Search or add a thesis

Advanced Search (Beta)
Home > Liquid Phase Exfoliation of Graphite to Graphene & its Applications in Polymeric Nanocomposites

Liquid Phase Exfoliation of Graphite to Graphene & its Applications in Polymeric Nanocomposites

Thesis Info

Access Option

External Link

Author

Nawaz, Khalid

Program

PhD

Institute

National University of Sciences & Technology

City

Islamabad

Province

Islamabad

Country

Pakistan

Thesis Completing Year

2015

Thesis Completion Status

Completed

Subject

Applied Sciences

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/6685/1/Khalid_Nawaz_Materials_Engineering_2015_NUST_14.04.2016.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726590521

Similar


Nanocomposites are superior to conventional one in terms of its mechanical performance. Pristine /functionalized graphene sheets (FGS) were incorporated into a range of model polymers. Solvent aided blending was adopted for better dispersion of FGS and graphene sheets in these polymers. Graphene was added to selected polymers like polyurethane (PU), poly (vinyl chloride) (PVC), poly (acrylonitrile) (PAN), poly (vinyl alcohol) (PVA) and poly (vinyl acetate) (PVAc) in order to improve the mechanical performance of these materials. Different forms of graphene nanosheets like pristine/FGS with different lateral dimensions were selected in order to study its effects on the mechanical performance of selected polymers in terms of young’s modulus, tensile strength and elongation at break. Graphene nanosheets were functionalized with octadecylamine and were incorporated in polyurethane and it was observed that 2.5 vol% is the mechanical percolation level for this polymer as above this loading there was improvement in the mechanical performance of polyurethane while at this loading the elongation at break was suffered slightly. Similarly in case of poly(vinyl chloride) a critical loading(1.5wt%) was observed at which there was improvement in mechanical properties of these polymers and almost no elongation at break was observed for this loading and the modulus determined in this case was superior to calculated from Halpin-Tsai equation. Two type of graphene nanosheets with different flake size (one and 3.5 micron) were incorporated in poly (acrylonitrile). Its comparative study was conducted it was observed the big flake improved the performance of polymers in terms of modulus and UTs while the response of small flake in terms of elongation at break was better than big flakes. Large area graphene oxide were synthesized and were introduced to poly(vinyl alcohol) and the role of these nano fillers were very pronounced in terms of modulus, UTS and elongation at break was not disturbed but slightly improved. Graphene flakes were studied through transmission electron microscopy(TEM) and Raman spectroscopy while dispersion of these flakes were in selected polymers was confirmed by scanning electron microscopy(SEM) and the mechanical performance of these nanocomposites were conducted on Zwick-Roell tensile tester. Graphene-based v polymer nanocomposites can be a new versatile soft material with numerous advantages. Graphite was exfoliated to graphene using NMP and water as solvent as well. 63mg/ml concentration was obtained during tip sonication in NMP while in case of water as media the maximum concentration obtained was 7mg/ml using sodium cholate as surfactant. The concentration of graphene nanosheets were studied through UV-visible spectroscopy while quality of flakes was studied through TEM and Raman spectroscopy.
Loading...
Loading...

Similar Books

Loading...

Similar Chapters

Loading...

Similar News

Loading...

Similar Articles

Loading...

Similar Article Headings

Loading...

مرزا فرحت اﷲ بیگ دہلوی

مرزا فرحت اﷲ بیگ دہلوی
اس مہینہ کاایک ادبی حادثہ مرزا فرحت اﷲ بیگ دہلوی کی وفات ہے۔ مرزاصاحب مولوی نذیر احمد صاحب دہلوی کے شاگرد تھے لیکن حق یہ ہے کہ زبان کی شگفتگی، انداز بیان کی دلکشی اورعبارت کی چستی و حلاوت میں شاگرد استادسے سبقت لے گیا تھا۔ اب ملک میں جس قسم کے ادیب پیداہورہے ہیں اس کے پیش نظر توقع نہیں کہ کوئی آئندہ’’دلی کا آخری مشاعرہ‘‘یا’’پھول والوں کی سیر‘‘کی پرانی داستانیں اس کمال سحرکاری کے ساتھ سُنا سکے گا۔اﷲ تعالیٰ مرحوم کی مغفرت فرمائے اورپسماندگان کوصبرجمیل کی توفیق ارزاں ہو۔
[مئی۱۹۴۷ء]

 

نفع کی شرعی حد

Human have a natural instinct and tendency to seek profit. Being Prepared for any hard work without it is an afterthought. Offend a glimpse Islamic rules and its features to fulfill the aspiration of acquisition. Has advocated certain dimensions of oppression and deception.e.g, purchase commodities out of the city through stock picked commercial convince and the specialist citizen trader selling the goods to the villagers at cheap prices and the principles to supply and demand is explained and all the cases in which supply and demand are raised by artificial crises is described, while the Fatwa of Saudi Arabic permanent fatwa committee is also included in the international fatwa center.

