Although conventional methods such as mechanical fastening, adhesive bonding and hot air welding have proven effective in dry conditions, they exhibit diminished efficacy in submerged environments. Hence, a thermoplastic welding technique with minimal dependence on surrounding media is essential. Ultrasonic spot welding (USW) represents a promising approach to thermoplastic joining, offering high efficiency and low operating costs. In this study, we investigate the efficacy of water-submerged ultrasonic spot welding (S-USW) for joining amorphous polyvinyl chloride (PVC) to PVC and semi-crystalline polypropylene (PP) to PP under submerged conditions. Our experimental results show that S-USW leads to a remarkable 39% and 21% increase in lap-shear strength for PVC/PVC and PP/PP welds, respectively, as compared to traditional USW techniques. We corroborate these findings with additional metrics such as Shore-D hardness tests, optical microscopy and scanning electron microscopy imagery, which collectively confirm the improved efficacy of S-USW over USW for joining PVC and PP.

中文翻译：

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热塑性塑料浸没式超声波点焊可行性实验研究

尽管机械紧固、粘合剂粘合和热风焊接等传统方法已被证明在干燥条件下有效，但它们在水下环境中的功效会减弱。因此，对周围介质依赖性最小的热塑性焊接技术至关重要。超声波点焊 (USW) 是一种很有前途的热塑性连接方法，具有高效率和低运营成本。在本研究中，我们研究了水浸式超声波点焊 (S-USW) 在水下条件下将非晶聚氯乙烯 (PVC) 连接到 PVC 以及将半结晶聚丙烯 (PP) 连接到 PP 的效果。我们的实验结果表明，与传统 USW 技术相比，S-USW 使 PVC/PVC 和 PP/PP 焊缝的搭接剪切强度分别显着提高 39% 和 21%。我们通过肖氏 D 硬度测试、光学显微镜和扫描电子显微镜图像等其他指标证实了这些发现，这些指标共同证实了 S-USW 在连接 PVC 和 PP 方面比 USW 具有更高的功效。