Rongyuan Chen

Preparation, characterization and properties of PLA/TiO2 nanocomposites based on a novel vane extruder

Polylactide/TiO2 nanocomposites with different contents of nanoscale TiO2 were prepared by melt blending with a vane extruder in this work. SEM and TEM microphotographs indicate that the nanoparticles were well dispersed in the polymer matrix under the elongational flow field of the vane extruder. Crystallization and melting behavior were examined with DSC. The results show that TiO2 nanoparticles have an inhibition for the cold crystallization process of PLA to some extent and the cold crystallization temperature of nanocomposites shifted to a maximum value at about 106 °C with low TiO2 loadings (0.5 wt% or 1 wt%). Dynamic rheological measurements and TGA results show that the introduction of TiO2 has significantly improved the thermal stability. The toughness, surface wettability and UV resistance of the composites were also investigated in detail.

Novel dynamic elongational flow procedure for reinforcing strong, tough, thermally stable polypropylene/thermoplastic polyurethane blends.

Thermoplastic polyurethane (TPU)/polypropylene (PP) blends of different weight ratios were prepared with a self-made vane extruder (VE), which generates global dynamic elongational flow, and a traditional twin-screw extruder (TSE), which generates shear flow. High-resolution scanning electron microscopy and polarizing microscopy showed a structure feature of fiber morphology and a clear interlocking structure of spherulites of PP/TPU blends prepared with a VE. The wide-angle X-ray diffraction results showed that the TPU/PP blend based on dynamic elongational flow had evident crystalline structure of the β form as a function of PP (90 wt %), compared to that of the conventional shear flow processing techniques. A significant improvement of the mechanical properties was obtained; the samples prepared with a VE had superior mechanical properties compared to those of the samples prepared with a TSE. Interestingly, differential scanning calorimetry curves showed that dynamic elongational flow could successfully improve the crystallinity of the PP/TPU blends. Furthermore, dynamic thermomechanical and thermogravimetric analysis curves revealed the apparent partial miscibility and strong interaction of the PP/TPU blends influenced by dynamic elongational flow, compared to that of TSE-extruded. Further research will provide significant understanding of the spherulite interface and high-performance manipulation of PP/TPU blends under dynamic elongational flow, achieving superior PP/TPU blends.

Influence of process parameters on property of PP/EPDM blends prepared by a novel vane extruder

Abstract In this study, thermoplastic elastomers based on polypropylene (PP) and ethylene-propylene-diene terpolymer (EPDM) were prepared via direct melt blending in a novel vane extruder. The influence of processing temperature and rotor speed on the degree of cross-linking of the EPDM phase, the tensile properties, the melting behavior and the crystallization morphology of PP/EPDM blends was investigated. It was observed that the volume fraction (Vr) of the vulcanizate arriving swelling equilibrium reached the maximum value when the processing temperature was 190°C. The tensile properties showed better performance at 195°C, at which the PP/EPDM blend obtained good dispersive mixing performance. Moreover, the Vr of the vulcanizate arriving swelling equilibrium reached the maximum value when the rotor speed was 60 rpm, at which the dispersive mixing performance and tensile properties of the PP/EPDM blend were better.

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.

Poly(lactic acid)/polypropylene and compatibilized poly(lactic acid)/polypropylene blends prepared by a vane extruder: analysis of the mechanical properties, morphology and thermal behavior

