Effects of vinyl isocyanate coupling agent on the tensile properties of Kraft fiber‐unsaturated polyester composites

Abstract

A vinyl isocyanate (VI) synthesized from toluene diisocyanate and 2-hydroxyethyl methacrylate was used as a novel coupling agent to obtain strong chemical interfacial adhesion and therefore, improve the tensile properties of Kraft fiber-reinforced unsaturated polyester (UPE) composites. Results characterized by fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), and scanning electron microscope (SEM) indicated that the novel coupling agent VI had a significant effect on the tensile properties of composites due to the formation of chemical bonds between the VI-Kraft interfaces and the VI-UPE interfaces. The tensile properties of composites modified by VI were much better than those of the control composite without VI modification. The VI-modified composites after severe hygrothermal aging exhibited lower losses of tensile properties and desirable tensile durability. The improvement in tensile properties, less interfacial separation after severe hygrothermal aging, lower damping values, and higher glass transition temperature are sufficient to show that the interfacial adhesion between the Kraft fiber and the UPE matrix was significantly improved because the coupling agent VI has both active isocyano groups which react with the Kraft fiber and vinyl groups which are copolymerizable with the UPE resin.

Effects of the short‐fiber tip geometry and interphase properties on the interfacial debonding behavior of rubber matrix composites

“…The reason was that the surface of the aramid fiber was smooth, there was a lack of polar groups and chemical activity. In generally, epoxy resin coating was used as the surface treatment method of the aramid fiber . Thus, the elastic modulus of the interphase varied between E e = 3 GPa (fiber coated with the epoxy resin) and E m = 2 MPa (rubber matrix).…”

Effects of Alkali Treatment and Polyisocyanate Crosslinking on the Mechanical Properties of Kraft Fiber-Reinforced Unsaturated Polyester Composites

“…Therefore, the addition of 5% polyisocyanate as a crosslinking agent could result in a satisfactory increase in the tensile properties, whereas a further increase of polyisocyanate content did not bring about any improvements. This may be attributed to a saturation of the crosslinking efficiency of the polyisocyanate with the kraft fiber-polyester interfaces (Gao et al 2013). Considering the higher cost of polyisocyanate crosslinker (about US$2.90/kg) when compared to the unsaturated polyester resin (about US$1.94/kg), the optimal polyisocyanate level as a crosslinking agent was determined to be 5%, which yields an acceptable mechanical improvement while maintaining a low composite cost.…”

Effects of crosslinking on the mechanical properties and biodegradability of soybean protein‐based composites

“…To fully make use of the wood scrap with more value added, environmental friendly bio‐composites may offer a solution by combining the modified soybean protein with the wood flour or wood fiber . Compared with lignocellulosic fibers, the low‐aspect‐ratio wood flours as reinforcement of composite have some advantages such as low cost, ease to obtain and process from wood scrap, less challenging to obtain proper blend with polymer matrix, etc …”

“…Interfacial adhesion is known to have a significant effect on the properties of composites. It has been confirmed that the poor interfacial adhesion could be improved using compatibilizers or crosslinkers to form bridges of chemical bonds between the wood reinforcements and the polymer matrices . Glyoxal, glutaraldehyde, and polyamidoamine‐epichlorohydrin (PAE) are the most commonly used crosslinking agents for soybean protein.…”

“…8 Compared with lignocellulosic fibers, the low-aspect-ratio wood flours as reinforcement of composite have some advantages such as low cost, ease to obtain and process from wood scrap, less challenging to obtain proper blend with polymer matrix, etc. 9 Interfacial adhesion is known to have a significant effect on the properties of composites. It has been confirmed that the poor interfacial adhesion could be improved using compatibilizers or crosslinkers to form bridges of chemical bonds between the wood reinforcements and the polymer matrices.…”