Novel Vacuum Bag Processing Approaches to Void Reduction in Carbon/EpoxyComposites

摘要

Vacuum bag and autoclave cure methods for fabricating reproducible qualitypolymer composites are well established and standardized. As this field of composites processing continues to mature, the thrust of developmental work naturally shifts to areas of need. One current thrust area is an expanding effort to develop more cost effective processing methods that do not sacrifice part quality. Several novel void reduction techniques were investigated in this study. They are vibration-assisted vacuum composite processing (VAVCP), porous scrim layering (PSL), microporous membrane processing (MMP), and Narmco Materials, Inc.'s Thick Laminate Prepreg (TLP). In VAVCP, low frequency vibration was applied during the pregelation period of the cure cycle of vacuum bag processed carbon/epoxy laminates. This process affected only established gas bubbles. Decreased void content in excess of 50% and increased laminate densification of 0.8% were measured.d Data also indicated an approximate 10% increase in size of the remaining voids. The PSL process had no detectable effect on void content. MMP showed the ability to remove volatile water vapor from within the preform interior. Narmco's TLP lowered void content of vacuum bag processed laminates by 50%. Volatile gas and mechanically entrapped gas bubbles respond to different methods of removal from the preform interior.