Morphology development of PP/POE blends with high loading of magnesium hydroxide

Abstract

The influence of high loading magnesium hydroxide (Mg(OH) 2 , MDH) on the morphology and properties of the polypropylene (PP)/ethylene-octene copolymer (POE) blends has been investigated via scanning electron microscopy, dynamic mechanical thermal analysis and tensile mechanical testing. It was demonstrated that the mechanical properties, especially the elongation at break, are highly related to the phase structure exhibited by the composites. In the PP/POE 90/10 and 70/30 blends, the addition of a high 10 loading of MDH lowered the average diameter of the dispersed POE domains, also the MDH and POE domains were separately dispersed in the PP matrix. Meanwhile, the elongation at break of the samples sharply declined to an unacceptable level. While in the PP/POE 50/50 blends, a co-continuous structure was formed and it could be maintained even after large amount of MDH was added. The co-continuous structure was found to be a key factor for tolerating high loading of additives and retaining acceptable 15 mechanical properties, especially the elongation at break. Fig. 6 SEM micrographs of the PP/POE/MDH composites (weight ratio of PP/POE as 50/50) with different MDH contents: (a) 50 wt%; (b) 55 wt%; (c) 60 wt% 75

Optimization of the Mechanical Properties of Polyolefin Composites Loaded with Mineral Fillers for Flame Retardant Cables

“…Table 7 and Figure 2 report the results of tests obtained on composites produced using the 3 wt.% of coupling agent and varying the n-MDH dosage in the range between 56 wt.% (33.8 vol.%) and 64 wt.% (41.6 vol.%), aimed to find the required amount of filler for providing the best trade-off between good flame retardant properties (expressed by Limited Oxygen Index LOI, usually >32 %O2 [30,31]) and adequate mechanical properties required for cable application (i.e., tensile strength >10 MPa and elongation at break >150% [23]). Notably, tensile strength and elongation at break are both enhanced by increasing the dosage of the coupling agent thanks to the double effect provided by the compatibilizing grafted MAH groups and the flexibility conferred by the ULDPE matrix [29].…”

“…Among the listed polymers, those based on VLDPE and mLLDPE (low density polyethylene copolymers based on octene, hexene, or butene obtained through metallocene catalysts) are preferred, being helpful for the elongation at break and primarily on the workability during processing. ULDPE (ethylene α-olefin copolymer) and C 3 -C 2 copolymers, produced with both metallocenic and Ziegler-Natta catalyst, result the most preferred since the more amorphous character and long chain branching better withstand high percentages of fillers [23][24][25][26][27][28][29][30][31][32][33][34][35][36].…”

“…break and primarily on the workability during processing. ULDPE (ethylene α-olefin copolymer) and C3-C2 copolymers, produced with both metallocenic and Ziegler-Natta catalyst, result the most preferred since the more amorphous character and long chain branching better withstand high percentages of fillers [23][24][25][26][27][28][29][30][31][32][33][34][35][36].…”

“…As reported earlier, the major limitation of HFFRs is their excessive content within the polymer matrix. For this reason, copolymers such as ethyleneco-vinyl acetate (EVA) or ultra-low-density ethylene alpha-olefin copolymers were chosen as polymeric matrices, since the high amorphous content allows to incorporate large contents of filler [23]. In this direction, it was decided to test formulations as similar as possible to those used in the cable industry, by varying in one case the polymer matrix, i.e., a blend of EVA with 28% by weight (11% by mols) of vinyl acetate comonomer (EVA28) and a polymer that can be PE or PP, and subsequently the type of the mineral filler.…”

Distribution of an antioxidant in polypropylene/ethylene–octene copolymer blends studied by atomic force microscopy-infrared

“…5,8 In recent years, ethylene-octene copolymer (POE) has attracted much industrial interest as an excellent impact modifier and proved more effective in toughening iPP due to lower interfacial tension and better compatibility between POE and iPP and easier processability than other elastomers, and is gradually replacing EPR and EPDM in iPP toughening. 7,9 So far, numerous studies have been carried out on the miscibility, mechanical properties, morphology and microstructure of iPP/POE blends. It was reported that iPP and POE are partially miscible and their blends usually exhibit a two-phase morphology.…”