PE-POM blends

Results/Morphology. LM micrographs of the melt structure of the PE-POM blends at 170 c are displayed in Figure 2. The components are phase separated. The diameter of the dispersed particles of the POM, that is the minor component in these figures, decreases from about 20pm after one extrusion run to about 5pm after five ones. 

Figure 2. LM micrographs of a PE/POM = 85/15 vol.-% blend after one (a), and five (b) extrusion cycles. Scale bar corresponds to 30pm.

To prepare the graft copolymer, a PO (MW = 50 to 1,000 kg/mol) was either dissolved or swollen in an inert hydrocarbon, monomers (>80 wt% of a methacrylic ester, CH2=C(CH3)COOR) and an initiator was added to the heated mixture while stirring. As a result, acrylic branches of a relatively high molecular weight (MW = 20 to 200 kg/mol) were grafted onto the PO macromolecules. The graft copolymer could be used as a compatibilizer-cwm-impact modifier in a variety of polymers selected from between PO, acrylic polymers, SAN, EVAc, PA, PEST, PC, POM, PAr, PVC, ABS, PVDC, cellulosics, polyester-polyether block copolymers, PEA, PEEK, PEI, PES, CPVC, PVDF, PPE, PPS, PSF, TPU, PAI, PCL, polyglutarimide, blends of PEST with PC or PVC [Ilendra et al., 1992, 1993]. 

POM was blended with 1-5 wt% of either PE, EVAc, PEG POM was blended with 90-99 wt% of LDPE PE or PP with EVAc and either POM, PMMA, PS or SMM POM was blended with EVAc and HOPE POM was first blended with TPU, then with either PA, LLDPE, PP, PBT or PET Burg et al., 1972 Rudin and Schreiber, 1964b Yamamoto et al., 1971 Ishida and Masamoto, 1974 Flexman, 1992... 

PPS and PEEK blended with a fluoro(co)-polymers and reinforced with either CF or GF were wear resistant with a short break-in period for forming a self lubricating film [Davies and Hatton, 1994]. Many commercial blends contain fluoropolymers (primarily PTFE) for the improved weatherability, wear and solvent resistance SUPEC — self-lubricating blend of crystalline PPS with PTFE and 30 wt% GF, Lubricomp blends from LNP and similar/JTP blends from RTP Co. (e.g., 15 wt% PTFE, 30 wt% GF and any of the following resins ABS, PA, PEST, PC, PE, PEI, POM, PP, PPE, PPS, PS, PSF, PVDF, SAN, TPU, PEEK, PES, etc.), Sumiploy from Sumitomo Chem. Co., etc. [Utracki, 1994]. 

These blends are immiscible, thus should be compatibilized and toughened. Addition of POM to PC improves the solvent and chemical resistance (MUler 1972). PC blends with POM and TPU were easy to mold into articles having high impact strength (Silvis et al. 1990). POM-b-PC was used either as a compatibilizer or as a modifier of performance for such polymers as PES, PEEK, PA, and PAN (Dhein et al. 1993). 

Polycarbonate, PC. PC was introduced in 1958. To improve its processability, impact behavior, and solvent resistance, PC must be modified. The first blends with polyolefins, PO, or with ABS were developed in 1960. These were rapidly followed by alloys with polysiloxanes in 1961, PAES in 1965, PET in 1966, POM in 1968, PSF -n ABS in 1969, PES -n ABS in 1970, PBT in 1971, PA or PPE + SBR in 1973, PPS in 1974, PS in 1976, styrene-maleimide (SMI) in 1977, polyaramid (PARA) in 1979, etc. Owing to the chemical nature of the statistical segment, PC can be readily compatibilized or modified, becoming a frequent component of polymer blends. Its affinity to acrylates has been widely explored. However, only in 1986 was its miscibility with polymethylmethacrylate, PMMA, disclosed [Kambour, 1986]. These blends were found to be suitable for glazing materials and optical disks. Another miscible blend of PC (with aliphatic polyester of neopentyl glycol) was discovered in 1991 [Lundy et al., 1991]. Commercial PC/PA blends are relatively recent. In 1992 Toray Industries introduced Toray-PC and Rohm Haas Paraloid. Both blends contain about 30 % of PARA and PA, respectively. 

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