Construction Of Calcium Alginate Fiber-reinforced Hydrogel System And Research On The Performance

Traditional fiber composite hydrogels are mostly reinforced with high-strength and high-modulus fibers,which enhance the mechanical properties of hydrogel materials,but the biocompatibility and bonding effect between the fibers and the matrix are poor,which limit their applications in tissue engineering and other fields.In this paper,calcium alginate fibers with good biocompatibility were prepared by wet spinning,and then the bundled fibers were twisted to form a helical structure to enhance their mechanical properties.Then the fibers were compounded with hydrogel to prepare fiber composite hydrogels with good mechanical properties and mechanical anisotropy,and the enhancement mechanism was investigated.The main research contents of this paper are as follows.（1）The calcium alginate fibers with uniform morphology were prepared by wet spinning process,and the mechanical properties of calcium alginate fibers were enhanced by introducing helical structure and stretching oriented alginate polymer chain segments through twisting effect.The test results showed that the mechanical properties of the bundle fiber with 80 twists were optimal,with an average tensile strength of 10.270±0.854 MPa and an average toughness of 5.210±0.200 MJ/m³,which were improved by 127.36%and 155.14%,respectively,compared with the bundle fiber without twists.（2）Calcium alginate bundle fibers with 80 twist were compounded with poly（acrylamide-acrylic acid）hydrogels,then the pure and fiber-composite hydrogels were soaked in different concentrations of ferric chloride solution.Then the different types of hydrogels prepared were subjected to tensile tests and pure shear tests,and the effects of different factors on the performance of the fiber composite hydrogels were analyzed according to the test results and the enhancement mechanism was investigated.The results showed that the addition of calcium alginate fibers significantly improved the mechanical properties compared with the pure hydrogel,and the tensile strength and toughness of the bundled fiber composite hydrogel increased by 681.86%and 1243.60%,respectively,compared with the pure hydrogel.The test results were comprehensively analyzed,and finally 0.01 mol/L ferric chloride solution was selected.The tensile strength and toughness of the pure gel after soaking in ferric chloride solution increased by 7204.34%and 9135.42%,respectively,compared with the pure gel.The above results indicated that both the addition of calcium alginate bundle fibers and soaking in ferric chloride solution could significantly improve the mechanical properties of the pure hydrogel.Subsequently,the fiber composite hydrogel soaked in ferric chloride solution was tested and found to have a tensile strength of 2.540±0.172 MPa and a toughness of 6.572±0.382 MJ/m³,which were both improved compared with the pure hydrogel soaked in ferric chloride solution and the fiber composite hydrogel not soaked in ferric chloride solution,indicating that Fe³⁺and calcium alginate fibers can synergistically enhance the mechanical properties of the fiber composite hydrogel.The pure shear test showed that the fracture energy of pure hydrogel was 1.320±0.320 KJ/m²,and the fracture energy of 3 and 6 bundles of fiber composite hydrogel soaked with ferric chloride increased by 951.5%and 1103.8%,respectively,which indicated that the fibers could effectively bond with the matrix and enhance the tear resistance of the composite hydrogel.Finally,the enhancement mechanism of the fiber composite hydrogel was investigated based on the test results.（3）The anisotropic tensile test of the fiber composite hydrogel showed that the tensile strength of the fiber parallel to the tensile direction was 3.048±0.431 MPa and the toughness was 1.987±0.215 MJ/m³,while the tensile strength of the fiber perpendicular to the tensile direction was 0.695±0.183 MPa and the toughness was 1.231±0.261 MJ/m³.The tensile strength and toughness of the fiber parallel to the tensile direction were improved compared with those perpendicular to the tensile direction.The tensile strength and toughness of fibers parallel to the tensile direction were increased by 338.56%and 61.41%,respectively,compared with those perpendicular to the tensile direction,which proved the obvious mechanical anisotropy of the fiber composite hydrogel.