Reactive oligomer to improve the impact characteristics of structural composites used in civil and medical applications

Composite materials are increasingly utilized in many civil engineering and medical applications such as conveying tubes and pipelines, making artificial human parts, dental applications, reinforcing structures, etc. The glass reinforced composite is one of the most common composite that is used for its good mechanical properties and also its rationally low price. Polymeric resins such as epoxy are used as the constitutive material in producing glass reinforced composites. In this research paper we improve the impact resistance of the glass-reinforced composite using Hycar reactive oligomer. Mechanical impact strength tests have been conducted using a notched sample. The obtained test results show that the impact resistance of Hycar modified glass-reinforced composite is enhanced by addition of the Hycar to the glass reinforced composite. Moreover the glass transition temperature (T g) of the samples has been measured experimentally using a differential scanning calorimeter (DSC) instrument. The results of measuring T g however shows that these g improvements in impact resistance of the composite material are accompanied with a slight reduction in the glass transition temperature of the modified composite samples. Moreover the damaged surfaces of fractured samples were investigated using scanning electron microscopy (SEM) techniques. © IDOSI Publications, 2012

Investigation of abrasion and morphology of rubber/nano titanium oxide nanocomposites

Rubber/Titanium oxide nanocomposites might be considered as potential materials in medical and industrial applications due to the flexibility of the polymer and antibacterial properties of nanometric additive. In this research paper, the morphology and physical properties of nanocomposites based on Styrene Butadiene rubber have been investigated in the presence of nano titanium oxide additive. The nanocomposites have been prepared by mechanical blending using two roll mills. Nano Titanium oxide particles have been added to Styrene Butadiene rubber and the abrasion and thermal properties have been surveyed. Optical microscopic observation and scanning electron microscopic pictures have been used to investigate the morphology of nanocomposites based on rubber. Abrasion test results showed that the nano Titanium oxide particles could enhance the abrasion resistance of Styrene Butadiene rubber matrix due to appropriate properties of nano Titanium oxide particles. © 2006-2014 Asian Research Publishing Network (ARPN)

Modeling the stability of freestanding cnt probe/sensor in the vicinity of graphene layers considering casimir dispersion force

Carbon nanotube (CNT) is one the most important nano-elements in fabrication of probes, sensors and other ultrasmall devices that have a wide usage in engineering and medicine. In this paper, the deflection and instability of a freestanding CNT probe/sensor in the vicinity of the graphene layers are investigated. A nano-scale continuum model in conjunction with Euler beam theory is employed to obtain nonlinear constitutive equation of freestanding CNT by considering the effect of Casimir dispersion force. A numerical finite difference method is employed to solve the nonlinear governing equation. © 2006-2014 Asian Research Publishing Network (ARPN)

Numerical study of size-dependent instability of nems considering molecular force and elastic support conditions

Nano-electromechanical systems (NEMS) sensors are recently used as powerful medical detectors for detection of disease. In this research paper, the modified couple stress non-classic continuum theory is applied to examine the size effect on the pull-in instability of beam-type NEMS sensor at submicron separations considering the van der Waals attraction. The proposed model takes the non-classic support conditions into account using rotational springs at supported end of the simply supported nano-beam. In order to solve the nonlinear constitutive equation of the nano-beams, finite difference numerical solution employed. The results reveal significant influence of the size dependency, elastic support conditions and van der Waals attraction on the pull-in characteristics of beam-type NEMS. © 2006-2014 Asian Research Publishing Network (ARPN)

A simple model to compute the blood flows through obstructed blood vessels

The aim of this article is to measuring the blood flow, when they pass through obstructed blood vessels. In many medical arteries the amount of the blood flow inside canals and obstructed vessel is important and reduces due to the arteries. However, the problem with measurements in such circumstances lies in the lack of precise and appropriate experimental data needed for the calculation of the blood passes through the vessel. To overcome the shortcoming, hence, the effect of the most common type orifices, i.e., Square edge Orifice (D & D/2 taps), were put to the test, by simulating the flow with the use of CFD methods and Fluent 6.0 software, for 0.25 <=beta <= 0.5 and 10,000 <= Re-D <= 200,000, fixed temperature of 300(K). Therefore, relations were obtained for blood as the incompressible fluid. Kharaji M. Gh., Dadjoo F., Alirezaei Y., Falavand A., Langari A. A simple model to compute the blood flows through obstructed blood vessels. Life Sci J 2012;9(4):1782-1788] (ISSN:1097-8135). http://www.lifesciencesite.com. 27

