Syndiotactic polystyrene mechanical properties

Raman spectroscopy is sensitive to polymer conformation. For example, a polymer blend of polybutadiene-polystyrene in which polybutadiene is used to increase toughness of the polystyrene can be examined by Raman microscopy to identify its heterogeneity. Polybutadiene has three isomer conformations (cis-1,4, trans-1,4 and syndiotactic-1,2). These three types of isomers can be identified from C=C stretching modes as shown in Figure 9.36. The Raman spectra of the copolymer indicate the difference in amounts of isomer types at the edge and the center of the polybutadiene-polystyrene sample. Relative amounts of these isomer types affect the mechanical properties of the copolymer. 

The mutual repulsion between substituents may cause some displacement. As a result, the plane of symmetry is bent in the form of a helix. This occurs also in biopolymers (double-helix of deoxyribonucleic acid (DNA)). Different stereoisomers have different mechanical and thermal properties. For example, atactic polystyrene is an amorphous polymer whereas syndiotactic polystyrene is a crystalline substance. The chemical design of macromolecules determines their properties as extent of crystallization, melting point, softening (glass transition temperature), and chain flexibility which in turn strongly influence mechanical properties of the materials. 

In the present text we attempt to do justice to the different topics of polymers and their uses. This text is generally suitable for researchers rather than students. The first chapter of this book discussed sorption mechanism of organic compound in the nanopore of syndiotactic polystyrene crystal. In the second chapter, a discussion was done to illustrate a physico-chemical characterization and processing of pulse seeds. The chemo-enzymatic polymerization for peptide polymers were illustrated in the third chapter. In the fourth chapter, an electrokinetic potential method was used to characterize the surface properties of polymer foils and their modifications. Also, an emulsion polymerizations was discussed in the fifth chapter. Nonconventional methods of polymer surface patterning, polymer characterization using atomic force microscope, biopolymers in the environment, and carbon nanostructure and their properties and applications were discussed in the sixth, seventh, eighth and ninth chapters respectively. Finally, let us point that although many books in the field of pol)nner science appear, none of them are complementary. 

Syndiotactic polystyrene (sPS) is a relatively new material discovery in semicrystalline pol5nners with a high melting point and rapid crystallization rate, which makes it possible to injection mold the material. The stereospecific polymerization was made possible by the combination of a transition metal catalyst with weakly coordinating cocatalysts, such as methylaluminoxane. The excellent balance of mechanical, electrical, solvent resistance, and dimensional stability properties combined with a relatively low price (based on styrene monomer) have made this material a competitor to existing engineering plastics. The products also have excellent heat performance and are finding application in antomotive (under the hood), electrical, and electronic connector systems. 

The physical and mechanical properties of a polymeric material critically depend on many factors, one of which is stereochemistry. Polymers that have chiral centers in the repeated unit can exhibit two structures of maximum order, isotactic and syndiotactic [27]. Sequential stereocenters of isotactic polymers are of same relative stereochemistry whereas those of syndiotactic polymers are of opposite relative configuration. Due to their stereoregularity, isotactic and syndiotactic polymers are typically crystalline, which is an important feature for many applications. Isotactic polymers are used in a wide range of applications. Typical examples include isotactic polyolefins and almost all natural polymers. In contrast, syndiotactic polymers have limited applications mainly due to their hard productivity and inherently alternating stereochemistry. The properties of syndiotactic polymers are usually similar to or in some cases better than isotactic counterparts according to the studies on syndiotactic polystyrene and other syndiotactic polyolefins [28]. Syndiotactic PLA is expected to be a versatile polymer with controllable stereochemistry. 

