Development Of Shape Memory Alloy Based Quarter Car Suspension System

It is well-known that suspension systems plays a major role in automotive technology. Most of the today’s vehicle applies a passive suspension systems consisting of a spring and damper. The design of automotive suspension have been a compromise between passenger comfort, suspension travel and road holding ability. This work aims in reducing the suspension travel alone by developing a quarter car model suspension for a passenger car to improve its performance by introducing shape memory alloy spring (Nitinol) instead of traditional spring. A two way shape memory alloy spring possesses two different stiffness in its two different phases (martensite and austenite). In this study, road profile is considered as a simple harmonic profile and vibration analysis of aminiature quarter car model suspension system has been carried out experimentally. Using theoretical method, the displacement of the sprung mass is also studied and discussed. The vibration analysis have been carried out for the suspension system at both phases of the spring and the results gives a significant improvement in reducing the displacement of sprung mass for various excitation frequencies

Biomimetic electrospun polyurethane matrix composites with tailor made properties for bone tissue engineering scaffolds

Bone tissue scaffolds require appropriate properties conducive for new tissue growth. In this study, we prepared a novel electrospun nanofiber scaffold using polyurethane (PU), rosemary (RM) oil and copper sulphate (CuSO4) respectively. The properties of the developed membranes were established through scanning electron microscopy (FESEM), atomic force microscopy (AFM), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), thermal gravimetric analysis (TGA), contact angle and mechanical testing. Further, blood compatibility and cytocompatibility assay were carried out to evaluate their biological responses. The developed composites rendered appropriate surface morphology with tailor made wettability and roughness. Composites with engineered physicochemical properties improved the blood and cytocompatible properties which can be potentially exploited for bone tissue engineering applications

Grapefruit Oil and Cobalt Nitrate-Loaded Polyurethane Hybrid Nanofibrous Scaffold for Biomedical Applications

The goal of this work is to fabricate a new composite based on polyurethane (PU), grapefruit (GP) oil, and cobalt nitrate [Co(NO3)2] using an electrospinning technique. Morphology results revealed the reduction in the fiber diameter of the composites compared to pristine PU control. The interaction of PU with GP and Co(NO3)2 was confirmed by hydrogen bond formation evident in infrared analysis. The fabricated PU/GP composites depicted a more hydrophobic behavior, while PU/GP/Co(NO3)2 showed a hydrophilic behavior than the pristine PU. Atomic force micrographs (AFM) revealed that the developed composites showed a decrease in the surface roughness (Ra) compared to PU. The addition of GP and Co(NO3)2 improved the mechanical strength of the pristine PU. The blood compatibility assays concluded not only the increase in blood clotting levels but also the less toxic nature of the fabricated composites compared to the pristine PU. Hence, the newly designed composites possessing outstanding physicochemical and biological properties may be used as a potential candidate for scaffolding in tissue engineering applications

Fabrication of a Novel Silver-Based Electrical Contact Composites and Assessment of Its Mechanical and Electrical Properties

The electrical contactors play a crucial role in closing the circuit in many power distribution components like overhead lines, underground cables, circuit breakers, transformers, and control systems. The failure in these components mainly occurs due to the break-down of contactors due to the continuous opening and closing action of contacts. Silver (Ag)-based oxide contact materials are widely used in practice, among which silver tin oxide (AgSnO2) is most common. An attempt is made in increasing the performance of AgSnO2, by adding Tungsten Oxide (WO3) in various weight proportions, thus finding the optimal proportion of AgSnO2WO3 to have increased mechanical and electrical performances. All the composite samples are fabricated in-house using powder metallurgy process. The assessment of physical and electrical properties namely, density, hardness, porosity, and electrical conductivity, showed that 90%Ag-8.5%SnO2-1.5%WO3 composite yielded superior results. With help of morphological tests, wear characteristics are also investigated, which showed that 90%Ag-8.5%SnO2-1.5%WO2 composite has a wear coefficient of 0.000227 and a coefficient of friction of 0.174 at an optimized load of 10 N and sliding velocity of 0.5 mm/s

Morphological, thermal, and blood-compatible properties of electrospun nanocomposites for tissue engineering application

In this work, the morphological, thermal, and blood compatibility properties of prepared polyurethane (PU) and gandharvahasthadi eranda thailam (GHT) nanocomposites were investigated. Morphological and thermal characterization revealed reduced diameter, improved surface roughness, and higher thermal degradation compared to control. The activated partial thromboplastin time (APTT) and prothrombin time (PT) assay revealed that the fabricated nanocomposites displayed delayed blood clotting time owing to improved surface morphology. The hemolytic assay suggested that nanocomposites would be nonhemolytic material due to low hemolytic index of about 1.15% compared to pure PU (2.733%) portraying its safety with the red blood cells. Thus, the newly developed PU/GHT composite scaffold possessing better physicochemical and blood compatibility may be considered as a potential substitute scaffold for replacing damaged tissue. POLYM. COMPOS., 39:E132–E139, 2018

