Transparent heterogeneous blends

In general, the multiphasic heterogenous nature of the impact grade styrene-based polymers is the root cause of their opaque-turbid nature. In determining the transparency of the blends, size and the size-distribution pattern of the dispersed phase along with the refractive index difference between the continuous and the dispersed phases are two very important criterion [133]. 

PVA and PAcr.Ac. are compatible polymers on the whole range of composition [40-45], These blends are homogeneous and the films are transparent evidencing a good clarity [43,57] or semitransparency [43], However a heterogeneous IPN [45] was obtained by acrylic acid polymerization in a PVA matrix. 

New Transparent Impact-Resistant Polymer Blends from Resins and Rubbers Having Minimized Compositional Heterogeneities... 

The phenomenon appears to be similar to the so-called miscibility window in some blends with random copolymers [ten Brinke et al., 1983]. Microphase separation and the evolution of the multiblock copolymer phase in the form of smallsized particles (up to 100 nm in diameter) is the physical basis of their transparency. Thus, these transparent blends are considered micro-heterogeneous systems [Papkov et al., 1998]. Detailed theoretical and experimental investigations are required to understand details of this phenomenon [Sikora and Karasz, 1993]. 

Fig. 5 Films of intrinsically immiscible polymers with and without promotion by supramolecular linking, (a) Heterogeneous film of plain poly(butylmethacrylate) and polystyrene functionalized with 2,7-diamido-l,8-naphthyridine (DAN), (b) Transparent blend of poly(butylmethacrylate) functionalized with ureidoguanosine (UG) and polystyrene functionalized with DAN, thereby enabling quadruple hydrogen bonding of DAN and UG to facilitate polymer mixing. Reprinted with permission from [101]. Copyright 2006 American Chemical Society...

---