Sharif Digital Repository

Friction stir welding (FSW) of thermoplastic materials is an attractive but a challenging process due to inherent chemical and mechanical characteristics of polymeric materials. In the present work, thermo-mechanical models were employed to investigate the effect of processing parameters on of FSW of polycarbonate (PC). The heat flux during the joining process was localized around the PC join line and led to the formation of circular rings on the upper surface. According to the simulation results, increasing the tool rotational velocity reduced the temperature gradient and decfeased the suseptibelity of crack formation around the joint line. Cracks were formed at low frictional heats and... 

Amphiphilic copolymers consist of hydrophilic and hydrophobic monomer units have attracted great technological attention recently, owing to their unique properties and their ability to stabilize various interfaces in aqueous systems. This paper presents a novel and facile approach to produce spherical polyacrylamide, polystyrene and hydrophobically modified polyacrylamide (HM-PAM), as one of the most important type of amphiphilic copolymers, using a continuous aerosol-photopolymerization for the first time. To this end, the monomer droplets were generated by an atomizer, then photopolymerization was initiated ‘‘in flight’’ by ultraviolet (UV) irradiation of the aerosol monomer droplets...