Longfang Ren

Effects of Crystallization Temperature and Blend Ratio on the Crystal Structure of Poly(butylene adipate) in the Poly(butylene adipate)/Poly(butylene succinate) Blends

The effects of crystallization temperature and blend ratio on the polymorphic crystal structures of poly(butylene adipate) (PBA) in poly(butylene succinate) (PBS)/poly(butylene adipate) (PBS/PBA) blends were studied by means of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (XRD) and atomic force microscopy (AFM). It was revealed that the polymorphism of PBA can be regulated by the blend ratio even in a non-isothermal crystallization process. The results demonstrate that high temperature favors flat-on α crystals, while low temperature contributes to edge-on β crystals. It was also found that the effect of blend ratio on the crystallization mechanism of PBA is well coincident with that of the crystallization temperature. The increment of PBS content in the PBS/PBA blend gives rise to more β-form crystals of PBA. For those PBS/PBA blends with low PBA content, the interlamellar phase segregation of PBA makes its molecular chains so difficult to diffuse from one isolated microdomain to another that high crystallization temperature and sufficiently long crystallization time will be required if the PBA α-type crystals are targeted.

Effects of crystallization condition of poly(ethylene succinate) on the crystallization of poly(ethylene oxide) in their blends

The effects of the crystallization temperatures of poly(ethylene succinate) (PES) on the crystallization behavior of poly(ethylene oxide) (PEO) in their blends were investigated by means of differential scanning calorimetry, atomic force microscopy, and laser confocal fluorescent microscopy. It was found that confined and fractional crystallization of PEO takes place in the PES/PEO blends at all blend ratios if PES is crystallized at higher crystallization temperatures. And morphological observation gives a direct evidence of the different location distribution of PEO, resulting in the confined and fractional crystallization behavior.

Study on the improvement of water vapor permeability and moisture absorption of microfiber synthetic leather base by collagen

The microfiber synthetic leather base pretreated by sulfuric acid was modified by collagen in which the organic phosphine FP was used as a cross-linking agent, for the purpose of increasing the active groups and improving its properties. Compared with the pretreated base, it was found that the amino content in the modified base was two times and the carboxyl content was three times. The water vapor permeability of the modified base increased by 65% and the moisture absorption increased by 181%. It was further found that the tensile strength of the modified base was 19.06 N/mm2, the elongation at break was 54% and the tear strength was 112.34 N/mm. The test results of Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, thermogravimetric analysis and water contact angle showed that the collagen molecules had evenly cross-linked with fiber. The modified base microfiber dispersion was greatly increased, the hydrophility was enhanced and the relative average roughness was decreased. Moreover, modification by collagen also affected the thermal properties of the base.

Preparation of partially end-capped amino-terminated hyperbranched polymer and dyeing properties enhancement to polyurethane membrane

In this study, a series of products with different water solubility, which were named as partial end-capped amino-terminated hyperbranched polymers (HBPs) 1–6, were obtained by changing the mass ratio of raw materials. The structure was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The polyurethane was respectively mixed with partial end-capped amino-terminated HBPs to prepare different blend membranes by the drying method. The results showed that the water solubility of partial end-capped amino-terminated HBPs had obvious effects on the dyeing properties of blend membranes. When the mass ratio of amino-terminated HBP and single-blocked isophorone diisocyanate was 3:2, the performance of prepared partial end-capped amino-terminated HBP 4 was the best. The structures of blend membranes were characterized by FTIR spectroscopy, X-ray diffraction and scanning electron microscopy (SEM). When the mass fraction of partial end-capped amino-terminated HBP 4 was 2%, dye uptake improved from 12% to 85%. The dry-rub fastness and wet-rub fastness reached 4.5 and 3, respectively. The K/S values indicated that the surface chroma also deepened. The results indicated that partial end-capped amino-terminated HBP and polyurethane had hydrogen-bond interaction and certain phase separation.

Study on Biodegradability of Acrylic Retanning Agent DT-R521

The methods of respiratory curve and COD30 were adopted to evaluate the biodegradability of acrylic retanning agent DT-R521, which was used as the substrate of microorganism. The main results obtained by the method of respiratory curves were as follows: When the concentration of substrate was 0 3000mg/L, the respiratory curves of the substrate were under the curve of endogenous, which showed that the substrate has inhabiting effect on microorganism. When the concentration of the substrate was 1500mg/L, the utilization of the substrate by microorganism was the most. The main results obtained by the method of COD30 were as follows: when sludge concentration was 1000mg/L and pH was 7, the biodegradation rate of 500mg/L DT-R521 was 26.21%. Under above condition, the biodegradation rates of DT-R521 with other concentrations were much smaller. Moreover, as indicated in the respiratory curves, the effect of sludge concentration, salinity and co-metabolism on the biodegradability of the substrate was obvious. Under the experimental conditions, when the concentration of the substrate was 1500mg/L, the sludge concentration was 3000mg/L and salinity was 0.7%, the biodegradability of the substrate was the best. The glucose was as co-metabolism substrate and when its concentration was 300mg/L, the biodegradability of the substrate was obviously increased.