Compatibilization, Compatibilizers

The strength can also be increased by using about the same amounts of the two polymers so that they form two continuous phases. Here, both phases can assist the blend to be strong. Another approach is to use compatibilizers. Compatibilizers are materials that help bind together the phases allowing stress or strain to be shared between the two phases. Many compatibilizers are block copolymers where one block is derived from polymers of one phase and the second block is composed of units derived from polymers of the second phase. The two blocks get locked into the structures of the like phases and thus serve to connect the two phases. 

However, a reactive styrene acrylonitrile copolymer (SAN)/gly-cidl methacrylate copolymer was found to be an effective reactive compatibilizer for the blends. Ethyltriphenyl phosphonium bromide was used as the catalyst. Probably, the epoxide groups react either with carboxyl or with hydroxyl groups of the PLLA end groups. This so modified polymer acts as the compatibilizer. Compatibilized PLLA/ABS blends exhibit an improved impact strength and an im-... 

In blends of PTT and ABS, two separate glass transition temperatures are observed, which indicates that the blends are phase separated in the amorphous phase. A styrene/butadiene/maleic anhydride copolymer or glycidyl endcapped epoxy resin may act as a compatibilizer. Compatibilized PTT/ABS blends show a finer morphology and better adhesion between the phases. 

Compatibility tests Compatibility value Compatibilization Compatibilizers... 

Interphase theories Immiscible blends density profile compatibilized compatibilized - semi experimental, p vs. ((). Helfand Tagami, 1971, 1972 Helfand Sapse, 1975 Noolandi, 1984 Utracki, 1991 1992... 

Chemical compatibilization Compatibilization by incorporation of a compatibilizo, usually either a copolymer or multipolymer... 

Physical compatibilization Compatibilization by physical means high stress field, thermal treatment, irradiation, etc. 

Reactive compatibilization Compatibilization during reactive processing, extrusimi, or injection molding... 

Interphase a nominal third phase in binary polymer alloys, engendered by interdiffusion or compatibilization at the interfaces between the two polymer domains. The interphase thickness A/ varies between 1 and 60 nm depending on polymers miscibility and compatibilization Compatibilization process of modification of the interphase in immiscible polymer blends, resulting in reduction of the interfacial energy, development, and stabilization of a desired morphology, leading to the creation of a polymer alloy with enhanced performance ... 

PP/LLDPE + EP blockpol. + SEBS triblock -1- SEBS-g-MA 72/18/10 Type of compatibilizer Nucleation density at Tc = 135 °C - tT with EP - J. with SEBS Spherulite growth rate upon compatibilization Interfacial free energy of PP crystal surfaces J, with compatibilization Compatibilization changes the int ace morphology = > Additional nucleation sites from interfaces Finer dispersion of LLDPE can cause more unidimraisional growth of crystals Flaris et al. (1993)... 

UHMWPE Ultra-high-molecular-weight polyethylene VDF-HFA Copolymer of vinylidene fluoride and hexafluoro acetone VDF-TFE Copolymer of vinylidene fluoride and tetrafluoro ethylene VLDPE Very low-density polyethylene compat. Compatibilization, compatibilized, etc. cone. Concentration... 

Often, even immiscible and/or incompatible polymers are also made compatible by addition of a compatibilizer. Compatibilizers are believed to primarily reside at the polymer/polymer interfaces. The compatibilizer can be presynthesized or formed by in situ polymerization. Often the product engineer can make a judicious choice of compatibilizer resulting in improvement of mechanical properties, sometimes with synergistic effects. The compatibilizer is believed to stitch itself across the polymer/polymer interfaces. The addition of a compatibilizer lowers the interfacial tension between the two immiscible phases. The compatibilizer may sometimes be made of block copolymer composed of two different components. One of the block components may be miscible with polymer A, and the block component may be miscible with polymer B. Even if a polymer A and polymer B are immiscible, such a block copolymer would compatibilize the blend of A and B. 

Figure 6. Changes of strength at break in PVDF/PS blends. O - no compatibilizer, compatibilizer.

Styrene is polymerized in the presence of butadiene rubber. Polystyrene and polyethylene are mechanically mixed in the presence of compatibilizer according to special technology. COMPATIBILIZATION Compatibilizer miscible with both pol3nners BLEND MANUFACTURE Extrusion... 

Plastic manufacturing involves the use of compatibilizers. Compatibilizers are types of plastic additives tltat can have a direct affect on the recycling of plastic mixtures. Tlicy allow for the bonding of two otherwise unadhering pla.siic.s when blended together. 

In addition to reactive compatibilization, compatibilization of immiscible polymer blends may also be achieved through introduction of preformed block or graft copolymers, non-bonding specific interaction, and the addition of low molecular weight coupling agents. 

Table 18.7 shows the domain size obtained from small-angle light scattering (SALS) experiments. From the table, it is obvious that R is decreasing by the addition of compatibilizers (compatibilizer effect). It is found that the Izod impact strength tends to increase with decreasing R. However, the impact... 

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