@article{machikiti_pourdeyhimi_genzer_efimenko_2023, title={Tuning Interfacial Adhesion in Polyester/Polyamide Systems}, volume={7}, ISSN={["1520-5045"]}, url={https://doi.org/10.1021/acs.iecr.3c01517}, DOI={10.1021/acs.iecr.3c01517}, abstractNote={Polymer–polymer adhesion is critical in polymer processing and application areas where lamination, welding, composites, blending, and coextrusion are involved. Polyethylene terephthalate/polyamide (PET/PA) pairs are widely used to produce bicomponent fibers. The strong adhesion due to the formation of chemical bonds in the interfacial region limits post-production fiber processing. The adhesion strength in the PET/PA systems showed that PET/PA66 had the highest adhesion energy, followed by PET/PA6, PET/PA11, and PET/PA12 for all processing conditions. We developed a method that enables adhesion control by introducing a poly(octadecene-alt-maleic anhydride) (POMA) alternating copolymer by either direct interfacial modification or addition into the PET phase. Upon POMA introduction to the system, the reduction in interfacial adhesion strength between PET and polyamides is observed. We established the relationship between adhesion strengths in PET/polyamide systems, processing conditions, and concentration of the POMA modifier.}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Machikiti, Zvikomborero and Pourdeyhimi, Behnam and Genzer, Jan and Efimenko, Kirill}, year={2023}, month={Jul} }
 @article{machikiti_pourdeyhimi_genzer_efimenko_2022, title={Controlling PA6/PET adhesion to facilitate interfacial fracture}, volume={171}, ISSN={["1873-1945"]}, DOI={10.1016/j.eurpolymj.2022.111196}, abstractNote={Microfibers get often produced in the form of bicomponent polymer systems. The materials of choice are Nylon 6 (PA6) and poly(ethylene terephthalate) (PET). This combination of PA6 and PET is preferable because of its beneficial attributes (i.e., thermal stability, mechanical strength, etc.). PA6 and PET exhibit high adhesion when processed at elevated temperatures due to chemical bonds formation by aminolysis of the ester group in PET with a secondary amine in PA6. These fibers are split/fibrillated by mechanical energy (hydroentangling or needle punching). For energy input, it is desirable to have adhesion between the PA6 and PET materials that is not too strong to allow for easy polymer splitting. Therefore, we developed a method for tailoring the PA6/PET interface adhesion by adding modifiers that react preferentially with the PA6 component. The reactivity between PA6 and PET was investigated by spin coating thin films of PA6 and PET on silicon wafers and annealing them at high temperatures. The reaction between PET and small molecules containing secondary amines (i.e., caprolactam, diallyamine, diethylamine, and diisopropylamine) shows a chemical bond between the ester group in PET and the secondary amine group. The poly(styrene-alt-maleic anhydride) (PSMA) and poly(octadecene-alt-maleic anhydride) (POMA) were chosen as model polymer interfacial modifiers. The feasibility of modifying secondary amines is examined by reacting the two modifiers, PSMA and POMA, with small molecules containing secondary amine groups. PA6 and PET display high fracture toughness (i.e., adhesion strength) at elevated temperatures and longer annealing times because of strong interactions between the amine and ester groups in PA6 and PET, respectively. We then assess the adhesion strength between PA6 and PET modified with PSMA and POMA. Both modifiers reduce interfacial adhesion strength between PA6 and PET. Therefore, it is feasible to tailor adhesion at the PA6/PET interface, which could prove helpful in microfibers production.}, journal={EUROPEAN POLYMER JOURNAL}, author={Machikiti, Zvikomborero and Pourdeyhimi, Behnam and Genzer, Jan and Efimenko, Kirill}, year={2022}, month={May} }