Modification Of Sisal Fiber By Sol-gel Technology And Its Effect On The Mechanical Properties Of Composites

In this paper,the silica sol was prepared by Sol-gel technology using the ethyl orthosilicate?TEOS?as the main raw material to improve the performance of sisal fiber?SF?.Two different treatment methods were used.First,a homogeneous solution with TEOS,absolute ethanol,water,and hydrochloric acid was prepared to treat the fiber.The effects of the amount of water,the pH value,the conservation temperature and the conservation time on the properties of sisal fibers were studied.Orthogonal experiments show that single fiber tensile strength is the largest when the H₂O:TEOS?molar ratio?is 8,the pH value is 4.1,the conservation time is 5 h,and the conservation temperature is 25°C,this is an 27.00%increase compared to untreated fiber.Second,a homogeneous solution with TEOS,absolute ethanol,and acetic acid were used to modify hygroscopic fiber.The results show that the tensile properties of single fibers increased with the increase of fiber moisture absorption rate.The tensile strength of fiber increased by nearly 29.21%when the fiber moisture absorption rate is 22.70%.Compared to the first treatment method,the improvement of tensile properties was more obvious.Traditional alkali treatment,silane treatment?KH550?,TEOS treatment,and TEOS-KH550 combination treatment were used for comparative analysis,and thermal gravimetric analyzer?TGA?,scanning electron microscope?SEM?,infrared absorption spectroscopy?FTIR?and instron material testing machine were used to characterize the performances of the fibers.SEM shows that a coating can be clearly observed on the surface of fibers by TEOS,KH550,and combination treatment.FTIR indicates that the presence of Si-O-Si bond absorption peak is clearly observed by the TEOS and TEOS-KH550 combination treatment.The heat resistance of the combination treated fibers is significantly improved.Compared to untreated fibers,the tensile strength and modulus increased by 31.58%and 15.82%,respectively.Single fiber fragmentation test was used to determine the interface property between the fiber and polypropylene matrix.The results show that the interface shear strength value of the combination treatment is the highest,so the interface performance is the best.The addition of MAPP can significantly improve the interfacial property between the fiber and the matrix,which is nearly 2 times higher than that without MAPP,and the interfacial shear strength value of the combination treatment with MAPP increased by nearly 77.73%.Compared to the untreated fiber composite,the tensile strength increased by 21.72%and the modulus increased by 28.17%.Impact strength increased by approximately 21.28%.Flexural strength and modulus increased by 3.61%and 16.02%,respectively.And the sol-gel technique has a significant improvement in the modulus of composites.In conclusion,the sisal fiber/polypropylene resin composites modified by sol-gel technology were successfully prepared,and the mechanical properties of the composites were improved significantly.