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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Development of Inhibiting Materials Resistant to Nitroglycerine Migration

Chen, Chi-he 12 July 2004 (has links)
Oligomers of hard and soft segments of unsaturated polyesters were synthesized in two steps. For the hard segment, isophthalic acid was reacted with 1,2-propanediol first, then maleic anhydride was added for further esterification. For the soft segment, diethylene glycol was used to replace 1,2-propanediol. In the previous study, the excess amount of glycol was 20% in weight. In this study, glycol was 10 and 5 wt% in excess, respectively. Decreasing the excess amount of glycol from 20 to 5 wt%, the number average molecular weight of both hard and soft segments increased about 30-40% from 1000 g/mol, and the degree of isomerization of maleic acid changed from 40.5 to 57.3% for the oligomers of the soft segment. The hard and soft segments synthesized in this study were blended in weight ratios from 0 to 100 % in an interval of 20 %, and then cured with styrene for further mechanical testing. The micro-tensile strength of cured soft and hard segments increased 1.3 and 8 times, respectively, in this study compared with that of specimens prepared under the condition of 20 wt% in excess of glycol. Therefore, the criteria of inhibitors can also be achieved by varying the excess amount of glycols. To evaluate the nitroglycerine migration and the erosion rate, only two (60% hard segment and 40% soft segment) of the formulas which passed the criteria of mechanical properties were investigated by replacing lithophone with magnesium hydroxide. In the case of 10 wt% in excess of glycol, the migration of nitroglycerine at infinite time (M
2

Development of inhibitors based on organic-inorganic hybrid materials via sol-gel process

Li, Yi-chun 04 July 2006 (has links)
Oligomers of hard and soft segments of unsaturated polyesters (UP) were synthesized. They were blended in different ratios and cured with various amounts of styrene. Based on the criteria of tensile strength and strain, hard segment/soft segment (60/40 wt %) UPs containing 35 wt % and 45 wt % of extra amount of styrene were chosen for further studies. Inorganic-organic hybrid materials were prepared by incorporating tetraethoxysilane and poly(dimethylsiloxane) into the UP resins via the sol-gel process by changing the ratios of HCl/TEOS, H2O/TEOS, TEOS/PDMS and the reaction time. The specimens of these hybrid materials after curing were characterized using the tensile tester, rheometer, scanning electron microscope (SEM), 29Si-NMR and thermogravimeter. In the condition of HCl/TEOS molar ratio 0.07, H2O/TEOS molar ratio 4, TEOS/PDMS weight ratio 90/10 and the reaction time 3 hours, the results of 29Si-NMR, SEM and silicone mapping indicate that these silica gels with 3D network were well dispersed in the UP resins. These specimens had tensile strength of 512¡Ó16 kgf/cm2 and elongation of 11¡Ó4 % which are above the criteria of inhibitors. From the erosion testing, flame retardants was added unsaturated polyester and inorganic-organic hybrid materials that can help to resist heat flame, remain of a fire on the surface had the char forming.

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