MODIFICATION OF JACK PINE TMP LONG FIBERS BY ALKALINE PEROXIDE – PART 1. CHEMICAL CHARACTERISTICS OF FIBERS AND SPENT LIQUOR
The purpose of this work was to improve the quality of jack pine TMP long fibers, particularly with respect to the strength properties, by alkaline peroxide treatment. This paper reports the chemical characteristics of the treated long fibers and the spent liquors originating from various treatments. It was observed that, in comparison with hydrogen peroxide, the alkalinity of the treatment solutions had a greater influence on most fibre characteristics and spent liquor properties.
Acidic group topochemistry and fibre-to-fibre specific bond strength
Nous donnons ici la description d'une technique d'introduction selective des groupes d'acide carboxylique sur les fibres de pâte kraft. En nous servant d'une nouvelle technique faisant appel a la microscopie electronique a balayage et a la spectrometrie RX a energie dispersive (SEM-EDS), nous avons confirme la topochimie des groupes acides. L'essai de resistance du papier a montre que l'introduction selective des groupes acides sur la surface exterieure de la fibre ou a proximite pouvait ameliorer grandement la force specifique de cohesion interfibres.
Space Qualification Testing of a Shape Memory Alloy Deployable CubeSat Antenna
Abstract : Increasingly capable CubeSat missions require antenna with improved Radio Frequency performance over the traditional CubeSat antennas. Deployable quadrifilar helical antennas (QHA) enable an acceptable stowing volume and deploy to provide increased gain and bandwidth over traditional patch and dipole antennas. Extensive ground testing is required to ensure the antenna is space qualified and to characterize the antenna deployment in the space environment. AFIT requires a QHA to perform a future CubeSat geolocation mission and contracted Helical Communication Technologies (HCT) to design and manufacture a Shape Memory Alloy (SMA) L-band deployable QHA. Vibration, thermal vacuum, laser vibrometer, and Voltage Standing Wave Ratio (VSWR) experiments were conducted on the HCT antenna to verify the hardware in a simulated launch environment and to characterize the SMA deployment in the simulated space environment.The HCT QHA successfully passed all required NASA General Environmental Verification Standards space qualification testing. Several anomalies experienced by the QHA encourage a redesign. The deployed antenna length varied from 250-290 mm and future RF testing is required to determine if the antenna geometry variations are significant enough to impact the geolocation mission.This research documents the test results for a QHA deployable CubeSat antenna testing and aids the development of CONOPS for the future AFIT CubeSat mission utilizing the HCT QHAs.