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ABSTRACT1,6‐Hexanediol diacrylate (HDDA), pentaerythrithyl tetramethacrylate (PETMA), and triallyl‐isocyanurate (TAIC) were used as representative monomers to modify polypropylene (PP) in the presence of dicumyl peroxide (DCP) in a mixer. Fourier transformed infrared spectroscopy (FTIR) results confirmed that all the three polyfunctional monomers have been grafted on PP backbone. The shape of torque curves suggested the occurrence of grafting and/or crosslinking structure. The rheological behaviors of HDDA modified PP showed the highest G′ and lowest tan δ at low frequency, shear‐thinning shifted to lower frequency in η*–ω plot, as well as more deviation from semicircle characteristic of linear PP at high viscosity in Cole–Cole plot. And, the improvement of the mechanical properties followed the order as below: TAIC < PETMA < HDDA. Meanwhile, the foamability of the modified PP samples was also investigated. The cellular structure and morphology of the obtained foams were observed by scanning electron microscopy (SEM), and the results indicated that the foamability of the three modified PPs followed the same order, demonstrating HDDA modified PP foam possessed the highest cell density and expansion ratio, and the most well‐defined closed cell structure and uniformly cellular morphology. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1675–1681, 2013

Blends of recycled poly(ethylene terephthalate) (R-PET) and (styrene-ethylene-ethylene-propylene-styrene) block copolymer (SEEPS) compatibilized with (maleic anhydride)-grafted-styrene-ethylene-butylene-styrene (SEBS-g-MAH) were prepared by melt blending. The compatibilizing effects of SEBS-g-MAH were investigated systematically by study of the morphology, linear viscoelastic behavior, and thermal and mechanical properties of the blends. The results show that there is good agreement between the results obtained by rheological measurement and morphological analysis. The rheological test shows that the melt elasticity and melt strength of the blends increase with the addition of SEBS-g-MAH.The Cole-Cole plots and van Gurp-Palmen plots confirm the compatibilizing effect of SEBS-g-MAH. However, the Palierne model fails to predict the linear viscoelastic properties of the blends. The morphology observation shows that all blends exhibit a droplet-matrix morphology. In addition, the SEEPS particle size in the (R-PET)/SEEPS blends is significantly decreased and dispersed uniformly by the addition of SEBS-g-MAH. Differential scanning calorimeter analysis shows that the crystallization behavior of R-PET is restricted by the incorporation of SEEPS, whereas the addition of SEBS-g-MAH improves the crystallization behavior of R-PET compared with that of uncompatibilized (R-PET)/SEEPS blends. The Charpy impact strength of the blends shows the highest value at SEBS-g-MAH content of 10%, which is about 210% higher than that of pure R-PET. J. VINYL ADDIT. TECHNOL., 00:000-000,

In this work, zinc N,N‐dimethyldithiocarbamate (ZDMC) was used to mediate the melt modification of polypropylene (PP) with 1,6‐hexanediol diacrylate (HDDA) in an internal mixer in the presence of dicumyl peroxide (DCP). Fourier transformed infrared spectroscopy analysis revealed that HDDA was directly grafted onto PP backbone. The dependence of torque on processing time indicated that the presence of ZDMC restrained the degradation of PP, and the end‐torque value increased with the addition of ZDMC. Dynamic rheological measurement indicated that the modified PP possessed higher G′ and lower tan δ at low frequency, displaying an increase in η* and disappearance of Newtonian plateau in η*–ω plot, as well as larger radius of semicircle in Cole–Cole plot. All the rheological characterizations, together with the decreased gel content with the increase of ZDMC, confirmed the formation of long‐chain branching. Subsequently, the foamability of the modified samples was investigated by one‐step compression–molding process. The cellular structure and morphology of the obtained foams were observed by scanning electron microscopy, and the results showed that the addition of ZDMC decreased the cell size, increased the cell density, and brought about well‐defined closed cell structure. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

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