Tammaro Daniele, Villone Massimiliano Maria, Maffettone Pier Luca
Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, University of Naples Federico II, P.le Tecchio 80, I-80125 Napoli, Italy.
Polymers (Basel). 2022 Aug 7;14(15):3214. doi: 10.3390/polym14153214.
We report the design, production, and characterization of microfoamed strands by means of a green and sustainable technology that makes use of CO to create ad-hoc innovative bubble morphologies. 3D foam-printing technology has been recently developed; thus, the foaming mechanism in the printer nozzle is not yet fully understood and controlled. We study the effects of the operating parameters of the 3D foam-printing process to control and optimize CO utilization through a maximization of the foaming efficiency. The strands' mechanical properties were measured as a function of the foam density and explained by means of an innovative model that takes into consideration the polymer's crystallinity content. The innovative microfoamed morphologies were produced using a bio-based and compostable polymer as well as polylactic acid and were then blown with CO. The results of the extensive experimental campaigns show insightful maps of the bubble size, density, and crystallinity as a function of the process parameters, i.e., the CO concentration and temperature. A CO content of 15 wt% enables the acquirement of an incredibly low foam density of 40 kg/m and porosities from the macro-scale (100-900 μm) to the micro-scale (1-10 μm), depending on the temperature. The foam crystallinity content varied from 5% (using a low concentration of CO) to 45% (using a high concentration of CO). Indeed, we determined that the crystallinity content changes linearly with the CO concentration. In turn, the foamed strand's elastic modulus is strongly affected by the crystallinity content. Hence, a corrected Egli's equation was proposed to fit the strand mechanical properties as a function of foam density.
我们报告了通过一种绿色可持续技术设计、生产和表征微发泡股线的过程，该技术利用二氧化碳创造特定的创新气泡形态。三维泡沫打印技术最近已得到发展；因此，打印机喷嘴中的发泡机制尚未得到充分理解和控制。我们研究了三维泡沫打印过程操作参数的影响，通过最大化发泡效率来控制和优化二氧化碳的利用。测量了股线的力学性能作为泡沫密度的函数，并通过一个考虑聚合物结晶度含量的创新模型进行解释。使用生物基可堆肥聚合物以及聚乳酸制备了创新的微发泡形态，然后用二氧化碳进行发泡。大量实验活动的结果显示了气泡尺寸、密度和结晶度随工艺参数（即二氧化碳浓度和温度）变化的有洞察力的图谱。15重量%的二氧化碳含量能够获得低至40千克/立方米的令人难以置信的低泡沫密度，以及从宏观尺度（100 - 900微米）到微观尺度（1 - 10微米）的孔隙率，这取决于温度。泡沫的结晶度含量从5%（使用低浓度二氧化碳）变化到45%（使用高浓度二氧化碳）。实际上，我们确定结晶度含量随二氧化碳浓度呈线性变化。相应地，发泡股线的弹性模量受到结晶度含量的强烈影响。因此，提出了一个修正的埃格利方程来拟合股线力学性能作为泡沫密度的函数。
