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Displaying 176 - 200 of 1856

Quantifying Strain via Buckling Instabilities in Surface Modified Polymer Brushes

May 21, 2020
Author(s)
Cassandra M. Reese, Wei Guo, Brittany J. Thompson, Phillip K. Logan, Christopher Stafford, Derek L. Patton
We present a quantitative method of measuring the compressive strain of wrinkled polymer films and coatings with knowledge of the "skin" thickness, wrinkle wavelength, and wrinkle amplitude. The derived analytical expression is validated with a well

Effects of temperature and humidity on high-strength p-aramid fibers used in body armor

April 14, 2020
Author(s)
Amy E. Engelbrecht-Wiggans, Faraz A. Burni, Emilien Guigues, Shefei Jiang, Vivian Yu, Thang Huynh, Zois Tsinas, Deborah Jacobs, Amanda L. Forster
To improve the reliability and design of body armor, it is imperative to understand the failure modes and the degradation rates of the materials used in armor. Despite the best efforts of manufacturers, some vulnerability of armor materials to aging due to

On the Nature of Macroradicals Formed upon Radiolysis of Aqueous Poly(N--?vinylpyrrolidone)Solutions

April 2, 2020
Author(s)
Richard D. Holbrook, Clelia Dispenza, Maria Antonietta Sabatino, Natascia Grimaldi, Bjorn Dahlgren, Mohamad Al-Sheikhly, James F. Wishart, Zois Tsinas, Mats Jonsson
In this work we have explored the nature of macroradicals formed upon radiolysis of aqueous poly(N-­‐vinylpyrrolidone) (PVP) solutions using pulse radiolysis, density functional theory (DFT) and literature data. On the basis of literature data on site-­

Using Microprojectiles to Study the Ballistic Limit of Polymer Thin Films

April 1, 2020
Author(s)
Shawn H. Chen, Amanda J. Souna, Christopher L. Soles, Stephan J. Stranick, Edwin P. Chan
The dynamic impact between a particle and a planar material is important in many high impact events, andthereisagrowingneedtocharacterizethemechanicalpropertiesoflight-weightpolymeric materials at dynamic loading conditions. Here, a laser-induced

Design and Characterization of an Architecturally ‘Perfect’ Family of Linear Low-Density Polyethylenes (LLDPEs) by Multi-Detector Size Exclusion Chromatography

March 27, 2020
Author(s)
Sara V. Orski, Luke Kassekert, Wesley Farrell, Grace A. Kenlaw, Marc Hillmyer, Kathryn L. Beers
Separations of commercial polyethylenes, which often involve mixtures and copolymers of linear, short-chain, and long-chain branched chains, can be very challenging to optimize as species with similar hydrodynamic sizes or solubility often co-elute in

Effect of Elevated Temperature and Humidity on Fibers Based on 5-amino-2-(p-aminophenyl) benzimidazole (PBIA)

March 19, 2020
Author(s)
Amy E. Engelbrecht-Wiggans, Ajay Krishnamurthy, Lucas H. Kaplan, Amanda L. Forster, Thanh N. Hoang, Viviana Bentley
Traditionally, soft body armor has been made from materials such as poly(p-phenylene terephthalamide) (PPTA) and ultra-high molar mass polyethylene (UHMMPE). However, to diversify the fiber choices in the United States body armor market, copolymer fibers

Nanoscale Pattern Decay Monitored via in-situ Heated Atomic Force Microscopy

March 12, 2020
Author(s)
Sonal Bhadauriya, Jianan Zhang, Jaejun Lee, Michael R. Bockstaller, Alamgir Karim, Richard J. Sheridan, Christopher Stafford
We combine in-situ heated atomic force microscopy (AFM) with automated line-by-line spectral analysis to quantify the relaxation or decay of nanopatterned polymer films at temperatures above the glass transition. This approach enables assessment of pattern

Macroscopic degradation behaviors of polyethylene under the influence of UV radiation and temperature

February 17, 2020
Author(s)
Hsiang C. Hsueh, Jae H. Kim, Sara Orski, Andrew Fairbrother, Deborah Jacobs, Donald L. Hunston, Christopher C. White, Li Piin Sung, Lakesha Perry
Accelerated weathering tests were performed to investigate the effects of multiple ultraviolet (UV) light intensities and temperatures on the tensile behavior of high-density polyethylene (HDPE). In the macroscopic degradation behavior of HDPE, tensile

Compressive deformation analysis of large area pellet-fed material extrusion 3D printed parts in relation to in situ thermal imaging*

February 8, 2020
Author(s)
Eduardo M. Trejo, Xavier Jimenez, Kazi M. Billah, Jonathan Seppala, Ryan Wicker, David Esplain
In large area pellet extrusion additive manufacturing, the temperature of the substrate just before the deposition of a new subsequent layer affects the overall structure of the part. Warping and cracking occur if the substrate temperature is below a
Displaying 176 - 200 of 1856