Preparation And Application Of Melt-spun Degradable Conductive Polyurethane Fiber

Polyurethane materials are widely used in many fields of national production and daily life due to their unique structure and excellent performance.The polyurethane products currently used are difficult to degrade naturally and are prone to harm the environment and organisms.Therefore,it is necessary to develop polyurethane with degradable properties.This paper uses biodegradable polylactic acid(PLA)as a hard segment to synthesize biodegradable polyurethane(BTPU).Then,it was compounded with aminopropyl terminated multi walled carbon nanotubes(CNTs)and a biodegradable BTPU/CNTs conductive fiber was prepared using melt spinning technology,and its sensing performance was studied.In order to improve the sensing performance of BTPU/CNTs conductive fibers,BTPU was modified with aminopropyl terminated polydimethylsiloxane(PDMS)to prepare degradable Si/BTPU/CNTs conductive fibers,and their conductivity was studied.The main research content and conclusions are as follows:(1)PLA was synthesized by ring opening polymerization of L-lactide(L-LA),which was used as a reactant with polytetramethylene(PTMG)and isophorone diisocyanate(IPDI).Polylactic acid based degradable polyurethane(PLA-BTPU)with different PLA contents was obtained through stepwise addition polymerization.The research results indicate that the surface morphology of PLA-BTPU film is regular and has good mechanical properties;The maximum elongation at break of 5%PLA-BTPU can reach 967%,with a breaking strength of 6.95 MPa and an elastic modulus of 1.75 MPa.In addition,the mass loss rate of 5% PLA-BTPU after 4 weeks of degradation in PBS buffer was as high as 5.9%.(2)Composite 5% PLA-BTPU with different mass fractions of CNTs(6%,8%,and 10%),and prepare BTPU/CNTs conductive fibers using melt spinning technology.The research results indicate that the surface of BTPU/CNTs fibers is smooth and the cross-section is approximately circular;The fiber has excellent mechanical properties.The BTPU/10% CNTs conductive fiber obtained by spinning at 200℃ has good mechanical and sensing properties.The breaking strength can reach 9.2 MPa and the elongation at break can reach 792%;The sensing strain working range can reach 30%,and the sensitivity can reach 30.After 5000 tensile release cycles,it has demonstrated good durability and stability.(3)In order to better improve the elongation at break and flexibility of PLABTPU,polydimethylsiloxane(PDMS)terminated with aminopropyl group was selected to chemically modify 5% PLA-BTPU to obtain modified polyurethane(Si/BTPU).Mechanical performance testing found that the elongation at break and flexibility of Si/BTPU were improved,with a maximum elongation at break of 1220%,a fracture strength of 5.88 MPa,and an elastic modulus of 1.59 MPa for Si/BTPU with a 1% PDMS content.In addition,the mass loss rate of 1% Si/BTPU after 4weeks of degradation in PBS buffer can reach 4%.(4)Composite 1% Si/BTPU with CNTs and prepare Si/BTPU/CNTs conductive fibers using melt spinning technology.The research results indicate that Si/BTPU/CNTs fibers have better mechanical and sensing properties.The Si/BTPU/10% CNTs conductive fibers obtained by spinning at 200℃ have a breaking strength of 8.25 MPa and an elongation at break of 1054%;The sensing strain working range can reach 395%,with a sensitivity of up to 42.It has demonstrated good durability and stability after 10000 tensile release cycles.Simultaneously able to accurately and quickly respond to human activities such as finger bending,wrist bending,elbow bending,and knee bending.