Effect of silane-modification of diatomite on its composites with thermoplastic polyurethane

• Published in: Materials chemistry and physics 2020-12, Vol.256, p.123683, Article 123683
• Main Authors: Kucuk, Fatma, Sismanoglu, Sedef, Kanbur, Yasin, Tayfun, Umit
• Format: Article
• Language: English
• Subjects: Adhesion; Coupling agents; Diatomaceous earth; Diatomite; Functional groups; Glass transition temperature; Inclusions; Isocyanates; Mechanical properties; Mechanical tests; Melt mixing; Photomicrographs; Polymer matrix composites; Polyurethane resins; Silanization; Surface modification; Tensile strength; Thermal stability; Thermomechanical treatment; Thermoplastic polyurethane; Urethane thermoplastic elastomers
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2020.123683

Diatomite (KG) surface was modified by four different silane coupling agents having amino, epoxy, triamine and octyl functional groups for enhancement of interfacial adhesion between thermoplastic polyurethane (TPU) and diatomite. EDX and FTIR spectroscopy techniques were used to evaluate the surface functionalities of modified and neat KG samples. TPU/KG composites were fabricated using melt-compounding process. Mechanical, thermo-mechanical, thermal, melt-flow and morphological properties of composites were reported. Mechanical tests revealed that tensile strength and hardness of TPU extended to higher levels while its flexibility was retained after KG additions. Epoxy-silane modified KG exhibited the highest results in the case of mechanical properties. Glass transition temperature of TPU shifted to higher values by the additions of modified KG. Thermal stability of TPU raised by KG inclusions regardless of modification type. Modified KG containing composites yield lower MFI values with respect to neat KG. Enhancement of interfacial adhesion between TPU and KG phases was confirmed by SEM micrographs of composites in which silane-modified KG surfaces were covered by TPU matrix. Silane modifiers involving amine and epoxy groups led to significant improvement in properties of KG-filled TPU composites. Epoxy-based silane displayed the highest performances thanks to strong interfacial interactions between epoxy functional group and isocyanate segment of TPU. [Display omitted] •Modification of diatomite surface with four different silane modifiers confer performance of eco-grade TPU composites.•Composite involving epoxy-silane modified diatomite exhibited the best mechanical behavior among all composites.•Thermal degradation temperature of TPU shifted to higher levels by inclusion of diatomite.•Addition of silane modified diatomite caused no obvious change for MFI parameter of TPU.