Grafting filler surface

As shown for the synthesis of PS [291], the monomer may be localized in the vicinity of the filler surface by previously grafting a polymer capable of swelling in the base monomer. Copolymeric latex of polychloroprenemethacrylic acid was added to the aqueous dispersion of chalk. The acid groups reacted with chalk and the latex particles became chemically grafted to chalk. When further portions of styrene were added they were completely absorbed by modified chalk. 

The enthalpy of interaction of the grafted polymer with the filler surface is given by... 

In the present paper, we report on the compatibilization of clay with polyolefins, specifically low and high density poly-ethylenes (LDPE, HDPE), through the radical-induced polymerization of maleic anhydride (MAH) in the presence of the polymer and clay, so that the MAH is grafted on the PE and the anhydride groups concurrently react with the filler surface (l, 2). 

Chemically modified silica fillers with grafted methyl groups or methyl and silicon hydride groups, influenced the micro- and macrostructures of various copolymers. Changes in cross-linking, orderliness, crystallinity, microtacticity and conformation of macromolecules have been detected in the presence of fillers. Surface functionality of the silica filler determines the disposition of macromolecular chains at the interface. 

Consequently, for filling with modified aerosils, two competing processes occur stiffening of polyurethane macromolecules by the filler surface, and their plasticization by glycol molecules grafted onto filler surface. The double influence of these fillers on the... 

Gaylord evaluated various clays in polyethylene using peroxide/maleic anhydride treatments [18]. He found very variable results, largely influenced by the nature of the clay surface, and concluded that some filler surfaces could actually inhibit the free radical grafting processes. 

The chemical modification of the filler surface is frequently used to increase the affinity of the dispersed phase with the polymeric phase or with the solvent used to prepare the casting solution. The nature of the chemical moieties grafted depends on the features of the polymer or the solvent considered for the particular membrane preparation procedure, and either covalent or noncovalent bonds can be considered. 

The polar nature of wood-based fillers also simplifies the chemical modification of the filler surface. Grafting is one of the most widely studied methods of improving adhesion at the fibre-matrix interface. By attaching a suitable polymer segment to wood fibres having a solubility parameter similar to that of the polymer matrix, the compatability between the polymer and fibre can be improved. Kokta and co-workers reported an improvement in the mechanical properties of PS filled with styrene-grafted hard wood fibres [54]. 

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