Compatibilized PP/TPU Blends Through γ-radiation And Compatibilizers

In this work, the blends with different ratios of polypropylene/thermoplastic polyurethane(PP/TPU) were prepared through melt mixing by using a twin-screw extruder, with EPDM-g-MAH (mEPDM) and POE-g-MAH (mPOE) were used as the compatibilizer. Radiation treatment of different doses(D≤25kGy) was applied to the blends. The effect of the y -radiation and compatibilizer on their mechanical properties , thermo properties and rheological behavior was systematically investigated.PP and TPU are immiscible, The compatibility of simply blended PP/TPU can get improved through the γ-radiation in air at modest radiation dose (D) and the introduction of the compatibilizer, and the strengths rigidity and toughness of the blend were improved greatly. The ability of compatibilization is ranked in a decreasing order as EPDM-g-MAH > POE-g-MAH > γ-radiation. About 5(phr) compatibilizer was enough to improve the compatibility of the blend. Use Y -radiation and compatibilizer together showed a better result than only use one way.DMA showed that the the glass-transition-temperature (Tg) and dynamic storage modulus (E') of γ -irradiated PP/TPU and PP/mEPDM/TPU were increased. And the effect of Y -radiation on the Tg and E' of PP/mEPDM/TPU blend was less than that of PP/TPU.After 25kGy Y -radiation, Tm°, Tmp and tmf of PP/TPU3 blend were decreased, and Tc° , Tcp maintained almost unchanged, while △Hm, Tcf and AHc increased. Because of the introduction of the compatibilizer to PP/TPU3 blend, Tm°, Tmp and Tmf were decreased, while Tco, Tcp,Tcf,△Hm and AHc all increased. When the γ -radiation was applied to the PP/mEPDM/TPU3 blends, △Hm and AHc were decreased while Tc increased.PP formed small crystallite in both PP/compatibilizer/TPU blend and Y -irradiated PP/compatibilizer/TPU blend, and the elastomer dispersed among thecrystals in the form of particles. The size of crystallite was decreased with the increase of the content of compatibilizer and D. Compared with the PP/TPU3 blend, PP's crystals in PP/compatibilizer/TPU3 blend were smaller.SEM indicated that mEPDM enhanced the interaction between PP and TPU, improved the compatibility between PP and TPU, When the mEPDM content was 5 by phr, the compatibility can be improved remarkably.When the radiation dose (D) was in the range of 1~25kGy, the melt flow rate (MFR) of the γ -irradiated PP/TPU was recreased remarkably with the increase of D. The MFR of PP/mEPDM/TPU were decreased with the increase of the mEPDM content, while increased with the increase of the D. MFR of PP/mEPDM/TPU3(85:5:15) is the half as PP/TPU3(85:15) blend. When D is high, MFR of the blend was influenced slightly by the mEPDM's content.Within the range of shear rate studied, the melt of PP, PP/TPU and PP/mEPDM/TPU blends all represented a pseudo-plastic fluid flow character. The apparent viscosity of PP/TPU and PP/mEPDM/TPU melt decreased with the increase of shear rate and shear stress, decreased with the rise in temperature, and increased with the increase of the content of EPDM-g-MAH in the blend, but the viscous flow activity energy decreased.