Analytical Polymers Engineering LLC

Post 42-DOE Design of experiments: One of the important steps in Design of Experiments (DOE) is identifying the variables whose variations could impact the output. To determine these variables, experience and a screening test can be useful. Once the key variables are selected, an appropriate DOE approach can be established. Types of DOE: 1-Factorial Design, 2-Box-Behnken Design, 3- Central Composite Design. The primary purpose of DOE is to understand the significance and influence of each variable on the output within the selected levels (variable domain range). A crucial step in DOE is backward elimination, a step-by-step method that removes the least important factor—specifically, the one with the highest p-value. In backward elimination, the optimal significance level (α) is typically set to 0.1, representing the threshold for statistical significance. If a term in the model has a p-value greater than α, it is considered insignificant and removed from the model. This process continues until all remaining terms have p-values below α, ensuring that only statistically significant factors are retained. #DesignOfExperiments #DOE #ProcessOptimization #StatisticalAnalysis #ManufacturingExcellence #QualityEngineering #DataDrivenDecisionMaking #ProductDevelopment #ResearchAndDevelopment #SixSigma #LeanManufacturing

Post 41-Dental Floss from Costco: Have you noticed a change in the quality of Costco’s floss? Our FTIR testing suggests that the new version may no longer show PTFE peaks. PTFE (polytetrafluoroethylene) is a type of per- and polyfluoroalkyl substance (PFAS), which has raised health concerns. Some studies indicate that individuals using PTFE-based floss, such as Oral-B Glide, may have higher levels of certain PFAS compounds in their bodies.

Post 40-Polyurethane selection in medical device: TPU is gaining attention in medical devices due to its excellent biostability, broad mechanical properties, and superior hydrolysis resistance, especially in polycarbonate- and polyether-based grades. It also offers strong regulatory support, easier processing, and lower costs, making it a preferred material in medical and industrial applications. Check out Posts 1 and 7 on our page for more on TPU’s importance. Below is a design summary table comparing TPU grades. At Analytical Polymers Engineering LLC, we're developing a comprehensive roadmap for TPU aging and shelf-life design using NETZSCH STA 449—an integrated DSC/TGA/FTIR & GC-MS system for real-time reaction analysis: effect of moisture, heat, UV and time. Just an update from Lubrizol that Carbothane is available in both aromatic and aliphatic grades, Tecothane and Pellethane are only available in aromatic grades. #TPU #MedicalDevices #PolymerScience #MaterialsEngineering #Biostability #PolymerAging #AnalyticalPolymers #AcceleratedAging #MedicalPolymers

Post-39-Moisture Adsorption in Medical Device Design Moisture adsorption is a crucial factor in medical device materials, affecting their mechanical properties. In general, moisture increases material softness and, over time, can degrade polymers through hydrolysis, specially in the presence of certain additives. Moisture uptake depends on temperature, relative humidity (RH), and polymer composition. At 50% RH, the moisture concentration in air is 10.3 g/m3 at 23°C and 64.7 g/m3 at 60°C. At 100% RH, these values double, highlighting the significant moisture content in humid conditions. RH represents the air’s moisture-holding capacity; at 100% RH, air is saturated, causing condensation on polymer surfaces. For moisture to impact a polymer, it must diffuse into the material, typically following Fick’s law diffusion. Nylon 12, when dried in a desiccator, adsorbs 0.9% water at 50% RH and 1.5% in 24 hours at room temperature, reaching a saturation limit (maximum moisture uptake) of 1.8% after 5 days in water. Submersion slightly increases this limit from 1.8% to 2%, showing that moisture uptake depends on water exposure. Hydrolysis of polymer will be much faster at 100RH or submerged because higher concentration water molecule. Drying removes moisture, and heat can accelerate this process. However, temperatures above 60°C may alter the crystalline structure, affecting performance. For critical post-processing, a desiccant or dry box is a safer drying method. Moisture significantly impacts tensile modulus (stiffness): ?Dry sample: 470 N/mm2 ?50% RH: 420 N/mm2 ?100% RH & submerged: 334 N/mm2 This demonstrates how humidity and water exposure reduce material stiffness. #MedicalDevices #Polymers #MaterialScience #MoistureAdsorption #Engineering #BiomedicalEngineering #PolymerScience #MedicalMaterials #TensileModulus #HumidityEffects

