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.
Highlights
Natural fibers have attracted much attention due to their renewability and complete degradation or composting in the soil without any toxic or harmful gases produced
Impact strength and elongation at break can indicate the fracture resistance of the composite under the action of high-speed stress, which is mainly related to the structure of matrix and filler, the degree of two-phase bonding and the difficulty of filler pulling out from the matrix
It was found that the bamboo flour (BF)/MDI-2/PBAT showed higher tensile strength than that of other composites
Summary
Natural fibers have attracted much attention due to their renewability and complete degradation or composting in the soil without any toxic or harmful gases produced. Previous works have confirmed that blending plastic with appropriate sisal, bagasse, bamboo flour (BF), flax, wood powder, or other cellulose fibers could significantly reinforce the mechanical properties of the plastic composite, especially the bending modulus and impact strength [2,3,4,5,6,7]. The morphology of the fracture surface and rheology behavior of the composites were fully characterized
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