Accession Number:

ADA516868

Title:

Improved Dynamic Strain Hardening in Poly(Urethane Urea) Elastomers for Transparent Armor Applications

Descriptive Note:

Conference paper

Corporate Author:

ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE

Personal Author(s):

• Hsieh, Alex J.
• Sarva, Sai S.
• Rice, Norman

Report Date:

2009-09-01

Pagination or Media Count:

14.0

Abstract:

The U.S. Army Joint Service ChemicalBiological Protective Facemask program requires a lens system that can be folded while providing a high level of optical quality, chemical resistance, ballistic protection, scratch resistance, and environmental durability. In general, materials with good barrier properties lack significant energy absorptiondissipation abilities upon impact, whereas rigid transparent polymeric materials that are extremely tough exhibit poor resistance to chemical hazards and abrasion. The Army Research Laboratory is currently engaged in collaboration with the Institute for Soldier Nanotechnologies ISN to help design novel polymeric materials with improved physical and mechanical properties by exploiting novel molecular mechanisms. This report presents recent experimental findings exploring the role of molecular mechanisms on the dynamic mechanical deformation of a model set of transparent segmented polyurethane urea, PUU, elastomers. As expected, increasing the hard segment content improved the barrier properties, and also increased the stiffness and flow stress levels. Tailoring of the microstructure was critical in altering their rate-dependent mechanical behavior. It was observed that promoting phase mixing among the hard and soft segment domains of the microphase-separated PUU material greatly enhanced its rate-dependent stiffening and strain hardening behavior. Furthermore, the resulting increase in intermolecular interaction also enhanced the barrier properties. These insights can aid in the design of PUUs for articles that manifest improved protective abilities under impact, while maintaining their flexibility during normal use, which is greatly desired for chemicalbiological protective faceshield applications.

Descriptors:

• *STRAIN HARDENING
• *ELASTOMERS
• *ARMOR
• *PROTECTIVE MASK FACEPIECES
• TOXIC HAZARDS
• POLYMERS
• TRANSPARENCE
• PHASE
• CHEMICAL AGENTS
• MILITARY APPLICATIONS
• POLYURETHANE RESINS
• ENERGY ABSORBERS
• UREA
• URETHANES
• NANOTECHNOLOGY
• BIOLOGICAL AGENTS
• MICROSTRUCTURE
• OPTICAL EQUIPMENT
• COLLABORATIVE TECHNIQUES
• REPRINTS

Subject Categories:

• Fabrication Metallurgy
• Elastomers and Rubber
• Armor
• Protective Equipment

Distribution Statement:

APPROVED FOR PUBLIC RELEASE