Properties and Structure of Polystyrene

Because of the chain-stiffening effect of the benzene ring the TgS of commercial materials are in the range 90-100°C and isotactic polymers have similar values (approx. 100°C). A consequence of this Tg value plus the amorphous nature of the polymer is that we have a material that is hard and transparent at room temperature. Isotactic polystyrenes have been known since 1955 but have not been of commercial importance. Syndiotactic polystyrene using metallocene catalysis has recently become of commercial interest. Both stereoregular polymers are crystalline with values of 230°C and 270°C for the isotactic and syndiotactic materials respectively. They are also somewhat brittle (see Section 16.3). 

Being a hydrocarbon with a solubility parameter of 18.6MPa - it is dissolved by a number of hydrocarbons with similar solubility parameters, such as benzene and toluene. The presence of a benzene ring results in polystyrene having greater reactivity than polyethylene. Characteristic reactions of a phenyl group such as chlorination, hydrogenation, nitration and sulphonation can all be performed with 

The pure hydrocarbon nature of polystyrene gives it excellent electrical insulation characteristics, as a result of both the fundamentally good characteristics of the material and to the low water absorption of such a hydrocarbon polymer. The insulation characteristics are therefore well maintained in humid conditions. 

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Figure 4.6 E/10) vs. temperature for polyblends of polystyrene and a 30/70 butadiene-styrene copolymer. Numbers on the curves are the weight percent of polystyrene in the blend. (From Toboisky A. /., Properties and Structure of Polymers, John Wiley Sons, New York, 1960. With permission of Dorothy Toboisky.)... 

It is well known that the properties and structures of the surface and interface are different from those in a bulk state. The 3D observations made using con-focal microscopy are very useful for discussing the effects of the surface/inter-face on the phase-separation structure. Kumacheva et al. studied the morphology of the surface and bulk of a polystyrene (PS)/PMMA blend prepared by casting from a toluene solution [20]. The cross-sectional image of a PS/PMMA blend is shown in Figure 19.4, where the bright areas correspond to the PMMA domains. The depth-dependent phase-separation structure was... 

As mentioned in the previous section, hollow zeolite spheres of LTA, FAU, BEA, MFI can be prepared in the presence of polystyrene beads as templates by using an LBL self-assembly technique. Recently, several research groups have tried to adopt similar methods to synthesize zeolite-template composites on the surfaces of templates with various shapes and sizes, properties, and structures through self-assembly or in situ-crystallization approaches. Subsequent removal of the templates forms zeolite materials with analogical skeletons of the templates. Up to now, the reported templates include microspheres, carbon fibers, polyurethane foams, and microbe structures,[144,145] as well... 

The structure of a multi block copolymer does not seem suitable for the purpose. On the other hand, the structure of graft copolymers with short polysiloxane branches is considered to be the exact structure for the purpose, since one may maintain film forming properties, flexibility of slloxane chain (high permeation rate), and high selectivity. The flexibility of the slloxane chain can be maintained in side chains of graft copolymers and film forming properties and selectivity of permeation can be provided by backbone For this purpose, polystyrene was chosen as the backbone material... 

A polymer is a macromolecule that is constructed by chemically linking together a sequence of molecular fragments. In simple synthetic polymers such as polyethylene or polystyrene all of the molecular fragments comprise the same basic unit (or monomer). Other polymers contain mixtures of monomers. Proteins, for example, are polypeptide chains in which each umt is one of the twenty amino acids. Cross-linking between different chains gives rise to yet further variations in the constitution and structure of a polymer All of these features may affect the overall properties of the molecule, sometimes in a dramatic way Moreover, one... 

Pastukhov, A. V. Physico-chemical properties and structural mobility of hypercros-slinked polystyrenes , Dr.Sci. Thesis, Moscow, 2009. 

There have been attempts to control activities in response to envirorunental changes using property and structural changes of a biocatalyst that is fixed onto an enviromnent (stimuli)-responsive polymer substrate. For example, if a maleic acid/styrene copolymer is adsorbed onto a polystyrene microcapsule in which an enzyme is fixed, the polymer chains spread at pH>5 due to the dissociation of carboxylic groups. As a result, the permeability of the microcapsule increases and the apparent activity of the... 

Preparation, Structure, Properties, and Applications of Co-Crystals and Nanoporous Crystalline Phases of Syndiotactic Polystyrene... 

Structure, preparation, properties, and applications of the nanoporous crystalline phases of syndiotactic polystyrene are described in section 3 of this chapter. 

There are at the present time many thousands of grades of commercial plastics materials offered for sale throughout the world. Only rarely are the properties of any two of these grades identical, for although the number of chemically distinct species (e.g. polyethylenes, polystyrenes) is limited, there are many variations within each group. Such variations can arise through differences in molecular structure, differences in physical form, the presence of impurities and also in the nature and amount of additives which may have been incorporated into the base polymer. One of the aims of this book is to show how the many different materials arise, to discuss their properties and to show how these properties can to a large extent be explained by consideration of the composition of a plastics material and in particular the molecular structure of the base polymer employed. 

TPEs from blends of rubber and plastics constitute an important category of TPEs. These can be prepared either by the melt mixing of plastics and rubbers in an internal mixer or by solvent casting from a suitable solvent. The commonly used plastics and rubbers include polypropylene (PP), polyethylene (PE), polystyrene (PS), nylon, ethylene propylene diene monomer rubber (EPDM), natural rubber (NR), butyl rubber, nitrile rubber, etc. TPEs from blends of rubbers and plastics have certain typical advantages over the other TPEs. In this case, the required properties can easily be achieved by the proper selection of rubbers and plastics and by the proper change in their ratios. The overall performance of the resultant TPEs can be improved by changing the phase structure and crystallinity of plastics and also by the proper incorporation of suitable fillers, crosslinkers, and interfacial agents. 

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