Surface Modification of Poly(Vinylchloride) for Manufacturing Advanced Catheters

2020 ◽  
Vol 27 (10) ◽  
pp. 1616-1633 ◽  
Author(s):  
Oana Cristina Duta ◽  
Aurel Mihail Ţîţu ◽  
Alexandru Marin ◽  
Anton Ficai ◽  
Denisa Ficai ◽  
...  
Keyword(s):  
Surface Modification ◽  
Chemical Modification ◽  
Medical Devices ◽  
Low Cost ◽  
Physical And Mechanical Properties ◽  
Polymeric Materials ◽  
Modern Medicine ◽  
Structural Failure ◽  
Chemical Grafting ◽  
One Step

Polymeric materials, due to their excellent physicochemical properties and versatility found applicability in multiples areas, including biomaterials used in tissue regeneration, prosthetics (hip, artificial valves), medical devices, controlled drug delivery systems, etc. Medical devices and their applications are very important in modern medicine and the need to develop new materials with improved properties or to improve the existent materials is increasing every day. Numerous reasearches are activated in this domain in order to obtain materials/surfaces that does not have drawbacks such as structural failure, calcifications, infections or thrombosis. One of the most used material is poly(vinylchloride) (PVC) due to its unique properties, availability and low cost. The most common method used for obtaining tubular devices that meet the requirements of medical use is the surface modification of polymers without changing their physical and mechanical properties, in bulk. PVC is a hydrophobic polymer and therefore many research studies were conducted in order to increase the hydrophilicity of the surface by chemical modification in order to improve biocompatibility, to enhance wettability, reduce friction or to make lubricious or antimicrobial coatings. Surface modification of PVC can be achieved by several strategies, in only one step or, in some cases, in two or more steps by applying several techniques consecutively to obtain the desired modification / performances. The most common processes used for modifying the surface of PVC devices are: plasma treatment, corona discharge, chemical grafting, electric discharge, vapour deposition of metals, flame treatment, direct chemical modification (oxidation, hydrolysis, etc.) or even some physical modification of the roughness of the surface.

Effect of Surface Modification on Mechanical Properties of Buri Palm (Corypha Utan) Fibre Composite Reinforcement

2020 ◽  
Vol 17 (4) ◽  
Author(s):  
M. Zalinawati ◽  
J.P. Siregar ◽  
C. Tezara ◽  
J. Jaafar ◽  
M.H.M. Hamdan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Surface Modification ◽  
Fibre Composite ◽  
Alkali Treatment ◽  
Low Cost ◽  
Physical And Mechanical Properties ◽  
Single Strand ◽  
Geometrical Parameters ◽  
Palm Fibre

Natural fibre materials are replacing synthetic fibre materials since they are considered as a low-cost, lightweight, and biodegradability engineering materials with a good specific strength. However, the effects of some process and geometrical parameters (such as fibre type, size, and concentration, and chemical modification) on the strength of the final natural composite product are not well documented. The purpose of the research is to analyse the physical and mechanical properties of single-strand buri palm fibre under different conditions and surface modification. The buri palm fibre was treated using 5 wt.% and 10 wt.% sodium hydroxide (NaOH) with a duration of 1 and 24 h immersion throughout the whole process. For a single-strand test, the samples were carefully extracted from the corresponding woven fibre by hand. While the woven buri palm fibre composite was fabricated by employing 4 and 5-layering sequences in the hand lay-up technique followed by the compression method. The buri palm fibre showed that a higher concentration of NaOH solution and immersion period led to a lower density. The effectiveness of the alkali treatment in the removal of cellulose and hemicellulose from the fibre strands was verified by chemical composition in FTIR investigation. The highest tensile strength of 159.16 MPa was indicated from the result of single-strand treated with 5 wt.% NaOH for 24 h immersion. This treatment was found as the most appropriate treatment and is employed to fabricate both 4-layer and 5-layer stacking sequence composite. The 5-layer treated composite gives the highest tensile strength and flexural strength of 33.51 MPa and 56.72 MPa, respectively. In conclusion, the mechanical properties increased with the addition of each sequence layering treated fibres in the composite. The obtained results indicate that the utilisation of buri palm fibre as a reinforcement in the epoxy composite can be used in the lightweight and moderate load applications, such as the interior parts in the automotive industry.

