Crystallinity-associate impact damage-mode transition and its low-temperature intensification: influence on residual compressive strength of carbon fiber/polyphenylene sulfide laminates

초록

This study investigated low-velocity impact damage and compression-after-impact (CAI) performance of stamp-formed carbon fiber/polyphenylene sulfide (CF/PPS) laminates produced under three mold-temperature conditions that resulted in different matrix crystallinity levels (Xc1: 28.72 %, Xc2: 18.56 %, Xc3: 7.17 %). Specimens were impacted at −65, −20, and 25 °C at 20 J, followed by C-scan and room-temperature CAI testing. Layer-resolved X-ray microscopy (XRM) was additionally performed on one selected specimen from each condition at −65 °C. Across the processing conditions, higher measured crystallinity and lower impact temperature coincided with higher maximum impact force and lower absorbed energy. Rear-surface fiber fracture was observed in Xc1 at 25 °C, whereas Xc2 exhibited fracture only at −65 °C, thereby bracketing transition intervals across processing conditions and temperatures. For the individual XRM-scanned specimens, cumulative interfacial delamination areas were 240.5, 1128.1, and 2084.9 mm2 for Xc3, Xc2, and Xc1, respectively; these are single-specimen observations. Xc2 achieved the highest room-temperature compressive strength and CAI residual strength. Because mold temperature also altered cooling history, the observed between-condition differences cannot be attributed exclusively to crystallinity, and residual thermal-stress contributions cannot be excluded. © 2026 Elsevier Ltd

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