Study on the healing performance of poly(ε‐caprolactone) filled ultraviolet‐curable 3D printed cyclic trimethylolpropane formal acrylate shape memory polymers

Abstract

The research and application of ultraviolet‐curable 3D printed shape memory polymers have been focused on artificial intelligence, bionic engineering, and medical devices, and so forth. However, this photopolymer has the disadvantages of low toughness and easy to be damaged. As a healing agent and toughening agent, the thermoplastic polymer polycaprolactone (PCL) is used to improve the utility value of 3D printed cyclic trimethylolpropane formal acrylate (CTFA) shape memory composites. The filling content of PCL is evaluated through multiscale observation, mechanical test, thermal analysis and comparison before and after healing. PCL with 5% filling content not only improves the flexibility and scratch healing ability of 3D printed samples, but also maintains the shape memory characteristics of the samples. The blending structure constructed by PCL and CTFA polymers plays an important role in balancing the various properties of the 3D printed composites.

Investigating the Structure–Property−Processing Relationship of Polycaprolactone-Based 3D Printed Self-Healing Polymer Blends

“…For the latter, Zhang et al incorporated PCL into BMA/PEGDMA at 3:1 ratio and observed a reduction in mechanical strength while increasing its ductility. Wen et al observed similar behavior when PCL was blended into CTFA/TPO. In both of these cases, the matrix material had greater tensile strength but was more brittle, as compared to PCL (for example, BMA/PEGDMA had a tensile strength of approximately 30 MPa and a strain at break of 10% and CTFA with TPO had a tensile strength of approximately 40 MPa and a strain at break of 10%).…”

“…Although this is different than the testing method we employed, it is comparable as both these test methods evaluate the adhesion strength of PCL upon healing. Wen et al 10 found that their vat-polymerized CTFA and TPO blended with PCL exhibited self-healing starting at 5 wt % PCL but were unable to produce good prints at 20 wt % PCL. Self-healing was determined based on cut tests and visual examination.…”

“…This system exhibited near-complete restoration of properties beginning at a PCL concentration of 20 wt % for lap-shear specimens. Wen et al 10 presented another 3D-printed PCL-based self-healing polymer blend based on cyclic trimethylolpropane formal acrylate (CTFA) and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) processed using an LCD 3D printer. At 20 wt % PCL, this material cracked and broke upon printing.…”

“…The focus of this study will be on an extrinsically self-healing polymer system. One extrinsic self-healing approach involves the introduction of a low melting temperature thermoplastic healing agent, that when heated, diffuses into cracks and defects to facilitate healing. − This strategy has been employed for thermoplastic polymer blends, as well as thermoplastic/thermoset polymer blends. Poly­(ε-caprolactone) (PCL) is commonly used as a healing agent due to its favorable mechanical properties and relatively low melting temperature (∼60 °C).…”

Influence of gamma irradiation on acrylate‐based shape memory polymers in the presence of various crosslinkers

“…Acrylate polymers demonstrate a model system for assessing SMPs' strain tolerance and have a variety of potential uses. Little compositional modifications have a considerable impact on mechanical properties when copolymerizing different acrylate monomers, including elastic modulus, strain‐to‐failure, T g , brittleness at ambient temperatures, and rate of deformation in the rubbery rule 20,17,21,22 . Its high glass transition temperature of 94°C for poly(isobornyl acrylate), or P(IBoA), and 19.6 kg/mm 2 of hardness at 20°C 23 are only two of its unique physical properties.…”