How hydrogen bonds influence the slow crack growth resistance of polyamide 12

Messiha, Mario; Frank, Andreas; Arbeiter, Florian; Pinter, Gerald

doi:10.1016/j.polymer.2021.124437

Cited by 7 publications

(7 citation statements)

References 30 publications

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“…This ability to resist autoclaving should be associated with the establishment of the noncovalent secondary interactions (hydrogen bonds) between the PVA and PBO chains. A similar phenomenon is known in nylon (polyamide), [ 97,98 ] where the presence of secondary hydrogen bonds between the amide groups of the molecular chains is responsible for the higher chemical, mechanical and thermal resistance of the material. Regarding FTIR, the spectra revealed minor variations in the intensity of the peaks corresponding to the PVA segments (see Section 2.2) in 6P1Z_AUT (Figure S3a, Supporting Information).…”

Section: Resultsmentioning

confidence: 59%

Super‐Strong Hydrogel Composites Reinforced with PBO Nanofibers for Cartilage Replacement

Oliveira

Silva

Loureiro

et al. 2022

Macromolecular Bioscience

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Cartilage replacement materials exhibiting a set of demanding properties such as high water content, high mechanical stiffness, low friction, and excellent biocompatibility are quite difficult to achieve. Here, poly(p‐phenylene‐2,6‐benzobisoxazole) (PBO) nanofibers are combined with polyvinyl alcohol (PVA) to form a super‐strong structure with a performance that surpasses the vast majority of previously existing hydrogels. PVA–PBO composites with water contents in the 59–76% range exhibit tensile and compressive moduli reaching 20.3 and 4.5 MPa, respectively, and a coefficient of friction below 0.08. Further, they are biocompatible and support the viability of chondrocytes for 1 week, with significant improvements in cell adhesion, proliferation, and differentiation compared to PVA. The new composites can be safely sterilized by steam heat or gamma radiation without compromising their integrity and overall performance. In addition, they show potential to be used as local delivery platforms for anti‐inflammatory drugs. These attractive features make PVA–PBO composites highly competitive engineered materials with remarkable potential for use in the design of load‐bearing tissues. Complementary work has also revealed that these composites will be interesting alternatives in other industrial fields where high thermal and mechanical resistance are essential requirements, or which can take advantage of the pH responsiveness functionality.

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Section: Resultsmentioning

confidence: 59%

Super‐Strong Hydrogel Composites Reinforced with PBO Nanofibers for Cartilage Replacement

Oliveira

Silva

Loureiro

et al. 2022

Macromolecular Bioscience

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“…Subsequently, a cycle of reformation and rupture of H-bonds due to continuing plastic deformation occurs until the sample fails. The excess work done to overcome the constraints on molecular motion imposed by, and the repeated deformation of the dynamically cross-linking H-bonds results in the observed increase in toughness. − Strain hardening response ( E H ) associated with the dynamical reformation of H-bonds during the plastic deformation process is expected to increase σ f . It is important to realize that failure strength would increase even with little to no improvement in strain hardening due to H-bonding, because of the previously observed monotonic increase in yield strength; the intrinsic strain hardening mechanisms of the polymer will ensure an increase in failure strength (beyond yield stress, i.e., σ f ≥ σ y for E H ≥ 0) as long as the fibers are not brittle.…”

Section: Resultsmentioning

confidence: 99%

Influence of Size and H-bonding on the Elasto-Plastic Mechanical Behavior of PVP–TA Nanofibers

Gaikwad,

Kolluru

2024

ACS Appl. Polym. Mater.

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Developing advanced structural polymers with simultaneously high strength and toughness remains a significant materials design challenge. Two strategies that have been used in different polymers to address this challenge are dynamically cross-linking polymer chains through hydrogen bonds (H-bonds) and reducing the dimensions of polymeric structures to submicron length scales (i.e., size effects). The current study aims to understand the direct role of relatively weak H-bonds in improving the elasto-plastic mechanical properties of the much stronger glassy state polymers, which remains unclear in the existing literature. At the same time, the potential to combine H-bonding and size effects to synergistically achieve greater improvements in strength and toughness will be studied in this work. To this goal the large deformation elasto-plastic deformation response of single poly(vinylpyrrolidone)–tannic acid (PVP–TA) nanofibers of varying fiber diameters and TA concentrations (i.e., H-bonding) were characterized through submicron-scale tensile experiments. The results indicated that H-bonding was capable of directly and significantly improving the mechanical behavior of glassy PVP. H-bonding and size effects were found to affect the elastic and plastic properties differently. While these two effects were synergistic in the elastic regime, their interaction was more complex in the plastic deformation regime in general and for the thinnest fibers in particular. These observations provide useful insights into the design of improved H-bonded polymers for small-scale multifunctional applications.

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“…Failure strain ( ε f ) increases as the H‐bond induced crosslinking sites create load‐bearing segments between them, even as the segments between physical crosslinks are broken. [ 43 ] Increases in E H and ε f lead to increased failure strength ( σ f ), while the additional energy dissipated during the post‐yield regime to constantly disrupt the dynamically reforming H‐bonds should manifest as increased toughness ( U T ). This is indeed observed from Figure 4a–d, wherein, E H , σ f , ε f , and U T increase up to 10 wt.% of TA.…”

Section: Resultsmentioning

confidence: 99%

H‐Bonded Amorphous Polymer Glass Nanofibers with Simultaneously Large Enhancement in Strength, Toughness, Ductility, and Thermal Stability

Gaikwad,

Kolluru

2023

Macro Materials & Eng

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Understanding the direct effects of hydrogen bonding (H‐bonding) on the mechanical response of glassy state polymers remains a challenge, largely owing to the use of semicrystalline polymers in such studies, wherein, separating the contributions due to the changes in degree of crystallinity and direct H‐bonding effects on the observed mechanical properties is extremely difficult. This limitation is overcome by studying the mechanical behavior of amorphous, glassy polyvinylpyrrolidone (PVP), H‐bonded with tannic acid (TA). Uniaxial tension experiments on individual submicron scale PVP fibers (0.6–1.0 µm diameters) with different TA concentrations are conducted to capture their elasto‐plastic deformation characteristics. Amorphous PVP‐TA complexes exhibited some distinctive trends in elasto‐plastic properties with increasing H‐bond density, which are not observed earlier. These distinctive trends are discussed in terms of the competing effects of H‐bond driven crosslinking and TA‐induced reduction in entanglement density, and their differing roles during elastic and plastic deformation. The improvements in elasto‐plastic properties (particularly ductility and toughness) are simultaneously accompanied by uniquely significant thermal stability (i.e., glass transition temperature, Tg) improvements, that can help improve the practical applicability, operational life, and performance of these materials.

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How hydrogen bonds influence the slow crack growth resistance of polyamide 12

Cited by 7 publications

References 30 publications

Super‐Strong Hydrogel Composites Reinforced with PBO Nanofibers for Cartilage Replacement

Super‐Strong Hydrogel Composites Reinforced with PBO Nanofibers for Cartilage Replacement

Influence of Size and H-bonding on the Elasto-Plastic Mechanical Behavior of PVP–TA Nanofibers

H‐Bonded Amorphous Polymer Glass Nanofibers with Simultaneously Large Enhancement in Strength, Toughness, Ductility, and Thermal Stability

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