Yanhong Feng

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.

Properties of heat-treated sisal fiber/polylactide composites

Sisal fibers (SFs) were pretreated by heat treatment (HT). The SFs were mixed with a biodegradable material, polylactide (PLA), and the composites were prepared by hot press molding. The effects of the HT temperature and time on the mechanical properties of the composites were investigated, and the HT mechanism was studied by scanning electron microscopy and infrared, x-ray photoelectron, and nuclear magnetic resonance spectroscopies. The results show that an appropriate HT can remove strongly hydrophilic materials such as hemicelluloses from the fibers, and thus decrease their hydrophilicity, thereby improving the retting between the fibers and the matrix. This improves fiber–matrix interfacial adhesion, which can improve the mechanical properties of the composites. The HT also influences the fiber strength to some extent and affects the mechanical properties of composites.

Mechanical Properties of Poly(Butylene Succinate) Reinforced with Continuously Steam-Exploded Cotton Stalk Bast

Poly(butylene succinate) (PBS) was reinforced by cotton stalk bast fibers (CSBF), which had been pretreated by the continuous steam explosion method. The influence of water content in CSBF during the explosion and fiber content on the mechanical properties of CSBF/PBS biocomposites was investigated. The results showed that the incorporation of CSBF decreased the tensile and impact strength, while significantly enhanced the flexural strength, flexural modulus and tensile modulus. The mechanical properties of biocomposites reinforced by exploded fibers were much better than that of the biocomposites reinforced by non-exploded fibers. Biocomposites reinforced by fibers with 40 and 50 wt% water contents during the explosion had the best mechanical properties. The morphology of CSBF and biocomposites was evaluated by SEM, which demonstrated that fibers with 40 and 50 wt% water contents had better separation and rougher microsurfaces, indicating a better adhesion between PBS matrix and fibers.

Composites of sisal fiber/polypropylene based on novel vane extruder: Effect of interface and damage on mechanical properties

Sisal fibers were pretreated by alkali and maleic anhydride, and then mixed with polypropylene to fabricate sisal fiber-reinforced composites by a self-made vane extruder based on elongational flow field. Maleic anhydride-grafted polypropylene was used as compatilizer to increase the fiber/matrix interactions. The influence of treatment on the fibers structure, the damage to fibers in processing, interfaces of composites and the mechanical properties of composites were investigated. It was observed that the surface of treated fibers was improved obviously compared with that of untreated fibers, which was believed to increase the adhesion between the fibers and matrix. However, the treated fibers were more likely to be damaged during processing. In comparison to unmodified system, the incorporation of treated fibers could significantly enhance the mechanical properties of composites, especially adding the compatilizer of maleic anhydride-grafted polypropylene. The flexural and impact strengths were maximum for the sisal fiber/polypropylene and maleic anhydride-grafted polypropylene composites, and its tensile strength was also improved significantly. The major contribution of this change should be that the morphology of fibers could be well preserved in elongational flow field, which based on the vane extruder showed a good application in fiber-reinforced composites.

Pithecellobium Clypearia Benth Fiber/Recycled Acrylonitrile-Butadiene-Styrene (ABS) Composites Prepared in a Vane Extruder: Analysis of Mechanical Properties and Morphology

The effect of compatibilizer types and concentrations on the mechanical properties and morphology of Pithecellobium Clypearia Benth Fiber (PCBF)/recycled ABS composites prepared by a vane extruder were characterized. In addition, the percentage of compatibilizer was fixed at 8%, and the effect of lubricant concentrations on the mechanical properties and torque behaviors of the composites was also studied. Maleic anhydride grafted ABS (ABS-g-MAH) and maleic anhydride grafted PS (PS-g-MAH) were used as compatibilizers; the lubricant used was Struktol TPW 604 (blend of aliphatic carboxylic acid salts and mono diamides). The composite with 8% ABS-g-MAH showed superior mechanical properties compared to the composite without compatibilizer and the 8% PS-g-MAH compatibilized composites. Compared with PS-g-MAH, ABS-g-MAH was more effective for the composites to improve the interfacial interaction and mechanical properties. The comprehensive mechanical properties of PCBF/recycled ABS composite filled with 4% lubricant were better than the composites without lubricant and the composites with any other content of TPW 604. Moreover, the torque of the composites in an internal mixer decreased with an increasing lubricant content.

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.

The Effects of Temperature and Roll Pressing on the Properties of iPP Sheets

By using a processing of gas-cooling and roll pressing (GCRP), the temperature, strain and stress of isotactic polypropylene (iPP) sheets can be controlled and both β-modification and α-modification can be found in the sheets. The tensile strength of sheet in longitudinal direction increased by 14.1% at most, tensile modulus 14.2%, flexural strength 50.3% and impact strength 22.2%. Therefore, the strength and toughness of iPP can be increased simultaneously by GCRP.

Preparation and Characteristics of Biocomposites Based on Steam Exploded Sisal Fiber Modified with Amphipathic Epoxidized Soybean Oil Resin

Sisal fiber was pretreated by continuous screw extrusion steam explosion to prepare steam exploded sisal fiber (SESF) preforms. An amphipathic bio-based thermosetting resin with poor mechanical properties was cured by epoxidized soybean oil (ESO) and citric acid (CA). The obtained resin was used to modify SESF preforms and prepare eco-friendly biocomposites. The molar ratios (R) of carboxylic groups to epoxy groups and resin contents in biocomposites were adjusted. The biocomposites were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier-transfer infrared spectroscopy (FT-IR), tensile testing, scanning electron microscopy (SEM), water absorption and water contact angle measurements. The maximum thermal decomposition temperature of the biocomposites was 373.1 °C. The curing efficiency of the resin in the biocomposites improved with the increase of resin content, and reached a maximum at R = 1.2. The tensile strength of the biocomposites reached a maximum of 30.4 MPa at R = 1.2 and 40% resin content. SEM images showed excellent interfacial bonding and fracture mechanisms within the biocomposites. The biocomposites exhibited satisfactory water resistance. ESO resin cured with polybasic carboxylic acid is therefore a good bio-based modifier for lignocellulose, that prepare biocomposites with good mechanical properties, hydrophobicity, and thermostability, and which has a potential application in packaging.

Environmentally-Friendly Extraction of Cellulose Nanofibers from Steam-Explosion Pretreated Sugar Beet Pulp

Cellulose nanofibers (CNFs) with an average diameter of 22 nm were prepared from sugar beet pulp (SBP) via an environmentally-friendly method. Steam-explosion pretreated SBP was treated with hydrogen peroxide (H2O2) bleaching, high-speed blending, and ultrasonic treatment. Thermogravimetric analysis showed that hemicellulose was partially hydrolyzed in the steam-cooking stage, pectin was removed in the explosion stage, and lignin was removed by H2O2 bleaching. The removal of non-cellulosic components was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. Morphological analysis showed that steam-explosion pretreatment largely extracted the binder materials of hemicellulose and pectin. This exposed the microfibrillated cellulosic fibers, which promoted subsequent nanofibrillation. X-ray diffraction showed that the CNFs had a crystallinity index of 62.3%. The CNFs had good thermal stability, and thus have potential for use as fillers in polymer matrices. The only chemical reagent used in this green method was H2O2. Combining H2O2 bleaching with steam explosion, high-speed blending, and ultrasonic treatment reduced the overall energy consumption and increased the efficiency of the CNFs extraction. The method, therefore, has potential application in industrial processes.