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Tobacco stem, the residue from cigarette manufacturing, is usually discarded as waste, leading to serious resource waste and environmental problems. This study provides an effective utilization available for this solid residue by using it as the starting material in the preparation of activated carbon with chemical activation. Activated carbons with high specific area and various surface functions have been prepared, and the effects of the amount and type of activating agents on the physical and chemical properties of activated carbon were investigated as well.

Ground tire rubber (GTR) with crosslinked structure has hardly any plasticity and processability, which makes its property very poor. Thermal-mechanical shearing devulcanization method can effectively destroy the crosslinked structure and restore GTR a certain extent of plasticity and processability. This article investigated the characteristic and reprocessing performance of reclaimed rubber prepared through thermal-mechanical shearing devulcanization. The relationship between the devulcanization level (indicated by gel fraction and crosslink density) and the mechanical property was analyzed by sufficient experiments. Fourier transform infrared spectroscopy and elemental analyzer studies revealed the chemical structure of GTR changed and many complex reactions occurred after devulcanization. The gel permeation chromatography indicated the specific changes of molecular weight and molecular weight distribution in devulcanization process. The differential scanning calorimetry revealed various vulcanized abilities and vulcanized structures of reclaimed rubber. The scanning electron microscope further confirmed the recovery of plasticity after devulcanization and the distinct vulcanized structures between revulcanizates. The determination of devulcanization level and mechanical properties verified that mechanical properties especially tensile strength reached to the optimum value only at an appropriate devulcanization level.

The crystallization behavior of PVDF (poly (vinylidene) fluoride) in PVDF-dimethylphthalate(DMP) system was investigated in the liquid-liquid (L-L) phase separation region, solid-liquid (S-L) phase separation region and different quenching conditions via thermally induced phase separation (TIPS). Differential scanning calorimetry (DSC) indicated the crystallinity of PVDF in PVDF-DMP system increased in the early stage of phase separation and polymer-rich phase crystallized completely in the late stage of phase separation. The scanning electron microscopy (SEM) showed the different quenching temperatures had effects on the spherulite size of polymer rich phase and the ultimate membrane structure in the different phase separation regions. The wide angle Xray diffraction (WAXD) was used to quantify the crystal structure of PVDF in PVDF-DMP system. The a-phase PVDF was obtained when the system quenched to different temperatures above 408C, and the area of diffraction peaks changed when quenching temperatures changed. While the b-phase PVDF was formed when PVDF-DMP system was quenched form liquid nitrogen and crystallized for 24 h in 258C water bath.