موقع الكتاب في العملية النّقدية عند المحدّثين وأهمّ وسائل صيانته دراسة تأصيليّة

In this research paper the method invented by the critic scholars of hadeeth for the maintenance of quality. It is the sake of delivering the hadeeth to us the way it was narrated by the prophet peace be upon him. This study came to highlight the greatness of the critical approach of the Muḥaddithīn, this unique and precedent based approach has been opted and enjoyed the respect of the opponents. I have paid special regard to the timeline, which reflects the evolution of the Muḥaddithīn criticism, from the Era of the Prophet (PBUH) to the end of the Hadīth Narration Era. This paper shows the extent to which the critic scholars go in order to maintain the book; their attention is not limited to the Oral narration as claimed by the opponents of Sunnah and their stooges. This is done by examining the classified works of scholars that had preserved the bases and the rules followed in the criticism process, as explained in this study.

Synthesis and Characterization of Novel Shape Memory Polyurethanes

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.