From a technological point of view, poly(lactic acid) (PLA) is one of the most important polymers produced from renewable sources, due to its versatility, relatively acceptable processability, and low cost. However, a significant limitation exists in its slow crystallization kinetics, which results in amorphous products having low mechanical properties and thermal resistance. For this reason, quantitative knowledge of the phenomenon of crystallization kinetics is fundamental. In this work, the crystallization kinetics in quiescent conditions of a commercial grade of PLA was analyzed in terms of nucleation and growth rates by direct morphological observations at different crystallization temperatures (T_c) and by calorimetric analysis in isothermal and non‐isothermal conditions. The optical analysis showed a spherulitic morphology with radial growth of the lamellae. The analysis of the growth rate evidenced the α/α'‐crystals polymorphism with a transition temperature of ~120°C. Based on experimental observation, the crystallization kinetics of the two crystalline phases were assessed.

中文翻译：

---

PLA的等温结晶：α和α'相的成核密度和生长速率

从技术的角度来看，聚乳酸（PLA）由于其多功能性，相对可接受的加工性和低成本而成为可再生资源生产的最重要的聚合物之一。然而，其缓慢的结晶动力学存在显着的局限性，这导致无定形产物具有低的机械性能和耐热性。由于这个原因，对结晶动力学现象的定量认识是基础。在这项工作中，通过直接形态学观察在不同的结晶温度（T _c）下，根据成核和生长速率分析了商业级PLA的静态条件下的结晶动力学。）并通过等温和非等温条件下的量热分析。光学分析显示出球状形态，且薄片径向生长。对生长速率的分析表明，α/α'晶体具有约120°C的转变温度。基于实验观察，评估了两个结晶相的结晶动力学。