Abstract Poly(lactic acid) (PLA)/polypropylene (PP) blends with different weight fractions were prepared by a novel vane extruder. The mechanical properties, morphology, crystallization behavior and thermal stability of the blends were investigated. The tensile strength, flexural strength and elongation at break decreased nonlinearly when the PP content was not more than 50 wt% and then increased with an increase in the PP content. The flexural modulus decreased with increasing PP weight fraction. The PLA/PP 90:10 blend exhibited the optimum impact strength. Scanning electron microscopy measurements revealed that the PLA/PP blends were immiscible. Phase separation occurred significantly at a blend ratio of 50:50. Regarding the PLA/PP 90:10 blend, the mean diameter of the disperse-phase PP particles was the smallest at 1.11 μm. Differential scanning calorimetry measurements showed that low content of PP enhanced the crystallization of PLA. The PLA component in the blends impeded the crystallization of PP when PP was used as the matrix. The thermogravimetric analysis measurement involved a two-step decomposition process of the blends. The thermal resistance of the blends was improved by compounding with PP. As compatibilizers, both the maleic anhydride-grafted PP and the ethylene/n-butyl acrylate/glycidyl methacrylate terpolymer helped improve the mechanical properties, crystallization property and thermal resistance of the PLA/PP blends.

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.

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.

Investigation on Properties of Polypropylene/Multi-walled Carbon Nanotubes Nanocomposites Prepared by a Novel Eccentric Rotor Extruder Based on Elongational Rheology

ABSTRACT The properties of polymer matrix composites are related not only to the chemical composition of the materials but also to the processing equipment used for their preparation which has a direct influence on the microstructure of the composites. In this paper polypropylene (PP)/multi-walled carbon nanotubes (MWCNTs) nanocomposites were prepared by melt blending through a self-developed, eccentric rotor extruder (ERE). The structure and elongational deformation mechanism of an ERE were described in detail. The morphological, rheological, thermal and mechanical properties of the resulting PP/MWCNTs nanocomposites were investigated. Scanning electron microscopy (SEM) and rheological analysis showed that the MWCNTs were well dispersed in the PP matrix. The thermal stability was investigated by thermogravimetric analysis (TGA) and indicated that the addition of MWCNTs could effectively improve the thermal stability of pure PP. The percentage of crystallinity and tensile strength of the composites were improved as a result of the heterogeneous nucleation effect of the MWCNTs in the PP matrix. The research results revealed that the enhancement of the properties of PP/MWCNTs composites could be attributed to a better dispersion of the MWCNTs in the matrix as compared to samples prepared by conventional extrusion.

Crystallization behavior and thermal stability of poly(butylene succinate)/poly(propylene carbonate) blends prepared by novel vane extruder

This work focused on the study of crystallization behavior and thermal stability of degradable poly(butylene succinate) (PBS) and poly(propylene carbonate) (PPC) blends prepared by vane extruder based on elongation force field, which is novel equipment for polymer processing. Dicumyl peroxide (DCP) was applied in this work as compatibilizer for PBS/PPC blend. Crystallization behavior and melting behavior of the blends were investigated by differential scanning calorimetry (DSC) testing. Thermal stability of the blends was studied by thermogravimetric (TG) testing. Furthermore, the melt flow indices (MFI) of the blends were examined by a MFI instrument. The results showed that the crystallization temperature of PBS decreased with the addition of PPC and DCP. The glass transition temperature of PPC increased and the melting temperature of the blend increased with the addition of PPC and DCP, which indicated that the entanglement between the molecular chains of PBS and PPC was enhanced. Thermogravimetric ana...

Preparation, melting behavior and thermal stability of poly(lactic acid)/poly(propylene carbonate) blends processed by vane extruder

Poly (lactic acid) (PLA)/Poly (propylene carbonate) (PPC) blends were prepared by vane extruder which is a type of novel polymer processing extruder based on elongation force field. Scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetric (TG) were used respectively to analyze the compatibility, the melting behavior and thermal stability properties of PLA/PPC blends affected by the different content of PPC. The results showed that with the increase of the PPC content, the glass transition temperature of PLA was reduced, and the glass transition temperature of PPC was increased, which indicated that PLA and PPC had partial compatibility. The cold crystallization temperature of PLA increased with the increase of the PPC content, which showed that PPC hindered the cold crystallization process of PLA. The addition of PPC had little impact on the melting process of PLA, and the melting temperature of PLA was almost kept the same value. Thermogravimetric analysis showed that the thermal stability of PPC was worse than that of PLA, the addition of PPC reduced the thermal stability of PLA.