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Synthesis and Characterization of Novel Shape Memory Polyurethanes

Thesis Info

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Author

Naheed, Shazia

Program

PhD

Institute

Government College University

City

Faisalabad

Province

Punjab

Country

Pakistan

Thesis Completing Year

2017

Thesis Completion Status

Completed

Subject

Chemistry

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/12114/1/Shazia%20naheed%20chemistry%202017%20gcu%20fslbd%20prr.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727457762

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Shape memory polyurethanes (SMPUs) have attracted much attention from academic and industrial researchers due to strong potential in biomedical and consumer applications. Shape memory materials are featured by the ability to remember and recover their original shape from a significant and seemingly deformation when a particular stimulus is applied. The attractive feature is the glass transition temperature which can be tailored for shape restoration. In order to better and more efficiently investigate application possibilities, polyurethane shape memory polymers have been synthesized to correlate structural properties and molecular engineering at required thermal transition by varying structural contributors including nature of diisocyanates, macrodiol and chain extenders. The present work has been divided into three major sections, which have been further divided into sub sections. In the first section shape memory polyurethane were synthesized by step growth polymerization technique varying the molecular weight of PCL and chain extenders. Thermo-mechanical, structural, morphological and shape memory behavior of polyurethane elastomers were analyzed and discussed. The results revealed that by increasing molecular weight of PCL as well as chain extender length, the thermal transitions of soft segments increased, SEM and AFM studies help to confirm phase segregation, also increasing shape memory properties were observed. In the second section optimized %age of glycerin was used to synthesize polyurethane elastomer along with increasing molecular weight of PCL and chain extenders length. DSC, DMTA results showed increasing thermal stability with increasing polyol and chain extender molecular weight. The glycerin based polyurethane showed crystallinity, phase separation and hydrophilic surface in high molecular weight PCL, while increasing HSC exhibited good shape memory behavior. The third section consists of nano filler based polyurethane. All composite showed variable trends, however addition of nano filler showed improvement in the thermo-mechanical as well as shape retention and shape recovery behavior of SMPUs.
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دوست کی فرمائش

دوست کی فرمائش

بڑا افسوس ہے تیری بے وفائی کا
صدا غم رہے گا تیری اس جدائی کا

جس باغیچے کو ہم نے پرورش کیا
کسی موسم میں بھی سوکھنے نہ دیا
پھولوں کے عین شباب میں جدا کردیا
بڑا امتحان تھا میری صبر آزمائی کا

پھولوں کے نکھار نے دل میں بسیرا کیا
اندھیرا تھا دل میں سویرا کیا
جدائی کے غم نے برا حال میرا کیا
درد اٹھتا رہے گا دل پہ چوٹ لگائی کا

پھولوں کے نکھار پہ بلبلیں بھی آنے لگیں
جھرمٹ بناکے وہ گیت گانے لگیں
پھولوں پہ بیٹھ کے وہ خوشیاں منانے لگیں
بڑا دکھ ہوا پھولوں کی خوشبو چرائی کا

مالی نے کی پھولوں کی بہت ہی رکھوالی
مگر لالچ میں آکر توجہ ہٹالی
صورت حال گئی نہ اس سے سنبھالی
بڑا چرچا ہوا اس کی رسوائی کا

چاولہ سائیں پھولوں کی مہک ہے بہت نرالی
بلبلوں کو بھی مل جائے گی اک دن دیس نکالی
چمن رہ جائے گا سب خالی کا خالی
تجھے کیا ملے گا دنیا میں دل بہلائی کا

Intake of Anti-Epileptic Drugs and their Influences on Sexual Dysfunctions

Epilepsy which is also called seizures disorder is an uncontrolled action of the central nervous system. It is not a single disease but a set of neurological disorders. Actually in this situation, the brain does not receive a precise signal and as a result an abnormal condition is produced that is usually involuntary in action. In this review, we aimed to focus on the relationship of anti-epileptic drugs with sexual dysfunction and adaptation of better remedies that improve a patient’s family life. Sexual dysfunction is a common comorbidity in people with epilepsy which badly affects their quality of life. Sexual dysfunction is caused by different factors like psychiatric problems, anti-epileptic drugs (AEDs) and social factors etc. Sexual dysfunctions include ejaculatory failure, lessen libido, penile erection in men and irregular menstrual cycle in women. Common drugs such as Topiramate, Gabapentin (GBP), Valproate (VA), Carbamazepine (CBZ), Olanzapine (OL) and Risperidone (RTG) that are in practice to treat epilepsy usually produced adverse effect on sexual dysfunction. Even though a lot of studies have been carried out to control sexual dysfunction in epilepsy’s patient, but still research is going on. Medicine such as Cyproheptadine, Mianserin, Buspirone, Yohimbine were found better to treat epilepsy with minimum side effects of sexual dysfunction. Moreover, it is also seen that certain vasodilators,  folate , and vitamin supplements are effective in improving the quality of life.

Speculative Study of Rotating Nanofluids over a Stretching Surface

A nanoparticle phenomenon is interesting due to the fact that it behaves like a bridge between substance and its atomic/molecular structure. As particles of a material break and approach their nano size, their intrinsic properties change quite dramatically. For example, platinum which is an inert element at macro scale becomes a catalyst at nano scale. Similarly silicon insulators become conductors and gold which is solid, inert and yellow, changes itself to a red liquid with unusual catalytic properties at nano scale. Thus nanoparticles have considerably different attributes as compared with particles of the same species and not in nanoscale. Nanotechnology is a rising science of today. It is growing swiftly and has numerous applications in almost every discipline of our daily life e.g., in medicines, foodstuff, chemicals, automobiles and many more. Nanoparticle study is at present a part of focused and systematized notice due to a comprehensive range of its possible uses in biomedical, optical, material manufacturing, transportation, energy and electronic fields. Since last two decades nanofluids have attracted the attention of scientists as an important research topic. Due to their intense use in extremely progressive technical and biomedical devices such as in nuclear reactors, microchips cooling, radiators and nano medications etc., nano particles are quite useful. Being comprised of low molecular mass but high thermal conductance, these fluids are considered to be vastly effective cooling managers. Rotating fluids flow over elastic stretching sheets are fairly apparent in several industrial procedures such as material management conveyers, extrusion of elastic panes and cooling of an endless metal plate in a cooling bath. Furthermore in procedure of glass blowing, constant moulding, and turning of fibres also consist of the rotary flow over enlarging surface. The role of stretching is of vital importance as can be visualized in above procedures in which flow of heat and mass is produced by the stretching practice of surface. The properties preferred for a result of such a progression would mostly rest on two features. First is the rate of cooling of fluid and second is the rate of stretching surface boundary on which liquid is lying. During the engineering procedure, heat transmission level at the stretched surface is deeply perceived as it is much related with the quality of the ultimate product. Keeping in view this outstanding feature of the modern day development engineering, numerous investigators have concentrated their attention on this precise area of study.