12060-59-2 Purity
0.99999000000000005
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Specification
Poly(butylene succinate-butylene terephthalate) (PBST) and polylactic acid (PLA) blends were prepared by melt blending using styrene-maleic anhydride copolymer (PSMA) as a compatibilizer. The effects of different contents of PSMA on the thermal properties, crystallization properties, mechanical properties, rheological behavior and morphology of PBST/PLA blends were studied. SEM results show that PBST and PLA are immiscible, and PLA is dispersed in the PBST matrix as spherical particles, while the addition of PSMA effectively improves the compatibility between the two polymers. The compatibility is also verified by DSC testing. With the increase in the amount of PSMA, the T difference between PBST and PLA decreases until they are almost merged into one. After adding PSMA, the crystallization temperature and crystallinity of PBST in the blend are reduced, but there is no obvious effect on the crystal structure of the blend. In addition, when the amount of PSMA was 3-4 wt%, the comprehensive mechanical properties of the blend were optimal, and the tensile strength was 61.7% higher than that of the binary blend without PSMA. Rheological tests showed that the blend exhibited typical shear-thinning behavior and was a pseudoplastic non-Newtonian fluid.
PBST, PLA, PSMA, and PE wax were dried in a vacuum at 50°C for 12 h to remove physically adsorbed surface water. The dried raw materials were weighed according to the formula listed in Table 1 and premixed in a high-speed mixer for 8 min. As an external lubricant, the amount of PE wax added was 0.6 wt%. The premixed mixture was poured into the mixing chamber of the torque rheometer for melt blending. The process conditions were: rotor speed 35 rpm, reaction time 10 min, and temperature 175 C in all three zones. After processing in the torque rheometer, the resulting PBST/PLA blend was cooled and granulated. Next, the mixed granules were added to the barrel of the microinjection molding machine and injected into a standard spline for testing. The temperatures of the mold zone and injection zone were set to 55° C. and 180° C., respectively. The injection time and holding time were 6 seconds and 35 seconds, respectively.
There is a creative strategy to control the microstructure and properties of polymer membranes by controlling the interphase miscibility. The transition from styrene maleic anhydride copolymer (SMA) to sodium styrene maleic anhydride copolymer (SMANa) enhances their miscibility with poly (vinylidene fluoride) (PVDF) and reduces the exchange rate of nonsolvent and solvent components during membrane formation. As a result, nonsolvent induced phase separation (NIPS) was successfully used to prepare PVDF/SMANa membranes with uniform pore distribution. In addition, the membrane microstructure was further optimized by changing the stock solution composition and coagulation bath temperature. The hydrophilicity and antifouling properties of the PVDF-based membranes were significantly improved due to the segregation and enrichment of SMANa on the membrane surface and pore walls. Due to the uniform porous structure, the optimized membranes showed excellent permeation flux and BSA rejection, which were significantly better than the values previously reported for other similar PVDF-based membranes. This study provides novel insights into the design and construction of PVDF/amphiphilic copolymer composite membranes with excellent properties.
To obtain SMANa, SMA powder was immersed in 100 g/L NaOH solution at 30 °C for 0.5-10 h, then collected by vacuum filtration and dried at 60 °C for 24 h. Subsequently, PVDF/SMANa composite membranes were prepared by the classical NIPS method with DMAC as solvent and PVP as pore former. A certain amount of PVDF, SMANa and PVP were dissolved in DMAC and stirred continuously at 70 °C for 24 h to form a uniform casting solution. The casting solution was then cast onto a nonwoven fabric through a 300 μm casting knife. The nonwoven fabric with the membrane was immediately immersed in a coagulation bath of water. After complete coagulation, the membrane was placed in room temperature deionized water for 48 h to remove residual DMAC and PVP, and then tested. In addition, a PVDF/SMA membrane was used as a control, and its preparation was the same as that of the PVDF/SMANa membrane.