Synthesis and Characterization of Interpenetrating Polymer Networks for Applications in Extraterrestrial Radiation Shielding PDF Download
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Author: Josiah Arevalo Hammack Publisher: ISBN: Category : Polymer networks Languages : en Pages : 128
Book Description
During interplanetary voyages spacecraft are exposed to a variety of ionizing radiations, including high intensity electromagnetic radiation and galactic cosmic rays, creating conditions that are harmful to both instrumentation and human passengers. Current shielding methods offer a degree of protection, but they are not suitable for long term missions or for habitation on extraterrestrial environments, and traditional terrestrial shields are too heavy to be carried on these missions. Organic polymers offer a versatile, lightweight solution to many of the difficulties in shielding, however they also present difficulties establishing a sufficiently high hydrogen content while maintaining high mechanical and thermal stability. By mixing two polymer species together it is possible to produce a material that combines the properties of both polymers, yet due to the immiscible nature of most polymeric materials, using polymer blends is not a practical solution. However it is possible to bypass the issue of immiscibility by dissolving different polymer species together and crosslinking like chains together, forming an interpenetrating polymer network (IPN). This research focuses on the synthesis and characterization of IPNs consisting of aliphatic and aromatic polymer species, containing a high hydrogen content and good mechanical properties, respectively, to be used in extraterrestrial environments to provide protection from ionizing radiation for humans and instrumentation alike.
Author: Josiah Arevalo Hammack Publisher: ISBN: Category : Polymer networks Languages : en Pages : 128
Book Description
During interplanetary voyages spacecraft are exposed to a variety of ionizing radiations, including high intensity electromagnetic radiation and galactic cosmic rays, creating conditions that are harmful to both instrumentation and human passengers. Current shielding methods offer a degree of protection, but they are not suitable for long term missions or for habitation on extraterrestrial environments, and traditional terrestrial shields are too heavy to be carried on these missions. Organic polymers offer a versatile, lightweight solution to many of the difficulties in shielding, however they also present difficulties establishing a sufficiently high hydrogen content while maintaining high mechanical and thermal stability. By mixing two polymer species together it is possible to produce a material that combines the properties of both polymers, yet due to the immiscible nature of most polymeric materials, using polymer blends is not a practical solution. However it is possible to bypass the issue of immiscibility by dissolving different polymer species together and crosslinking like chains together, forming an interpenetrating polymer network (IPN). This research focuses on the synthesis and characterization of IPNs consisting of aliphatic and aromatic polymer species, containing a high hydrogen content and good mechanical properties, respectively, to be used in extraterrestrial environments to provide protection from ionizing radiation for humans and instrumentation alike.
Author: S. Marturunkakul Publisher: ISBN: Category : Languages : en Pages : 7
Book Description
Polymeric materials with second order nonlinear optical (NLO) properties are of much interest for applications such as waveguide electrooptic modulation and frequency doubling devices. These NLO properties are presented when the chromophores are aligned in a noncentrosymmetric manner. The alignment of NLO chromophores in the poled polymers must be sufficiently stable at temperatures above 100 deg C in order to use them in practical devices. Several approaches have been adopted to enhance the temporal stability of the poled polymers. Enhanced temporal stability of second order NLO properties in several poled polymer systems has been achieved by crosslinking reactions. The resulting crosslinked network has a higher glass transition temperature and a denser matrix which prevent the aligned NLO chromophores from relaxing to a random orientation. However, slow decay of second order NLO properties at elevated temperatures was still observed in the polymers. Furthermore, the general form of the relaxation curves for the crosslinking polymers do not appear to be distinctly different from those for the guest/host systems. We have selected an interpenetrating polymer network (IPN) containing aligned NLO chromophores to test these issues. An IPN is a structure in which two or more networks are physically combined. The IPN is known to be able to remarkably suppress the creep and flow phenomena in polymers. Permanent entanglement of the two polymer chains restrict their mobility which leads to a significantly more stable NLO material. In this paper, we report on the design, synthesis and characterization of an NLO active IPN ... Interpenetrating polymer network, Nonlinear optical polymer.
Author: Josiah Arevalo Hammack
Author: Josiah Arevalo Hammack
Author: P. R. Srikanth Sharma
Author: Gregory D. Phelan
Author: Kassu Gebreyes
Author: Shahin Maaref
Author: Yuqian Du
Author: Cheryl Mary Robson
Author: Jag J. Singh
Author: J. A. McCluskey
Author: S. Marturunkakul