Xiaochun Yin

Characteristics Study of Polymer Melt Conveying Capacity in Vane Plasticization Extruder

A vane extruder is novel equipment for polymer processing. The materials were conveyed and plasticized by a group of vane plasticization units and the materials suffered normal stress during processing. An analytic model was developed to analyze the conveying capacity of melt in the vane plasticization unit of which the melt can be conveyed positively. The analysis of conveying capacity of melt in the vane plasticization unit shows that the conveying capacity increased with the rotate speed, eccentricity distance, vane width, inner-diameter of stator. And the leakage flow model was developed to show that the leakage flow is increased with the width of leakage gaps but decreased with the apparent viscosity of melt. The experiment results show a linear variation of production with rotating speed, and small dependence effect of production with die pressure variation.

Synthesis of a bioadsorbent from jute cellulose, and application for aqueous Cd (II) removal

A low-cost, high-adsorption-capacity, eco-friendly bioadsorbent for removing Cd2+ from aqueous solution is reported. J-g-P(AM-co-AANa) was prepared by hydrolysis of the grafted copolymer, which was synthesized by free radical polymerization of acrylamide (AM) with jute fibers (JSE) pretreated by continuous screw-extrusion steam explosion. Fourier transform infrared and solid-state 13C nuclear magnetic resonance spectroscopies, confirmed that amino and carboxylate groups were introduced into J-g-P(AM-co-AANa). X-ray diffraction showed that the crystallinity of J-g-P(AM-co-AANa) was significantly lower than that of JSE. The surface morphology of bioadsorbent was investigated by scanning electron microscopy (SEM). The adsorption capacity of Cd2+ on J-g-P(AM-co-AANa) was evaluated for different solution pH values, contact times, and initial Cd2+ concentrations. The adsorption kinetics followed the pseudo-second-order kinetic model, and the rate controlling step was chemisorption. The adsorption isotherm was well fitted by the Freundlich model, and the adsorption process was multilayer adsorption. The maximum adsorption capacity was 344.8 mg/g, which indicated that the bioadsorbent was effective for removing Cd2+ from aqueous solution.

Preparation and mechanical properties of pithecellobium clypearia benth fibre/polypropylene composites processed by vane extruder

Pithecellobium Clypearia Benth fibre (PCBF) comes from steam-exploded Chinese medicine residue was filled in polypropylene (PP) matrix to prepare for PCBF/PP composites using vane extruder based on elongational deformation. The testing technologies related to the structure and morphology of PCBF with different times of steam explosion treatment were conducted by nuclear magnetic resonance (NMR), automatic surface area analyser and scanning electron microscopy (SEM). The effects of different times of steam explosion treatment, PCBF content, coupling agent content and extruding speed on the comprehensive mechanical properties of PCBF/PP composites were studied in this paper. The results showed that the PCBF has a higher content of cellulose, an increased aspect ratio and an enlarged specific surface area after third time steam explosion treatment. The tensile strength, tensile modulus, flexural strength and flexural modulus of PCBF/PP composites increase with the increasing times of steam explosion treatment when the times not more than three, and then decrease with increasing times of steam explosion treatment when the times exceed three. The tensile properties and flexural properties of PCBF/PP composites change with the increasing of PCBF content, coupling agent content and extruding speed nonlinearly. Furthermore, the SEM of PCBF/PP composites showed better interfacial interaction between the fibre and the matrix.

Properties and Morphology of Poly(Lactic Acid)/Calcium Carbonate Whiskers Composites Prepared by a Vane Mixer based on an Extensional Flow Field

ABSTRACT Binary composites of poly(lactic acid) (PLA)/calcium carbonate whiskers (CCW) with different weight fractions were prepared with a vane mixer based on extensional rheology. The mechanical properties, thermostability, crystallization behavior, rheology behaviors and micromorphology of the composites were analysed to study the effect of the CCW fibers on the composites properties; a pure PLA sample was also prepared for comparison. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) revealed that the CCW fibers had excellent compatibility with the PLA matrix and the CCW fibers were dispersed and distributed evenly in the PLA matrix under the action of the extensional flow field produced by the vane mixer. Differential scanning calorimetric (DSC) analysis showed that introducing a vane mixer into the PLA processing could increase the degree of crystallization (χc) of the composites significantly, and moderate CCW fibers adding could further increase its χc value. Thermogravimetric analysis (TGA) revealed that adding the CCW fibers reduced the thermostability of the composites. The G′, G″, η* and the torque, TN, of the composites, obtained from rheology analyses, declined obviously, because of the hydrolysis and chains scission induced by residual water and fatty acid when the CCW content less than 4%. Tensile tests proved that filling moderate amounts of CCW fibers into PLA could increase its tensile strength and strain at break, increasing by 5% and 29.6%, respectively.