Search or add a thesis

Advanced Search (Beta)
Home > Preparation, Characterization and Studies of Conducting Polymer Composites and Blends

Preparation, Characterization and Studies of Conducting Polymer Composites and Blends

Thesis Info

Access Option

External Link

Author

Khan, Abdul Shakoor

Program

PhD

Institute

Quaid-I-Azam University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2009

Thesis Completion Status

Completed

Subject

Physics

Language

English

Link

http://prr.hec.gov.pk/jspui/handle/123456789/1334

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726998711

Asian Research Index Whatsapp Chanel
Asian Research Index Whatsapp Chanel

Join our Whatsapp Channel to get regular updates.

Similar


This work mainly concerns with the preparation, characterization and studies of some nanostructured composites and blends of Intrinsic Conducting Polymers (ICPs) with special reference to their charge transport mechanisms and device applications. These nanostructured composites consisted of two phases; a conducting phase and an insulating phase. Different series of nanocomposites with ICPs; Polypyrrole (PPy), Polyaniline (PANI) and Poly (p-phenylene vinylene) (PPV) as conducting phase and MMT clays and other lamellar structured materials such as CdPS 3 as an insulating phase were prepared and studied. A series of Polyaniline / Montmorillonite clay (PANI.MMT) composites was synthesized by in situ polymerization of aniline in the presence of varying amount of MMT clays in acidic medium. DC electrical conductivity was studied as a function of MMT loading and temperature to understand the charge transport mechanism in these composites. The conductivity followed quite well the temperature-dependence relationship σ(T) = σ 0. exp[-T o /T) 1/2 ], characteristic of one-dimensional variable-range hopping (1-D VRH). Frequency dependant AC conductivity followed the universal power law; this work is described in chapter 3. Another series of nanocomposites; PPy intercalated in the interlamellar region of Aluminum Pillared Montmorillonite (Al PMMT) clay with varying amounts of Al PMMT were prepared and studied. The Pyrrole was polymerized into the layers of Al PMMT replacing the Aluminum pillars and forming regular aligned chains of PPy, which not only enhanced AC and DC conductivities, but also affected the mechanism of conduction to switched from 3-D VRH in case of pristine PPy to 1-D VRH in all PPy Al PMMT nanocomposites. Maxwell Wagner effect was observed in dielectric spectroscopy. TGA curves of both the series of clay based ICP nonocomposites showed that the thermal stability is enhanced by insertion of ICPs in MMT clays. Blends of Polypyrrole and Polyaniline with poly (methyl methacrylate) (PMMA) in the presence of Hydroquinone were also prepared and studied. The percolation threshold in PANI.DBSA PMMA with 1% hydroquinone blends was observed as low as 3% which is very low as compared to that of theoretical value of 16%. iiThe percolation threshold in PPy.DBSA PMMA was recorded as 7% which shows that PPy.DBSA has less interaction with PMMA as compared to that of PANI.DBSA. These results were further confirmed by FT-IR, Raman spectroscopy and dielectric spectroscopy. Single crystal Cadmium hexathiohypodiphosphates Cd(PS 3 ) 2 generally written as CdPS 3 and Poly (p-phenylene vinylene) (PPV) were successfully synthesized. PPV was synthesized by chemical polymerization method. Intercalation of K + , Eu + and then PPV into the layers of CdPS 3 was confirmed by XRD. PPV intercalated in layers of CdPS 3 and heated at 120°C (CPPV120) show enhanced conductivity and luminescence properties. Electrical Properties of polypyrrole (PPy) doped with dodecylbenzene sulfonic acid (DBSA) were studied with and without a plasticizing agent hydroquinone. Hydroquinone was used as a compatibilizer to maximize solubility of PPy.DBSA in organic solvents which facilitated easy processing of flexible and mechanically strong PPy films for device applications. In order to assess the effect of hydroquinone on the electrical properties of PPy.DBSA /Aluminum (Al) Schottky junction, capacitance- voltage (C-V) and current density-voltage (J-V) characteristics were measured in Indium Tin Oxide (ITO)/PPy.DBSA /Al and ITO/PPy.DBSA .hydroquinone/Al structures. The observed J-V and C-V characteristics can be satisfactorily fitted to the modified Schottky equations. The junction parameters were found to be strongly influenced by hydroquinone. From C-V characteristics, the built-in voltage and charge concentration were also found to be influenced by the presence of hydroquinone. These results indicate that addition of hydroquinone to PPy.DBSA imparts better diode quality to the doped polymer/metal Schottky junction.
Loading...
Loading...

