Extrinsic and Intrinsic Approaches to Self-Healing Polymers and Polymer Composites. Ming Qiu Zhang

2.29 (a) Typical load–displacement curves recorded during indentation...Figure 2.30 (a) Sealed PP tubes containing the mixture of epoxy monomer DTHP...Figure 2.31 Typical fluorescence microscopy images (using an Axio Oberver Z1...Figure 2.32 Effect of (a) tube spacing and (b) foaming agent content on flex...Figure 2.33 Photos of the back surface of the composite laminates with the h...Figure 2.34 Fluorescent microscopy photos of the back face of the composite ...Figure 2.35 (a) Effect of healing time on flexural strength and healing effi...Figure 2.36 Through‐scan mode ultrasonic images of the indentation damaged c...Figure 2.37 Effect of room temperature storage time on flexural strength and...

      3 Chapter 3Scheme 3.1 Curing of epoxy in the presence of (C₂H₅)₂O·BF₃.Figure 3.1 Design of the self‐healing PS.Scheme 3.2 Molecular structures of epoxy resins (EPON 828 and DTP), polymeri...Figure 3.2 Scanning electron microscopy photos of DTP‐loaded microcapsules [...Figure 3.3 Fourier transform infrared spectra of EPON 828, EPON 828‐loaded m...Figure 3.4 Scanning electron microscopy photos of DTP‐containing microcapsul...Figure 3.5 Size distribution of DTP‐containing microcapsules. Preparation co...Figure 3.6 Influence of different levels of the five factors (see Table 3.1)...Figure 3.7 Ultraviolet irradiation time dependence of microcapsule yield ini...Scheme 3.3 Photodecomposition of the initiators.Figure 3.8 Schematic drawing of (a) cross‐section of a piece of sisal leaf, ...Figure 3.9 Infiltration time dependence of the loading of (C₂H₅)₂O·BF₃ on di...Figure 3.10 Morphologies of (a) as‐received carbon black, (b) (C₂H₅)₂O·BF₃‐l...Figure 3.11 Schematic drawing of the proposed route for preparing hollow mic...Figure 3.12 Scanning electron microscopy micrographs of (a) hollow microcaps...Figure 3.13 Yields of hollow microcapsules as a function of UV irradiation t...Figure 3.14 Fourier transform infrared spectra of hollow microcapsules.Figure 3.15 Loading rate of (C₂H₅)₂O·BF₃ in hollow microcapsules as a functi...Figure 3.16 In‐situ FTIR spectra tracking the reaction between epoxy and gro...Figure 3.17 (a, b) Dependences of healing efficiency of the self‐healing epo...Figure 3.18 Influence of content of the healing agent on mechanical properti...Figure 3.19 (a) Scanning electron microscopy image in conjunction with (b) E...Figure 3.20 Time dependence of healing efficiency of the self‐healing epoxy ...Figure 3.21 (a, b) Dependence of healing efficiency of the self‐healing epox...Figure 3.22 Dependences of impact strength of healed self‐healing epoxy comp...Figure 3.23 Dependence of healing efficiency of the self‐healing epoxy compo...Figure 3.24 Scanning electron microscopy micrographs of fractured surfaces o...Figure 3.25 Influence of content of (C₂H₅)₂O·BF₃‐loaded capsules on (a) tens...Figure 3.26 (a) Micrograph of hollow silica walled microcapsules, (b) high m...Figure 3.27 Time dependence of temperature of epoxy cured by ethanol solutio...Scheme 3.4 Mechanism of the reaction between SbF₅·HOC₂H₅ and epoxy.Figure 3.28 (a) Infrared absorption of epoxide groups as a function of time ...Figure 3.29 (a) Scanning electron microscopy image of the impact fracture su...Figure 3.30 Healing efficiency versus healing time of self‐healing specimens...Figure 3.31 (a) Crack length versus fatigue cycle of (1) neat epoxy, (2) con...Figure 3.32 Effect of storage time in ambient air on healing efficiency of t...Figure 3.33 Temperature of crack tip of self‐healing specimen as a function ...Scheme 3.5 The reaction mechanism involved in TfOH‐epoxy cure.Figure 3.34 (a) Time dependence of temperature of epoxy cured by different d...Figure 3.35 Temperature dependence of tan δ of (a) unfilled epoxy and (...Figure 3.36 Healing efficiency versus room temperature healing time of self‐...Figure 3.37 (a) Crack length versus fatigue cycle of (1) neat epoxy, (2) con...Figure 3.38 Dependence of fatigue life extension on time of storage in ambie...Figure 3.39 Influence of thermal exposure of self‐healing epoxy composite sp...Figure 3.40 (a) Time‐dependent rheological behaviors of IBH/NaBH₄/GMA mixtur...Scheme 3.6 Redox cationic polymerization of GMA.Figure 3.41 (a) Dependence of healing efficiency of PS on content of pre‐emb...Figure 3.42 (a) Fourier transform infrared spectra of GMA, IBH, PMF, and IBH...Figure 3.43 Dependences of impact strength and healing efficiency of authent...Figure 3.44 (a) Scanning electron microscopy micrograph of the fracture surf...

