Purpose

This study aims to investigate the effect of the material thickness and build orientation on the mass transfer of low molecular weight substances through polyamide 12 (PA12) structures produced by laser sintering (LS).

Design/methodology/approach

Disc-shaped PA12 sheets having a nominal thickness ranging from 700 to 2,000 µm were built in horizontal, vertical and diagonal orientations and their permeation properties to oxygen and water vapor were measured. The structural properties of the sheets were examined by X-ray micro-computed tomography, differential scanning calorimetry and polarized light microscopy.

Findings

All the LS sheets that were investigated had water vapor and oxygen permeation coefficients that are in the range of those of PA12 produced by traditional manufacturing technologies. Despite significant differences in the porosity characteristics, the permeation properties of sheets built in different orientations were similar. The pores seem to have no measurable effect on the mass transfer rates in the sheets, and the transport processes seem to predominantly follow the rules of a regular solution-diffusion mechanism. The results showed a non-significant trend toward thickness-dependent permeation coefficients, which agrees with the observed differences in the crystal structures of the sheets.

Practical implications

The results are an important basis for the qualification of LS technology for direct manufacturing in applications requiring special barrier performance.

Originality/value

This study provides new information on mechanisms of mass transport through LS PA12 and the effect of the material thickness and build orientation. Furthermore, the results enhance understanding of the structural properties of thin polymeric sheets produced by LS.

中文翻译：

---

厚度和构建方向对激光烧结聚酰胺 12 片材水蒸气和氧气渗透性能的影响

目的

本研究旨在研究材料厚度和构建方向对低分子量物质通过激光烧结 (LS) 产生的聚酰胺 12 (PA12) 结构的传质的影响。

设计/方法/方法

标称厚度范围为 700 至 2,000 µm 的盘形 PA12 片材以水平、垂直和对角线方向构建，并测量了它们对氧气和水蒸气的渗透性能。通过X射线显微计算机断层扫描、差示扫描量热法和偏光显微镜检查片材的结构特性。

发现

所有被调查的 LS 板材的水蒸气和氧气渗透系数都在传统制造技术生产的 PA12 的范围内。尽管孔隙率特征存在显着差异，但以不同方向构建的片材的渗透特性相似。孔似乎对片中的传质速率没有可测量的影响，并且传输过程似乎主要遵循常规溶液扩散机制的规则。结果显示厚度依赖渗透系数的趋势不显着，这与观察到的片材晶体结构的差异一致。

实际影响

结果是 LS 技术在需要特殊阻隔性能的应用中直接制造的重要基础。

原创性/价值

这项研究提供了关于通过 LS PA12 的质量传输机制以及材料厚度和构建方向的影响的新信息。此外，结果增强了对 LS 生产的聚合物薄板结构特性的理解。