In this study, polyamidoamine (PAMAM) was added to raw lacquer in different proportions, and the curing process and properties of lacquer film were investigated by using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT‐IR), and scanning electron microscopy (SEM). To investigate the cross‐linking state between PAMAM and urushiol, NMR was used in this study. The experiments revealed that the comprehensive mechanical properties of modified‐film, especially the impact strength, were significantly improved. In addition, the touch‐free drying time of lacquer film decreased, and its alkali resistance was improved due to the cross‐linking of PAMAM and urushiol molecules.
The polypropylene-graft-cardanol was prepared by reactive extrusion, which is solvent-free melt process, continuous processing, and controllable over residence time. The effect of monomer and initiator concentration on grafting ratio, grafting efficiency, and melt flow index (MFI) was also studied. The yield was quantified by UV-vis spectrometer. The chemical structure was investigated by infrared spectroscopy and gel ratio. A possible mechanism was supposed. The particular structure of cardanol can retain the MFI value of matrix resins and prevent polypropylene (PP) from being decomposed.The grafting ratio could be easily obtained from an experimental formula deduced from the linearity relationship between grafting ratio and MFI. The effect of cardanol grafted onto PP on the compatibility of PP and bamboo powder was studied by contact angle measurements, scanning electron microscopy, and tensile properties test.
In this study, lauryl methacrylate grafted onto bamboo fibers (BF-g-LM) was prepared to improve the interfacial compatibility between hydrophilic bamboo fibers (BFs) and hydrophobic plastic. The lauryl methacrylate (LM) was initiated by benzoxyl peroxide (BPO) and grafted onto BFs via a free-radical chain-transfer reaction. LM was grafted onto BFs with ether bonds, and differential scanning calorimetry indicated that the ether pyrolysis of BF-g-LM occurred at 280 C. The optimum preparation conditions were obtained as follows: 0.30 g of pretreated bamboo flour was immersed in 0.225 mol/L LM. The reaction was then initiated by 0.025 mol/L BPO, and this reaction was sustained for 4 h at 80 C. BF-g-LM served as coupling agent between the BFs and the polypropylene (PP) matrix, as shown by scanning electron microscopy analysis. The elongation at break of the BF/PP composites with BF-g-LM increased to two times compared to that of the BF/PP composites without BF-g-LM. The impact strength and maximum deflection also increased to 75 and 580%, respectively. In conclusion, BF-g-LM is a promising coupling agent that can be used in BF-reinforced thermoplastic composites.
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