Date of Graduation
Statler College of Engineering and Mineral Resources
Lane Department of Computer Science and Electrical Engineering
Muhammad A Choudhry
In this thesis, experimental results and their analysis are presented on the phase transformations of microcrystalline cellulose (MCC) under two different treatments. First, MCC was subjected to ball milling in air for different times tBMi = 5, 10, 15, 30, 45, 60 and 120 minutes. Second, phase transformation of MCC under hydrothermal treatment (HTT) in distilled water using an autoclave was investigated by varying the pressure P, temperature T for different time tau. Both of the post treated samples were analyzed by X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) Spectroscopy, surface area measurements, Scanning Electron Microscopy (SEM) and Thermo-gravimetric Analysis (TGA).;Experimental results on the structural changes observed in microcrystalline cellulose subjected to ball milling for upto 120 minutes are reported. Under ball milling, the Segal crystallinity XCR systematically decreases with increase in ball milling time tBM with the largest rate of decrease observed for the initial time tBM< 30 minutes. These results show transformation of crystalline cellulose to an amorphous cellulose phase. The results on the XRD above tBM> 30 minutes are inconclusive to prove the presence of cellulose. Therefore evidence about the presence of cellulose above t BM> 30 minutes is shown by analyzing the results from FTIR spectroscopy.;Under hydrothermal treatment in water using an autoclave in which pressure P, temperature T and time of treatment tau were varied, the cellulose structure was observed to completely breakdown at the minimum conditions of P ≈ 400 PSI, T . 230°C and tau ≈ 30 minutes. Analysis of the XRD patterns yields information only about conversion of crystalline to amorphous form and the presence of cellulose is still vague. Results of the FTIR spectroscopy shows that for higher P, T and tau, the cellulose structure has completely broken-down resulting in new chemical phases. This different chemical nature of the converted sample is also evident from its thermal behavior under TGA as compared to that of unconverted sample.
Pyapalli, Sai Kishore, "Phase transformations of microcrystalline cellulose under ball-milling and hydrothermal treatment" (2013). Graduate Theses, Dissertations, and Problem Reports. 4991.