Polymer Derived Sioc Ceramic Via Thermolysis Of Photocrosslinked Polymethylhydrosiloxane (Pmhs)

Jack Tabb

School Name

Governor's School for Science and Math

Grade Level

12th Grade

Presentation Topic

Engineering

Presentation Type

Mentored

Mentor

Mentor: Dr. Pilla; Department of Automotive Engineering, Clemson University

Abstract

Ceramics are a class of materials that possess high thermal stability, chemical inertness, and high hardness. However, processing of ceramics is energy intensive, with temperatures above 1500 °C. Due to their ease of processing at lower temperatures, ceramics processed from a polymeric precursor, known as polymer derived ceramics (PDC), have received wide attention for more than four decades. These ceramics also allow fine tuning of the microstructure because of their bottom-up synthesis with a good control over chemistry. However, the porosity generated during both thermal crosslinking of polymers and the thermolysis is the major drawback that limits these materials from widespread application. In this regard, this work aims at producing highly dense, crack-free ceramics via thermolysis of photocured polymers. Polymethylhydrosiloxane (PMHS) was chosen as a precursor to obtain a SiOC ceramic. PMHS was cured under UV using Irgacure as a photocatalyst to obtain a highly dense polymer. The crosslinked polymer was characterized using thermogravimetric analysis to determine the thermolysis temperature and the ceramic yield. The crosslinked polymer was thermolyzed by being heated at a rate of 5 °C per minute and held at 1000°C, for one hour in an inert atmosphere. The as-thermolyzed ceramic was observed with scanning electron microscopy to determine the presence of porosity, the amount of free carbon was determined using Raman spectra, and the crystalline nature of the ceramic was determined using X-ray diffraction (XRD).

Location

Owens G07

Start Date

4-16-2016 2:15 PM

COinS
 
Apr 16th, 2:15 PM

Polymer Derived Sioc Ceramic Via Thermolysis Of Photocrosslinked Polymethylhydrosiloxane (Pmhs)

Owens G07

Ceramics are a class of materials that possess high thermal stability, chemical inertness, and high hardness. However, processing of ceramics is energy intensive, with temperatures above 1500 °C. Due to their ease of processing at lower temperatures, ceramics processed from a polymeric precursor, known as polymer derived ceramics (PDC), have received wide attention for more than four decades. These ceramics also allow fine tuning of the microstructure because of their bottom-up synthesis with a good control over chemistry. However, the porosity generated during both thermal crosslinking of polymers and the thermolysis is the major drawback that limits these materials from widespread application. In this regard, this work aims at producing highly dense, crack-free ceramics via thermolysis of photocured polymers. Polymethylhydrosiloxane (PMHS) was chosen as a precursor to obtain a SiOC ceramic. PMHS was cured under UV using Irgacure as a photocatalyst to obtain a highly dense polymer. The crosslinked polymer was characterized using thermogravimetric analysis to determine the thermolysis temperature and the ceramic yield. The crosslinked polymer was thermolyzed by being heated at a rate of 5 °C per minute and held at 1000°C, for one hour in an inert atmosphere. The as-thermolyzed ceramic was observed with scanning electron microscopy to determine the presence of porosity, the amount of free carbon was determined using Raman spectra, and the crystalline nature of the ceramic was determined using X-ray diffraction (XRD).