Rheological Properties of Carbon Nanofiber-Filled Polyamide Composites and Blend of these Composites and TPE

For the purpose of developing new engineering materials with sufficient balance among mechanical, electrical, processability, triboloical properties, etc., in this study, we investigated the dynamic viscoelastic properties of carbon nanofiber (CNF) filled polyamide (PA) composites and the blend of these composites and thermoplastic elastomer (TPE) in the molten state, which were mainly obtained in our previous studies. It was found that vapor grown carbon fiber (vapor grown carbon fiber) has a stronger influence on the dynamic viscoelastic properties of the composites in the molten state. Rheological percolation thresholds seem to exist between 1vol.% and 5vol.% of VGCF contents. On the other hand, the effect of the addition of TPE (styrene-ethylene/butylene-styrene copolymer (SEBS) and maleic anhydride grafted SEBS (SEBS-g-MA)) on the dynamic viscoelastic properties of VGCF/PA6 composites in the molten state differed at each viscoelastic value. It was clarified that the dynamic viscoelastic properties of VGCF/PA6/SEBS-g-MA ternary composites are higher than those of VGCF/PA6/SEBS ones. Furthermore, the influence of processing sequences on the dynamic viscoelastic properties of VGCF/PA6/SEBS-g-MA composites in the molten state differed according to the mixing steps of materials. These may be attributed to the change in the internal structure caused by addition of TPE, type of SEBS and processing sequences

Influence of processing sequence on the tribological properties of VGCF-X/PA6/SEBS composites

In order to develop the new tribomaterials for mechanical sliding parts with sufficient balance of mechanical and tribological properties, we investigated the influence of processing sequence on the tribological properties of the ternary nanocomposites: the polymer blends of polyamide 6 (PA6) and styrene-ethylene/butylene-styrene copolymer (SEBS) tilled with vapor grown carbon fiber (VGCF-X), which is one of carbon nanofiber (CNF) and has 15mn diameter and 3 mu m length. Five different processing sequences: (1) VGCF-X, PA6 and SEBS were mixed simultaneously (Process A), (2) Re-mixing (Second compounding) of the materials prepared by Process A (Process AR),(3) SEBS was blended with PA6 (PA6/SEBS blends) and then these blends were mixed with VGCF-X (Process B), (4) VGCF-X was mixed with PA6 (VGCF-X/PA6 composites) and then these composites were blended with SEBS (Process C), and (5) VGCF-X were mixed with SEBS (VGCF-X/SEBS composites) and then these composites were blended with PA6 (Process D) were attempted for preparing of the ternary nanocomposites (VGCF-X/PA6/SEBS composites). These ternary polymer nanocomposites were extruded by a twin screw extruder and injection-molded. Their tribological properties were evaluated by using a ring-on-plate type sliding wear tester under dry condition. The tribological properties such as the frictional coefficient and the specific wear rate were influenced by the processing sequence. These results may he attributed to the change of internal structure formation, which is a dispersibility of SEBS particle and VGCF-X in ternary nanocomposites (VGCF-X/PA6/SEBS) by different processing sequences. in particular, the processing sequences of AR, B and D, which are those of re-mixing of VGCF-X, have a good dispersibility of VGCF-X for the improvement of tribological properties

Tribological properties of nanosized calcium carbonate filled polyamide 66 nanocomposites

For the purpose of developing high performance tribomaterials for mechanical sliding parts such as gears, bearings and so on, nanosized calcium carbonate (nano-CaCO3) tilled polyamide 66 (PA66) nanocomposites were investigated. The nano-CaCO3 was a kind of precipitated (colloid typed) CaCO3, and its average particle size was 40, 80 and 150 nm. Surface treatment was performed by fatty acid on the nano-CaCO3 and its volume fraction in the nanocomposite was varied from 1 to 20vol.%. These nanocomposites were melt-mixed by a twin screw extruder and injection-molded. Tribological properties were measured by two types of sliding wear testers such as ring-on-plate type and ball-on-plate type one under dry condition. The counterface, worn surface and wear debris were observed by digital microscope and scanning electron microscope. It was found that the nano-CaCO3 has a good effect on the tribological properties, although the effect on the frictional coefficient and specific wear rate is differed by the volume fraction and the type of sliding wear modes. This is attributed to the change of wear mechanisms, which is the change of form of the transfer films on the counterface and the size of wear debris. It follows from these results that PA66/nano-CaCO3 nanocomposites may be possible to be the high performance tribomaterials

