IPS, isotactic polystyrene

The numerical values in parentheses are the experimental values ° of Cj and hg (from Cj). N6 polycaproamide (nylon-6), N66 poly(hexamethylene adipamide) (nylon-6,6), iPP isotactic polypropylene, iPS isotactic polystyrene, PET poly(ethylene terephthalate). 

IPN Interpenetrating polymer network IPS Isotactic polystyrene IR Synthetic c/s-l,4-polyisoprene... 

Isotactic polystyrenes (IPS), 10 180 23 365 Isotactic propylene polymers, 17 703, 704 Isotactic-syndiotactic stereoblock PP, 16 110... 

When SPS is compared with isotactic polystyrene (IPS), a substantial difference is seen in the crystallization. IPS is also crystalline PS, but it has not been commercialized because of its very slow crystallization rate. In contrast, SPS... 

Abstract. We performed depolarized light scattering (DPLS) and polarized optical microscope (POM) measurements on the strnctnre formation process or the crystallization process of isotactic polystyrene (iPS) nnder shear flow below and above the nominal melting temperature Tm- It was found in the DPLS measurements that an anisotropic oriented structure on a pm scale was formed even above the nominal melting temperature. This was also confirmed by POM measurements. This oriented structure must be a precursor of primary nucleation, at least, in the early stage of the formation process. The structure and its formation mechanism are discussed based on the analysis of the DPLS data. 

Fig. 5.1. Temperature protocol for the shear experiments on isotactic polystyrene (iPS)...

Although they have high stereoregularity in the polymer backbone, isotactic polystyrene and syndi-otactic polystyrene are still not perfect from a material applications point of view. The rather slow crystallization rate of iPS prevents its commercial application whereas the high syndiotacticity of... 

Polyethylene obviously shows the simplest polymer structure. The all-trans conformation is energetically the most stable conformation and has been established by numerous diffraction experiments. For polymers with pendant side groups, e.g. isotactic polypropylene (iPP) and isotactic polystyrene (iPS), the extended all-trans conformation is of high energy due to steric repulsion of the side groups (Fig. 2.19). 

The discovery of isotactic polystyrene (IPS) gave a new dimension to this material since it now could crystallize and provide a melting point (Tm) of around 250 °C. Although it still has a Tg of 100 °C, the material will maintain its shape and may be used for many applications above this Tg and below the Tm. IPS has been the subject of several intense efforts for commercialization. Ultimately it has been unsuccessful for one primary reason that being the rate at which the polymer will crystallize is too slow under normal forming... 

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