Low-Temperature Sintering of Stereocomplex-Type Polylactide Nascent Powder: From Compression Molding to Injection Molding
Low-Temperature Sintering of Stereocomplex-Type Polylactide Nascent Powder: From Compression Molding to Injection Molding
复制标题
立体络合物型聚丙交酯初生粉末的低温烧结：从压缩成型到注射成型
DOI：
10.1002/mame.201800178
复制
发表时间：
2018
影响因子：
3.9
通讯作者：
Fu Qiang
中科院分区：
文献类型：
--
作者：
Fu Meirui;Liu Zhenwei;Bai Dongyu;Ling Fangwei;Bai Hongwei;Zhang Qin;Fu Qiang
聚L-丙交酯(PLLA)和聚D-丙交酯(PDLA)之间的立体复合体(SC)结晶在改善聚乳酸(PLA)性能方面具有巨大的潜力，但SC-PLA的实际加工受到熔体稳定性不足和SC晶体在240℃以上完全熔融后严重降解的严重阻碍。在以前的工作中，提出了利用粉末冶金原理低温(180-210℃)压缩烧结来制备SC-PLA产品。然而，它的工业应用仍然具有挑战性，主要原因是生产效率低(需要半个小时)以及制造复杂形状产品的能力较弱。本文报道了一种利用低温注射成型技术快速制备复杂形状SC-聚乳酸制品的方法，其中SC-聚乳酸初生粉部分熔融。为确保适当的粉末流动性，加入少量单甘酯作为润滑剂。结果表明，自成核和流动诱导成核都促进了Sc在相邻未熔化粉末颗粒之间的晶化，从而使烧结周期缩短到约2min。通过这种方法，首次通过注射成型成功地制造出了性能优良的复杂形状的SC-解放军产品(如齿轮)。
Stereocomplex (SC) crystallization between poly(l‐lactide) (PLLA) and poly(d‐lactide) (PDLA) exhibits tremendous potential to improve the properties of polylactide (PLA), but the practical processing of SC‐type PLA (SC‐PLA) is significantly hindered by the insufficient melt stability and serious degradation after complete melting of SC crystallites over 240 °C. In a previous work, powder metallurgy inspired low‐temperature (180–210 °C) compression sintering is proposed to fabricate SC‐PLA products from its nascent powder. However, its industrial application is still challenging mainly due to the low production efficiency (half an hour is required) as well as the weak ability to fabricate products with complex shapes. In this work, an effort to rapidly fabricate complex‐shaped SC‐PLA products using low‐temperature injection molding technology is reported, where SC‐PLA nascent powder is partially melted. To ensure appropriate powder flowability, small amounts of glyceryl monostearate are incorporated as a lubricant. The results show that, both the self‐nucleation and flow‐induced nucleation effects facilitate the SC crystallization across the interfaces between adjacent unmelted powder particles, which considerably shortens the sintering cycle to about 2 min. In this way, complex‐shaped SC‐PLA products (such as gears) with superb performance are successfully fabricated by injection molding for the first time.