No abstract

Semiaromatic polyamides containing thioether units were synthesized through the reaction of 4,4 0 -thiodibenzoyl chloride (TDC) and diamine by the method of interfacial polycondensation. The inherent viscosities of the resultant polyamides prepared with optimum synthesis conditions were 1.08À1.26 dL/g. These polyamides had excellent thermal properties with glass transition temperatures (T g ) of 119.8À190.1 °C, melting temperatures (T m ) of 281.4À355.5 °C, and initial degradation temperatures (T d ) of 433.5À466 °C. They had wider processing windows than traditional semiaromatic polyamides. At the same time, they had better tensile strengths of 62.1À86.5 MPa, better low-temperature mechanical properties, lower water absorption, lower dielectric constants of 3.16À3.81 at 100 kHz, and better melt flowability properties. The results suggest that these semiaromatic polyamides containing thioether units [poly(hexanelene 4,4 0 -thiodibenzoamide) (PA-6), poly(octanelene 4,4 0thiodibenzoamide) (PA-8), and poly(decanelene 4,4 0 -thiodibenzoamide) (PA-10)] represent a promising type of heat-resistant and processable engineering plastic.

In this research study, air plasma-treated polyphenylene sulfide film was used to prepare polyphenylene sulfide/glass fiber cloth composites for improving interfacial adhesion and mechanical properties. The effect of air plasma treatment on the properties of polyphenylene sulfide films was investigated by X-ray photoelectron spectroscopy and water contact angle analysis. According to the X-ray photoelectron spectroscopy analysis, it was found that plasma treatment led to the emergence of oxygen-containing polar groups on the film surface. The intensity of sulfide oxides (S = O and O = S = O) on the surface of polyphenylene sulfide films increased to 79.03% after it was modified by air plasma. Water droplet contact angle analysis indicated that plasma treatment significantly increased the hydrophilicity of the polyphenylene sulfide film. The contact angle was 38 degrees for plasma-treated polyphenylene sulfide film, compared to 78.5 degrees for untreated polyphenylene sulfide film. Tensile strength and notched impact strength of plasma-treated polyphenylene sulfide/glass fiber cloth (50/50) composite increased by 11% (from 248.49 MPa to 275.70 MPa) and 18% (from 52.26 KJ/m2 to 61.43 KJ/m2), respectively, compared with the raw specimen, which was consistent with the morphology analysis result. Meanwhile, the mechanical properties of the composites were improved with the increased discharge power density and treatment time.

No abstract

Aromatic polyamides containing thioether units were synthesized by interfacial polycondensation of 4,4′‐thiodibenzoyl chloride (or 4,4′‐bis(4‐chloroformylphenylthio)benzene) with aromatic diamines containing a nitrile unit. Their structure was established using 1H NMR and Fourier transform infrared spectroscopy. The inherent viscosities of the polyamides prepared with optimum synthesis conditions were in the range 0.71–0.84 dL g−1. These polyamides showed excellent thermal properties with glass transition temperatures of 210.5–219.6 °C, melting temperatures of 313.8–315.0 °C and initial degradation temperatures of 440–459 °C. They could be processed by melting due to their relatively wide processing window. Their tensile strengths were 71.3–79.1 MPa, water absorption was 0.17–0.22 wt%, and melt flowability was in the range 64.5 to 315.2 Pa s and 68.5 to 422.3 Pa s at different shear rates. At the same time, they were soluble in aprotic solvents such as N‐methyl‐2‐pyrrolidone, dimethylformamide and dimethylsulfoxide. The results suggest that these aromatic polyamides containing thioether units represent a promising type of heat‐resistant and processable engineering plastic. © 2012 Society of Chemical Industry