Dual Nickel/Palladium-Catalyzed Reductive Cross-Coupling Reactions Between Two Phenol Derivatives

2020 ◽  
Author(s):  
Baojian Xiong ◽  
Yue Li ◽  
Yin Wei ◽  
Søren Kramer ◽  
Zhong Lian
Keyword(s):  
Functional Group ◽  
Low Cost ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Phenol Derivatives ◽  
Cross Coupling Reactions ◽  
Palladium Catalyzed ◽  
One Step ◽  
Aryl Tosylates ◽  
Low Sensitivity

Cross-coupling between substrates that can be easily derived from phenols is highly attractive due to the abundance and low cost of phenols. Here, we report a dual nickel/palladium-catalyzed reductive cross-coupling between aryl tosylates and aryl triflates; both substrates can be accessed in just one step from readily available phenols. The reaction has a broad functional group tolerance and substrate scope (>60 examples). Furthermore, it displays low sensitivity to steric effects demonstrated by the synthesis of a 2,2’disubstituted biaryl and a fully substituted aryl product. The widespread presence of phenols in natural products and pharmaceuticals allow for straightforward late-stage functionalization, illustrated with examples such as Ezetimibe and tyrosine. NMR spectroscopy and DFT calculations indicate that the nickel catalyst is responsible for activating the aryl triflate, while the palladium catalyst preferentially reacts with the aryl tosylate.

Opening up a New Field of Modern Medical Research 1

2020 ◽  
Author(s):  
Xiaoguang Li
Keyword(s):  
Chinese Medicine ◽  
Traditional Chinese Medicine ◽  
Human Body ◽  
Low Cost ◽  
Acupuncture Point ◽  
Modern Medicine ◽  
Body Structure ◽  
Special Effect ◽  
Special Knowledge ◽  
Opening Up

Modern medicine tells us that the human body is an organism composed of heart, lung, liver, kidney, spleen, stomach, brain, nerves, muscles, bones, blood vessels, blood and so on, while traditional Chinese medicine believes that besides these tissues and organs, the human body still has another part of the structure, traditional Chinese medicine calls them Jing Luo and Shu Xue. Jing Luo means the longitudinal line of the human body and the accompanying net, translated into English Meridians and Collaterals. Shu Xue means holes distributed on Jing Luo and outside Jing Luo, because stimulating Shu Xue's position by acupuncture, massage and other methods can cure diseases, so Shu Xue is translated into English acupuncture point, abbreviated as acupoint or point. Meridians and acupoints are the special knowledge of human body structure in traditional Chinese medicine. Traditional Chinese medicine not only draws the distribution map of the meridians and acupoints in the human body, but also has been using them to treat diseases for thousands of years. There are hundreds of these acupoints, stimulating each one by acupuncture, massage or other methods will have a special effect on the human body and can treat various diseases. But what effect does stimulating every acupoint have on the human body so that it can treat various diseases? The discussion of traditional Chinese medicine is vague and incomprehensible, and can not be proved by experiments. According to the author's research for more than 30 years, this paper makes a clear and accurate exposition of the effects on the human body and diseases that can be treated with acupoint massage. These statements can be proved by experiments, so they are believed to be reliable. It is hoped that meridians, acupoints and massage therapy can be incorporated into modern medicine and become a part of modern medicine after being proved by others through experiments. Massaging acupoints can not only treat many diseases that are difficult to be treated with drugs, but also have simple methods and low cost.

scholarly journals Physical and Mechanical Properties of Natural Leaf Fiber-Reinforced Epoxy Polyester Composites

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1369
Author(s):  
Sanjeev Kumar ◽  
Lalta Prasad ◽  
Vinay Kumar Patel ◽  
Virendra Kumar ◽  
Anil Kumar ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Synthetic Fibre ◽  
Low Cost ◽  
Fibre Length ◽  
Physical And Mechanical Properties ◽  
Natural Fibres ◽  
Risk Environment ◽  
Insulation Property ◽  
Natural Leaf

