{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T16:37:03Z","timestamp":1790959023960,"version":"4.1.0"},"reference-count":34,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T00:00:00Z","timestamp":1787529600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>Controlling fibril generation and retaining their morphology during secondary thermal processing remain critical challenges for in-situ microfibrillar composites. Herein, we propose a \u201cmelt blending\u2013hot drawing\u2013low-temperature injection\u201d cascade strategy to fabricate polypropylene\/polyamide 66 (PP\/PA66) composites. By decoupling the synergistic effects of draw ratio (\u03bb) and compatibilizer (PP-g-MAH), an optimal fibrillation window was identified (15 wt% PA66, 3 wt% compatibilizer, \u03bb = 9), which balances interfacial tension and viscous drag to form a dense, oriented microfibrillar network. This solid-state network accelerates matrix nucleation (though slightly restricting overall crystallinity) and induces gel-like rheological behavior through severe structural confinement. Crucially, we demonstrate that conventional high-temperature injection (265 \u00b0C) triggers Rayleigh instability, causing fibril break-up and mechanical degradation. Conversely, low-temperature injection (210 \u00b0C) successfully achieves the \u201cgeometric freezing\u201d of the metastable fibril network. Consequently, the optimal composite exhibits maximized static strength (45.3 MPa) and a continuous, significant leap in notch impact toughness (10.16 kJ\/m2). This work bridges the gap between flow-induced fibrillation and thermodynamic morphological retention, offering a robust physical mechanism for high-performance polyolefin composites.<\/jats:p>","DOI":"10.3390\/polym18172049","type":"journal-article","created":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T09:20:02Z","timestamp":1787563202000},"page":"2049","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Geometric Freezing of In-Situ Fibrillated PP\/PA66 Composites via Low-Temperature Injection: Decoupling the Role of Draw Ratio and Compatibilization"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8652-8791","authenticated-orcid":false,"given":"Run","family":"Zhang","sequence":"first","affiliation":[{"name":"Guangxi Zhuang Autonomous Region Construction Engineering Quality Testing Center Co., Ltd., Nanning 530005, China"},{"name":"College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing 100029, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-9912-2280","authenticated-orcid":false,"given":"Chenchao","family":"Fu","sequence":"additional","affiliation":[{"name":"College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing 100029, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Guozheng","family":"Zhao","sequence":"additional","affiliation":[{"name":"Guangxi Zhuang Autonomous Region Construction Engineering Quality Testing Center Co., Ltd., Nanning 530005, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Weiheng","family":"Mo","sequence":"additional","affiliation":[{"name":"Guangxi Zhuang Autonomous Region Construction Engineering Quality Testing Center Co., Ltd., Nanning 530005, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Famin","family":"Zhao","sequence":"additional","affiliation":[{"name":"Guangxi Zhuang Autonomous Region Construction Engineering Quality Testing Center Co., Ltd., Nanning 530005, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiangrong","family":"Li","sequence":"additional","affiliation":[{"name":"Guangxi Zhuang Autonomous Region Construction Engineering Quality Testing Center Co., Ltd., Nanning 530005, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qiuxu","family":"Chen","sequence":"additional","affiliation":[{"name":"Guangxi Zhuang Autonomous Region Construction Engineering Quality Testing Center Co., Ltd., Nanning 530005, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lin","family":"Zhuo","sequence":"additional","affiliation":[{"name":"Guangxi Zhuang Autonomous Region Construction Engineering Quality Testing Center Co., Ltd., Nanning 530005, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"108771","DOI":"10.1016\/j.compositesb.2021.108771","article-title":"Continuous fibre-reinforced thermoplastic acrylic-matrix composites prepared by liquid resin infusion\u2014A review","volume":"215","author":"Obande","year":"2021","journal-title":"Compos. 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