Can You Super Glue PLA? Understanding the Bonding of PLA Parts Together

In PLA, the most significant advantage is that it is widely used, to the extent that it is considered the easiest material to work with for 3D printing. In the other hand, makers, and enthusiasts find an oft-repeated question-how to join or repair PLA parts without losing any strength, appearance, or functionality? Enter: super glues. But is super glue the best solution for bonding PLA, or are there better alternatives? This article will lay down the science behind PLA bonding and analyze the pros and cons of super glue for this application. It will then offer you several techniques and methods to give you strong, reliable joins for your PLA pieces, enabling you to repair a small print or assembly bigger projects with the know-how to get professional results.

Polylactic Acid, commonly known as PLA, boasts a unique combination of properties that have made it a material of choice in various applications, most noticeably in 3D printing and packaging. It is a biodegradable product, made from renewable resources such as cornstarch or sugarcane, and is therefore environmentally friendly compared to petroleum-based plastics. PLA tends to have a lower melting temperature, typically ranging from 190 to 220°C, which is advantageous for ease of processing in additive manufacturing. It is also a very safe material to work with, emitting very few or no toxic fumes when heated.

On the other hand, PLA does not possess excellent heat resistance properties; therefore, it tends to be brittle when compared to plastics like ABS. Another shortcoming is that its mechanical properties vary according to grade and processing, but it typically exhibits a tensile strength in the range of 37-60 MPa. To cater to such limitations, PLA variants generally are modified or blended with other materials to suit more demanding applications that require improved performance and durability.

Bonding PLA prints can be a little tricky due to PLA’s specific properties. It has a relatively low melting point, so excessive heat during bonding can cause deformation or warping. The surface is very smooth, so without incident preparation, strong adhesion is not viable. Surface contaminants, such as dust or oil, can prevent successful bonding. Therefore, solutions involve sanding or modifying the surface texture to increase gripping, along with a proper choice of adhesive. Cyanoacrylates and epoxy are generally the most commonly recommended glues for bonding PLA, although this may vary depending on the application.

Super glue, or cyanoacrylate adhesive, can quickly bond with PLA parts formed due to its shorter curing time and more exceptional binding properties. It works better with small joints that are not load-bearing or for any project that requires precision. Effectiveness varies with surface tension, surface stratification, and the quality of PLA. Therefore, always ensure that the surface is clean and lightly sanded; the parts have also been well-aligned before applying any adhesive. When bonded with super glue, many applications using PLA come together reasonably well, but this adhesive is not considered beneficial for applications requiring flexibility or stress resistance over time.

The epoxy resins serve as an adhesive, with superior bonding strength for PLA, and very high tensile strength. When the two components are mixed, a chemical reaction occurs between them, resulting in the hardening and final bonding of the parts, which can withstand significant stress and weight. Unlike super glue, epoxy resin fulfills applications requiring long-term durability against environmental factors such as moisture, heat, and vibration. Although the bond may require anything from a few hours to a full day to cure, it ultimately provides a firm and reliable adhesion. For good adhesion, apply it evenly after thoroughly mixing the resin components onto cleaned and prepared surfaces. It is beneficial for repair purposes, structural joints, or functional parts as a good alternative to other adhesives.

1. Prepare the Surfaces: First, clean the PLA surfaces from dust, grease, or any debris. Use mild detergent and water, or isopropyl alcohol, to clean and ensure they are dry.
2. Roughen the Edges (Optional): By sanding lightly, you can enhance the bond strength. Use fine-grit sandpaper to sand the areas where the glue will be applied.
3. Apply the Super Glue: Carefully put a small drop of super glue onto one surface and spread it evenly for even adhesion.
4. Join the Pieces: Press the PLA parts firmly together, ensuring they are aligned correctly. Hold firmly for 10-30 seconds while gluing sets.
5. Allow to Cure: After joining, leave the parts undisturbed for a few more minutes until the bond is completely set. For full strength, allow the bonding for 24 hours before applying any loads/stresses onto it.
6. Clean Excess Glue: Any glue that squeezes out should be wiped immediately with a damp cloth or an acetone solution, taking care not to disturb the joint.

For good bonding of PLA material with super glue, ensure you have these items on hand:

• Super Glue (Cyanoacrylate): A super glue of reasonable quality meant for general plastic applications, especially PLA.
• Sandpaper (Fine Grit): Used for light sanding of surfaces for better adhesion.
• Clamps or Weights: To press the glued pieces tightly until the glue sets.
• Cleaning Supplies: Alcohol wipes or a damp cloth to clean the surfaces before gluing.
• Acetone-Based Solution (Optional): For cleaning any excess glue that comes out during bonding.

1. Prepare the Surfaces: Ensure that both PLA surfaces are clean, free from dust, dirt, and grease. One should use an alcohol wipe or a damp cloth to clean the areas that will be bonded, and then allow them to dry completely.
2. Light Sanding (Optional): Gently sand the bonding surfaces with fine-grade sandpaper to enhance adhesion. Make sure to thoroughly wash off or dust out any dust that forms while sanding.
3. Apply the Glue: A thin layer of adhesive must be applied evenly onto one of the surfaces. It is recommended to avoid excessive application of glue, as it may spill during the bonding process.
4. Align and Press: Carefully align the surfaces and press them together firmly. Apply pressure evenly over the bonding area using clamps or weights.
5. Wipe Away Excess Glue: If excess glue has spilled at the edges, clean the area immediately with a damp cloth or an acetone-based solution, if recommended for the adhesive you are using.
6. Allow Curing Time: Allow the adhesive to cure according to the manufacturer’s instructions. Some adhesives need several hours, while for stronger bonding, it is best to leave them undisturbed for 24 hours.

