Optimizing fiber wetout for composites manufacturing

Abstract

Decreased mechanical strength in a fiber reinforced plastic part can often be traced to poor or incomplete impregnation of the reinforcing fiber with the matrix. To properly understand the impregnation process in the design of new composites manufacturing machinery (specifically in unidirectional tape machines), or to optimize wetout in existing machine designs, the raw process materials and their relationship within the process environment must be examined. The critical factors are: resin viscosity vs. temperature; the work of adhesion between the fiber and resin; and the problem of forcing the resin to completely penetrate a fiber bundle. If these factors are known, nip rolls can be designed to meet a specific process envelope, or in the case of existing equipment, the existing process envelope for specific fiber/matrix combinations can be manipulated for maximum fiber wetout.

Wettability and Interfacial Properties of Carbon Fiber and Poly(ether ether ketone) Fiber Hybrid Composite

“…Moreover, for wettable surfaces with connected depressions, the liquids can tend to spread along grooves, thereby leading to smaller contact angles than those on smooth surfaces . However, this phenomenon is closely connected with the polarity and viscosity of liquids. − The increased polarity or hydrogen-bond-accepting ability of a test liquid leads to the decreased wettability of inert surfaces of materials such as CFs, and this is reflected by a larger water contact angle . In addition, for molten thermoplastics or uncured resins, the contact angle might be influenced by large viscosity values.…”

“…However, this phenomenon is closely connected with the polarity and viscosity of liquids. − The increased polarity or hydrogen-bond-accepting ability of a test liquid leads to the decreased wettability of inert surfaces of materials such as CFs, and this is reflected by a larger water contact angle . In addition, for molten thermoplastics or uncured resins, the contact angle might be influenced by large viscosity values. However, we assume that the presence of microscopic grooves does not significantly modify the flow close to the contact line and therefore marginally influences the macroscopic contact angle defined on the basis of an asymptotic form of the observed slope between the solid and the liquids as the contact line is approached. , The tested average roughness R a is 147 ± 17 nm.…”

Παραγωγη Αριστοποιημενων Συνθετων Υλικων Ενισχυμενων Με Ινες Υψηλου Μετρου Ελαστικοτητας

“…9.4. ΑΡΙΣΤΟΠΟΙΗΣΗ ΤΗΣ ΔΙΑΒΡΟΧΗΣ ΤΩΝ ΙΝΩΝ ΚΑΤΑ ΤΗΝ ΠΑΡΑΓΩΓΙΚΗ ΔΙΑΔΙΚΑΣΙΑ ΤΩΝΣΥΝΘΕΤΩΝ ΥΛΙΚΩΝ[336].9.4.1.0 ρόλος του ιξώδους της ρητίνης σε συνάρτηση με τη θερμοκρασία.…”