Mechanical and Physical Properties of Injection Molded Halloysite Nanotubes-Thermoplastic Polyurethane Nanocomposites

AbstractThe high aspect ratio of nanoscale reinforcements enhances the mechanical properties of pure polymer matrix. Researchers reported the mechanical properties of thermoplastic polyurethane and halloysite nanotubes (TPU-HNTs) nanocomposites formed through casting and compression molding. Few researchers reported on TPU-HNTs formed through injection molding. Therefore, the present work described the preparation, characterization, and processing of TPU and HNT nanocomposites via injection molding. TPU and HNTs were mixed using a brabender mixer with concentration ranging from 1wt.% to 7wt.% with varying mixing parameters (mixing speed, mixing time, and mixing temperature). Injection molding was used to form tensile bars shaped with varying molding parameters (injection temperature, injection time, and injection pressure). Significant increment of tensile strength was found at 1wt.%HNT loading concentration. The tensile strength of the TPU-HNT nanocomposite exhibited 24.29MPa at 1wt.% loading concentration, which was higher than that of pure TPU. The Young's modulus of the TPU-HNT nanocomposite was 15.45MPa at 7wt.%. Physical properties were analyzed using Thermogravimetric Analysis (TGA) and Field emission scanning electron microscopy (FESEM). FESEM results showed that HNTs were well dispersed in TPU matrix. TGA results showed that the addition of HNTs enhanced the thermal properties. Thus, TPU-HNT has improved mechanical and physical properties compared with pure TPU due to the addition of nanofiller

Effects of deposition time and counter-electrode size on the fabrication of lscf-sdc carbonate composite cathode for sofc

The electrophoretic deposition (EPD) process has shown great potential in the development of cathodes for solid oxide fuel cell (SOFC). This study thus aimed to determine the feasibility of the electrophoretic deposition technique in producing composite cathode films. Two parameters were investigated, namely, the effects of counter electrode size and those of deposition time on the thickness and quality of an LSCF-SDC carbonate cathode composite deposited onto an SDC carbonate substrate. The effects of the changed parameters were observed by applying constant suspension pH and voltage. Five different deposition times ranging from 10 to 30 min were selected. The counter electrode sizes used were 25 × 25 mm2 and 50 × 50 mm2 . Then, the cathode composite films were sintered at 600°C for 90 min. Microstructural characterization and film thickness measurement were performed using a scanning electron microscope (SEM). The 50 × 50 mm2 counter electrode was found to produce a cathode composite film with higher thickness. The effects of the selected parameters (deposition time and counter electrode size) were also determined by analyzing the weight and thickness of the obtained LSCF-SDC carbonate films. The results showed that for the selected time interval, a film thickness of 4.6 to 30.8 μm is generated. Further studies on fabricating LSCF-SDC carbonate cathode composites by electrophoretic deposition present promising potential given that the film thickness obtained agree well with those derived in previous studies on various types of cathode materials

Effect of temperature on the mechanical performance of highly conductive composites for HT-PEMFC application

This study is a follow-up study of a previous study that examined the effect of temperature on the mechanical performance of the polymer carbon composite (CCP). In this study, the optimal formulation obtained from previous studies, was tried for use in polymer fuel cells of high temperature polymer electrolytes. The standard used is, the standard for bending strength specified by the US Department of Energy (DOE) Agency, which has determined the bending strength should be higher than 25 a. Preparation of CCP bipolar plates is done by internal mixing and then molded by compression stirring method. Bending strength and hardness test are carried out at 26°C to 200°C, for 80% CNT/NG mixture and 20% by weight of EP, with a resin/hardener ratio of 3: 1. This composition has successfully met the bending strength standards set by the DOE on testing performed at room temperature. However, the composite electrical conductivity is still less than the standard set by DOE, reaching only 50 S/cm. The results show that the composite plate of CNT/NG/EP mixed with a 5/75/20% by weight composition is not suitable for HT-PEMFC, because the filler and matrix composite interface failed to hold the bonds at temperature higher than the melting point of the EP. It is therefore recommended that this composite material be used only at low temperatures and is also not recommended for use as a fuel cell plate

Process optimization of melt spinning and mechanical strength enhancement of functionalized multi-walled carbon nanotubes reinforcing polyethylene fibers

Carboxylic functional groups were introduced on multi-walled carbon nanotubes (MWCNTs) using the Ultraviolet (UV) Ozone treatment. Three melt spinning process parameters (spinning temperature, spinning distance, and the number of spinning revolutions) were evaluated by robust design (Taguchi’s method) for a composite of fibers with the objective of enhancing the mechanical strength. The optimized melt spinning parameters were obtained. The predicted strength value of CNTs–PE fibers was determined using statistical analysis, and this value is close to the verification experiment value. Thus, robust design was successfully applied in this study. The crystallization of bulk pure PE was significantly increased by the formation of fibers through mechanical drawing of the melt spinning. The addition of CNTs in the polymer matrix accelerates the nucleation and crystal growth of the polymer. No CNT alignment in the PE matrix was observed on the sectioned surface of the fiber using Scanning Electron Microscopy (SEM). The degree of crystallization of the PE polymer plays an important role in the mechanical strength enhancement

