Surface treated fillers

The different results for untreated fillers (Omyalite 90, Calofort U, Silica Tixosil 365 and Tixosil NM61), and surface treated fillers (Omyalite 95T, Calofort S) are reported in Table 2. 

Figure 11.7 The effects of untreated and surface treated filler loading on the tensile behavior of injection-molded PP specimens. (From Reference 44 with permission from Elsevier.)...

Compounders are always free to buy individual additives and combine them to their specific needs. In some cases, particularly when the additive is difficult to compound, it is best masterbatched by speciahsts and then sold to the processor who simply lets it down with natural. Many processors prefer not to become involved in the chemical details and buy combined masterbatches containing several additives aU together in the same masterbatch. This is particularly common in stabfiizer packages, surface-treated fillers and fibers, lubricant packages, colorants + odorants, polyblends, and antifog/antistat/lubricant additives. While this saves the processor a lot of detail formnlatmg effort, it makes it mnch more difficult for him to identify and solve problems when the componnd does not perform properly. 

Lee, M.C.H. Effects of polymer-filler adhesion on the properties of polychlor-oprene elastomers filled with surface-treated fillers. J. Appl. Polym. Sci. 1987,33, 2479-2492. 

The dispersants found using the rheological test were used to surface treat fillers, and the properties of the resultant composites were measured. In many cases, the dispersants were found to be very effective. The limitation of the rheological dispersant optimization method is that it measures only the amount... 

Computerized techniques are sometimes employed for cost/performance evaluations. The particle shape, size and distribution, oil absorption, dispersibilty and impurities of fillers affect its performance. Use of fillers with fine particle size and a refractive index closer to PVC results in the least reduction of clarity. Surface gloss decreases with coarse types and higher loadings cause whitening. Surface treated fillers are more easily dispersed. The presence of heavy metal impurities such as iron or zinc are avoided since they cause thermal degradation of PVC. 

Surface treated fillers are used more often as they enable the compounder to achieve properties approaching those obtained in black formulations. This particularly is true in the case of peroxide formulations containing recently introduced types [31]. WoUastocoat 10,022 (methacrylate treated), WoUastocoat 10,014 (vinyl silane treated), and WoUastocoat 10,012 (amino silane treated) are examples of treated calcium metasiUcates that are preferred to enhance physical properties in non-black peroxide curing formulations. 

Aziz et al. [55] advocated that the water absorption of the PDMS elastomers might depend on the surface-treated filler component. Presence of hydrophilic, non-surface-treated silica fillers in the polymer matrix, increase the water uptake of the material (Cosmesil St, Prestige). The presence of -OH groups on the surface of the silica fillers helps to absorb water into the polymer matrix [57]. In the same manner, surface-treated hydrophobic silica filler containing polymer matrixes (Cosmesil HC, A-2186, MED-4920) had negUgible water absorption. The surface groups on these silica particles repel water molecules, and hence prevent water absorption into the material [55]. 

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