Post 38-Kink resistance in medical tubing refers to the tubing's ability to maintain its lumen (open pathway) and resist collapsing or occlusion when bent or twisted. This property is critical in medical applications such as catheters, infusion sets, or other tubing to ensure consistent fluid or air flow. How to Measure Kink Resistance: One way to measure kink resistance is the bending radius test, but a more standardized approach involves tensile testing in bending mode, which measures the flexural modulus. Another method is regular tensile testing, which assesses elongation at yield, representing how much the tube can stretch without deformation. As shown in the figure below, PEEK, PET, and Nylon 12 have increasing levels of kink resistance, with Nylon 12 exhibiting the highest resistance. Factors That Affect Kink Resistance: Tube dimensions (e.g., wall thickness), Concentricity of the tube, Type of polymer/durometer, Additives used, such as BaSO?, Temperature, moisture, and sterilization processes. One parameter that is very also important is Extrusion orientation: Tubes produced under high molecular orientation during extrusion tend to have lower kink resistance. Braided Tubes and Composite Structures: For a braided tube (e.g., when a polymer layer is reinforced with Ni-Ti wire), the elastic region of the tube increases due to the super elasticity of the braid. In such cases, the tube Post becomes a composite structure, making it anisotropic and requiring separate modeling. For single-lumen polymer tubes with isotropic structures, regular tensile testing (yield point elongation and strength) provides sufficient information regarding kink resistance. See you at MD&M West. #MedicalTubing #KinkResistance #MaterialScience #Polymers #MedicalDevices #Nitinol #Biomechanics #Catheters #Extrusion

Post 37-Tungsten (W in Element table) is dispersed in polymers to create radiopaque properties, enabling physicians to track catheters during procedures. The dispersion of tungsten is critical, as the quality of dispersion significantly impacts mechanical properties, kink, shelf life, and the degradation of polymers. SEM-EDS mapping performed in our lab shows the dispersion of tungsten in the cross-section of a Pebax tube (35 durometer). Analysis of the cross-section provides unique insights into the quality of dispersion and can predict the mechanical/performance of the part when assembled into the final product. #MedicalDevices #RadiopaqueMaterials #TungstenApplications #PolymerDispersion #CatheterDesign #SEMAnalysis #MaterialCharacterization #Pebax

Post 36- Gels in Polymers and Biomedical: Cause and Prevention #PolymerGels #Extrusion #BiomedicalBalloon https://lnkd.in/gVtBNucu

At Analytical Polymers Engineering LLC, we are proud to support St. Jude Children’s Research Hospital, a beacon of hope and innovation in pediatric healthcare that is active in 60 countries. Humanity has always evolved through the pursuit of knowledge and the power of compassion. Research not only expands the boundaries of what we know but also transforms lives, offering solutions to challenges once deemed insurmountable. It is this synergy of knowledge and humanity that defines progress and inspires us to make a difference. As we celebrate Thanksgiving, we extend our gratitude to all who contribute to advancing research and fostering compassion in our communities. Together, let’s continue building a world where science and kindness unite to create brighter futures for all, Happy thanks giving to you all. Knowledge is light, and you can overcome the dark only with light. #SupportStJude #Thanksgiving2024

Post 35-Trilayer tubing leverages Pebax for flexibility and HDPE for strength, delivering superior mechanical properties and enhanced maneuverability in biomedical applications. The HDPE layer ensures high burst pressure and compression resistance, making it ideal for rigorous medical procedures while providing Lubricity and Secure Bonding. HDPE also provides a smooth inner surface for easy device insertion, the tie layer ensures strong bonding with Pebax for reliable structural integrity. The uniformity of tie layer is a key in design, along with proportion of Pebax to HDPE, see the published work where detail analysis and characterizations are presented for this kind of tubing: https://lnkd.in/gYGaEYQ9 #BiomedicalEngineering #TrilayerTubing #HDPE #MedicalTechnology

Post 34-The porous structure of PTFE serves as a scaffold that supports cell growth and enhances biocompatibility, known as ePTFE (expanded PTFE). PTFE is a challenging material to process due to its high melting temperature (~620°F) and resistance to solvents. To create ePTFE, the following steps are involved: 1?? Paste Preparation: PTFE powder is mixed with a 20% lubricant (e.g., Isopar) to form a paste. 2?? Preform Creation: The paste is pressurized into a cylindrical rod called a "preform." 3?? RAM Extrusion: The preform is extruded to produce tubes, sheets, or profiles. 4?? Stretching and Heating: Tubes are heated and stretched, which removes the lubricant and forms the porous structure by separating lamellae. 5?? Sintering: In the final stage, heat setting stabilizes the porous structure. The morphology of ePTFE can vary significantly, as seen in these two commercial samples, where porosity and pore size differ from one product to another. #ePTFE #PTFE #MaterialScience #Polymers #Biocompatibility #PorousMaterials #BiomedicalEngineering #AdvancedMaterials #Manufacturing