In recent times, demand for light weight and high strength materials fabricated from natural fibres has increased tremendously. The use of natural fibres has rapidly increased due to their high availability, low density, and renewable capability over synthetic fibre. Natural leaf fibres are easy to extract from the plant (retting process is easy), which offers high stiffness, less energy consumption, less health risk, environment friendly, and better insulation property than the synthetic fibre-based composite. Natural leaf fibre composites have low machining wear with low cost and excellent performance in engineering applications, and hence established as superior reinforcing materials compared to other plant fibres. In this review, the physical and mechanical properties of different natural leaf fibre-based composites are addressed. The influences of fibre loading and fibre length on mechanical properties are discussed for different matrices-based composite materials. The surface modifications of natural fibre also play a crucial role in improving physical and mechanical properties regarding composite materials due to improved fibre/matrix adhesion. Additionally, the present review also deals with the effect of silane-treated leaf fibre-reinforced thermoset composite, which play an important role in enhancing the mechanical and physical properties of the composites.

scholarly journals Novel BiOBr by compositing low-cost biochar for efficient ciprofloxacin removal: the synergy of adsorption and photocatalysis on the degradation kinetics and mechanism insight

RSC Advances ◽  
2021 ◽  
Vol 11 (25) ◽  
pp. 15369-15379
Author(s):  
Wandi Song ◽  
Jianghua Zhao ◽  
Xiuhong Xie ◽  
Wang Liu ◽  
Shuxia Liu ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Solvothermal Method ◽  
Degradation Kinetics ◽  
Low Cost ◽  
Kinetics And Mechanism ◽  
One Step ◽  
Ciprofloxacin Removal

1. The C-loaded BiOBr was synthesized via a one-step solvothermal method. 2. C/BiOBr showed an obvious synergistic effect of adsorption and photocatalysis on the degradation of ciprofloxacin.

Functionalized aluminum-catalyzed silicon nanowire formation and radial junction photovoltaic devices

Nanoscale ◽  
2021 ◽  
Author(s):  
Wipakorn Jevasuwan ◽  
Naoki Fukata
Keyword(s):  
Surface Modification ◽  
Solar Cells ◽  
Surface Defects ◽  
Silicon Nanowire ◽  
Photovoltaic Devices ◽  
Step Process ◽  
One Step ◽  
Length Reduction

Vertical Al-catalyzed SiNW arrays with shaped surfaces were synthesized by a one-step process and NW-based solar cells were demonstrated with optimized NW surface defects through surface modification and length reduction.

Materials Selection for Sandwich Pipes Under the Combined Effect of Pressure, Bending and Temperature

2007 ◽  
Author(s):  
Allan R. de Souza ◽  
Theodoro A. Netto ◽  
Ilson P. Pasqualino
Keyword(s):  
Structural Strength ◽  
Material Selection ◽  
Low Cost ◽  
Polymeric Materials ◽  
External Pressure ◽  
Core Material ◽  
Annular Layer ◽  
Oil And Natural Gas ◽  
Longitudinal Bending ◽  
Logic Approach

Recent researches point to the great potential of the sandwich pipe conception for ultra deepwater exploitation and production of oil and natural gas. Its configuration is very simple and comprises two concentric metallic pipes with a core material, polymeric or ceramic, in the annulus. The main functions of the annular layer are: to provide satisfactory thermal insulation so as to avoid the formation of wax and hydrates along the pipeline during production shutdown; to improve the overall structural strength of the system. Polypropylene and cement have been recently proposed for these applications. The reason for the choice of these materials was the low cost and the extensive availability in industry. Here a systematic material selection approach is employed in order to assess the applicability of other polymeric materials. The attributes of materials needed to meet the design specification are thoroughly studied. The list of possible materials was enlarged and the modified digital logic approach is used with the purpose to define a top group of materials for further numerical comparative study. Finite element analyses are carried out to assess the structural strength of the sandwich pipe under pure external pressure or longitudinal bending and combined external pressure and bending. Additionally, the effect of thermal gradient is included to the numerical analyses to evaluate each pre-selected material of the top group. Results indicate that other potential materials such as PEEK and polycarbonate can improve the structural performance of the sandwich pipe conception and yet meet other several design criteria.

Sign in / Sign up

Export Citation Format

Share Document