Preparation And Properties Of ABS/Palygorskite Clay Composites

Acrylonitrile-butadiene-styrene (ABS) is a widely used thermoplastic material due to its banlanced mechanical properties, good chemical resistance and processing advantages. However, in many application cases, it needs the property of flame retardant. At present, the major flame retardant ABS materials containing halogen are restricted. Because they produce lots of toxic gases and corrosive smokes while burning. In view of these situation, intumescent flame retardant (IFR) and palygorskite silicate clay which are halogen-free and low toxicity were determined to be the main flame retardant for ABS. In this paper, considering the specialty of ABS resin for halogen-free flame retardant, three aspects were studied including modification of palygorskite clay, ABS/palygorskite clay composites and ABS/IFR/ palygorskite clay composites.In the first part, the palygorskite clay was successfully grafted by Vinyl tris-(2-methoxyethoxy) silane (KH-172). X-ray diffraction (XRD) analysis, thermo- gravimetric analysis (TGA) and transmission electron microscopy (TEM) were used to charaterize the puritied palygorskite clay and the silane modificated palygorskite clay. All results demonstrated that there was notable chemical absorption and physical absorption in the surface of palygorskite clay.In the second part, ABS/PGS and ABS/OPGS composites were prepared by melt blending. TGA results showed that the addition of PGS or OPGS accelerated the catalytic carbonization of ABS, which could improve flame retardancy of the composites, but it is not very efficent. It was found that puritied palygorskite clay contentis 3 % could improve the mechanical property of ABS resin, such as, tensile strength and elongation at break. The morphology of the fractured surface and the degree of dispersion for the clay in the ABS matrix also observed by scanning electron microscopy (SEM). The results show that the dispersity and compatibility of orgpalygorskite clay in the composite materials was improved after modified. It was possibly due to the surface of palygorskite clay changed from hydrophilicity to lipophilicity.In the last part, two kinds of IFR systems were established for ABS composite. The IFR system was composed of pentaerythritol (PER) as an carbon source, ammonium polyphosphate (APP) as an acid source and blowing agent, melamine (MEL) as a bolwing agent, respectively. The influences of ratio and contents of these IFR systems on flame resistance, mechanical properties, microstructure of ABS composites were systematically studied. The results showed that IFR based on APP and PER had the best flame resistance on ABS composite. When the ratio of APP and PER was 2:1 and the content was 35 %, the flame resistance was higher than that of ABS/APP/PER/MEL composites. However, the kind of IFR brought bad effects on mechanical property of ABS composite. In order to improve the mechanical properties of ABS/APP/PER composites, ABS/IFR/OPGS composites were prepared by adding the OPGS by melt blending method. The results show that the OPGS and IFR have a synergistic effect both improve the flame retardant and mechanical properties for ABS composite material.