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The chain‐extension behavior of 2,2′‐bis(2‐oxazoline) (BOZ) was studied to evaluate the coupling effect on polyamide‐6 (PA6) in a Haake Rheocord mixer and an extruder. The relative torque of PA6 dramatically increased within 1–2 min, and the results were similar whether the added amount of BOZ in PA6 was the theoretical amount or twice as much at 240 °C; however, after 5 min, the coupling results showed an optimal dosage of the chain extender, a lack of which caused a deficiency of chain extension and an excess of which led to a greater blocking reaction. The final torque was 2.16 times as much as that of a control sample when the reaction temperature was 240 °C, and the added amount of BOZ in PA6 was 1.156%; at the same time, the initial carboxyl content of the chain‐extended products decreased to 40% for PA6, and this corresponded to the intrinsic viscosity of PA6 increasing to 1.636 dL/g, whereas that of the control sample was 1.384 dL/g. Furthermore, the effects of BOZ on the thermal and mechanical properties of chain‐extended PA6 were investigated. The degree of crystallinity decreased as the chain extender was added to PA6. The Izod impact strength, tensile strength, and elongation at break of the resultant products dramatically improved under wet conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1976–1982, 2007

The influence of ammonium polyphosphate (APP) with and without synergistic agents -aluminum hypophosphite (Al(H 2 PO 2 ) 3 ), epoxy resin (E-44), and Zeolite 4A -in acrylonitrile-butadiene-styrene/poly(ethylene terephthalate) (ABS/PET) blends was investigated. The limiting oxygen index (LOI) and UL94 tests were used to investigate flame properties. The results showed that APP with and without synergistic agents all improved the flame retardancy of ABS/PET systems. The ABS/PET/ APP þ 2 wt % Al(H 2 PO 2 ) 3 , ABS/PET/APP þ 2 wt % E-44, and ABS/PET/APP þ 3 wt % Zeolite 4A systems achieved the best flame retardancy rating of V0 and LOI values were 32, 34, and 30.5, respectively. The thermal degradation behaviors analyzed by thermogravimetric analysis (TGA) indicated APP mainly accelerated the degradation of PET and led to the increase of charring residues. Al(H 2 PO 2 ) 3 and E-44 resulted in synergistic effects on the charring process of ABS/PET/APP. SEM revealed that the intact, dense, and strong char layer formed on the surface of the ABS/PET/APP/ Al(H 2 PO 2 ) 3 (or E-44) system, which was significantly different from the loose and porous char layer of ABS/PET and ABS/PET/APP systems.

The adjuvant of organic bentonite (OBT), zinc oxide (ZnO), zeolite 4A (4A), aluminum phosphinate (AlPi), terephthaloyl-biscaprolactam (TBC), 2,2 0 -bis(2-oxazoline) (BOZ), and manganese dioxide (MnO 2 ) on flame retardant enhancement of acrylonitrile-butadiene-styrene copolymer (ABS)/polyamide 6 (PA6)/styrene-maleic anhydride (SMA)/ammonium polyphosphate (APP) blends were investigated by using the limiting oxygen index (LOI), the UL-94 (vertical flame) test, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The LOI datas and vertical flame tests showed that the synergistic flame retardant effect of OBT, ZnO, 4A, AlPi, BOZ, and MnO 2 on the ABS/PA6/SMA/APP blend was good, and the LOI value of ABS/PA6/SMA/APP/MnO 2 (55/15/5/ 25/2) system was 33% and class V-0 of UL-94 test was passed. The TGA data demonstrated that the incorporation of adjuvant was known to improve the fire properties essentially accompanied by only minor changes in thermal decomposition. The strong influence of oxygen on the thermal degradation of the ABS/PA6/SMA/APP system, and the oxygen could modify the carbonaceous structure. The microstructures observed by SEM indicated that the adjuvant can promote formation of compact intumescent inorganic-carbonaceous char layers in ABS/PA6/SMA/APP blends. Furthermore, the effects of adjuvant on the mechanical properties of ABS/PA6/SMA/APP blends were also investigated. The Izod impact strength of the ABS/PA6/ SMA/APP/Adj composite showed a little depressing.