Preparation And Properties Of Polyvinyl Alcohol Based Hydroxylamine Nitrate Gels

Gel propellant is to use a small amount of gelling agent to gel the liquid component(fuel,oxidizer or a mixture of the two)about 3 to 1000 times its weight,so that a large amount of solid fuel is uniformly suspended in the system to form a gel system with a certain structure and specific properties and can maintain long-term stability.As an alternative to hydrazine liquid propellant,hydroxylamine nitrate gel propellant has the advantages of high energy,high density and low toxicity,and has the special rheological properties and state of existence of gel system.Therefore,the study of hydroxylamine nitrate gel propellant with high strength and high toughness has become the focus of researchers.In this paper,physical-chemical double cross-linked polyvinyl alcohol(polyacry lamide-acrylic acid)double network hydrogels were prepared by polymerizing acrylamide-acrylic acid with polyvinyl alcohol gel as the first network by UV irradiation.the PVA/PAm AAc double network hydrogels have high mechanical strength,good swelling capacity and self-recovery ability.The tensile strength and elongation at break can reach 0.870 MPa and291% at the second network(PAm AAc)content of 150% and AAc content of 20%;and the tensile strength and elongation at break of the gel system can be controlled by adjusting the acrylic acid content.Combined with the design idea of multi-network structure hydrogel,on the basis of PVA/PAm AAc double network structure hydrogel,given that chitosan is a kind of natural polysaccharide with a large number of amino and hydroxyl groups in the molecule and green and non-toxic,the second network of chitosan modification is introduced.A strong PVA/PAm AAc-CS hydrogel was prepared by in situ free radical co-polymerization using the feature that acrylic acid can dissolve chitosan.It was found that the tensile strength of PVA/PAm AAc-CS hydrogel with CS/AAc monomer ratio of 3:7 and 10% addition of the composite monomer reached 632 k Pa and the tensile elongation at break reached 402.3%.The series of gels with different ratios of PVA/PAm,different amounts of cross-linking agent and different additions of graphene oxide(GO)were prepared by adding graphene oxide which can cross-link with PVA gel and PAm gel by using polyvinyl alcohol(PVA)gel as the first network and PAm by acrylamide(Am)radical polymerization as the second network.The second network content,cross-linker content and GO content in the hydrogels have a large influence on the mechanical properties of the hydrogels.Among them,the tensile strength and elongation at break of the gels were up to 1.612 MPa and 337.2%,and had good swelling properties.