Study of thermal properties of improved adhesives for medical applications

Adhesives are of important materials in medicine applications. These materials are used in many applications such as disposal medical devices, structural bonds, bone cement, prostheses, etc.. In order to use these materials in medicine applications, the thermal properties of these materials should be evaluated. We measured the thermal properties of the adhesive which has been modified with Hycar rubber. It is found that increasing in Hycar leads to decrease in thermal properties of adhesive. This means that we can not increase the Hycar content beyond the critical value. Because this might result in diminishing adhesive efficiency especially in human bodies where the operation temperature reaches 37 centigrade degrees. Kharaji M Gh, Alimoradi F, Yekrangi A, Mohammadian E, Langari A. Study of Thermal Properties of Improved Adhesives for Medical Applications. Life Sci J 2012;9(2):1308-1310] (ISSN: 1097-8135). http://www.lifesciencesite.com. 19

Use Of Fuzzy Logic For Risk/Benefit Assessment In Medical/Biological Cases

In recent decade safety of medical and biological products has been concerned in the light of benefit/risks and risk assessment. For new medical products and new drugs, unanticipated side effects that rise after consuming the new product is a dominant factor in decision making. The aim of this project is to design a fuzzy inference system for risk assessment of medical cases. Classical risk assessment in the crisp space precisely determines boundary sharply dissevers safe state from unsafe one. In contrary, fuzzy set shows smooth change from safe to unsafe state. It indicates that safety can be considered as a fuzzy issue because plant safety cannot be strictly classified as safe or unsafe, as inherent hazards always occur. Hafshejani M K, Sattari Naeini M, Mohammadsharifi A, Yahiapoor M. Use of Fuzzy Logic for Risk/Benefit Assessment in Medical/Biological Cases. Life Sci J 2012; 9(3): 2270-2273] (ISSN: 1097-8135). http://www.lifesciencesite.com. 40

Mechanical characteristics of tire/clay modified epoxy used in fabrication of medical prostheses and artificial human parts

Epoxy is used in many dental and medical applications such as manufacturing prostheses. This polymer is not toxic and is a good candidate for easily forming of artificial hand, leg, etc. In recent years, the recycled waste tire has been concerned as inexpensive modifier for improving the toughness characteristics of many thermoset resins such as epoxy. Herein, the influence of addition of nanoclay on mechanical characteristics of waste tire-modified epoxy was investigated. Mechanical properties i.e. compressive and flexural characteristics, fracture toughness and impact strength of the samples were investigated. The fracture surfaces of the specimens were examined using scanning electron microscope (SEM). Moreover the glass transition temperature (Tg) of the samples were measured. Results reveal that nanoclay can improve the mechanical characteristics of waste tire-modified epoxies. © IDOSI Publications, 2012

Use of Reactive Oligomer to Improve Fracture Resistance of Epoxy Used in Medical Applications and GRP Pipelines

Abstract: Epoxy is used as the polymeric matrix material in many medical and pipeline applications. As some examples this polymer is applied in fabrication of prostheses, dental applications, scaffolds, manufacturing glass reinforced pipelines (GRP) etc.. Herein, the toughness improvement of an epoxy resin was investigated systematically. For this purpose, we have utilized vinyl-terminated butadiene acrylonitrile (VTBN) reactive oligomer that is known as a toughening agent for epoxy-based thermoset polymers. In order to evaluate the fracture resistance of the final composition, we have used several mechanical tests i.e. Fracture toughness test, Impact resistance test and unidirectional compression test. Moreover, in order to interpret the mechanical test data, damaged surfaces of fractured samples were investigated using scanning electron microscopy (SEM) techniques. It is found that VTBN improves fracture toughness of the epoxy resin more than twice. However this improvement fails by adding more than 25 % VTBN. Moreover the impact strength of epoxy has been substantially improved. This is attributed to the high cavitations of VTBN particles. However, these improvements are accompanied with a slight reduction in compressive characteristics of modified samples. This is the result of low modulus of VTBN. Key words: Epoxy resin Vinyl-terminated butadiene acrylonitrile (VTBN) Mechanical propertie