Blends of polyether sulfone (PES) and polyphenylene sulfide (PPS) with different weight ratios (10/0, 8/2, 6/4, 4/6, 2/8, 0/10) were prepared by melt extrusion using a twin-screw extruder. In this work, the thermal stabilities of blends were evaluated by thermogravimetric analysis and the dynamic mechanical properties were investigated by means of dynamic mechanical analysis. The fracture surfaces were observed with a scanning electron microscopy. In addition, the mechanical property tests were also carried out and the impact strength of blends was improved by 110% compared to that of pure PPS. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41703.

Isothermal melt crystallization kinetics and nonisothermal cold crystallization kinetics of co-PI based on 3, 3′, 4, 4′-biphenyltetracarboxylic dianhydride (s-BPDA)/1, 3-bis-(4-aminophenoxy) benzene (TPER)/4, 4′-oxydianiline(4, 4′-ODA), and TPER PI (s-BPDA/TPER) have been investigated. Avrami equation was used to analyze isothermal melt crystallization progress of TPER PI and co-PI, primary crystallization processes was found to be changed as the introduction of 4, 4′-ODA. Total activation energy ΔE for TPER PI and co-PI were found to be −404 and −86 kJ mol⁻¹ by Arrhenius equation. Jeziorny's analysis, Ozawa's analysis, and Mo's approach were used to investigate nonisothermal cold crystallization progress of TPER PI and co-PI. Activation energy ΔE_non for TPER PI and co-PI were found to be 247 and 193 kJ mol⁻¹ by Kissinger equation. The result indicated that co-PI exhibited lower crystallization rate than TPER PI when isothermally crystallized from melt, but higher crystallization rate under cold nonisothermal crystallization progress. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

A series of uncontrolled molecular weight homopolyimides and copolyimides based on 3,3′,4,4′-biphenyltetracarboxylic dianhydride (s-BPDA)/4,4′-oxydianiline (4,4′-ODA)/1,3-bis(4-aminophenoxy)benzene (TPER) were synthesized. All the polyimides displayed excellent thermal stability and mechanical properties, as evidenced by dynamic thermogravimetric analysis and tensile properties testing. A singular glass transition temperature (T_g) was found for each composite from either differential scanning calorimetry (DSC) or dynamic mechanical analysis (DMA), but the values determined from tan δ of DMA were much different from those determined from DSC and storage modulus (E′) of DMA. The Fox equation was used to estimate the random T_g values. Some composites exhibited re-crystallization after quenching from the melt; upon heating, multi-melting behavior was observed after isothermal crystallization at different temperatures. The equilibrium melting temperature was estimated using the Hoffman-Weeks method. Additionally, DMA was conducted to obtain E′ and tan δ. Optical properties were strongly dependent on the monomer composition as evidenced by UV-visible spectra. X-ray diffraction was used to interpret the crystal structure. All the results indicated that composites with TPER composition ≥ 70% were dominated by the TPER/s-BPDA polyimide phase, and ≤40% by the 4,4′-ODA/s-BPDA polyimide phase. When the ratio between the two diamines was close to 1:1, the properties of the copolyimides were very irregular, which means a complicated internal structure. Copyright © 2011 Society of Chemical Industry