Until 2003, Chen s [28], Qu s [29-31], and Hu s [32] groups independently reported nanocomposites with polymeric matrices for the first time the. In Hsueh and Chen s work, exfoUated polyimide/LDH was prepared by in situ polymerization of a mixture of aminobenzoate-modified Mg-Al LDH and polyamic acid (polyimide precursor) in N,N-dimethylactamide [28]. In other work, Chen and Qu successfully synthesized exfoliated polyethylene-g-maleic anhydride (PE-g-MA)/LDH nanocomposites by refluxing in a nonpolar xylene solution of PE-g-MA [29,30]. Then, Li et al. prepared polyfmethyl methacrylate) (PMMA)/MgAl LDH by exfoliation/adsorption with acetone as cosolvent [32]. Since then, polymer/LDH nanocomposites have attracted extensive interest. The wide variety of polymers used for nanocomposite preparation include polyethylene (PE) [29, 30, 33 9], polystyrene (PS) [48, 50-58], poly(propylene carbonate) [59], poly(3-hydroxybutyrate) [60-62], poly(vinyl chloride) [63], syndiotactic polystyrene [64], polyurethane [65], poly[(3-hydroxybutyrate)-co-(3-hydroxyvalerate)] [66], polypropylene (PP) [48, 67-70], nylon 6 [9,71,72], ethylene vinyl acetate copolymer (EVA) [73-77], poly(L-lactide) [78], poly(ethylene terephthalate) [79, 80], poly(caprolactone) [81], poly(p-dioxanone) [82], poly(vinyl alcohol) [83], PMMA [32,47, 48, 57, 84-93], poly(2-hydroxyethyl methacrylate) [94], poly(styrene-co-methyl methacrylate) [95], polyimide [28], and epoxy [96-98]. These nanocomposites often exhibit enhanced mechanical, thermal, optical, and electrical properties and flame retardancy. Among them, the thermal properties and flame retardancy are the most interesting and will be discussed in the following sections. 

The purpose of providing a brief overview on recent reviews of nanocomposite materials that discuss synthesis, structure properties, and applications is to bring to the reader s attention the nascence of this field and justify the rare availability of degradation studies of these materials when we have only recently embarked on our journey to understanding the fundamentals about them. Nevertheless, a few examples of degradation studies of nanocomposite materials are provided with the hope of advances towards mechanistic aspects of degradation with nanomaterials components. Chrisaffis et al [56, 57] report studies on the decomposition mechanisms of syndiotactic polystyrene (sPS) nanocomposites with two different types of nano fillers multi-walled carbon nanotubes (MWCNTs) and carbon nanodiamonds (NDs). sPS is a semicrystalline polymer considered to be a... 

The precise synthesis by homogeneous catalysts created a new polymer, syndiotactic polystyrene (SPS), in 1985. SPS is categorized as an engineering plastic based on its performance. Since the discovery of SPS, many studies have been done to characterize and understand the nature of SPS. In this chapter, the properties of SPS are presented in terms of rheological, mechanical, and electrical properties. 

PROPERTIES OF SYNDIOTACTIC POLYSTYRENE TABLE 133 Mechanical Properties of Neat Polymers... 

Zhang, X. Q., Son, Y. Effects of maleated syndiotactic polystyrene on the morphology, mechanical properties, and crystallization behavior of syndiotactic polystyrene/polyamide 6 blends. Journal of Applied Polymer Science, 89(9), 2502-2506 (2003). 

Kolarik, J., Eambri, L., Sloul) M., Konecny, D. Heterogeneous polyamide 66/ syndiotactic polystyrene blends Phase structure and thermal and mechanical properties. Journal of Applied Polymer Science, 96(3), 673-684 (2005). 

Park, C. I., Choi, W. M., Kim, M. H., Park, O. O. Thermal and mechanical properties of syndiotactic polystyrene/organoclay nanocomposites with different microstructures. J. Polym. Sci Part B Polym. Phys., 42,1685-1693 (2004). 

Syndiotactic polystyrene has high heat resistance, excellent chemical resistance and dielectric properties[27], transparency, and good thermal processability. However, brittleness is major faults for many applications. It has been reported that mechanical properties such as tensile strength and modulus of the materials can be enhanced by inducing... 

In this study, we investigated the structure development of uni- or biaxial film stretching for syndiotactic polystyrene cast film. The films were characterized by differential scanning calorimetry, and x-ray diffraction. Mechanical properties of the films were also measured by Instron tensile tester. 

We investigated the thermal, mechanical properties and crystallographic structure developments of uni- and biaxially stretched syndiotactic polystyrene films, and their orientation. 

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