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A Soft Tooling Process Chain for Injection Molding of a 3D Component with Micro Pillars

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Enhancing Mechanical and Thermal Performance of Injection-Molded PLA via Nucleation and Processing Optimization.

Peng Gao¹, Max Johnson¹, Duncan Woodward¹

¹Materials Science Engineering, Western Washington University, Bellingham, WA 98225, USA.

|July 15, 2026

Summary

Orotic acid (OA) nucleation and injection molding significantly enhance polylactic acid (PLA) crystallization and thermal properties. Optimized PLA-OA achieves high heat deflection temperatures (HDT) without post-annealing, ideal for food packaging.

Keywords:

crystallization injection molding nucleating agent polylactic acid

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Process of Making Three-dimensional Microstructures using Vaporization of a Sacrificial Component

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Last Updated: Jul 16, 2026

A Soft Tooling Process Chain for Injection Molding of a 3D Component with Micro Pillars

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Published on: August 4, 2018

Process of Making Three-dimensional Microstructures using Vaporization of a Sacrificial Component

Process of Making Three-dimensional Microstructures using Vaporization of a Sacrificial Component

Published on: November 2, 2013

Area of Science:

Materials Science
Polymer Science
Chemical Engineering

Background:

Polylactic acid (PLA) is a biodegradable polymer with limited thermal stability.
Improving PLA's heat deflection temperature (HDT) is crucial for expanding its applications, particularly in food packaging.

Purpose of the Study:

To investigate the combined effects of orotic acid (OA) nucleation and injection molding parameters on PLA's crystallization and thermo-mechanical performance.
To achieve high-crystallinity and high-HDT PLA without requiring post-annealing.

Main Methods:

Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) to analyze crystallization behavior.
Mechanical testing (tensile and flexural) to evaluate thermo-mechanical properties.
Heat deflection temperature (HDT) measurements to assess thermal performance under varying processing conditions.

Main Results:

2 wt% OA significantly accelerated PLA crystallization, reaching 52-53% crystallinity under optimized low packing pressure and long hold times.
Tensile modulus increased with hold time, while tensile strength decreased due to skin layer relaxation.
Flexural strength increased with packing pressure; flexural modulus decreased with decreasing crystallinity under higher pressure.
Optimized PLA-OA samples exhibited significantly improved HDT, ranging from 100 °C to 131 °C, compared to the baseline 58 °C.
Highest HDT values correlated with high crystallinity, extended lamellar development, and strong α-phase formation.

Conclusions:

Combining OA nucleation with controlled injection molding is an effective strategy to produce high-crystallinity, high-HDT PLA.
This approach eliminates the need for post-annealing, offering a more efficient route for manufacturing thermally stable PLA.
The developed PLA-OA materials are suitable for demanding applications like hot-fill and reheatable food packaging.