Optimizing Interfacial Shear Strength in Bamboo Fiber Composites Through Polydopamine Surface Modification
Topic(s) : Material science
Co-authors :
Carla Natali SCHNELL (LUXEMBOURG), Gregory MERTZ (LUXEMBOURG), Abdelghani LAACHACHI (LUXEMBOURG), David RUCH (LUXEMBOURG), Carlos FUENTES (LUXEMBOURG)Abstract :
Fiber Reinforced Polymer is widely recognized as the most employed composite, and recent attention in the field has shifted towards natural fiber composites. In this context, bamboo presents advantages as one of the fastest-growing renewable natural resources, with a growth cycle of 3–5 years. Bamboo fiber (BF) has garnered attention for its appealing attributes, including low density, high specific mechanical properties, and biodegradability [1]. However, the interfacial bonding of natural fibers with typical polymeric matrices used for composite is poor. An opportunity to enhance interfaces can be derived from environmentally friendly surface modification inspired by mussels [2].
In this study, BFs were subjected to chemical modification using dopamine (DA). DA can undergo oxidative self-polymerization in an alkaline solution, leading to the formation of an adhesive polydopamine (PDA) coating. The surface modification of fibers with PDA was conducted by combining BFs with 2.0 mg/mL DA in a 50 mmol tris buffer solution at room temperature. The impact of PDA deposition time (4h, 8h, and 24h) was investigated concerning the final chemical properties of the fibers and the Interfacial Shear Strength (IFSS) using two distinct polymer matrices (polypropylene (PP) and polylactic acid (PLA)). Furthermore, in the pursuit of minimizing PDA deposition times, polyethyleneimine (PEI) 2.0 mg/mL was introduced into the DA solution.
The morphology of the treated fibers surface was examined using Scanning Electron Microscopy (SEM). As depicted in Figure 1a-b, a uniformly coated fiber surface was observed when the fibers were subjected to treatment with PDA alone and when treated with a combination of PDA and PEI. To gain a more comprehensive understanding of the PDA or PDA-PEI treatment effects, fibers were further characterized through FTIR, TGA, NMR, contact angle measurements and, mechanical properties.
The IFSS fibers was assessed through the pull-out test method, measuring the resistance to shear force between the polymer matrix and an individual fiber. A fiber was embedded into the polymer matrix (Figure 2a). Subsequently, a pull-out test was conducted using a Textechno equipment. The findings indicate a higher IFSS for the untreated fiber with PLA (12.1 MPa) compared to PP (7.78 MPa). Moreover, the IFSS of fibers embedded in PP increases by 80% (14.3MPa) after a 24-hour treatment with PDA, compared to untreated fibers. This enhancement increase could be primarily attributed to the acquisition of a less polar fiber. In a separate instance, when fibers were treated only for 1 hour with PEI-DPA, the IFSS within the same matrix, exhibits a 30% increase (10.1 MPa). The addition of PEI serves a dual purpose: it regulates the aggregation mechanism of PDA and expedites its deposition onto the fiber.
The significance of this work lies in acquiring a stable solution with dopamine that can be efficiently applied in a controlled manner within a short timeframe.
In this study, BFs were subjected to chemical modification using dopamine (DA). DA can undergo oxidative self-polymerization in an alkaline solution, leading to the formation of an adhesive polydopamine (PDA) coating. The surface modification of fibers with PDA was conducted by combining BFs with 2.0 mg/mL DA in a 50 mmol tris buffer solution at room temperature. The impact of PDA deposition time (4h, 8h, and 24h) was investigated concerning the final chemical properties of the fibers and the Interfacial Shear Strength (IFSS) using two distinct polymer matrices (polypropylene (PP) and polylactic acid (PLA)). Furthermore, in the pursuit of minimizing PDA deposition times, polyethyleneimine (PEI) 2.0 mg/mL was introduced into the DA solution.
The morphology of the treated fibers surface was examined using Scanning Electron Microscopy (SEM). As depicted in Figure 1a-b, a uniformly coated fiber surface was observed when the fibers were subjected to treatment with PDA alone and when treated with a combination of PDA and PEI. To gain a more comprehensive understanding of the PDA or PDA-PEI treatment effects, fibers were further characterized through FTIR, TGA, NMR, contact angle measurements and, mechanical properties.
The IFSS fibers was assessed through the pull-out test method, measuring the resistance to shear force between the polymer matrix and an individual fiber. A fiber was embedded into the polymer matrix (Figure 2a). Subsequently, a pull-out test was conducted using a Textechno equipment. The findings indicate a higher IFSS for the untreated fiber with PLA (12.1 MPa) compared to PP (7.78 MPa). Moreover, the IFSS of fibers embedded in PP increases by 80% (14.3MPa) after a 24-hour treatment with PDA, compared to untreated fibers. This enhancement increase could be primarily attributed to the acquisition of a less polar fiber. In a separate instance, when fibers were treated only for 1 hour with PEI-DPA, the IFSS within the same matrix, exhibits a 30% increase (10.1 MPa). The addition of PEI serves a dual purpose: it regulates the aggregation mechanism of PDA and expedites its deposition onto the fiber.
The significance of this work lies in acquiring a stable solution with dopamine that can be efficiently applied in a controlled manner within a short timeframe.