Effect of Diisocyanates as Compatibilizer on the Properties of BF/PBAT Composites by In Situ Reactive Compatibilization, Crosslinking and Chain Extension

Abstract

Due to the hydrophobic nature of poly (butylene terephthalate) (PBAT), and the hydrophilic nature of bamboo flour (BF), a BF/PBAT (50/50) blend shows low mechanical properties, and especially shows poor impact strength. In order to increase the interfacial adhesion between BF and PBAT, diisocyanate was used as a reactive compatibilizer to modify bamboo powder. A series of BF/PBAT composites were prepared by the method of mixing and melting in an internal mixer. After adding reactive compatibilizer 4,4 -methylenebis(phenyl isocyanate) (MDI), BF/PBAT (50/50) composites with high mechanical properties were successfully prepared. The tensile strength, elongation at break, and impact strength of the BF/MDI-2/PBAT composite with 2 wt % MDI content were increased by 1.9, 6.8, and 4.3 times respectively over the BF/PBAT blend without the added MDI. The higher toughening effect of MDI in BF/PBAT composites can be mainly ascribed to the improved interface bonding between BF and PBAT. The isocyanate group of MDI can react with the hydroxyl group on the BF surface and in situ formation of the carbamate group on the BF surface. The residual isocyanate can then react with the hydroxyl group of PBAT and form carbamate groups. The rheological behaviors demonstrate that addition of appropriate amounts of MDI, 1 wt % and 2 wt %, can promote the flowability of the molten BF/PBAT composites due to the decrease in interparticle interaction between bamboo powder and the increase in the thermal motion of the molecules.Bamboo fiber is composed of cellulose, lignin, hemicellulose, and other macromolecules, which have strong rigidity. In addition, it has the advantages of antibacterial, low cost, and high recovery rate. More significantly, bamboo flour can not only be used as a reinforcement, but also can act as a nucleation agent to improve the crystallization performance and crystallization rate of the composite [3,7-9].

Recent advances in compatibilization strategies of wood-polymer composites by isocyanates

“…Lately, Xie et al (2020) prepared biocomposites based on the PBAT matrix filled with bamboo flour and compatibilized them with the different content of MDI (from 1 to 4 parts by weight). The authors noted significant enhancement of the mechanical properties of composites, which in detail is presented in Table 6.…”

“…Changes in mechanical properties of PBAT/bamboo flour composites after compatibilization with MDI(Xie et al 2020) …”

Natural Protein‐Based Biocomposites with Superior Paramagnetism and Microwave Absorbing Properties by Incorporating Nanosized Fe2O3

“…Polymers from renewable resources have attracted more and more attention in the past few decades, due to environmental concerns and limited petroleum resources. [1][2][3] As a renewable and biodegradable polymer, natural protein is widely applied in DOI: 10.1002/mame.202100748 genetic engineering, eco-friendly materials, and novel composite materials. [4,5] Proteins, as naturally occurring polymers, are usually produced by animals, plants, and bacteria.…”

Effect of oligomers from epoxidized soybean oil and sebacic acid on the toughness of polylactic acid/bamboo fiber composites

“…In terms of production cost and growth cycle, BF is considered to be the most suitable renewable filler. 14 Meanwhile, the main disadvantages of PLA/BFs composites are the low compatibility and the poor interfacial adhesion between the hydrophilic natural of filler and the hydrophobic of polymer matrix. Natural fillers with polar hydroxyl groups on the surface form poor bonded interfaces with a nonpolar matrix, leading to an inefficient stress transfer under load and an even more decreasing fracture resistance.…”

“…In addition, it is antibacterial and has low cost and high recovery rate. In terms of production cost and growth cycle, BF is considered to be the most suitable renewable filler 14 …”