Feichao Zhu

The influence of drawing pressure on the properties of PET/PA6 bicomponent spunbonded fibers

The properties of fibers were significantly affected by drawing during the spunbond process. In this paper, the influence of drawing pressure on the properties of spunbonded PET/PA6 hollow pie wedge bicomponent filaments was studied, and their performance was characterized by differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, Beion F6 fiber fineness tester, and single fiber strength tester. The hollow pie wedge bicomponent fiber had a distinct interface between the two polymers due to poor compatibility. With increasing of drawing pressure, diameter of the fibers reduced regularly. When the drawing pressure increased, both the degree of crystallinity and orientation of bicomponent fibers enhanced, and the melting point of polyester component increased as well. Furthermore, with increasing of drawing pressure, the breaking strength of the fibers increased, but the breaking elongation and linear density decreased.

Effects of Poly(ϵ-caprolactone) on Structure and Properties of Poly(lactic acid)/Poly(ϵ-caprolactone) Meltblown Nonwoven

To obtain flexile poly(lactic acid)-based melt-blown nonwoven filtration material, poly(lactic acid)/poly(ϵ-caprolactone) melt-blown nonwoven with various components were melt-spun by melt-blown processing in the Melt-blown Experiment Line. The 3 wt.% tributyl citrate to poly(ϵ-caprolactone) was added in the composites as compatibilizer. The effect of poly(ϵ-caprolactone) on the structure, morphology, mechanical and filtration properties of poly(lactic acid)/poly(ϵ-caprolactone) melt-blown nonwoven was reported. Scanning electron microscopy micrographs revealed good dispersion of the additive in the fiber webs. The crystallinity of melt-blown webs with poly(ϵ-caprolactone) was more than that of poly(lactic acid) alone. The tensile strength, ductility and air permeability of poly(lactic acid) melt-blown nonwovens were enhanced significantly. The input of poly(ϵ-caprolactone) increased the diameter of fibers and decreased the filtration efficiency of poly(lactic acid)/poly(ϵ-caprolactone) melt-blown nonwoven.

LMPP Effects on Morphology, Crystallization, Thermal and Mechanical Properties of iPP/LMPP Blend Fibres

The thermal properties and morphological characterisation of isotactic polypropylene (iPP) homopolymer and its blends with low molecular low modulus polypropylene (LMPP) were studied. Firstly blends were prepared with variant LMPP contents, and their properties were characterised using SEM, DSC, XRD, and DMA. Later the mechanical properties of iPP/LMPP blend fibres were investigated. SEM results showed that the iPP/LMPP blends produced smoother surfaces when the LMPP content was increased, as well as the miscibility. All the Tg values with different LMPP percentages were in-between pure iPP and LMPP. The XRD results indicated the LMPP percentage decreased along with the degree of crystallinity of the iPP/LMPP blends (5% to 15%), which increased and then decreased as compared to pure iPP. The elongation at break increased when the LMPP content increased, with the maximum elongation at break of the LMPP 25% blend reaching 12.95%, which showed great stretch-ability, whereas the elastic modulus of iPP/LMPP blends decreased.

Preparation and properties of poly (lactic acid)/magnetic Fe3O4 composites and nonwovens

To develop degradable and magnetic PLA-based melt-blown (MB) nonwoven materials for air filtration applications, poly (lactic acid) (PLA)/magnetic Fe3O4 (PLA/Fe3O4) MB nonwovens were obtained by melt blowing using the PLA/Fe3O4 composites with different components prepared by melt-mixing as the masterbatch. The crystallization and melting behavior of the composites were examined with differential scanning calorimetry (DSC). Although the results showed that the Fe3O4 particles obviously hindered the cold crystallization process of PLA and the relative crystallinity degree of the composites decreased due to the addition of Fe3O4; there was no overall change in the crystal structure of PLA according to the wide-angle X-ray diffraction (XRD). Thermogravimetric analysis (TGA) and dynamic rheological measurements demonstrated that the introduction of Fe3O4 reduced the thermal stability of PLA. The effect of Fe3O4 particles on the morphology of the PLA/Fe3O4 composites and MB nonwovens was characterized by scanning electron microscopy (SEM). It revealed that the Fe3O4 particles were dispersed in a PLA mixture with the “sea-island” structure, and the addition of Fe3O4 particles also made the fiber surface rough and the nonwoven web turned fluffy to some extent. The magnetic properties and filtration performance of the MB nonwovens were also investigated in detail.

Optimization of Mechanical and Thermal Properties of iPP and LMPP Blend Fibres by Surface Response Methodology

Optimization of the mechanical and thermal properties of isotactic polypropylene (iPP) homopolymer blended with relatively new low molecular low modulus polypropylene (LMPP) at different blend ratios was carried out via surface response methodology (RSM). Regression equations for the prediction of optimal conditions were achieved considering eight individual parameters: naming, elongation at break, tensile strength and elastic modulus, crystallization temperature (TC), first melting temperatures (TM1), heat fusion (Hf), crystallinity, and melt flow rate (MFR), which were measured as responses for the design of experiment (DOE). The adjusted and predicted correlation coefficient (R2) shows good agreement between the actual and the predicted values. To confirm the optimal values from the response model, supplementary experiments as a performance evaluation were conducted, posing better operational conditions. It has been confirmed that the RSM model was adequate to reflect the predicted optimization. The results suggest that the addition of LMPP into iPP could effectively enhance the functionality and processability of blend fibres if correctly proportioned.

Study on dual-monomer melt-grafted poly(lactic acid) compatibilized poly(lactic acid)/polyamide 11 blends and toughened melt-blown nonwovens

With increasing demands on the high-performance and environmental-friendly melt-blown nonwovens (MBs) for separation and filtration, herein, we reported a poly(lactic acid)/polyamide 11 (PLA/PA11) 100% bio-based MBs in situ compatibilized by dual-monomer glycidyl methacrylate–styrene melt-grafted poly(lactic acid) (PLA-g-(St-co-GMA)). The morphology, crystallization, thermal and rheological behaviors of reactive extruded PLA/PA11/PLA-g-(St-co-GMA) melt blends were investigated, and the structure and filtration performance of corresponding MBs were fully characterized. The results indicated that the interface between PLA and PA11 were effectively improved due to the compatibilizer of PLA-g-(St-co-GMA). PA11 promoted the cold crystallization and enhanced the thermal stability of PLA matrix. The reactive blends displayed a higher viscosity with unchanged rheological behaviors compared with PLA. In comparison with PLA MBs, the average fiber diameter and pore size of PLA/PA11/PLA-g-(St-co-GMA) MBs were slightly increased, whereas the strength and toughness were significantly improved. All the PLA/PA11/PLA-g-(St-co-GMA) MBs presented high air permeability and low filtration resistance. High filtration efficiency (>99.8%) could also be obtained especially for the target particles with diameters larger than 2.5 µm.