Research Background
With the rapid development of 3D printing technology, heterogeneous material 3D printing (DMP) is gradually becoming a popular choice for manufacturing complex functional components. However, the adhesion between materials has always been one of the key factors limiting its performance. Recently, researchers conducted an innovative study to explore the influencing factors of adhesion performance at the thermoplastic elastomer interface, providing new insights for enhancing the application potential of 3D printing technology.
Research Methodology
This study employed an improved double cantilever beam (DCB) testing method to evaluate the adhesion strength between the thermoplastic layer and the HTPB layer:
- Test Design: The study utilized various material combinations, including PLA, ABS, PVDF, and their mixtures with PCL, to test the adhesion performance of different material interfaces.
- Material Preparation: Different ratios of PCL/PVDF mixtures were prepared using an extrusion method to evaluate their adhesion characteristics in DMP. The printing and processing of all materials were strictly controlled to ensure consistency.
- Formula Application: The following formula was used to calculate the Mode I fracture toughness:
where P is the applied force, $B4$ is the displacement at the load point, a is the separation length, and b is the sample width. - Surface Roughness Assessment: Surface profile measurements were conducted on PVDF samples printed in different orientations (XY and XZ) to analyze the relationship between surface roughness ($R_a$) and adhesion strength.
Experimental Design
The details of the experimental design include:
- Sample Selection: PLA, ABS, PVDF, and their 5% and 10% PCL mixtures were selected as thermoplastic materials for DMP printing.
- Printing Parameters: The printing process for different materials used the same printing parameters to ensure comparability. During printing, the thickness and width of the PVDF layer were strictly controlled to meet design requirements.
- Data Collection: DCB tests were conducted on multiple samples of each material to collect fracture toughness data and failure modes to analyze the adhesion performance between materials.
- Surface Feature Analysis: A profilometer was used to scan the surfaces of the printed samples to obtain surface roughness data, which was then correlated with adhesion performance.
Results and Analysis
The experimental results indicate that the effects of different materials and surface roughness on adhesion performance are significant:
- Impact of Surface Roughness on Adhesion: The surface roughness ($R_a$) measurements of PVDF samples showed that the printing direction had a significant impact on surface features, but the differences between different materials were relatively small.
- Fracture Toughness Test Results: The DCB test results showed that the interface of the PVDF and PCL mixture exhibited higher adhesion strength under Mode I, particularly in the 10% PCL sample, where the fracture mode was primarily adhesive failure.
- Impact of Material Selection on Adhesion: The adhesion performance of PLA and ABS differed from that of PVDF, with the failure mode of the PLA-U sample showing stronger adhesion, indicating that material compatibility plays a crucial role in interfacial adhesion.
- Failure Mode Analysis: Analysis of the fracture surfaces revealed that the HTPB layer residue was significantly higher in PLA and 10% PCL samples compared to PVDF samples, indicating superior adhesion performance of the former.
Overall Conclusion
This study reveals the importance of material selection and surface roughness on adhesion behavior in DMP through the investigation of thermoplastic elastomer interface adhesion performance. The results indicate that the addition of PCL significantly improves the adhesion performance between PVDF and HTPB, providing important references for future applications in heterogeneous material 3D printing. Future research could further explore different material combinations and their effects on adhesion performance to advance DMP technology.
Source: https://doi.org/10.1038/s44334-025-00023-2