Determination of fillers

For the quantitative determination of fillers, a small amount of the polymer material is weighed and dissolved in solvent. After centrifuging at the solution is pipetted off from the centrifugate. The residue is suspended once more in the same solvent, centrifuges again and after isolation is washed once more with the solvent and then several times with methanol. The residue is dried to constant weight and then the solid... 

Practically, structure determination of fillers is obtained by a very simple and easy method dibutyl phthalate absorption (DBPA) (Creeden, 1997). This method consists of filling up the voids in and between aggregates with DBP, which is a viscous liquid. Historically, the DPB volume was determined by making a solid pellet of carbon black and DBP with a spoon. Now, this delicate measurement is made automatically with a couple-monitored Banbury, in which a well-known quantity of dry carbon black is placed. DBP is then added drop by drop, and the structure value is obtained when torque reaches a given value. 

Journal of Applied Polymer Science 56, No. 12,20th June 1995, p. 1557-60 DETERMINATION OF FILLER CONTENT IN THERMOPLASTIC COMPOSITES BY FTIR ANALYSIS... 

The determination of filler particle density is carried out using the pyknometer method. The pyknometers used are smaller than those used for determining the density of aggregates. The capacity of the pyknometer used is usually 50 ml. 

The first of these factors is filler particles aggregation. The detailed description of this effect influence on structure and properties of composites, having glassy matrix, is given in review [3]. For the considered composites this effect is important first of all for determination of filler volume fraction cp/, which is calculated by division of filler mass fraction into its density. However, filler particles in real composites exist in the form of fractal aggregates, which density can be more smaller than monolithic object of such filler. Below the example of value cp/calculation for concrete composite will be given. 

Direct and indirect approaches more commonly used for determination of filler compound quality are summarised in Table 5.1, together with pertinent measured parameters and influencing factors. Further discussion of characterisation procedures follows in Section 5.4.2. 

Earlier attempts to apply ultrasonic wave-velocity measurements to in-line determination of filler concentration during compounding met with mixed success, however. In one study [51], measurements were undertaken by measuring ultrasonic transit times across... 

US velocity and attenuation measurements can also be used to determine solid-state material properties such as concentration and dispersion of fillers [908,909]. The active level of the acoustic emission signal of PP/talc composites was related to the degree of dispersion of the filler in the matrix [910]. LDPE/28-32 wt.% Mg(OH)2 and HDPE/0-10 wt.% Mg(OH)2 samples were examined over a wide range of temperatures (160-200°C) and pressures (up to 60 bar) to determine the effect of melt T, p and filler concentration on US velocity and attenuation in the melt [911]. Ultrasound velocity is affected by melt T, p and material density (filler content) US attenuation increases with increasing filler content. As US calculated filler concentrations deviated consistently from off-line TGA measured values (Fig. 1.43) it is obvious that further validation is required. In principle, extmsion processing data can be used to predict filler concentration. Accurate determination of filler concentration in real time is potentially useful to reduce excess and unnecessary usage of filler, to reduce scrap product and save production costs. 

The surface of printed paper has been examined through fully automated /xATR-FTIR mapping [464]. Compositional differences attributed to the printed ink, kaolinite, and cellulose distributions were revealed, which are not discemable in the visible. After spectral subtraction of the carbonate also DOP and an aromatic acrylate, both used in paper manufacturing, could be identified. Coles et al. [465] have compared /iFTIR and ATR-FTIR in the quantitative determination of fillers such as kaolin clay in polyethylene/vinyl acetate. Although ATR-FTIR is not as sensitive to kaolin as /xFTIR, the former provides a larger sampling area and more consistent results. ATR-FTIR is sometimes used for in-depth analysis. 

Acid-Base Behavior. The relative acidity-basicity of the filler, generally determined by measuring the pH value of a slurry of a specific mass of filler in 100 mL of deionized water, can influence the behavior of a filler in some systems. For example, the curing behavior of some elastomers is sensitive to the pH value of carbon black. 

True Density or Specific Gravity. The average mass per unit volume of the individual particles is called the tme density or specific gravity. This property is most important when volume or mass of the filled composition is a key performance variable. The tme density of fillers composed of relatively large, nonporous, spherical particles is usually determined by a simple Hquid displacement method. Finely divided, porous, or irregular fillers should be measured using a gas pycnometer to assure that all pores, cracks, and crevices are penetrated. 

Free Moisture. The free moisture of a filler is the water present on the surface of the particles. This weakly bound water can sometimes contribute to iaterparticle bonding (reinforcing) or filler—matrix iateraction, ie, biader adsorption or catalysis. A determination of free moisture is usually made by measuriag the percent loss on drying the sample at either 100 or 110°C. 

The retention of fillers in the sheet during the forming process is important. Both hydrodynamic mechanisms and colloidal or coflocculation phenomena are significant in determining filler retention (7). Polymeric retention aids are used to bridge between filler particles and fibers. Talc is sometimes used with mechanical pulp furnishes in order to reduce the deposition of pitch-like materials onto paper machinery. 

The PVC is simply P /Vf and is determined by the volume of filler added to the formulation. The CPVC occurs when the binder particles are close packed and Vv = 0. At the CPVC, there is Just enough binder to coat all of the filler particles and the substrate with at least monomolecular layer of binder, and fill the interstices between particles. 

The dry adhesive films on the two substrates to be joined must be placed in contact to develop adequate autoadhesion, i.e. diffusion of polymer rubber chains must be achieved across the interface between the two films to produce intimate adhesion at molecular level. The application of pressure and/or temperature for a given time allows the desired level of intimate contact (coalescence) between the two adhesive film surfaces. Obviously, the rheological and mechanical properties of the rubber adhesives will determine the degree of intimacy at the interface. These properties can be optimized by selecting the adequate rubber grade, the nature and amount of tackifier and the amount of filler, among other factors. 

The stress composites with 16% by mass of the filler other characteristics with 22% by mass of filler. 

Using calorimetry to estimate the degree of filler-polymer interaction as described in [99] the authors of [318, 319] determined that the filler reaction with PVC is exothermic, which is indicative of a stronger bond in the polymer-filler system. No thermal effect was noted for mechanical mixtures, except for a few cases where it was endothermal. 

Note that the variation of the enthalpy of filler interaction with the coat (dH) is fully determined by dH since AHj and AH2 remain practically constant. 

Anisodiametrical particles of filler appearance of anisotropy of properties and relaxation phenomena, determined by the turn of solid particles in a flow... 

This formula may be useful as a rheological method for determining the thickness of adsorption layer, which is formed as a result of interaction between a dispersion medium and filler, by the results of measuring the t] versus q> dependence. Especially curious phenomena, connected with surface effects, arise when a mixture of fillers of different nature is used according to concentration of an active filler the introduction of the second (inert) filler can either increase or decrease the viscosity of a multicomponent system [35],... 

Such a model makes it possible to calculate a change of fibers distribution along the length in the boundary layer. At present, practically the sole approach to the analysis of destruction when the fiber filler flows in the basic mass, outside the boundary layer, is an experimental determination of destruction kinetics for a given pair — fiber filler and polymer. Such dependencies can be obtained with the help of, say, rotary viscosimeters [47],... 

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