Fabrication and hemocompatibility assessment of novel polyurethane-based bio-nanofibrous dressing loaded with honey and Carica papaya extract for the management of burn injuries

Management of burn injury is an onerous clinical task since it requires continuous monitoring and extensive usage of specialized facilities. Despite rapid improvizations and investments in burn management, >30% of victims hospitalized each year face severe morbidity and mortality. Excessive loss of body fluids, accumulation of exudate, and the development of septic shock are reported to be the main reasons for morbidity in burn victims. To assist burn wound management, a novel polyurethane (PU)-based bio-nanofibrous dressing loaded with honey (HN) and Carica papaya (PA) fruit extract was fabricated using a one-step electrospinning technique. The developed dressing material had a mean fiber diameter of 190±19.93 nm with pore sizes of 4-50 µm to support effective infiltration of nutrients and gas exchange. The successful blending of HN- and PA-based active biomolecules in PU was inferred through changes in surface chemistry. The blend subsequently increased the wettability (14%) and surface energy (24%) of the novel dressing. Ultimately, the presence of hydrophilic biomolecules and high porosity enhanced the water absorption ability of the PU-HN-PA nanofiber samples to 761.67% from 285.13% in PU. Furthermore, the ability of the bio-nanofibrous dressing to support specific protein adsorption (45%), delay thrombus formation, and reduce hemolysis demonstrated its nontoxic and compatible nature with the host tissues. In summary, the excellent physicochemical and hemocompatible properties of the developed PU-HN-PA dressing exhibit its potential in reducing the clinical complications associated with the treatment of burn injuries

Fabrication and characterisation of nanofibrous polyurethane scaffold incorporated with corn and neem oil using single stage electrospinning technique for bone tissue engineering applications

In bone tissue engineering, the design of scaffolds with ECM is still challenging now-a-days. The objective of the study to develop an electrospun scaffold based on polyurethane (PU) blended with corn oil and neem oil. The electrospun nanocomposites were characterized through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), contact angle measurement, atomic force microscopy (AFM) and tensile strength. The assays activated prothrombin time (APTT), partial thromboplastin time (PT) and hemolysis assay were performed to determine the blood compatibility parameters of the electrospun PU and their blends of corn oil and neem oil. Further, the cytocompatibility studies were performed using HDF cells to evaluate their proliferation rates in the electrospun PU and their blends. The morphology of the electrospun PU blends showed that the addition of corn oil and corn/neem oil resulted in reduced fiber diameter of about 845 ± 117.86 nm and 735 ± 126.49 nm compared to control (890 ± 116.911 nm). The FTIR confirmed the presence of corn oil and neem oil in PU matrix through hydrogen bond formation. The PU blended with corn oil showed hydrophobic (112° ± 1) while the PU together with corn/neem oil was observed to hydrophilic (64° ± 1.732) as indicated in the measurements of contact angle. The thermal behavior of prepared PU/corn oil and PU/corn/neem oil nanocomposites were enhanced and their surface roughness were decreased compared to control as revealed in the AFM analysis. The mechanical analysis indicated the enhanced tensile strength of the developed nanocomposites (PU/corn oil - 11.88 MPa and PU/corn/neem oil - 12. 96 MPa) than the pristine PU (7.12 MPa). Further, the blood compatibility assessments revealed that the developed nanocomposites possess enhanced anticoagulant nature compared to the polyurethane. Moreover, the developed nanocomposites was non-toxic to red blood cells (RBC) and human fibroblast cells (HDF) cells as shown in the hemolytic assay and cytocompatibility studies. Finally, this study concluded that the newly developed nanocomposites with better physio-chemical characteristics and biological properties enabled them as potential candidate for bone tissue engineering

Influence of Dual Filler Reinforcement on the Curing and Tribo-Mechanical Behaviour of Natural Rubber Nanocomposite for Tire Tread Application

A huge amount of carbon black (40-60 phr) was commonly used as a reinforcing material in manufacturing of tires to improve the technical properties of pure rubber. Carbon black causes severe health hazard like skin cancer, respiratory problem due to its fly loss property. This study focusses on reducing the usage of carbon black by replacing it with minimal quantity of nanoclay to compensate the technical properties of rubber. Natural rubber nanocomposite are fabricated using solution and mechanical mixing method in presence and absence of compatibilizer. Cure characteristics, wear test and mechanical properties were examined. NR nanocomposite with dual filler in presence of compatibilizer showed enhancement in torque values, mechanical and wear resistant property. Wear resistance, tensile strength and modulus of dual filler nanocomposite was increased by 66.7%, 91% and 85% when compared to pure NR. Hence NR nanocomposite with dual filler in presence of compatibilizer was found as a proving and possible nanocomposite for tire application