Foaming, blends

The effect of blending LDPE with EVA or a styrene-isoprene block copolymer was investigated (178). The properties (thermal expansion coefficient. Young s modulus, thermal conductivity) of the foamed blends usually lie between the limits of the foamed constituents, although the relationship between property and blend content is not always linear. The reasons must he in the microstructure most polymer pairs are immiscible, but some such as PS/polyphenylene oxide (PPO) are miscible. Eor the immiscible blends, the majority phase tends to be continuous, but the form of the minor phase can vary. Blends of EVA and metallocene catalysed ethylene-octene copolymer have different morphologies depending on the EVA content (5). With 25% EVA, the EVA phase appears as fine spherical inclusions in the LDPE matrix. The results of these experiments on polymer films will apply to foams made from the same polymers. 

The efficiency of azodicarbonamide and sodium bicarbonate blowing agents for PE foams was considered (253). These systems, which generate GO2 gas, are more suitable for compression moulding of foams. Blends of the blowing agents have a reduced exotherm, so are more suitable for polymer systems that are temperature sensitive, such as ethylene copolymers. 

ETHYLENE-STYRENE INTERPOLYMER FOAM BLENDS MECHANICAL PROPERTIES AND SPORT APPLICATIONS... 

Foamed blends of ethylene-styrene interpolymer and LDPE were subjected to a range of mechanical tests, including compressive impact testing, Instron compression and Poisson s ratio measurements, compressive creep measurements and compression set and recovery measurements. The data obtained were compared with those for EVA and the suitability of these foamed blends as replacements for EVA in the manufacture of soccer shin guards and midsoles for sports shoes was evaluated. 20 refs. 

Reducing the SAN content promotes a finer dispersed and more homogeneous SAN phase, as can be seen by the TEM micrographs in Fig. 26. The altered microstructure shows a strong impact on the cell structure of the foamed blend systems at a PPE/PS ratio of 75/25 and a SAN content of 30 wt%, the cell size decreases,... 

The cellular structure of the quaternary blend systems after foaming at 180°C for 10 s is highlighted in Fig. 33. An excellent homogeneity down to the microscale can be detected for all foamed blend compositions. As already discussed in the previous section, simultaneous foaming of the PPE/PS and the SAN phase in the noncompatibilized blend leads to a bimodal cell size distribution. Besides larger cells induced by the highly expanded SAN phase, smaller cells are formed in the PPE/PS phase (Fig. 33a). 

Beside the development of new strategies for controlling cellular structure, the potential of foamed blend systems needs to be transferred into industrial applications. As demonstrated, blending allows one to reduce the cell size and to increase the cell density, beneficial for thermal insulation applications, while the mechanical or barrier properties can be improved via multiphase cell walls. 

Sahagun CZ, Gonzalez-Nunez R, Rodrigue D (2006) Morphology of extruded PP/HDPE foam blends. J Cell Plast 42 469 185... 

Of particular note to date are developments using ESI-based materials in foam applications. Novel foam structures offer attractive properties and characteristics including softness, esthetics and drape for a wide range of thermoplastic and crosslinked foam applications. Other product technologies of interest are as injection molded structural foams, as foamed layers in multilayer structures and as foamed blends of interpolymers with styrenic and olefinic polymers [77-79], Interpolymers also have potential for co-extruded film and sheet applications. 

PP, PE, PS, PMMA or PVC was blended sequentially cured and foamed blends Cakmak and Dutta, 1992 ... 

PP blended with EPR and EPDM, easily foamed blends with DeNicola ex/., 1997... 

Micro-domains Microfibrils Micro-foamed blends Micro-phase separation Microrheological parameters Microrheology of emulsions Microrheology... 

Blends should be avoided, unless they are properly examined and found not to cause foaming (blends of long-chain fatty with short-chain FA oils are known for their foaming effect). 

High foaming blend for liquid hand dishwash formulations. 

Table 11.17. Wire Extrusion Conditions for PVDF Foaming Blend ... 

Figure 39. TG curves of unpyrolysed trimethylolpropane trimethacrylate (SR 350) (crosslinked), foamed semi-rigid polyurethane, and unpyrolysed trimethylolpropane trimethacrylate/polyurethane foamed blends (SR 350/PU weight ratio = 5.25/1, low-PU and 1/1, high-PU) under nitrogen...

Chem. Descrip. High foaming blend of surfactants and emulsifiers Uses Machine cleaner to remove grease, wax, dye, and trimmer from surf, of all types of dyeing and finishing equip. 

Based on the proceedings of the eleventh international Cellucon conference held in Tsukuba, Japan, this book offers a comprehensive overview of recent research undertaken into all aspects of environmentally compatible polymers. It deals with natural and synthetic pol5nner materials such as gels, fibres, pulp and paper, films, foams, blends and composites and shows how environmental compatibility such as biodegradability and recyclabihty can de developed by utifising natlual polymers such as polysaccharides and polyphenols. 

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