Effect of the molecular weight of maleated polypropylenes on the melt compounding of polypropylene/organoclay nanocomposites

Abstract

Maleic anhydride grafted polypropylene (PP-g-MA) and organically modified clay composites were prepared in a plasticorder. PP-g-MAs, including Polybond PB3150, Polybond PB3200, Polybond PB3000, and Epolene E43, with a wide range of maleic anhydride (MA) concentrations and molecular weights were used. The structure was investigated with X-ray diffraction (XRD) and transmission electron microscopy (TEM). PP-g-MA compatibilizers gave rise to similar degrees of dispersion beyond the weight ratio of 3/1, with the exception of E43, which had the highest MA content and the lowest molecular weight. The thermal instability and high melt index were responsible for the ineffective modification by E43. Furthermore, PP-g-MA with a lower molecular weight and a higher melt index had to be compounded at a lower mixing temperature to achieve a reasonable level of torque for clay dispersion. Polypropylene/organoclay nanocomposites were then modified with different levels of PP-g-MA compatibilizers with a twin-screw extruder. The polypropylene/E43/clay system, as shown by XRD patterns and TEM observations, yielded the poorest clay dispersion of the compatibilizers under investigation. The curves of the relative complex viscosity also revealed a systematic trend with the extent of exfoliation and showed promise for quantifying the hybrid structure of the nanocomposites. The mechanical properties and thermal stability were determined by dynamical mechanical analysis and thermogravimetric analysis, respectively. Although PP-g-MA with a lower molecular weight led to better clay dispersion in the polypropylene nanocomposites, it caused deterioration in both the mechanical and thermal properties of the hybrid systems.

Preparation of polypropylene/nanoclay composite fibers

“…6a). The formation of such particles in PP/E43/5PF is probably due to the low miscibility of Epolene E43 in PP matrix [18,19]. This hypothesis is also confirmed in the SEM analysis of an etched PP/Epolene E43 composite.…”

Use of PP Grafted with Itaconic Acid as a New Compatibilizer for PP/Clay Nanocomposites

“…However, in the case of PP, the main difficulty encountered in preparing nanocomposites with O-clays is the lack of sufficient interaction between the hydrophobic polyolefin matrix and still relatively hydrophilic O-clays. [1,7,9,[15][16][17] However, depending on the hydrophilic/hydrophobic balance of a polymer, the polymer chains could enter into the interlayer space of the clay and form either tactoid, intercalated or an exfoliated nanocomposites. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] In the tactoid hybrid structure, the polymer chains mainly surround the stacks of the clay resulting in a material with properties similar to those of microcomposites.…”

Influence of maleic anhydride grafted polypropylene on the dispersion of clay in polypropylene/clay nanocomposites

“…Studies on the effect of compatibilizers on clay intercalation and exfoliation involve various PPCN-related aspects, such as different grafted functional groups, 2,3 grafting position, 4 grafting content [5][6][7][8][9][10][11][12] and compatibilizer loading. [13][14][15] In these studies, polypropylenegrafted maleic anhydride (PP-g-MA) oligomer is usually chosen as the compatibilizer.…”

“…[13][14][15] In these studies, polypropylenegrafted maleic anhydride (PP-g-MA) oligomer is usually chosen as the compatibilizer. 2,5,6,15,16 However, the addition of PP-g-MA oligomer deteriorates mechanical properties, especially at a higher loading, 10,12,15 whereas PP-g-MA compatibilizer with high molecular weight ((HMW) PP-g-MA) does not cause such deterioration. 7,12 Grafting content and MW are two important parameters of PP-g-MA compatibilizer.…”

“…To date, the research results on the effect of MA grafting content on clay intercalation and the mechanical properties of PPCN have been based on either comparison among different PP-g-MA oligomers 5,6,15,16 or comparison between PP-g-MA oligomer and HMW PP-g-MA. [7][8][9][10]12 The differences in MW in those compatibilizers are seldom considered when discussing the influence of grafting content on clay dispersion. It is thus quite necessary to elucidate the specific effect of the MA grafting content of the compatibilizer on the morphology and properties of PPCN without the interference of MW changes in the compatibilizer.…”