Similar Books

Loading...

Similar Chapters

Loading...

Similar News

Loading...

Similar Articles

Loading...

Similar Article Headings

Loading...

شاہ فیصل

شاہ فیصل
۲۴؍ مارچ ۱۹۷۵؁ء کو سعودی عرب کے شاہ فیصل شہید کردیئے گئے، اس حادثہ جانکاہ سے اسلامی ممالک میں اندوہ و غم کا ایک بادل امنڈ پڑا کہ آہ! اسلام کا پاسبان، اسلامی حمیت و غیرت کا نگہبان، اسلامی موانست و یگانگت کا حدی خوان نہیں رہا، اسلامی زندگی کی قوت پنہاں کو آشکار، مسلمانوں کے سینوں میں عزائم کو بیدار اور ان کی نگاہوں کو تلوار کرنے والا جاتا رہا۔
مدتوں کے بعد بڑی مشکل سے اسلامی دنیا میں ایک دیدہ ور پیدا ہوا، جس کے مقاصد جلیل تھے، جس کی ادائیں دلفریب اور نگاہیں دلنواز تھیں، اسلام کے اس بطل حریت نے صرف گیارہ سال حکومت کی، مگر اس کے سارے کارنامے اسلامی تاریخ کے زریں باب بن کر رہیں گے، سعودی عرب کو دنیا کے متمول ترین ملکوں کی صف میں لاکھڑا کیا، مکہ معظمہ اور مدینہ منورہ کو سج دھج کر فردوس نگاہ بنادیا، پٹرول کو جنگی اسلحہ سے زیادہ مہلک تسلیم کراکے دنیا کی اہم طاقتوں کو بھی اپنے سامنے جھکنے پر مجبور کیا، حاتم طائی کی افسانوی سخاوت کی شہرت کو بلند کرکے عربوں کو اپنے مالی امداد سے سربلند اور سرخرو کیا، بچھڑے ہوئے مسلمان ملکوں کی دست گیری کرکے ان کو آگے بڑھنے کا حوصلہ دلایا، اسلامی بینک، اسلامی سکریٹریٹ، اسلامی خبر ایجنسی اور اسلامی سربراہ کانفرنس کی روح رواں بن کر یہ خاموش پیام دیا کہ توحید کی امانت سینے میں رکھنے والے اخوت کا بیان اور محبت کی زبان بن کردہر کو اسم محمد سے اجالا کردیں، اور جب کتاب ملت بیضا کی شیرازہ بندی سے پھر سے ہورہی تھی تو آیات الٰہی کے اس نگہبان کو اﷲ تبارک و تعالیٰ نے اپنی مصلحت سے اپنے پاس بلالیا، جہاں رخ در رخ محمدی سے کہہ رہا ہوگا:
؂ اب تو ہی بتا تیرا مسلمان...

Gender based Differences in COVID-19 patients

Coronaviruses are a huge family of viruses that originate disease extending from the common cold to further fatal maladies. Objective: The study was conducted to determine the gender based differences in COVID-19 patients. Methods: Study included total 150 participants visiting Department of Medicine, Mayo Hospital, Lahore, Pakistan. Data were collected through self-structured questionnaire using non-probability convenient sampling. Prior written informed consents were taken from the participants. Ethical approval was taken fromThe University of Lahore, Lahore. Data were analyzed through SPSS version 25.0. Results: Results showed that among the comorbidities hypertension was most common in COVID-19 patients followed by diabetes mellitus, especially in females. Whereas renal disorders and asthma were most reported in males. Analysis revealed that there was a significant association (p=0.001) between disease severity and gender. Conclusion: Study concluded that there was significant association between gender and disease severity.

