Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. John C. Brody* and John W. Gillespie, Jr.* 5f. WORK UNIT NUMBER PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) September 2004 REPORT TYPE PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)Composite Manufacturing Science Laboratory University of Delaware Center for Composite Materials Newark, DE 19716 PERFORMING ORGANIZATION REPORT NUMBER SPONSOR/MONITOR'S ACRONYM(S)ARL-CR-552 SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) U.S. Army Research Laboratory ATTN: AMSRD-ARL-WM-MB Aberdeen Proving Ground, MD 21005-5069 SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTES*University of Delaware, Center for Composite Materials, Newark, DE 19716. ABSTRACTThis study characterizes and evaluates two types of preform binders-reactive thermosets and nonreactive thermoplastics. The interply adhesion between woven glass plies was measured as a function of binder type, concentration, and preforming conditions. It was found that reactive binders offer the potential to provide much larger interply adhesions between glass plies in a preform than thermoplastics and are thus superior choices for the fabrication of complex-shaped preforms requiring little or no springback. Laminated composite panels fabricated from preforms with varying binder concentrations were evaluated in regards to their interlaminar properties. It was found that both binder types degraded the interlaminar shear strength of a woven glass reinforced/vinyl ester composite. Additionally, composite laminates made from preforms and containing the thermoplastic binder showed decreases in the interlaminar fracture toughness of the composite by ~60%. However, composite laminates fabricated from preforms using the reactive epoxy binder showed an increase in fracture toughness by ~47%. Hence, it is concluded that a range of interlaminar properties can be achieved depending on the type of binder, the amount of binder, and the processing of the binder, and also that of the composite itself.

This study characterizes and evaluates the effects of a thermoplastic polyester preform binder on a thermosetting vinyl ester resin. It was observed that the binder material is soluble in the resin and that the dissolution of the binder drastically affects the viscosity of the resin. It was determined that the binder can significantly delay the gel time, and influence the reaction kinetics of the resin. Additionally, results show that the binder concentration and extent of dissolution affect the mechanical and thermophysical properties of the resin. Higher binder concentrations and larger dissolution times resulted in increased tensile strengths, elongations, and glass transition temperatures of the matrix resin. In order to characterize binder dissolution times, an experimental technique was introduced in which the binder dissolution is correlated to increases in the resin viscosity. The results from this study quantify the affects of thermoplastic polyester binders on vinyl ester resin and provide the basis for refining the processing window of composite laminates using preform binders.

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