{"394581":{"#nid":"394581","#data":{"type":"event","title":"Ph.D. Defense \u2013 Yifeng Hong","body":[{"value":"\u003Cp\u003EMSE Ph.D. Defense \u2013 Yifeng Hong\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EDate:\u003C\/strong\u003E Wednesday, May 6, 2015\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ETime:\u003C\/strong\u003E 1:30-4:30 pm\u003Cbr \/\u003E\u003Cstrong\u003ELocation:\u003C\/strong\u003E MRDC, Rm. 3515\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ECommittee members:\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EDr. Donggang Yao (Advisor, MSE)\u003Cbr \/\u003EDr. Meisha L. Shofner (MSE)\u003Cbr \/\u003EDr. Youjiang Wang (MSE)\u003Cbr \/\u003EDr. Karl I. Jacob (MSE)\u003Cbr \/\u003EDr. Yulin Deng (ChBE)\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003E\u003Cbr \/\u003ETitle: \u003C\/strong\u003EPROCESSING OF EXPANDABLE THERMOPLASTIC\/THERMOSET SYNTACTIC FOAM\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EAbstract:\u003C\/strong\u003E \u003Cbr \/\u003EWhile hollow glass microspheres are commonly used in syntactic foam, their abrasive and brittle properties usually result in poor processability and have adverse effects on the foam performance. Therefore, a number of attempts have been made in the industrial to replace hollow glass microspheres with polymeric foamed microspheres. Among many choices, expandable thermoplastic (ETP) microspheres filled syntactic foam has shown its high potential to become a novel class of engineering materials, especially for lightweight structural applications. However, conventional syntactic foam processing techniques usually experience difficulties such as high processing viscosity, low loading of foamed fillers, ineffective microsphere expansion, etc.\u003C\/p\u003E\u003Cp\u003ETo address these emerging issues, a microwave expansion process to produce thermoset-matrix syntactic foam containing thermoplastic foam beads was developed in this thesis work. In this process, unexpanded ETP microspheres were directly foamed in uncured thermoset matrix via microwave heating. Expandable polystyrene (EPS) microspheres and epoxy resin were chosen as a model material system. The resin viscosity and specific microwave energy are found to be the two primary control parameters determining the process window. Mechanical characterization showed that the syntactic foam can outweigh neat polymer in lightweight structural applications and was effectively toughened by foamed EPS. Furthermore, the microwave expansion process was found to be capable of molding syntactic foam parts of relatively sophisticated geometry with smooth surfaces.\u003C\/p\u003E\u003Cp\u003ETo broaden its impact, the microwave expansion process was extended to produce composite EPS foam. This process converts an expandable suspension into a composite foam with a honeycomb-like barrier structure. The suspension viscosity was found to highly influence the foam morphology. Results from mechanical tests showed that the existence of the barrier structure can considerably improve the mechanical performance of the composite foam. Fire-retardation tests demonstrated that the barrier structure can effectively stop the fire path into the foam, suppress toxic smoke generation, and maintain foam structure integrity.\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003ETo optimize the microwave expansion process, a general formulation was developed to model the EPS expansion.\u0026nbsp; A semi-analytical solution was first obtained based on the case of a single bubble expansion in an infinite matrix. The dimensionless bubble radius and pressure are defined and found to be as exponential functions of dimensionless expansion time. The semi-analytical solution can qualitatively predict the radial expansion of EPS microsphere observed in a real-time experiment. To have an accurate prediction, a numerical solution was obtained to the model that couples the nucleation and expansion of multiple bubbles in a finite matrix. The results show that the numerical solution can quantitatively predict the radial expansion of EPS. A parameter sensitivity study was performed to examine the effect of each parameter over the expansion process.\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"PROCESSING OF EXPANDABLE THERMOPLASTIC\/THERMOSET SYNTACTIC FOAM"}],"uid":"27707","created_gmt":"2015-04-08 11:28:43","changed_gmt":"2016-10-08 02:11:35","author":"Tatianna Richardson","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2015-05-06T14:30:00-04:00","event_time_end":"2015-05-06T17:30:00-04:00","event_time_end_last":"2015-05-06T17:30:00-04:00","gmt_time_start":"2015-05-06 18:30:00","gmt_time_end":"2015-05-06 21:30:00","gmt_time_end_last":"2015-05-06 21:30:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"221981","name":"Graduate Studies"}],"categories":[],"keywords":[{"id":"1366","name":"defense"},{"id":"1808","name":"graduate students"},{"id":"10774","name":"MSE"},{"id":"913","name":"PhD"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1788","name":"Other\/Miscellaneous"}],"invited_audience":[{"id":"78771","name":"Public"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}