A Study On Anti-dripping Polyester Fiber

For their excellent performance, polyester fibers have been widely applied as a textile and industrial material. However, polyester fibers are thermoplastic and flammable, when burning they tend to form molten drops, which can bring burns and other secondary damages, so the modification of polyester fibers to improve the performance of anti-dripping has become an interest of extensive research. At present the studies of anti-dropping of polyester mostly use anti-dropping additives (such as PTFE, nano-particles etc.) to blend with polyester matrix, or use copolymerization method, but these methods have the drawbacks such as difficult spinning with more addition or ineffective anti-dripping with less addition.This paper puts forward a way of forming a thermosetting resin network in the polyester fibers. First, a thermoplastic BENZOGUANAMINE (BG) was added to PET resin, and then the PET/BG blended fibers were prepared, and finally treat the blended fibers were dipped into formaldehyde solution, where BG and formaldehyde would react and form a three-dimensional network of thermosetting resin. When burning the resin can play a protective effect and be rapidly burned into charcoal carbonization. The anti-dripping effect was achieved through increasing the amount of molten droplet adsorption. The rheological properties of PET/BG blends and BG's mobility, the reaction characteristics of BG and formaldehyde, as well as the various structures and properties of PET fibers were studied by means of melt flow rate indexer, RH-7 Capillary Rheometer, EDS, titration method, SEM, FTIR, XRD, TG, DSC, oxygen index (LOI) and the anti-dropping tests.The main research contents and conclusions are listed as follows:(1) The rheological properties of PET, PET/BG blends were investigated by melt flow rate measurer and RH-7 Capillary Rheometer. Results indicated that the melt index of PET/BG blends increased along with increasing of the BG content; the apparent viscosity gradually decreased with raising temperature and shear rate, their melts showed non-Newtonian pseudo-plastic fluid characteristics; under different temperatures non-Newton index(n)and the structural viscosity index and the zero shear viscosity gradually increased along with temperature; the activation energy of viscosity flow increased along with the shear rate. Within the framework of the study, with the increase of BG content, non-Newton index of PET/BG blends melt increased, the structural viscosity index and the activation energy of viscosity flow reduced. That indicated adding of BG into PET had little influence on the spinning properties of the blended resin.(2) Melt flow rate measurement and the X-ray EDS results showed that BG migrated in the preparation process of PET/BG blends.(3) The reaction characteristics were studied using hydroxylamine hydrochloride and the iodometric method, which showed in the hydroxymethylation phase, the best reaction conditions were temperature 80℃, time 40min, pH 8.5; in the condensation stage, the condensation conditions were temperature 80℃, time 2h, pH 4~5. In these conditions, it was easy to form a network structure with multi-crosslinks.(4) SEM, FTIR, XRD results showed that compared with the traditional pure polyester fibers, the anti-dripping polyester fibers' surface was rough, BG in the PET/BG blended fibers and formaldehyde had reacted in the anti-dripping polyester fibers' preparation process, and the crystal structure of PET fibers was not changed with the addition of BG and the associated reactions.(5) The anti-dripping performance test, TG, DSC and oxygen index (LOI) measurements indicated that compared with the traditional pure polyester fibers, their thermal stability reduced, the number of drops of the anti-dripping polyester fiber in unit time(1min) decreased; along with the increase of BG content, char residue was raised, their anti-dripping effect strengthened and LOI increased gradually.