In this study, the effects of ultrasonic cell crushing apparatus on the properties of recycling bamboo pulp fibers and handsheets were evaluated. Repeated recycling of bamboo fibers led to the reduction in paper tensile strength, but ultrasonic treatment resulted in strength enhancement. The ultrasonic treatment of pulp fibers was found to be preferred as regards strength improvement due to enhanced inter‐fiber bonding strength. Pulp recycling also led to the reduction in pulp WRV (water retention value), while sonication was able to improve the WRV. Optical microscopic observations indicated that ultrasonic treatment was basically related to fiber swelling and fibrillation, which contributed to strength enhancement.

View full abstract

One‐pot preparation of poly[4‐(5‐oxy‐1,3‐dioxoisoindolin‐2‐yl)benzoyl] (PODB) crystals which was an aromatic poly(ester‐imide) was examined by means of the reaction‐induced crystallization during polymerization of 4‐acetoxyphthalic anhydride (APA) and 4‐aminobenzoic acid (AmBA). Two‐step heating program was suitable for the formation of PODB crystals. The reaction of APA and AmBA at 150℃, which was much lower than the polymerization temperature, was of importance to synthesize N‐(4‐carboxyphenyl)‐4‐acetoxyphthalimide. Even though the amide moiety was incorporated, the PODB crystals were formed as precipitates by heating at 150℃ and then at 280‐350℃. Morphology of PODB depended on the polymerization conditions and fibrillar crystals, rod‐like crystals and ribbon‐like crystals were obtained. This result provided a novel one‐pot procedure for the control of the PODB morphology.

View full abstract

Aromatic polyesters were synthesized by the polymerization of bio‐based 2,5‐furandicarboxylic acid (FDCA) with petroleum‐based 1,3‐ and 1,4‐diacetoxybenzene (DAB) from the viewpoint of the suppression of the petroleum consumption to develop the sustainable development society. Polyesters prepared at the molar ratio of 1,4‐DAB in DAB (χ) of less than 60 mol％ showed meltability under decomposition temperature. When the value of χ was 20‐60 mol％, the polyesters exhibited optical anisotropicity in melt phase, suggesting the thermotropic liquid crystallinity. The phase transition temperature of these polyesters depended on the composition and it was tunable by the χ value. The film of the polyesters prepared at χ of 20 mol％ possessed 1.2 GPa of the modulus, 26.0 MPa and 2.9％ of the strength and elongation at break, respectively. Polyesters based on FDCA possessed good thermal stability and mechanical properties comparable to common aromatic polyesters.

View full abstract