Polymer interaction energy, filler

The crystallisation behaviour of the pure iPPO and ccitposites was studied using differential scanning calorimetry and dilatcmetry. Results frem these studies will be qualitatively interpreted in terms of the filler-polymer interaction energy. 

Special considerations chemical composition of filler surface affects nucleation of filler traces of heavy metals decrease thermal stability and cause discoloration siuface free energy of fillers determines interaction large difference in thermal properties of fillers and polymer may cause stress hydrotalcite is used as acid neutralizer with stabilizing packages anatase titanium dioxide decreases UV stability presence of transition metals (Ni, Zn, Fe, Co) affects thermal and UV stability calcium carbonate and talc were found to immobilize HALS stabilizers in PP with organic masterbatches such as ethylene diamine phosphate V-0 classification can be obtained with 20-25 wt%, at the same time tensile strength and impact strength are substantially reduced... 

Some workers [1-2] argue that a necessary condition for such localization is the essential difference between the energies of interactions of polymer components with a surface of powder particles. The others [5-8], in contrast, suppose that this phenomenon takes place orrly when the polymeric components of a blend have low and approximately equal energies of the interaction with the filler surface. Some authors [3] hold that a filler is driven out to the interface due to the crystallization of polymer components of a mixtrrre. 

To reveal the causes and conditions necessary for carbon black to localize at the interface there was a need in evaluating the energy of adsorption interaction of polymers with the filler surface. 

The techniques used to disperse nanofillers within a polymer matrix can be broadly categorized into kinetic and thermodynamic approaches. In the kinetic approaches, an external energy sotuce, such as shear forces or ultrasoimd vibrations, is used to temporarily disperse the filler followed by a method to trap this state. The thermodynamic approaches, on the other hand, involve the use of covalently or noncovalently bonded chemical additives to mediate the interfacial energies and thereby improve the filler-polymer compatibility and/or reduce the attractive interactions between the fillets. In many cases, combinations of both kinetic and thermodynamic approaches are adopted for optimal results. 

An important consideration is the effect of filler and its degree of interaction with the polymer matrix. Under strain, a weak bond at the binder-filler interface often leads to dewetting of the binder from the solid particles to formation of voids and deterioration of mechanical properties. The primary objective is, therefore, to enhance the particle-matrix interaction or increase debond fracture energy. A most desirable property is a narrow gap between the maximum (e ) and ultimate elongation ch) on the stress-strain curve. The ratio, e , eh, may be considered as the interface efficiency, a ratio of unity implying perfect efficiency at the interfacial Junction. 

The authors of [99] proposed a calorimetric method for determining the degree of the polymer-filler interaction the exothermal effect manifests itself in the high energy of the polymer-filler adhesion, the endothermal effect is indicative of a poor, if any, adhesion. The method was used to assess the strength of the PVC-Aerosil interaction with Aerosil surface subjected to different pre-treatments... 

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