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The morphology of syndiotactic polystyrene (s-PS) injection moulded at 50°C and 160°C was examined using polarized optical microscopy, transmission electron microscopy, and Fourier transform infra-red microspectroscopy as a function of mould temperature. A skin/core effect was present and significant structural differences existed at the skin of samples moulded at these two temperatures. Bars moulded...
Temperature-concentration phase diagrams have been established for syndiotactic polystyrene (sPS)/toluene gels and sPS/chloroform gels. The occurrence of polymer-solvent compound formation is shown in both systems and confirmed by neutron diffraction investigations. In particular it is found that a compound with a stoichiometry close to 11 occurs in both types of gels. Infra-red analysis show that...
Syndiotactic polystyrene (sPS) was synthesised using homogeneous catalytic systems based on titanium derivatives (tetraethyl orthotitanate, (cyclopentadienyl)titanium trichloride), methylaluminoxane (MAO) and aluminium alkyls (trimethylaluminium, triisobutylaluminium). The polymers were characterised by gel permeation chromatography (GPC) and nuclear magnetic resonance (n.m.r.) spectroscopy. Trimethylaluminium...
The δ-phase of the syndiotactic polystyrene/ethylbenzene system, as formed by crystallisation from dilute solution, is shown to result in a lamellar morphology, with a monoclinic crystal lattice similar to that already reported for the complex with toluene. Combined SAXS, FTi.r., d.s.c. and t.g.a. measurements show that an increase in the X-ray long period between 80 and 120 o C is related...
The neutron scattering observed from δ-phase samples of syndiotactic polystyrene (sPS)/ethylbenzene is shown to be consistent with sheet-like arrangements of crystal stems arranged along the a direction. Adjacent stems therefore show an alternation in helicity. Simulations based on a statistical model have been used to calculate statistical parameters, such as the probability of adjacency (P ...
Thermal and spectroscopic properties of the annealed cast syndiotactic polystyrene (SPS) films were investigated and it was shown that the sample annealed at lower temperature than 170°C exhibited the presence of a conformational order but lack of crystalline regularity. This result indicated the formation of mesophase by annealing cast SPS films. CO 2 sorption properties of such a film were...
The melt-crystallized orthorhombic modification of syndiotactic polystyrene (s-PS) was investigated by transmission electron microscopy. Single crystals of the β′ modification were prepared from a thin film by melt crystallization at 240°C. Their high-resolution images viewed along the molecular stem axis were successfully obtained, from which images the lateral arrangement of the individual molecular...
Syndiotactic polystyrenes (sPS) with different molecular weights were hydrogenated over the Ni/SiO 2 and Pd-BaSO 4 catalysts. Although the Ni catalyst yielded a completely hydrogenated sPS with a lower molecular weight, the hydrogenation of sPS with a high molecular weight was incomplete. On the other hand, the Pd catalyst was capable of hydrogenating sPS with a high molecular weight...
The dynamic mechanical behaviour of a series of hydrogenated syndiotactic polystyrenes (HsPS) with various degrees of hydrogenation has been investigated. In the case of crystallized HsPS samples, the primary dispersion is much broader due to the overlapping of two glass relaxation processes arising from one purely amorphous component and the other amorphous component under restraint by crystallites,...
The crystal structure of the clathrate δ form of syndiotactic polystyrene containing 1,2-dichloroethane is presented. Polymer chains in s(2/1)2 helical conformation and 1,2-dichloroethane molecules are packed in the monoclinic unit cell with axes a=17.11 9, b=12.17 9, c=7.70 9 and γ=120 o according to the space group P2 1 /a. The crystalline density of the clathrate δ form is 1...
The δ phase of syndiotactic polystyrene/ethylbenzene has previously been shown to involve a sheet-like arrangement of crystal stems, with superfolding at higher molecular weights. SANS measurements have been made using tilted samples in order to separate in-plane and out-of-plane radii of gyration. Use of intensities from the whole area of the detector allows the determination of these quantities...
The effect of adding diblock copolymer poly(styrene-b-4-vinylpyridine) (P(S-b-4VPy), to immiscible blends of syndiotactic polystyrene (sPS)/thermoplastic polyurethane (TPU) on the morphology, thermal transition, crystalline structure, and rheological and mechanical properties of the blends has been investigated. The diblock copolymer was synthesized by sequential anionic copolymerization and was melt-blended...
Toluene vapour sorption behaviours in syndiotactic polystyrene (SPS) film were measured at 25 o C by the quartz crystal microbalance method. The sorption isotherm of this system was concave toward the pressure axis below the activity of toluene vapour (p/p 0 =0.3), indicating a strong interaction between toluene vapour and sorption sites in the mesophase consisting of TTGG conformation...
Porous, membrane-like structures with different supramolecular organisation are prepared from solutions of syndiotactic polystyrene in cyclohexanol. Liquid–liquid (L–L) demixing leads to the formation of amorphous materials. They transform into the helix or γ-phase on heating above Tg. Further heating leads to a melting–recrystallisation process that transforms the γ-phase into the zigzag or β-phase...
The drawing behavior of syndiotactic polystyrene (sPS) has been studied in the temperature range around its glass transition. Amorphous sheets have been prepared by quenching, and drawn at temperatures from 90–120°C. The development of orientation and crystallization has been examined using the optical birefringence method, standard thermal analysis, and X-ray diffraction. The effect of draw ratio,...
The effects of molecular weight of atactic polystyrene-b-poly(ethylene-co-butylene)-b-atactic polystyrene [SEBS] triblock copolymers on the morphology, impact strength, and rheological property of syndiotactic polystyrene (sPS)/ethylene-propylene rubber (EPR) blends are examined. From the morphological analysis, it is observed that the size of dispersed EPR phase in sPS/EPR/SEBS blends decreases and...
The high temperature application of styrenic polymers was extended beyond the glass transition temperature of amorphous PS by the two following modifications:Increasing the syndiotactic portion, producing crystallites, which act as physical cross-links in the temperature region between the glass transition and the melting point.Copolymerisation with DPE leading to an increase in the glass transition...
Blends of syndiotactic polystyrene (SPS) with polyphenylene ether (PPE) have been prepared to determine the effect of blending on the crystallisation mechanism of SPS. The miscibility of the blend was confirmed by both differential scanning calorimetry and dynamic mechanical thermal analysis. Crystallisation of the blends was studied under isothermal and non-isothermal conditions using differential...
Scanning electron microscopy, differential scanning calorimetry, IR spectroscopy, and X-ray diffraction analyses were used to characterize the unique morphology of cold-crystallized syndiotactic polystyrene (sPS). Cold-crystallization of sPS produced only α-type unit cell packed into crystalline domains of different morphologies. The morphology contains a granular-sphere texture when cold-crystallized...
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