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<p>4D printing is characterized by the combination of additive manufacturing techniques with the controllable modification of the shape of an object under external stimulus. This emerging field has demonstrated potential across various knowledge domains, paving new pathways for the development of adaptable smart structures activated through a contactless method. Nonetheless, a limited range of materials has been explored in this scenario, especially when associated with the fused&#xa0;filament fabrication technique. In this work, filaments of polylactic acid/poly(ethylene-co-vinyl acetate) (PLA/EVA) blends were prepared and their feasibility for 4D printing was investigated for the first time. Six formulations were analyzed, considering three mass fractions between the components and two different vinyl acetate contents within EVA. The generated filaments were characterized through thermogravimetry and differential scanning calorimetry. Calibration parts were 3D-printed with varying speeds and nozzle temperatures to assess the printability of each blend and determine an ideal processing window. Standardized specimens were manufactured for dynamic mechanical analysis and tensile tests. Finally, the shape memory behavior was quantified under thermal stimulus. The most promising formulation adopted miscible polymers at the weight ratio of 70/30, exhibiting tensile strength around 64&#xa0;MPa. Furthermore, it also presented the highest shape recovery ratios in the first iteration (86.8%) and throughout five cycles, stabilizing the restored format after remaining 90&#xa0;s under heated water. These outcomes suggest that such a blend is a strong candidate for potential functional 4D&#xa0;printing applications, especially in regards to the development of wearable assistive devices capable of adapting to different anatomical shapes.</p>

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Formulation and characterization of thermo-responsive blends for 4D printing

  • 期刊论文

  • 发表日期：

    2025年3月28日

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  • Alina de Souza Leão Rodrigues,
  • Marcelo Aparecido Chinelatto,
  • Anne Cristine Chinellato,
  • Zilda de Castro Silveira

摘要

4D printing is characterized by the combination of additive manufacturing techniques with the controllable modification of the shape of an object under external stimulus. This emerging field has demonstrated potential across various knowledge domains, paving new pathways for the development of adaptable smart structures activated through a contactless method. Nonetheless, a limited range of materials has been explored in this scenario, especially when associated with the fused filament fabrication technique. In this work, filaments of polylactic acid/poly(ethylene-co-vinyl acetate) (PLA/EVA) blends were prepared and their feasibility for 4D printing was investigated for the first time. Six formulations were analyzed, considering three mass fractions between the components and two different vinyl acetate contents within EVA. The generated filaments were characterized through thermogravimetry and differential scanning calorimetry. Calibration parts were 3D-printed with varying speeds and nozzle temperatures to assess the printability of each blend and determine an ideal processing window. Standardized specimens were manufactured for dynamic mechanical analysis and tensile tests. Finally, the shape memory behavior was quantified under thermal stimulus. The most promising formulation adopted miscible polymers at the weight ratio of 70/30, exhibiting tensile strength around 64 MPa. Furthermore, it also presented the highest shape recovery ratios in the first iteration (86.8%) and throughout five cycles, stabilizing the restored format after remaining 90 s under heated water. These outcomes suggest that such a blend is a strong candidate for potential functional 4D printing applications, especially in regards to the development of wearable assistive devices capable of adapting to different anatomical shapes.