Weak bonds in PLA projects can be a result of many factors; each has to be carefully paid attention to for strong and lasting adhesion:

• Surface Preparation Issues: This is one of the common offenders that cause less-than-minimum bond strength. The surface of PLA may have contaminants, oils, or irregularities that prevent proper adhesion. Try sanding it very lightly and cleaning it with isopropyl alcohol; it does wonders for bond strength.
• Incorrect Adhesive Selection: Some glues may or may not work with PLA. If you choose an adhesive that is not suitable for bonding plastics, particularly PLA, it will fail. For an effective glue, consider cyanoacrylate (super glue), epoxies, or adhesives designed explicitly for PLA.
• Insufficient Curing Time: Cutting the curing time short results in weak bonds. Allow the drying and curing times stated in instruction manuals to reach the strength attributed to the glue.
• Temperature and Humidity Factors: PLA can be sensitive to environmental conditions. Temperature, moisture, and other factors can weaken the material or interfere with adhesion. Get your work ready in a controlled environment within an appropriate temperature range for the adhesive.
• Uneven or Insufficient Adhesive Application: Partial bonding, with some areas remaining weak, resulted from uneven application or insufficient adhesive application. For best results, apply a uniform layer of adhesive, then apply pressure while bonding.

Glue stains or residue can be a nuisance when working with PLA or similar materials. To remove glue stains effectively while protecting the surface, gently scrape away any excess glue with a plastic scraper or another non-abrasive tool. For the tougher glue stains, place some isopropyl alcohol or acetone on a soft cloth and rub until the glue begins to dissolve. Of course, always test on an inconspicuous location before going full force to make sure your cleaner doesn’t react with the material. A bit more environmentally conscious, one will opt for a little warm, soapy water for less heavy stains and a gentle scrub. Prevention is always better: using painter’s tape and applying glue sparingly can therefore save one from potential residue build-up.

1. Choose the Right Adhesive: Choose an adhesive suitable for the materials being bonded. Read the product label to ensure compatibility and long-lasting results.
2. Prepare the Surfaces: Clean and dry all surfaces to be joined by adhesive. Remove dust, grease, or moisture that may interfere with good bonding.
3. Apply evenly: Apply a very thin, even coat so that weak areas develop or spillage anywhere does not occur.
4. Secure the Bond: Secure the bond by holding or clamping the materials together until they are fully dry or cured, as specified by the manufacturer’s instructions.
5. Follow Instructions: Use an adhesive following the manufacturer’s instructions or best practice guidelines, including storage and drying times.

Thicker gel superglue is best suited for tasks that require precision and control. For instance, liquid glue will slowly run down a vertical surface and cannot be applied to a porous one. The thick gel provides more handling time compared to its fast-liquid counterpart and reduces the chances of making a mess. While applying gel superglue:

• Prepare Surfaces: Ensure surfaces are clean, dry, and free from dust for optimal adhesion.
• Apply with Care: Dispense the gel adhesive sparingly to avoid any overflow. A small quantity of gel works perfectly fine.
• Align and Secure: Position the materials carefully before pressing them together, holding them firmly, or clamping them if necessary, until they set.
• Curing Time: Allow sufficient time to cure according to the product instructions; gel formulas may bond slightly slower than liquid glues.

Sacrificial pieces of PLA may be tested; initially, care was taken to ensure that each surface was clean and free of dust or any other residue. A small amount of the gel super glue was applied to a piece, and they were pressed together; then, they were clamped to prevent movement. After their curing period, the bonds were gently pressed and found to hold securely, demonstrating the secure bonding of PLA with the adhesive.

Here are five authoritative and professional titles you may consult to verify the correctness of your article: “Can You Super Glue PLA?” With their academic nature, these sources provide ample research material:

• Use of Cyanoacrylate (Super Glue) for Fixation and Prefabrication
  The study examines cyanoacrylate adhesives, including their properties and applications, which may provide insight into their compatibility with materials such as PLA.
• PLATech Overview: Tailored Polylactic Acid Polymer Formulations
  This work presents a comprehensive treatise on PLA properties in relation to its applications in adhesion, providing additional information on its compatibility with adhesives.
• Adhesion Optimization Between Incompatible Polymers
  This research aims to improve the adhesive strength between PLA and other materials, thereby increasing the understanding of super glue interactions with PLA.
• Improving Interfacial Adhesion of PLA Composites
  This study focuses on approaches to enhancing the bonding properties of PLA composites, providing valuable insights into the challenges and solutions in adhesive applications.
• Ultra-Strong Bio-Glue from Genetically Engineered Polypeptides
  While not directly addressing PLA, this review provides a more general examination of adhesive technology and its advancements, which can prove valuable in understanding the applicability of super glue to PLA.