Liu Junhui1，Guo Tuo2， Wu Man2， Chen Yulong1 ，Guo Qingjie1，2
1.College of Chemical Engineering， Qingdao University of Science and Technology， Qingdao 266000， China； 2.Center of Carbon Capture and Industrial Utilization， Jiangmen Laboratory of Carbon Science and Technology， Jiangmen 529100， China
Abstract
Objective Walnut shell-modified waste wind turbine blade （WTB） powder-filled polypropylene （PP） composites are high-performance recycled materials. However， their practical performance is largely governed by interfacial compatibility and overall mechanical properties within the WTB powder-PP system. Compared with a single WTB system， the introduction of walnut shell powder （WSP） enables synergistic enhancement of both strength and toughness， while also promoting the effective utilization of multiple solid wastes. As a result， impact resistance can be improved without a significant loss of rigidity. However， the main difficulty in constructing this multi-phase composite lies in the poor interfacial compatibility between the polar fillers （WTB powder and WSP） and the non-polar PP matrix， leading to filler agglomeration， interfacial debonding， and reduced toughness. To address this issue， a multi-component blending strategy combined with synergistic interfacial modification using PP‑g‑MAH and KH-550 is adopted. The effects of WSP content and interfacial modification on the mechanical properties， thermal stability， flame retardancy， and microstructure of the composites are analyzed. The research findings provide references for the high-value recycling of decommissioned wind turbine blades and the coordinated utilization of agricultural and industrial solid wastes.
Methods In this study， waste WTB powder and WSP were first divided into different formulation groups based on a multi-component blending system. The WTB powder was surface-modified with the silane coupling agent KH-550， and WSP was incorporated at varying contents to establish the base PP matrix formulation. Second， the composites were prepared via melt compounding and injection molding under different processing conditions， and the optimal processing parameters were determined. Then， the mechanical properties of composites with different WSP contents and different interfacial modifiers were tested to identify the optimal formulation for synergistic reinforcement and toughening. The effects of interfacial modification on the microstructural characteristics of the composites were quantitatively characterized via Fourier transform infrared spectroscopy （FTIR） and scanning electron microscopy （SEM）. According to the results of mechanical testing and microstructural characterization， the formulation parameters of the composites were optimized and validated via thermalgravimetric analysis （TGA） and limiting oxygen index （LOI） tests. Finally， the experimental results were compared with structural analysis to establish an efficient and stable multi-phase composite system with improved interfacial compatibility and balanced mechanical properties.
Results and Discussion Based on established formulation system， calculation results showed that under the same WSP content， the composite with 20 phr （recommended addition level per 100 parts of resin） of WTB powder showed increases in tensile and flexural strength of 6.9% and 12.2%， respectively， compared with the unmodified system. This confirmed the synergistic reinforcement of WTB powder and WSP. After dual interfacial modification using PP‑g‑MAH and KH-550， the interfacial bonding was improved. SEM results showed that the fracture surface transitioned from brittle fracture to ductile tearing， indicating enhanced interfacial adhesion. The optimal WSP content ranged from 20 phr to 25 phr， and the corresponding impact strength ranged from 34.8 J/m to 32.5 J/m， achieving a good balance of strength and toughness. As WSP content increased from 0 phr to 30 phr， the initial decomposition temperature decreased gradually. At the same time， the thermal stability in the low-temperatureregion decreased， while the char yield at high temperature increased rapidly from 2.3% to 8.6%. Under optimal conditions of 20 phr WSP and dual interfacial modification using PP‑g‑MAH and KH-550， the composite achieved a tensile strength of 30.8 MPa， flexural strength of 36.1 MPa， and impact strength of 34.8 J/m. The IL reached 25.6%， and the char yield was 6.8%.
Conclusion The study prepares a high-performance recycled composite based on walnut shell-modified waste wind turbine blade powder-filled polypropylene using a multi-component blending and interfacial modification strategy. Introducing 20~25 phrWSP effectively increases impact strength to 34.8 J/m， a 15.1% improvement compared to the unmodified system. To overcome the toughness loss caused by WTB powder incorporation， using a dual interfacial modification system of PP‑g‑MAH and KH-550 is effective in improving interfacial compatibility within the multi-phase system. The results demonstrate that interfacial modification is the key factor determining stress transfer efficiency， and the synergistic modification strategy enables the improvement in mechanical performance of the multi-phase composite. The composite showed an LOI of 25.6%， indicating potential as an engineering material with further flame-retardant improvement. Overall， this approach provides an efficient route for high-value utilization of waste wind turbine blades.
Keywords： waste wind turbine blade； polypropylene； walnut shell powder； resource utilization
Get Citation:Liu Junhui， Guo Tuo， Wu Man， et al. Properties of walnut shell powder‑modified waste wind turbine blade powder‑filled polypropylene composites［J］. China Powder Science and Technology， 2026， 32（5）： 1-13.
Received： 2026-03-22， Revised： 2026-05-05， Online： 2026-06-18。
Funding： The research was supported by the National Natural Science Foundation of China (Grant Nos. 22379079, U20A20124) and the Natural Science Foundation Project of Ningxia Hui Autonomous Region (Grant No. 2022AAC01001).
DOI：10.13732/j.issn.1008-5548.2026.05.009
CLC No.：TB332； TB4
Type Code：A
Serial No.：1008-5548（2026）05-0001-13
