Four Key Factors for Successfully 3D Printing Flexible PLA Material

Flexible PLA is a special type of polylactic acid (PLA) exhibiting rubber-like properties. Also known as flexible PLA or soft PLA, this material is processed with additional additives that reduce much of the inherent brittleness of standard PLA. The result is an elastic material suitable for printing flexible parts—such as phone cases, insoles, and watch bands. It is often compared to TPU, a popular flexible filament. Although both materials can withstand bending and stretching, flexible PLA does not fully replace TPU. This article discusses material properties and best practices for successful printing with flexible PLA. 0 1 What Are Flexible Filaments? Filaments used in Fused Deposition Modeling (FDM) are thermoplastics—materials that can be melted and re-solidified without loss of performance. Thermoplastics consist of long-chain molecules called polymers. If you could observe the polymers constituting a flexible filament, you would see both rigid and soft segments. The macroscopic properties we observe depend on the ratio between these two regions. This enables printing of highly flexible materials—some capable of snapping back like rubber bands, others producing tough, rubber-like materials akin to car tires, which bend under force yet retain structural integrity. Several types of flexible filaments exist, each with distinct characteristics and advantages: TPE: Short for thermoplastic elastomer, TPE is commonly used as a generic term for flexible filaments because it encompasses a broad range of such materials. TPU: Short for thermoplastic polyurethane, TPU is slightly stiffer than TPE, making it easier to print using conventional extruders. TPC: A thermoplastic copolyester engineered using a different approach to tailor flexibility. While TPC offers a wide spectrum of properties, it is typically softer than TPU and exhibits excellent elongation performance. PCTPE: Short for plasticized copolymer TPE—this flexible filament incorporates nylon into its blend, combining nylon’s durability with TPE’s flexibility. However, this shifts PCTPE toward the stiffer end of the flexible-material spectrum. Flexible PLA: A flexible variant of polylactic acid (PLA), one of the most common 3D printing filaments. It is produced by blending PLA with plasticizing additives—not by incorporating soft segments into its molecular structure, as with TPE-based materials. 0 2 Material Properties Flexible PLA shares many similarities with standard PLA, as both share the same base material. However, they also exhibit notable differences in strength, durability, and other material properties. Strength When subjected to pressure, flexible PLA deforms but rebounds to its original shape once the pressure is removed—a key characteristic distinguishing it from standard PLA, which is relatively brittle. Conversely, due to its tendency to bend, flexible PLA is unsuitable for load-bearing applications. Flexible PLA also retains rubber’s ability to absorb vibrations and impacts. This property proves useful for objects like tires—designed to maintain shape while enduring repeated forces over time that would fracture brittle materials.

Smart Use of Plastic Additives to Enhance Surface Performance of Plastic Products and Meet Increasingly Demanding Application Challenges!

Modifying the surface properties or characteristics of modified plastics can improve material performance and broaden their application scope. From an aesthetic standpoint, scratch resistance of fiber-reinforced nylon is significantly enhanced, while overall appearance is markedly improved. In high-performance applications requiring reduced wear or low coefficients of friction—such as bearings, bushings, and bearing housings—internal lubrication eliminates the need for external lubricants, thereby reducing maintenance requirements. Recently, German chemical company Wacker conducted surface-modification research to determine whether combining additive systems could improve the performance and processability of biodegradable polymers. This study was led by Oliver Fuhrmann, Senior Technical Manager for Genioplast Performance Additives at Wacker’s Silicones Business Unit, and Karl Weber, Senior Technical Manager for Polymers at Wacker. Dr. Ingo Jeschke, Senior Business Development Manager for Polymers at Wacker, serves as the technical contact for the company’s Vinnex products. The challenge of plastic waste is fueling growing interest in biodegradable polymers, with biodegradation viewed as a meaningful end-of-life solution contributing to a circular plastics economy. The European Bioplastics Association forecasts significant global capacity expansion for these polymers—especially biodegradable polyesters—in the coming years. Unfortunately, the potential applications of biodegradable polyesters remain limited. They often fail to deliver the performance expected by compounders, plastic processors, and end users—performance routinely achieved with conventional thermoplastics. Moreover, they are difficult to process, and their surface properties frequently fall short of expectations. Polyvinyl acetate-based polymeric organic additives have a strong track record in modifying biodegradable polyesters. Wacker markets such products under the brand name Vinnex; their polarity is precisely tuned for compatibility with biodegradable polyesters, resulting in exceptional effectiveness. The company also offers its Genioplast Pellet series of silicone-based organic additives for thermoplastic modification. These function as processing aids that reduce friction and enhance polymer performance. Integrated Benefits Wacker’s researchers investigated how combining these two additive systems affects the processing behavior and material properties of biodegradable polyesters. The project focused on polylactic acid (PLA) and calcium carbonate-filled poly(butylene succinate) (PBS), enabling evaluation of additive effects on both filled and unfilled polymer systems. Two commercially available polyester grades served as polymer substrates: NatureWorks’ Ingeo Biopolymer 4043D (PLA) and PTT MCC Biochem’s BioPBS FZ 91 PM (PBS). Both are semi-crystalline, derived from renewable feedstocks, and optimized by their respective manufacturers for plastic film production. PLA is characterized as a high-stiffness, high-strength material—but also extremely brittle and thermally unstable. Its high melt viscosity and low melt strength make melt processing challenging. Additionally, PLA suffers from low crystallinity, and post-crystallization is a primary reason why PLA products often become increasingly brittle over time. In contrast, PBS exhibits mechanical properties more similar to polyolefins.

Silicone Additives Help Brittle PLA Survive Simulated Outdoor Aging

3 days ago

Research indicates reactive polysiloxane additives significantly enhance the impact strength and weathering resistance of brittle polylactide (PLA). These modifiers prevent leaching and maintain tensile strength during simulated outdoor exposure better than unmodified PLA.

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