Mechanical Properties of Vehicle Nylon Pipes under Different Hot-Humid Aging Conditions
To improve the aging resistance of automotive nylon(PA)pipes,the mechanical properties and aging mechanism of PA pipes with different macroscopic interlayer structures and microscopic polymer structures under a hot-humid aging condition were investigated in this paper.Four specimens[PA11,PA12,PA12-polyethylene fluoride(ETFE),and PA12-PA binder(TIE)-ethylene-vinyl alcohol copolymer(EVOH)-TIE-PA612]were prepared on the industrial production platform.The PA specimens were aged under six kinds of conditions with different temperature and humidity.The tensile and impact properties and the mechanisms were revealed by means of the scanning electron microscope(SEM).The results show that PA12 pipe has good tensile properties but poor impact properties,its fracture form is toughness fracture.PA11 pipe has poor tensile properties but good impact properties,its fracture form is brittle fracture.The mechanical properties of PA pipe decrease with the increase of aging temperature,humidity,and aging time,and the tensile properties are more sensitive to the change of humidity.As the temperature and humidity increase and the aging treatment time prolongs,the impact work of PA pipe is in a decreasing trend.PA12-TIE-EVOH-TIE-PA612 pipe shows the least significant degradation of impact resistance under the same hot-humid aging condition.The smoothness of the fracture surface of PA12 after 240 h of hot-humid aging is significantly reduced.Among the four types of PA pipes,PA12 and PA12-TIE-EVOH-TIE-PA612 have excellent mechanical properties and aging resistance.This paper could provide some guidance for the material and structure designs of PA pipes for automotive use.
万方数据
维普
