Poly(D,L-lactic acid)

Updated: 2026-08-29

Overview

Medical-grade racemic polylactic acid (PLA) is a synthetic polymer derived from lactic acid monomers. Unlike optically pure PLA, the racemic form contains both D- and L-lactic acid units, resulting in amorphous properties ideal for controlled degradation in medical applications. As a biodegradable and biocompatible material, it meets stringent regulatory requirements for implantable devices and drug delivery systems. The medical industry values its predictable degradation rate, which can be tailored from months to years by adjusting molecular weight and crystallinity.

Physical and Chemical Properties

Racemic PLA exhibits a glass transition temperature (Tg) of 50-60°C and lacks a distinct melting point due to its amorphous nature. This contrasts with semi-crystalline PLA variants, making it more suitable for applications requiring uniform degradation. The material shows excellent mechanical strength (tensile strength 40-60 MPa) in its polymerized form, though properties degrade predictably as hydrolysis occurs. Its degradation products (lactic acid) are metabolized via the Krebs cycle, eliminating toxic byproducts.

Main Applications

In surgical settings, racemic PLA dominates absorbable suture production due to its optimal 6-12 month degradation profile. Manufacturers also utilize it in orthopedic fixation screws and plates that gradually transfer load to healing bones. The pharmaceutical industry employs it in microsphere drug delivery systems, where its degradation rate controls active ingredient release. Emerging applications include 3D-printed scaffolds for tissue engineering, leveraging its ability to support cell growth while degrading into non-inflammatory byproducts.

Safety and Storage

While biocompatible, processing racemic PLA requires precautions against thermal degradation above 200°C, which may produce lactide fumes. Facilities should maintain relative humidity below 30% during storage to prevent premature hydrolysis. Sterilization methods must avoid gamma radiation (causes chain scission) in favor of ethylene oxide or low-temperature plasma. Bulk material should be stored in vacuum-sealed bags with desiccant to maintain optimal molecular weight until processing.

B2B Procurement Guide

Medical device manufacturers should prioritize suppliers with: 1) Batch-specific hydrolytic degradation data, 2) Residual monomer content below 1%, and 3) ISO 13485 certification for medical polymer production. For research institutions, smaller quantities (100g-1kg) of high-purity material (≥99.5%) are commonly available from specialty chemical distributors. Large-volume buyers (>1 ton) can negotiate 10-15% discounts with direct manufacturers, particularly for customized molecular weight distributions.