Thermomechanical and Rheological Behaviours of Waste Glass Fibre-Filled Polypropylene Composites

The composites between the reinforced glass fibre wastes obtained from surfboard manufacturing industry and polypropylene were developed for value adding and environmental reasons. The thermomechanical and rheological behaviours of the composites were investigated. Glass fibre contents were varied from 5 to 30 wt%. The effects of maleic anhydride grafted polypropylene (MA-PP) compatibilizer on the behaviours were also determined. The results revealed that the addition of glass fibre was able to reduce the heat of fusion of the composite. Additionally, the tensile and flexural properties were increased with increasing the glass fibre contents following the rule of mixtures. The addition of MA-PP led to enhance tensile and flexural properties due to the improvement of the adhesion between matrix and glass fibre, which is correlated with morphological observations. From the rheological studies, the apparent flow activation energy revealed that the addition of glass fibre decreased the fluidity of the molten composite materials; however, it could be slightly improved by using MA-PP

Fabrication of micro-structured surface of plants-derived polyamide using femtosecond laser and their frictional properties

For the purpose of developing the new polymeric tribomaterials using biopolymer, the fabrication of micro-structured surfaces of plants-derived polyamide (PA) using femtosecond laser and their frictional properties were investigated. In this study, the effect of processing parameter such as laser power, laser speed and pitch distance on the fabrication of micro-structured surfaces of polyamide 66 (PA66) and plants-derived polyamide 1010 (PA1010) was investigated experimentally, and their frictional properties and wettability were evaluated. Polyamides (PA1010 and PA66) were extruded by a twin screw extruder and injection-molded to 30mm × 30mm × 3mm sheet. The micro-structured surfaces on the polyamides were fabricated by femtosecond laser. The micro-structured surfaces on the polyamides by laser fabrication were observed by laser microscope and scanning electron microscope (SEM). Frictional properties were measured by a ball on plate reciprocating type sliding wear tester under lubrication conditions. It was found that the surface microchannels are able to be fabricated by the femtosecond laser and have a good effect for the improvement of the frictional properties and wettability of PA66 and plants-derived PA1010. Laser power influences strongly on the microchannels size, wettability and frictional properties. This may be attributed that the micro-structured surface plays an important role in the key components for the polymeric tribomaterials. © 2016 Author(s).MEXT, Ministry of Education, Culture, Sports, Science, and Technolog

Thermal Properties of Hemp Fiber Reinforced Plant-Derived Polyamide Biomass Composites and their Dynamic Viscoelastic Properties in Molten State

To further enhance the mechanical, thermal, and tribological properties of short natural fiber-reinforced biopolymer composites, it is very critical to understand thermal properties of these biomass composites and their dynamic viscoelastic properties in the molten state. The aim of this study is to experimentally investigate the thermal properties of hemp fiber filled plant-derived polyamide 1010 composites and their dynamic viscoelastic properties in the molten state. It was found that the addition of HF with PA1010 has a strong influence on the thermal properties such as DMA, TGA, and DSC. HF is very effective for improving the thermal and mechanical properties. The effect of alkali treatment on the dynamic viscoelastic properties of the HF/PA1010 composites in the molten state differs according to whether alkali treatment uses silane coupling agent or not. The viscoelastic properties of NaClO2 are higher than those of NaOH. Silane coupling agents have a remarkable influence on rheological properties such as storage modulus, loss modulus, and complex viscosity in the low angular frequency region in the molten state, temperature dependences of rheological properties, and relationship between the phase angle and complex modulus. These rheological behaviors are also strongly influenced by the type of silane coupling agents

