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ABSTRACT:The preparation of nanocomposites of poly (ethylene terephthalate) (PET) and lamellar zirconium phosphorous compounds by melt extrusion was investigated. Two types of zirconium phosphorous compounds were synthesized by the direct precipitation reaction method: a-zirconium bis(monohydrogen orthophosphate) monohydrate (ZrP) and organic-inorganic hybrid layered zirconium phenylphosphonate (ZrPP). Composites containing 2 and 5 wt % ZrP and ZrPP were prepared in a twin-screw extruder and specimens were obtained by injection molding. The extent of dispersion of the layered filler in the composite matrix was investigated by X-ray diffraction and transmission electron microscopy (TEM). The crystallization and thermal properties were analyzed by differential scanning calorimetry and thermogravimetry, and the mechanical properties were evaluated by tensile tests. Whereas ZrP-containing composites showe characteristic diffraction peaks at 2y 11.78 (d ¼ 7.54 Å ), indicative of no delamination, ZrPP showed practically no low-angle diffraction peak at 2y 5.58 (d ¼ 15.24 Å ), indicating loss of the layered order. TEM images of ZrPP particles indicated the formation of an intercalated/partially delaminated nanocomposite. The behavior was attributed to the higher affinity of the polyester with phenyl groups on the platelet surface of ZrPP. In both cases, the addition of the fillers increased the crystallization rate and the modulus.

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The influence of hydrogenated olio(cyclopentadiene) (HOCP) on tensile mechanical properties of its blends with high density polyethylene (HDPE) has been studied at 20, 80, and 100°C. The nominal stress‐strain curves performed at 20°C indicate an increase of the modulus and a conspicuous decrease of the ultimate properties increasing the HOCP content in the blend. Blends with HOCP content > 20%‐wt are found to be very fragile at 20°C. These behaviors have been related to the presence of the HOCP‐rich phase that has the glass transition at about 55°C. At 20°C the HOCP oligomers act as a hardener for the HDPE. The nominal stress‐strain curves performed at 80 and 100°C show a strong decrease of the modulus (compared to the value at 20°C), plastic deformation for all the blends tested, and rupture of HDPE and blend samples at the beginning of the cold‐drawing. Moreover, the modulus and the ultimate parameters are found to decrease with the composition. The behaviors at 80 and 100°C have been related to several factors: the higher mobility of HDPE molecules at these temperatures compared to that at 20°C; the HOCP‐rich phase that is at temperatures higher than its glass transition, and so it acts as a plasticizer for the HDPE; and the decreases of crystallinity and number of entanglements when the HOCP is added to the HDPE component. ©1995 John Wiley & Sons, Inc.