Morphology co-continuous

Figure 10.2 Graded co-continuous morphology obtained at different depths along the propagation direction of light in a PSAF/MMA (10/90) blend irradiated with 365 nm UV light at room temperature. The number on the upper left in each figure indicates the Z-coordinates of the sample.

Nakanishi, H., Namikawa, N., Norisuye, T. and Tran-Cong-Miyata, Q. (2006) Autocatalytic phase separation and graded co-continuous morphology generated by photocuring. Soft Matter, 2, 149—156. 

Note 2 Representative mechanisms for coarsening at the late stage of phase separation are (1) material flow in domains driven by interfacial tension (observed in a co-continuous morphology), (2) the growth of domain size by evaporation from smaller droplets and condensation into larger droplets, and (3) coalescence (fusion) of more than two droplets. The mechanisms are usually called (1) Siggia s mechanism, (2) Ostwald ripening (or the Lifshitz-Slyozov mechanism), and (3) coalescence. 

Marin N, Favis BD (2002) Co-continuous morphology development in partially miscible PMMA/PC blends. Polymer 43 4723 1731... 

Willemse RC (1999) Co-continuous morphologies in polymer blends stability. Polymer 40 2175-2178... 

Immiscibility of polymers in the melt is a common phenomenon, typically leading to a two-phase random morphology. If the phase separation occurs by a spinodal decomposition process, it is possible to control the kinetics in a manner that leads to multiphase polymeric materials with a variety of co-continuous structures. Common morphologies of polymer blends include droplet, fiber, lamellar (layered) and co-continuous microstructures. The distinguishing feature of co-continuous morphologies is the mutual interpenetration of the two phases and an image analysis technique using TEM has been described for co-continuous evaluation.25... 

The physical interactions in TPE can be characterised by IR spectroscopy. A few examples of such studies are discussed here. Examples of PE based thermoplastic elastomers are NR/PE blends [50, 52]. TPE [49] based on 50/50 NR/LDPE, forms co-continuous morphological structure of both NR and LDPE. Thermal analysis shows that the blend is immiscible and from IR spectra of the 50/50 NR/LDPE blends [53], it is observed, the peaks of NR and PE exist almost in the same positions in the blend with a very little shift (Figure 5.12). The absorption band at 833 cm"1 for cis >C = C in NR (Figure 5.12) is shifted to 836 cm 1. Similarly the peak at 1370 cm"1 (C-H stretching of CH3 group) shifts to 1373 cm"1, while the peak for C=C double bond shifts from 1660 cm"1 to 1658 cm"1, and the band at 1467 cm"1 for -CH2 in LDPE (Figure 5.12) is shifted to 1462 cm 1. The spectra thus confirm that there exist only physical interactions in NR-PE blend. 

PS with recycled PP — co-continuous morphology performance, recyclability Morrow et al., 1994... 

In 1983, Monsanto developed blends with co-continuous morphology, Triax 2000. These alloys comprised PC, ABS, and styrene-methylmethac-rylate-maleic anhydride (SMMA-MA) [Jones and Mendelson, 1985]. One year later, PC was reactively blended with either ABS, SAN-GMA, and NBR, or with graft copolymers of acrylonitrile-butadiene-a-methyl styrene-methyl-methacrylate (MeABS) and acryloiutrile-a-methyl styrene-methyl methacrylate copolymer (MeSAN) [Kress et al., 1986]. The blends were commercialized by Bayer as Bayblend . 

HIPS, PE, and either SBS or SIS a co-continuous morphology SMMA and either a mixture of SBS and a tapered BSB triblock copolymer, or SBR... 

PC with 30 wt% SEBS for co-continuous morphology Gergen and Davison, 1977... 

PP with EPR, then with PE co-continuous morphology — impact Huff, 1978... 

Sequential compounding of PP, first with co-continuous morphology good Huff, 1980... 

PO with 30-40 wt% PS recycled high properties due to stable co-continuous morphology without compatibilization Morrow etaL, 1994... 

Several other machines of this type have been developed since. They all involve intensive mechanical shearing that produces extensive chain scission. Recombination of the free radicals in situ generates sufficient concentration of copolymer, to compatibilize the system. The generated under high stress, non-equilibrium morphology is then locked by quenching. Best performance has been observed for systems with co-continuous morphology. 

Blends of ethylene-methacrylic acid or ethylene-acrylic acid copolymers with PE (Formion ) show either dispersed or co-continuous morphologies. They have outstanding fuel and oil resistance, adhesion to glass and metals, and ease of foaming. The blends are injection molded into bumper end caps, bumper mb strips, fender stone guard, extmded into products such as carpet heel pad and window trim. Moldings can also be foamed for bumper guards. 

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