Yanyou Huang,Liangdong Ye,Qiaoyan Wei,Dacheng Li,Zengju Wu,Liling Zhang,Chuanheng Yu,Ziwei Li,Shaorong Lu
Improving the toughness of epoxy resins is critical for high-performance applications. In this study from molecular structure design, hyperbranched ionic liquids (HBIL) containing imidazole groups were synthesized through a one-step esterification method. These HBIL were subsequently combined with recycled polyethylene terephthalate (PET) to synergistically enhance the toughness of epoxy resins (EP). The mechanical, thermomechanical, and rheological properties, as well as the curing behavior of the epoxy composites, were systematically evaluated. The addition of HBIL reduced the viscosity and curing temperature of the epoxy composite. The impact strength of the epoxy composites with only 6 phr PET was increased from 6.48 kJ/m 2 to 18.19 kJ/m 2 . Furthermore, the addition of HBIL exhibited a synergistic effect with PET. The epoxy composites added with 6 phr PET and 4 phr HBIL showed an increase in impact strength, elastic modulus, and flexural modulus by 237 %, 28.5 %, and 12.4 %, respectively, and an increase in the glass transition temperature (T g ) by 5.8 °C compared with pure EP. Molecular dynamics (MD) simulations corroborated these experimental results, providing insight into the improved properties. This study introduces an innovative approach to developing epoxy composites with superior performance characteristics.
Jinrui Hu,Xiao Xu,XinYi Cao,Lulu Dong,Lixia Bao,Weibo Kong,Jiliang Wang
The recycling of poly(ethylene terephthalate) (PET) is vital for environmental sustainability, yet achieving recycled PET (rPET) and its composites with optimal processability and flexibility remains a challenge. This study presents a solvent-free reactive extrusion method to extend the chains of rPET using a macromolecular chain extender (i.e., methyl methacrylate-glycidyl methacrylate copolymer, marked as PMG) rich in epoxy groups and to produce rPET/recycled polyethylene (rPET/rPE) composites. The resulting composites exhibit excellent thermoplasticity and controllable mechanical properties, such as the rPET/rPE composite (70:30 by mass), with a tensile strength of 39.2 MPa and an elongation at a break of 81.4%. After five extrusion cycles, their mechanical properties just encounter a subtle decline, indicating robust sustainability and cycle performance. The formation of a dynamic physical cross-linking network arises from the distinct polarity, hydrophobicity, and melt viscosity of rPET and rPE, where the hard spherical rPET phase is evenly dispersed in the soft rPE matrix with PMG acting as an interfacial compatibilizer. This innovative approach not only enhances the properties of the recycled composites but also promotes their cost-effectiveness and environmental benefits, thus broadening the potential applications of rPET and rPE as partial substitutes for virgin PET and PE.
Three-dimensional printed concrete (3DPC) is increasingly recognized in the construction industry for its high design flexibility and the elimination of conventional formwork. However, weak interlayer adhesion remains a significant challenge. The potential of recycled polyethylene terephthalate (PET) fibers for reinforcing 3DPC is being explored, driven by their environmental sustainability and economic advantages. However, there is an inadequate interfacial adhesion between these recycled fibers and the 3DPC matrix. This study investigated the use of dopamine modification to address this issue and enhance the interlayer adhesion of fiber-reinforced 3DPC. Recycled PET fibers were surface-modified using dopamine treatment, forming a polydopamine (PDA) film that improved surface roughness and hydrophilicity. Both unmodified and modified fibers were incorporated into 3DPC at various volume fractions (0.1%, 0.3%, 0.5%). The effects on interlayer adhesion strength, compressive strength, and flexural strength were systematically evaluated and compared. The results showed that the inclusion of 0.3 vol% dopamine-modified fibers resulted in a 22.5% increase in interlayer adhesion strength compared to the control group, and a 14.8% improvement over unmodified fibers at the same content. Additionally, the compressive strength and flexural strength of 3DPC with 0.3 vol% MPET fibers increased by 22.5% and 27.6%, respectively, compared to the control group. Microstructural analysis using SEM and XRD revealed that the dopamine modification significantly improved the interfacial adhesion between fibers and the concrete matrix, explaining the superior performance of modified fibers. This study demonstrates that recycled PET fibers modified with dopamine can effectively enhance the interlayer adhesion of 3DPC. The findings affirm that surface modification techniques can significantly elevate the utility of recycled PET fibers in 3DPC, contributing to the sustainable advancement of construction materials.
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