Fabrication, Characterization, In-Vitro and In-Vivo Evaluation of Etoposide Loaded Polymeric Nanoparticles

The discovery of biodegradable and biocompatible polymeric materials has a significant step to overcome the problems associated with this field. The polylactic co-glycolide (PLGA) copolymer nanoparticles system in a size range of 10 to 500 nanometers can be used to entrap large number of drugs which have the ability to escape from reticuloendothelial system of the body, the polymeric loaded nanoparticles can remain within the blood circulation for a prolong time and can target the specific site, attached on its surface and release the entrapped therapeutic agent in a controlled and predictable manner. The release of the drug at a specific site or organ of interest can reduce their adverse effects due to the fact that there will be no significant concentration of the drug in blood circulation. Other important features of these polymeric systems are reduced dosing frequency and aqueous solubility which allows the use of these delivery systems effectively for those therapeutic agents which have sever toxic effect as well as having either no or less aqueous solubility. The objective of this work was to develop a PLGA based polymeric delivery system which could entrap Etoposide and enhance its delivery to the organ of interest for a prolonged period of time. The use of etoposide is compromised by its intrinsically poor water solubility as it is BCS class II drug The etoposide Poly(D,L-lactide-co-glycolide) nanoparticles of about 200 nm size were prepared by modified solvent evaporation method while utilizing different surfactants / stabilizing agents which include polyvinyl alcohol (PVA) and Poloxamer 407. The surfactant agents were used in the range of 0.25, 0.5, 1.0 and 1.5 percent concentrations. During the process of formulation of nanosuspensions the concentration of PLGA was kept constant i.e. 15 mg while that of the drug was kept Abstract XVIII as 1, 2, 3, 4 and 5 mg during the preparation of the suspensions. The %EE of the nanoparticles was in the range of 88 to 96%. The nano formulations were characterized in terms of particle size, polydispersibility index (PDI), Zeta potential (ZP), drug entrapment, particle morphology and in-vitro drug release. The size, PDI, ZP and entrapment efficiency of the selected formulations were in the range of (136 182 nm) (0.11-0.30) (-10 to -12) and (88% to 96%) respectively. The drug excipients compatibility was determined by preparing their samples in 1:1 mixture and were kept under stress conditions (45 ± 2 ᴼC and 75 ± 5 % RH) for 90 days and were then analyzed for physical consistency, drug content and FTIR spectra. The compatibility studies show that the drug and excipients used in this study were compatible and no effect of stress condition was observed on the samples. UV Visible Spectrophotometric and High-Performance Liquid Chromatography (HPLC) UV methods were developed and validated for the analysis and determination of Etoposide. The UV-visible spectrophotometric method was specific, accurate and linear in the range of 10-100 µg/ml, with R2 values of 0.998. The RP- HPLC-UV method was novel, sensitive, accurate, specific and validated for the determination of etoposide in physiological fluids. Its linearity was in the concentration range of 12– 1000 ng/ml. The limit of detection (LOD) and limit of quantification (LOQ) were 5 and 12 ng/ml respectively. In-vitro drug release from the NPs was determined by dialysis technique, the NPS were capable to sustained the drug in a predictable manner up to seven (07) days. The distribution of Etoposide NPs in different organs (liver, lungs, kidney, spleen, heart and brain) using mice as an animal model was determined using HPLC-UV method. It was observed that these tissues show the presence of drug for longer duration after administration of drug loaded NPs as compare to reference formulation. Abstract XIX The comparative tissue distribution after intravenous drug loaded NPs administration was in the order of liver > lung > kidney > spleen > heart. In conclusion, the results obtained in the present study showed that PLGA nanoparticles of about 200 nm can be prepared by solvent evaporation method which can encapsulate an anticancer agent etoposide and can release a drug in a sustained manner for up to 168 hours leading to reduction in dosing frequency as well as distributing the drug to the organ of interest. The pharmacokinetic parameters of the nanoformulations are significantly improved as compared to the marketed formulation of etoposide.