McCarthy

Bio: McCarthy is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 2 citations.

Effects of the Pre-Consolidated Materials Manufacturing Method on the Mechanical Properties of Pultruded Thermoplastic Composites

Abstract: The choice of a manufacturing process, raw materials, and process parameters affects the quality of produced pre-consolidated tapes used in thermoplastic pultrusion. In this study, we used two types of pre-consolidated GF/PP tapes—commercially available (ApATeCh-Tape Company, Moscow, Russia) and inhouse-made tapes produced from commingled yarns (Jushi Holdings Inc., Boca Raton, FL, USA)—to produce pultruded thermoplastic Ø 6 mm bars and 75 mm × 3.5 mm flat laminates. Flat laminates produced from inhouse-made pre-consolidated tapes demonstrated higher flexural, tensile, and apparent interlaminar shear strength compared to laminates produced from commercial pre-consolidated tapes by as much as 106%, 6.4%, and 27.6%, respectively. Differences in pre-consolidated tape manufacturing methods determine the differences in glass fiber impregnation and, thus, differences in the mechanical properties of corresponding pultruded composites. The use of commingled yarns (consisting of matrix and glass fibers properly intermingled over the whole length of prepreg material) makes it possible to achieve a more uniform impregnation of inhouse-made pre-consolidated tapes and to prevent formation of un-impregnated regions and matrix cracks within the center portion of the fiber bundles, which were observed in the case of commercial pre-consolidated tapes. The proposed method of producing pre-consolidated tapes made it possible to obtain pultruded composite laminates with larger cross sections than their counterparts described in the literature, featuring better mechanical properties compared to those produced from commercial pre-consolidated tapes.

Crystallisation behaviour and morphological studies of PEKK and carbon fibre/PEKK composites

Abstract: The increased interest in carbon fibre/poly(etherketoneketone) (CF/PEKK) as an option for high-performance applications calls for a thorough understanding of the composite's crystallisation behaviour, due to the essential role that crystallinity plays in performance. In this study, differential scanning calorimetry was used with a variety of thermal cycles to evaluate the effect of thermal history on crystallinity development in unreinforced PEKK and CF/PEKK. Different isothermal holding temperatures during cooling affected the ratio between primary and secondary crystallisation, and non-isothermal cooling cycles influenced the extent of crystallisation. The inclusion of carbon fibres increased the proportion of secondary crystallisation in the matrix and slowed down crystallisation kinetics. A Velisaris-Seferis model was used to model crystallisation kinetics for the isothermal data, and adapted Nakamura models were used for the non-isothermal data. Based on this work, optimum isothermal hold temperatures during cooling for CF/PEKK are estimated to lie in the range of 220–260 °C.

Consolidation of Continuous Carbon Fiber-Reinforced PAEK composites: A review

Abstract: Continuous-Carbon-Fiber (CF)/polyaryletherketone (PAEK) composites have recently attracted interest especially in the aerospace industry due to short-time processes and possible weldability and recyclability. However, their manufacturing remains challenging as it involves several steps such as tape fabrication, tape lay-up and consolidation. This last step mainly aims at achieving a sufficiently low void content composite to obtain the desired mechanical properties. To become an economically viable alternative over classical thermoset-based composites, “in-situ” or out-of-autoclave (OOA) consolidation processes have to become part of the manufacturing process of CF/PAEK. These techniques have, for now, some limitations which lead to difficulties in producing parts of the same quality as autoclave consolidated ones. Understanding the multi-scale rheological phenomena involved during consolidation is therefore critical, which constitutes the main goal of this review. Reflecting on the literature, guides for improving the OOA and “in-situ” consolidation, both in terms of process and materials, are finally suggested.

Effect of voids and crystallinity on the interlaminar shear strength of in-situ manufactured CF/PEEK laminates using repass treatment

Abstract: Voids and crystallinity, both affected by the temperature history, have an effect on the interlaminar shear strength of thermoplastic composites. In this paper, CF/PEEK laminates with varied porosity and crystallinity are manufactured by repass treatment (based on the laser-assisted forming) under different interlaminar temperature and times of treatment. The porosity and microscopic features of voids are characterized via the water displacement method and optical microscope, respectively. And further squeeze flow of fiber-resin composite and percolation flow of resin occur during repass treatment, which account for the inhabitation of voids. Crystallinity is analyzed through differential scanning calorimetry, which is affected by both cooling rate and recrystallization of the amorphous phase during repass treatment. The interlaminar shear strength of laminates with varied voids and crystallinity is tested, and the failure modes are studied by optical microscope and scanning electron microscope. As a result, the interlaminar shear strength of laminates, with less voids and higher degree of crystallinity, is improved 32.87% than that of the laminates without repass treatment.