Effect of HNTs addition in the injection moulded thermoplastic polyurethane matrix on the mechanical and thermal properties

The additions of nanofillers are able to enhance the mechanical properties of neat polymer matrix. There were few researchers reported on the mechanical properties of halloysite nanotubes reinforced thermoplastic polyurethane (HNTs-TPU) nanocomposites formed through casting and compression moulding. However, fewer researchers also reported study on HNTs-TPU formed through injection molding. The main objective of this paper was to study the effect of HNTs addition of TPU matrix on mechanical and physical properties. HNTs were mixed in TPU matrix using a brabender mixer with concentration ranging from 0.5 to 7 wt. % HNT loading (at specific mixing speed, mixing time and mixing temperature). Injection moulding was carried out to form tensile bar shaped specimens with specific moulding parameters (injection temperature, injection time and injection pressure). Increment around 35% of tensile strength of the specimen was found at 1 wt. % HNT loading concentration which exhibited the value of 24.3 MPa, compared to neat TPU; the best mixing. The Young’s modulus was increased with increasing HNTs loading. The elongation decreased with increasing HNTs loading. The FESEM results showed that HNTs were dispersed in TPU matrix. The TGA results showed that the addition of 1 wt. % HNTs enhanced the thermal properties. It can be concluded that HNTs-TPU has improved tensile and physical properties compared with neat TPU due to the addition of nanofiller

Pengoptimuman proses penyemperitan gentian karbon terkisar dan polipropilena bagi komposit polimer pengalir

Proses penyemperitan merupakan salah satu proses pra-pencampuran yang dapat membantu meningkatkan tahap serakan bahan pengalir dalam komposit polimer pengalir (CPC). Tahap keberaliran elektrik dilihat tidak begitu memuaskan walaupun telah melalui proses serakan melalui pengacuan mekanik. Kajian ini dijalankan bagi mengoptimumkan proses penyemperitan bahan gentian karbon terkisar (MCF) dan polipropilena (PP) iaitu suhu penyemperitan dan halaju putaran melalui kaedah reka bentuk eksperimen (Taguchi). Susunan orthogonal Taguchi L9 digunakan bagi menentukan aras yang paling optimum serta menjalankan analisis varian bagi memperoleh nilai keberaliran elektrik yang paling baik. Pengoptimuman parameter pada suhu penyemperitan 210ºC hingga 250ºC dan halaju putaran 50 hingga 90 rpm menggunakan komposisi bahan sebanyak 80 % bt. MCF dan 20 % bt. PP dengan tahap keberaliran elektrik meningkat pada tahap maksimum 3.67 S/cm. Pengoptimuman parameter ini menunjukkan bahawa reka bentuk eksperimen yang terhasil mampu menghasilkan nilai keberaliran elektrik yang tinggi serta mempunyai sifat mekanik yang baik

Jig Prototype for Computer-Assisted Total Knee Replacement and Its Flow Simulation

This paper discusses the design and development of a prototype of a knee surgery cutting jig, the jig holder, and the jig injection mold by Rapid Prototyping (RP). The aim of this study is to design a jig and a jig holder that allow surgeons to correctly, precisely, and consistently perform knee replacement surgery. The design concept for the surgery jig and jig holder was selected using the Pugh method with medical-grade 316L stainless steel for material fabrication. A rapid prototype model was built directly from its CAD model in stereo lithography (STL) format by using the Fused Deposition Method (FDM). MasterCAM and Moldflow simulation were performed to generated G-codes and a possibility of jig fabrication using Metal Injection Molding (MIM), respectively. The Moldflow result provided an enhanced interpretation of the injection mold design. A conceptual mold design was again developed by the FDM. The prototype of the cutting jig and its holder underwent a machining process. The prototype was then tested on dummy bones to determine the functional performance and efficiency of the said prototype. Results indicated an increase in cutting accuracy and cutting time compared with computer-assisted total knee surgery without the jig system

Rheological Analysis of Zirconia-Hydroxyapatite with Bi-Modal System of Binders; Low-Density Polyethylene and Palm Stearin

