Recently, we proposed a novel strategy for fabricating high-performance stereocomplex-type polylactide (SC-PLA) products through low-temperature (180–210 °C, lower than the melting temperature of SC crystallites) sintering from its nascent powder, without serious thermal degradation involved in the conventional melt processing at higher temperatures. During the sintering, some poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) chains from adjacent powdery particles can interdiffuse across the interfaces and subsequently co-crystallize into new SC crystallites capable of welding the interfaces. The interfacial strength is dominated by the content of the newly-formed SC crystallites, however, the fast cocrystallization of PLLA/PDLA chains could hinder their sufficient interdiffusion at the interfaces and thus only limited interface-localized SC crystallites could be formed. In this work, we attempt to substantially promote the chain interdiffusion via depressing the cocrystallization rate. To do this, SC-PLA nascent powders with different optical purities of the lactate units were prepared, and the role of optical purity in directing the chain interdiffusion and cocrystallization has been investigated. Very interestingly, we demonstrate that decreasing optical purity (from 99.5 to 96%) is favorable for the formation of numerous SC crystallites at the interfaces because the lowering of cocrystallization rate enables more PLLA/PDLA chains to interdiffuse sufficiently before their cocrystallization. As a result, SC-PLA products with superior heat resistance have been fabricated by the sintering of low-optical-purity SC-PLA powder. These fascinating findings could not only provide new understanding on the low-temperature sintering mechanism of SC-PLA powders but also greatly expand the possibilities for the fabrication of SC-PLA products with superb properties.

最近，我们提出了一种通过从新生粉末中进行低温烧结（180-210°C，低于SC微晶的熔化温度）来制造高性能立体复合型聚丙交酯（SC-PLA）产品的新策略，而无需严重烧结在较高温度下常规熔体加工中涉及的热降解。在烧结过程中，一些聚（l-丙交酯）（PLLA）和聚（d相邻粉末状颗粒的-Lactide（PDLA）链可以在界面上相互扩散，随后共结晶为能够焊接界面的新SC微晶。界面强度主要由新形成的SC微晶的含量决定，但是，PLLA / PDLA链的快速共结晶可能会阻碍它们在界面上的充分相互扩散，因此只能形成有限的界面局部SC微晶。在这项工作中，我们试图通过降低共结晶速率来促进链间相互扩散。为此，制备了具有不同光学纯度的乳酸单元的SC-PLA新生粉末，并研究了光学纯度在指导链相互扩散和共结晶中的作用。非常有趣的是 我们证明降低光学纯度（从99.5％到96％）有利于在界面处形成大量SC微晶，因为降低共结晶速率可使更多的PLLA / PDLA链在共结晶之前充分相互扩散。结果，通过烧结低光学纯度的SC-PLA粉末，制造了具有优异耐热性的SC-PLA产品。这些令人着迷的发现不仅可以为SC-PLA粉末的低温烧结机理提供新的认识，而且可以极大地扩展制造具有卓越性能的SC-PLA产品的可能性。5％至96％）有利于在界面处形成许多SC微晶，因为共结晶速率的降低使得更多的PLLA / PDLA链在它们的共结晶之前能够充分地相互扩散。结果，通过烧结低光学纯度的SC-PLA粉末，制造了具有优异耐热性的SC-PLA产品。这些令人着迷的发现不仅可以为SC-PLA粉末的低温烧结机理提供新的认识，而且可以极大地扩展制造具有卓越性能的SC-PLA产品的可能性。5％至96％）有利于在界面处形成许多SC微晶，因为共结晶速率的降低使得更多的PLLA / PDLA链在它们的共结晶之前能够充分地相互扩散。结果，通过烧结低光学纯度的SC-PLA粉末，制造了具有优异耐热性的SC-PLA产品。这些令人着迷的发现不仅可以为SC-PLA粉末的低温烧结机理提供新的认识，而且可以极大地扩展制造具有卓越性能的SC-PLA产品的可能性。