      4 Chapter 4Scheme 4.1 Structural scheme of the latent curing agent CuBr₂(2‐MeIm)₄.Figure 4.1 Schematic drawing of the principle of self‐healing epoxy material...Figure 4.2 Scanning electronic microscopy (SEM) micrograph of urea‐formaldeh...Figure 4.3 FTIR spectra of bisphenol‐A epoxy, urea‐formaldehyde encapsulated...Figure 4.4 Pyrolytic behaviors of bisphenol‐A epoxy, urea‐formaldehyde encap...Figure 4.5 FTIR spectra of 2‐MeIm and CuBr₂(2‐MeIm)₄.Scheme 4.2 Mechanism of the curing reaction between epoxy resin and the comp...Figure 4.6 Temperature dependence of conversion of curing reaction of epoxy ...Figure 4.7 Influence of the content of epoxy‐loaded microcapsules on the ten...Figure 4.8 Influence of (a) content of latent hardener and (b) content of ep...Figure 4.9 SEM micrographs of cured CuBr₂(2‐MeIm)₄‐epoxy system. Content of ...Figure 4.10 Influence of (a) content of latent hardener and (b) content of e...Figure 4.11 SEM micrographs of the fractured surfaces of the self‐healing ep...Figure 4.12 Schematic drawing of (a) the cross‐section of the laminates and ...Figure 4.13 Typical tensile stress–strain curves of the laminates with diffe...Figure 4.14 Typical load (P)–crack opening displacement (δ) curves of t...Figure 4.15 SEM micrographs of (a, b) the fractured surfaces of the self‐hea...Figure 4.16 Interlaminar fracture toughness of the laminates, G_IC, as a func...Figure 4.17 FTIR spectra of the fractured surface of (1) the laminates witho...Figure 4.18 Time dependence of weight of epoxy‐loaded microcapsules measured...Figure 4.19 Temperature dependence of storage modulus, E', and loss fact...Figure 4.20 Time dependence of storage modulus, E', of (a) unfilled epox...Figure 4.21 SEM micrographs of the fractured surfaces of the laminates conta...Figure 4.22 Flowchart of the damage healing procedures and CAI tests.Figure 4.23 Photographs showing the impact damage zones on the woven glass f...Figure 4.24 (a) Residual compressive strength and (b) normalized residual co...Figure 4.25 Influence of impact strength on residual compressive strength of...Figure 4.26 Influence of impact energy on the healing efficiency of CAI spec...Figure 4.27 T‐scan ultrasonic images of the impacted repairable composite la...Figure 4.28 SEM side views of (a) indented composite laminates and (b) inden...Figure 4.29 Influence of lateral pressure on σ^Healed of the composite l...Figure 4.30 Photographs of (a, b) composite laminates that were impacted at ...Figure 4.31 Influence of size of the microcapsules containing epoxy on heali...

      5 Chapter 5Scheme 5.1 Chemical structure of GMA.Figure 5.1 Optical microscopic images of GMA‐loaded microcapsules prepared a...Figure 5.2 FTIR spectrum of PMF‐walled microcapsules containing GMA in compa...Figure 5.3 DSC heating traces of GMA/DETA and ground GMA‐loaded microcapsule...Figure 5.4 Thermogravimetric analysis (TGA) and differential thermogravimetr...Figure 5.5 Typical load–displacement curves recorded during TDCB tests. The ...Figure 5.6 FTIR spectra of epoxy resins cured at different DETA/epoxy ratios...Figure 5.7 Effect of content of GMA‐loaded microcapsules on healing efficien...Scheme 5.2 Schematic drawing of crack healing in epoxy composite containing ...Figure 5.8 Effect of healing temperature on healing efficiency at a constant...Figure 5.9 SEM micrographs of the fractured surface of (a) virgin self‐heali...Scheme 5.3 Schematic drawing of crack healing in epoxy composite containing ...Figure 5.10 Time dependences of healing efficiency in comparison with that o...Figure 5.11 Effect of DETA to epoxy ratio on molecular weight between cross‐...Scheme 5.4 Schematic drawing of crack repair by living copolymerization of G...Figure 5.12 Profile of a multilayered microcapsule.Scheme 5.5 Mechanism for ATRP.Figure 5.13 ¹H‐NMR spectrum of resultant PMMA‐Br initiated with 2‐EBiB/CuBr/...Figure 5.14 Characteristics of living polymerization of MMA. (a) ln([M]₀/[M]...Figure 5.15 (a) GPC curves of PMMA before and after chain extension reaction...Figure 5.16 (a) Healing efficiency of PMMA composites containing 15 wt% GMA‐...Figure 5.17 SEM micrographs of fractured surfaces of PMMA composites contain...Figure 5.18 In‐situ confocal Raman microscopy observation [25]. (a) The typi...Figure 5.19 Healing effect of PMMA composites with styrene‐ and styrene/epox...Figure 5.20 Schematic drawing of the route for preparing the multilayered mi...Figure 5.21 3D distribution of the GMA‐loaded multilayered microcapsules in ...Figure 5.22 Time dependence of healing efficiency of the thermally molded se...Figure 5.23 Healing efficiencies of the thermally molded self‐healing PS com...Figure