The Pretreatment Of Aramid Pulp And Its Application In Thermoplastic

Aramid pulp as a differentiated product of aramid fiber,not only has excellent mechanical properties,heat resistance,wear resistance,etc.,but also the backbone fiber of the aramid pulp contains a lot of micro fibrils having a huge specific surface area to present a three-dimensional network structure.Therefore it has a widely application prospect in the aspect of comprehensive performance modification of thermoplastic.In order to take full advantage of the structure and performance of aramid pulp,the experiment uses inorganic powder isolating the micro fibrils of aramid pulp by the electrostatic adsorption of aramid pulp to reduce fiber entanglement,so that the micro fibrils can fully extend in the polymer matrix,playing a part in the polymer matrix modification.Firstly,this paper characterized the structure and properties of aramid pulp,showing that aramid pulp contains large amounts of micro fibrils,which random disperse between the trunk fibers of the aramid pulp,the fibrils contact and tangle to form interspace.Under the condition of fully understand the structure and properties of the pulp,we compared the isolation effect of different inorganic powders insulating the aramid pulp,and studied the influence of the isolation on the properties of polypropylene mechanical properties and processing.It found that the talcum powder segregated aramid pulp had the best comprehensive performance.The synergistic effect was created by talcum powder segregating the micro fibrils of aramid pulp and pulp also peeling the talcum powder.Secondly,the influence of the dispersion of aramid pulp and the talcum powder insulating the aramid pulp on the properties of polypropylene was investigated.The results showed that micro fibrils of aramid pulp could disperse in polypropylene,promoted the heterogeneous crystallization of polypropylene and improved the comprehensive performance.When 15 dosage of aramid pulp was used,the tensile strength,flexural strength,flexural modulus and impact strength of modified polypropylene were improved by 34.5%,35.1%,71.0% and 42% respectively compared with pure polypropylene.The talcum powder insulating the aramid pulp promoted the dispersion of pulp,which had a synergistic effect to further improved the mechanical performance of polypropylene.When 15 dosage of aramid pulp and 20 dosage of talcum powder were used,the material had comprehensive mechanical performance.The tensile strength,flexural strength,flexural modulus was 42.2MPa,60.1MPa,2340 MPa,which improved 34.8%,49.5%,118.7% respectively compared with pure polypropylene.The isolation of aramid pulp by talcum powder promoted the heterogeneous crystallization of polypropylene.The thermal properties and Vicat softening temperature increased,but processing performance decrease with the amount of talcum powder increased.Finally,the influence of the aramid pulp and modified talcum powder insulating aramid pulp on the properties of nylon 6 was investigated.The results showed that aramid pulp well dispersed in the matrix,significantly improved the mechanical properties and thermal performance of the material by the interlock and the role of hydrogen bonds of aramid pulp with the nylon 6,and promoted the heterogeneous nucleation crystallization of the matrix.The talcum powder insulating the aramid pulp promoted the dispersion of pulp,which further improved the mechanical properties of nylon 6.The tensile strength,flexural strength,flexural modulus of the material was 94 MPa,133MPa,3900 MPa,which improved 48.7%,39.9%,85.7% respectively compared with pure nylon 6.The isolation of aramid pulp by talcum powder promoted the heterogeneous crystallization of the nylon 6.The thermal properties and Vicat softening temperature increased,but processing performance decrease with the amount of talcum powder increased.