Vegetation Analysis, Grassland Productivity and Carrying Capacity of Deosai National Park, Gilgit-Baltistan

Deosai Plateau is one of the most important alpine ecosystems in Pakistan. It was declared as Deosai National Park in 1993 to protect its unique ecology with Himalayan Brown Bear as the flagship species. The alpine flora and ecological characters of Deosai Plateau, important environmental variables responsible for species distribution, life forms, chorology and vegetation structure, analysis on pasture conditions and trends, biomass productivity and carrying capacity were studied. Possible influences of grazing on alpine grasslands were also investigated. Key issues of pasture use have been incorporated in the study with a variety of recommendations. Vegetation sampling was carried out through line transect and quadrat method, covering major habitats and elevation ranges for measurement of species composition and their relationship with environmental variables. Hierarchical cluster analysis technique of Two Way Indicator Species Analysis (TWINSPAN) was used for vegetation classification in the first order. Relationship of alpine plant communities with environmental factors were studied through Ordination method of Deterrended Correspondence Analysis. One hundred and seventy five species, representing 111 genera and 37 families were found. Compositae and Ranunculaceae were the dominant families. Hemicryptophyte (71.4 %) and chamaephyte (14.9 %) were the dominant life forms of Deosai Plateau, suggesting the extreme weather conditions similar to arctic tundra. The flora was predominantly West Himalayan (31 %) and Himalayan (13 %), followed by Central Asian and Circumpolar elements (11 %). Six communities were differentiated on the basis of indicator species and justified in the ordination plots. Species diversity and richness were recorded highest in Carex-Agropyron-Koberesia community. The greatest dissimilarity was found between Artemisia-Polygonum-Thallictrum community and Agropyron- Festuca-Nepeta community with 95% dissimilarity. Each plant community showed a marked dissimilarity from others with more than 55% dissimilarity index. Senwai block showed highest diversity with a diversity index of 3.7 and species richness of 58 with low evenness score. Grassland vegetation data showed a total variance xv("inertia") of 8.58. Ordination axis; DCA1 and DCA2 accounted for a total of 12.27 % of the variance, with DCA1 explaining a high proportion (6.72%). Altitude and soil moisture had significant correlation with ordination axes. Elevation (ele), topographic wetness index (twi), cos-transformed aspect (aspv), soil brightness index (sbi) and slope were found significantly related with species turnover. Vegetation cover was higher on northern slopes at lower elevations in areas of relatively good soil moisture. The variables gvi, sbi, and twi had strong positive correlation, while savi, elevation and aspv had strong negative correlation with DCA1. The soil moisture factor along axis1 seems to be the decisive factor in vegetation distribution. gvi and slope variables showed strong negative relationship with DCA2. Assessment of pasture conditions through hyper-temporal vegetation indices of NDVI image series showed an overall 8-10 % retrogression of vegetation in productive grasslands. Regressive trend at minor intensity was observed throughout the productive grasslands of DNP with the exception of HBB core zone. The average biomass production in DNP was found 1243 kg/ha suggesting that DNP is currently having low biomass productivity. The average carrying capacity was found as 1.37 ha/A.U/3 months. Heavy influx of nomads with severe grazing problems, free grazing by peripheral communities mainly concentrated in north eastern parts with established permanent animal corals, extraction and unwise exploitation of fuelwood and medicinal plants although illegal under the law, unmanaged tourism, absence of incentives to buffer-zone communities and habitat fragmentation were identified as major issues of the park. Future studies on these issues, especially with relation to ecological health of the park and initiation of modern agri-silvi-pastoral initiatives in peripheral valleys, adapting pragmatic strategies to minimize and restrict nomadic grazing and implementation of a viable management plan with sufficient financial resources for the park authorities are strongly recommended.