Polylactic acid ( PLA is currently the most widely used and commercially promising bio-based biodegradable material. However, its crystallization rate and crystallization capability are insufficient. , which increases the difficulty of subsequent processing and application, thereby limiting PLA is being increasingly widely applied. In response to this drawback of PLA resin materials, Pliith Biotechnology Through the design of a unique molecular structure and the optimization of the polymerization process, we have developed A rapidly crystallizing PLA material with self-nucleating capability.

01 Crystal structure

PLA crystallization primarily involves three polymorphic forms: α, β, and γ. The formation of different crystal forms is closely related to the processing and heat‑treatment conditions. The α polymorph can be obtained by crystallization from the melt and from solution, the β polymorph can be formed under high draw rates and draw temperatures, and the γ polymorph can be grown epitaxially on hexamethylbenzene.

During the melt‑cooling process in processing, PLA predominantly forms α‑type spherulites, which are the most common and stable of the three crystalline forms. The size of spherulites ranges from the micrometer to the millimeter scale. During growth, uneven radial expansion typically gives rise to significant internal stresses. When spherulites reach a certain size, not only do interfacial bonds weaken, but accumulated stress can also induce cracks within the spherulite, markedly reducing the material’s toughness. This is precisely why the industry has long sought to control the crystalline size of PLA.

Figure 1 Schematic diagram of spherulite growth and fracture

02 Crystallinity

As a typical semi-crystalline polymer material, The crystallinity and crystal structure of PLA significantly influence its thermal resistance. When the material is amorphous or has a crystallinity below 25%, its Vicat softening temperature is less than 80°C; in contrast, PLA with a crystallinity exceeding 30% and a well‑developed crystal structure can achieve a Vicat softening temperature of 120°C or higher.

Figure 2 The relationship between PLA crystallinity and Vicat softening temperature

03 Crystallization ability and improvement

Due to the intrinsic physical properties of the molecular chain, pure PLA has a relatively slow crystallization rate, and products obtained through conventional processing exhibit low crystallinity, resulting in insufficient heat resistance.
By adjusting The crystallization rate of PLA can be enhanced by modifying its molecular structure, adjusting its molecular weight and molecular weight distribution, increasing its optical purity, incorporating nucleating agents or plasticizers, and optimizing processing conditions. Taking the addition of nucleating agents as an example, a variety of commercially available nucleating agents are currently available that can significantly improve PLA’s nucleation performance. However, these approaches often suffer from drawbacks such as stringent process control requirements, increased complexity in downstream processing steps, and greater overall processing difficulty.
To address this industry‑wide challenge, Pliith has engineered a molecular structure that incorporates organic nucleating monomer blocks directly into the polymerization process, thereby developing a rapidly crystallizing material with intrinsic nucleation capability. PLA resin exhibits a significantly enhanced crystallization rate (as shown in Figure 3) and is suitable for applications such as fiber spinning, injection molding of heat‑resistant parts, and thermoforming.