Study On The Manufacture Of Poly(Butylene Succiante-co-butylene Terephthalate) (PBST) Nonwoven And Its Structure And Properties

Recently, with preservation of environment and oil crisis concerns taken into consideration, the environment protection and sustainability of many disposable products have attracted much more attention. Poly(butylene succinate-co-butylene terephthate) (PBST), as a new aliphaticearomatic copolyester, has particularly been found to be the most attractive biodegradable synthetic polymers because of its desirable biodegradability and good mechanical properties. So far, the thermodynamic and degradation properties of PBST copolymers, film-forming property, spinning process and properties of fibers have been reported by many researchers. However, PBST nonwovens manufactured by meltblowing have never been attempted.In the above cases, the physical properties of PBST prepared for meltblowing were studied and PBST nonwoven with good properties was successfully yielded. The influences of process parameters on the properties of nonwovens were discussed in detail. Fractal geometry was used to evaluate the irregularity of pore size distribution. Furthermore, air permeability of PBST meltblowing nonwovens and its relationship with fractal dimension of pore size distribution were also investigated, which provided theoretical foundation and practical experience for its commercial process.Studying on thermal, crystalline and rheological properties offered foundation for the initial setting of web froming's technological parameters. It was found that PBST copolyester had relative higher melting temperature and good thermal stability, whose melting peak temperatures at about 180℃and decomposion temperatures at about 380℃. The crystal structure of PBST was triclinic system and degree of crystallinity was 46.5 percent. The apparent viscosity of PBST decreased with the increase of shear rate and temperature. The shear-thinning results indicated the PBST melts belonged to non-Newtonian pseudoplastic fluid. The flow activation energy of PBST decreased with the increasing of shear rate, so the sensitivity to temperature decreased.Orthogonality experimental design was employed, based on fiber diameter as measure index, to investigate the optimized process parameters. The result showed that die temperature was at 275℃, injection pressure was 0.25 mpa, the die to collector distance was 400mm and extruder rate was 4 rpm. The fiber diameter deceased with the increase of die temperature, the die to collector distance and injection pressure, but it rose with the increase of extruder rate. And extruder rate and injection pressure were the main factors effecting fiber diameter. Furthermore, the influences of the process parameters on the properties of fiberweb density, mechanical properties, filtration properties and thickness were also discussed in detail using single factor analysis method.Fractal geometry combining with computer image analysis was used to evaluate the irregularity of pore size distribution of PBST meltblwing nonwoven. Furthermore, air permeability of PBST meltblowing nonwovens and its relationship with fractal dimension of pore size distribution were also discussed in detail. The results revealed that pore structures of PBST nonwovens could be regarded as a fractal and the fractal dimension of pore size distribution declines with the decrease of mass per unit area of samples. Air permeability of PBST nonwovens which could be also regarded as a fractal has good consistency with fractal dimension of pore size distribution, and fractal dimension of air permeability declines with the decrease of mass per unit area of samples too. Therefore, evaluating the pore structures using fractal geometry is of great guiding significance in practical production.