Effect of salt concentration and temperature on the rheological properties of guar gum-dead sea salt gel

Dead Sea Salt (DSS) contains 21 minerials including magnesium, calcium, sulfur, bromide, iodine, sodium, zinc and potassium etc. On the other hand, Guar Gum (GG) is a natural polysaccharide, water soluble, having highest molecular weight and good gelling property. Due to such advantageous properties of DSS and GG, it has been taken interest to prepare a user friendly medicated gel (designated as GG-DSS gel) adding additional ingredients:e.g. Glycerol, Thymol, Ethanol, Seabuckthorn oil, and essencial oils for the improvment of the gel's medicated values and healing properties for the curing of general skin diseases/treatment. In this study, the viscoelastic behavior of GG-DSS gels were characterized by dynamic storage (G') and loss (G") moduli and complex viscosity as a function of angular frequency. The effect of DSS concentration and temperature on these properties of GG-DSS gels was investigated. All GG-DSS gels having different amount DSS shows G' higher than G" over a wide range of angular frequency. Both moduli have the trends to increase with the increase of temperature (temperature varies from 28°C to 50°C), and increase with the increase of DSS concentration higher than about 10%. In conclusion, it can be mentioned that the knowledge about the rheological properties of DSS-GG gels may be useful during the characterization of similar kinds of medicated gel. © 2016 Author(s).ERDF, European Regional Development Fun

Thermal properties of hemp fiber filled polyamide 1010 biomass composites and the blend of these composites and polyamide 11 elastomer

The aim of this study is to improve the performance of all inedible plants-derived materials for new engineering materials such as structural materials and tribomaterials. Thermal properties of hemp fiber tilled polyamide 1010 biomass composites and the blend of these composites and plants-derived TPE, were investigated experimentally. These biomass composites were extruded by a twin screw extruder and compression or injection molded. Thermal properties such as dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) of these biomass composites were evaluated. It was found that the addition of HF and the blend of bio-TPE With PA1010 have strong influence on the thermal properties such as DMA, TGA and DSC. In particular, IT has a good effect for the improvement of the thermal and mechanical properties. These properties of HF/PA1010/PA11E biomass composites are better than those of HF/PA1010/ITU ones

Influence of types of alkali treatment on the mechanical properties of hemp fiber reinforced polyamide 1010 composites

In order to develop the new engineering materials such as structural materials and tribomaterials based on all plants-derived materials, the purpose of this study is to investigate the influence of types of alkali treatment on the mechanical and tribological properties of hemp fiber (HF) reinforced plants-derived polyamide 1010 (HF/PA1010) biomass composites. HF were surface-treated by four types of surface treatments: (a) alkali treatment by sodium hydroxide (NaOH) solution, (b) alkali treatment by sodium chlorite (NaClO2) solution, (c) alkali treatment by NaOH solution and surface treatment by ureido silane coupling agent, and (d) alkali treatment by NaClO2 solution and surface treatment by ureido silane. The volume fraction of hemp fiber in the composites was fixed with 20vol.%. HF/PA1010 composites were extruded by a twin screw extruder and injection-molded. Mechanical properties such as tensile, bending and tribological properties by ring-on-plate type sliding wear testing were evaluated. It was found that the effect of the types of alkali treatment on the mechanical and tribological properties of the composites differed for each property. The mechanical and tribological properties are improved with both alkali treatments by NaOH and NaClO2 with or without the surface treatment by ureido silane coupling agent (A-1160). This may be attributed to the interfacial interaction and interphase adhesion between HF and PA1010 according to the type of these alkali treatments. The combination NaClO2 and A-1160 is the most effect improvement for the mechanical and tribological properties of HF/PA1010 biomass composites. It follows from these results that it may be possible to develop the new engineering materials with sufficient balance between mechanical and tribological properties. © 2016 Author(s)