Properties and Characterizations of PBT, PET, Bicomponent PP/PBT and PP/PET Melt Blown Microfiber Nonwovens after Heat-treatment

摘要

Polypropylene (PP)/PET and PP/PBT bicomponent (B/C) microfiber nonwoven websrnwere successfully produced in the new 24-inch Reicofil? bicomponent (B/C) melt blown (MB)rnpilot line in Textiles and Nonwovens Development Center (TANDEC), University of Tennessee,rnKnoxville. The side-by-side (S/S) configuration make it possible to introduce higher crimp andrnother advantages such as lower average fiber diameter, higher web quality and better bondingrnpropertiesrnIn this paper, covered are the properties and characterization of B/C PP/PET and PP/PBTrnmicrofiber nonwoven webs before and after exposure to heat (90~150°C ) for a period of timern(1~7min)rnAs shown in Figure 1, the 100% PET MB nonwoven web shrank significantly to aboutrn23% after exposure to 120 °C for 3 minutes. The Shrinkage of 100% PBT MB nonwoven web isrnnegligible. All bicomponent PP/PBT and PP/PET samples present excellent thermal dimensionalrnstability. As heated at the temperatures ranging 90 to 155°C for 3 minutes, the web shrinkage ofrnbicomponent MB nonwovens are all less than 5%, even though it increases slightly with therntemperature. It is very interesting to notice that a small amount of 25% PP in B/C PP/PET MBrnweb could significantly stabilize the heat shrinkage to approximately 5% even under 155 °C for 5rnminutes.rnThe relatively crystallized PP phase in the side-by-side configuration serves as a framernproviding opposite force to prevent the shrinkage of the PET phase. This mechanism may bernillustrated in Figure 4rnMicrofibers in Pure PET MB nonwoven webs have very low crystallinity index,rntherefore, the webs shrink as high as 25%, which results in increases in fiber diameter, basisrnweight, thickness and decrease in air permeability.rnBoth pure PBT and B/C PP/PBT, PP/PET MB nonwoven webs exhibit excellent thermalrndimensional stability. Due to this stability, these MB webs remain their original propertiesrnunaffected by heat as high as 155°C for 5 minutes. This may lead to new end-uses of these webs,rnparticularly, of B/C PP/PET MB webs in environments where heat effects must be considered,rnsuch as hot gas or liquid filtration.