53], whereas the use of thermostable ILs such as pyridinium, imidazolium, or phosphonium is poorly reported. However, their combinations with poly(styrene) (PS) [54], PE [55], PP [56], poly(vinylidene fluoride) (PVDF) [57], and PET matrices [58] have been reported in the literature. 

The role of solvent alcohol in the photosensitized copolymerization or graft polymerization of styrene with cellulose has been investigated. Photo-induced grafting of poly(styrene-a/r-acrylonitrile) to cellulose yielded a product containing hetero- and homo-polymer chains. The effects of the matrix and concentration on the rate of reaction and the products have been investigated in persulphate-initiated grafting of poly(styrene-a/t-acrylonitrile) onto cellulose. ... 

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