The two component micro-powder injection molding (2C-μPIM) process has evolved from μPIM process because of the increasing demand for multi-functional micro-components applications. In this research work, the selected materials to fabricate micro-sized bi-material parts are zirconia (ZrO2) and hydroxyapatite (HA). ZrO2 is chosen for structural integrity and bio-inert, while HA is mainly chosen for bio-active properties. The reason of employing the multi-component binders is to ensure the flowability of the feedstock. Feedstock rheological characteristics needs to be carefully investigated to avoid any undesirable and inhomogeneous mixture between powder and binder. A common binder system which is comprised of palm stearin and low-density polyethylene (LDPE) were mixed with individual ZrO2 and HA powder particles to prepare for ZrO2 and HA feedstocks. Typically, the feedstocks were obtained ZrO2 and HA powders independently with a binder ratio of 60 wt.% of palm stearin and 40wt.% low-density polyethylene (LDPE). The mixing was carried out in Brabender mixer. Before mixing, critical powder volume percentage (CPVP) analysis was carried out to determine the optimal powder loadings required to prepare the ZrO2 and HA feedstocks. In this research work, the obtained CPVP of ZrO2 and HA powders were 47.0 and 59.0 vol.%, respectively. Based on CPVP analysis, six feedstocks with optimal powder loadings of 43, 44 and 45 vol.% for ZrO2 and 54, 55 and 56 vol.% for HA were prepared. The rheological analysis involving viscosity, shear rate, flow behavior index, activation energy and moldability index was investigated using capillary rheometer. Based on the obtained rheology result, it shows that the overall shear rate and viscosity are within the 2C-μPIM process recommended range. All tested composition shows pseudoplastic behavior. The results of the study found that ZrO2 and HA with optimal powder loadings of 55 vol.% and 44 vol.% have good rheological properties compared to feedstocks with other powder loadings. This is because both materials meet the criteria of good rheological properties which are low viscosity, high shear rate, flow behavior index less than one, low activation energy and high moldability index

Rheological Analysis of Zirconia-Hydroxyapatite with Bi-Modal System of Binders; Low-Density Polyethylene and Palm Stearin

The two component micro-powder injection molding (2C-μPIM) process has evolved from μPIM process because of the increasing demand for multi-functional micro-components applications. In this research work, the selected materials to fabricate micro-sized bi-material parts are zirconia (ZrO2) and hydroxyapatite (HA). ZrO2 is chosen for structural integrity and bio-inert, while HA is mainly chosen for bio-active properties. The reason of employing the multi-component binders is to ensure the flowability of the feedstock. Feedstock rheological characteristics needs to be carefully investigated to avoid any undesirable and inhomogeneous mixture between powder and binder. A common binder system which is comprised of palm stearin and low-density polyethylene (LDPE) were mixed with individual ZrO2 and HA powder particles to prepare for ZrO2 and HA feedstocks. Typically, the feedstocks were obtained ZrO2 and HA powders independently with a binder ratio of 60 wt.% of palm stearin and 40wt.% low-density polyethylene (LDPE). The mixing was carried out in Brabender mixer. Before mixing, critical powder volume percentage (CPVP) analysis was carried out to determine the optimal powder loadings required to prepare the ZrO2 and HA feedstocks. In this research work, the obtained CPVP of ZrO2 and HA powders were 47.0 and 59.0 vol.%, respectively. Based on CPVP analysis, six feedstocks with optimal powder loadings of 43, 44 and 45 vol.% for ZrO2 and 54, 55 and 56 vol.% for HA were prepared. The rheological analysis involving viscosity, shear rate, flow behavior index, activation energy and moldability index was investigated using capillary rheometer. Based on the obtained rheology result, it shows that the overall shear rate and viscosity are within the 2C-μPIM process recommended range. All tested composition shows pseudoplastic behavior. The results of the study found that ZrO2 and HA with optimal powder loadings of 55 vol.% and 44 vol.% have good rheological properties compared to feedstocks with other powder loadings. This is because both materials meet the criteria of good rheological properties which are low viscosity, high shear rate, flow behavior index less than one, low activation energy and high moldability index

Influence of sintering parameters on the compressive yield strength of stainless steel foams produced by the space holder method

Metallic foams are a new class of materials that have a great potential to be used in various functional and structural applications. Due to their competitive price compared to aluminium, metallic foams are anticipated to become an alternative material for light-weight structures. In this study, stainless steel foams are fabricated using a powder space holder method. The materials used include stainless steel powder, a novel space holder glycine and binders consisting of palm stearin and of polyethylene (PE). The stainless steel foams are sintered at 1100oC, 1200oC and 1300oC with sintering times of 1, 2 and 3 h, respectively, to investigate the effects of the sintering parameters on the compressive yield strength of the stainless steel foams. The results showed that all of the stainless steel foams produced exhibit the general behaviours of metal foams. The sintering time is the most significant parameter that influences the compressive yield strength of stainless steel foams. Increasing the sintering temperature and sintering time will increase the compressive yield strength. The interaction between the sintering temperature and sintering time is found to be not statistically significant