Plasticizer concentration

Overall Assessment of Properties. Table 3 shows the effect for each criterion of increasing plasticizer concentration, increasing the size of the plasticizer molecule, increasing the linearity of the plasticizer molecule, and changing the acid constituent of the ester. An I indicates improved performance for a particular property, a P indicates poorer performance. I and P in parentheses indicate that any changes tend to be marginal. 

Flow calculators. These are available in the form of plastic concentric discs which can be rotated against each other. 

Figure 8 Effect of plasticization or copolymerization on (A) the modulus-time and (B) modulus -temperature curves. The curves correspond to different plasticizer concentrations or to different copolymer compositions. Curve B is unplasticized homopolymer A is eithei a second homopolymer or plasticized B.

Tarvainen et al. (2002) studied the film-forming ability of starch acetate (DS 2.8) and the effect of commotfly used plasticizers on the physical properties of starch acetate films. The properties were compared with ethylcellulose films. Mechanical studies, water vapor and drug permeability tests, and thermal analysis by differential scarming calorimetry (DSC) were used to characterize the film-forming ability of starch acetate and efficiency of tested plasticizers. Starch acetate films were foimd to be tougher and stronger than ethylcellulose films at the same plasticizer concentration. Also, in most cases, the water vapor permeability of starch acetate... 

As mentioned in the previous paragraph, binder and plasticizer concentrations for tape casting are much higher than for slip casting and for most other types of slurry... 

The above experiment on the effect of plasticizer content was repeated at 35.5° instead of 23.5 °C. The accelerating effect of radiation on the creep rate of stressed samples again appears to disappear at about the same plasticizer content where the expansion of the unstressed samples disappears however, both vanish at a lower plasticizer concentration (approximately 20% ) at 35.5° than at 23.5°C. Hence, we can conclude that an increase in temperature also diminishes the acceleration of creep rate caused by the radiation. 

The analogy between the mechanical and the electrical damping measurements is also borne out by the effect of plasticizer concentration on the temperature of maximum damping as shown in Figure 14 (31, 32, 33). 

Effect of Plasticizer Concentration. It is generally agreed that AT-i.e., the lowering of T -for most systems is directly proportional to the plasticizer concentration in the polymeric material. While some investigators (37) have insisted on using molar concentrations, it was later shown that weight concentrations can be used for comparisons of plasticizer efficiency in most cases (34,17). 

The behavior of plasticizers in a polymer has already been examined by Wiirstlin (16) with dielectric measurements. However, this method is not sensitive enough to detect the plasticizer behavior in the system at small plasticizer concentrations. Luther and Weisel (12) have also pointed out this fact as a result of their DC measurements of PVC-plasticizer systems. The following measurements deal with the behavior of plasticizers in polystyrene. 

Figure 10. Forming of a glass structure in a composed glass. The curve c-f-i shows the correlation between glass temperature and the plasticizer concentration. According to the sequence history (see text) the structure of the glass with the composition x and the temperature T is described by the coordinates of the glass point /, (x = x T0>) or the glass point f, (x = x", T ) respectively x = 1 corresponds to the pure polymer.

The improved thermal stability of the chlorinated paraffins also reflects the purity of the n-alkanes. The heat stability of PVC plasticized with chlorinated n-paraffin at 177°C. is better than that of similar compounds using commercial chlorinated wax. This is shown in Table I by the color that developed during thermal treatment for samples in which 40% of the dioctyl phthalate was replaced by chlorinated paraffins. (In this example and those that follow, the total plasticizer concentration is constant at 33 / %.) The color development in this test is significant as a measure of the comparative processing conditions that can be employed. 

Whereas Sears and Darby (7) found many types of compounds which would plasticize bisphenol A polycarbonate when the plasticizer concentration was 25 to 30%, the norbornane-tvpe polycarbonates could be plasticized only with larger amounts of plasticizer. When present in concentrations of 20 to 30%, conventional plasticizers acted as diluents—that is, the tensile modulus and tensile strength were depressed, as occurs with plasticizers, but the elongation was not appreciably increased. The antiplasticizers also acted similarly and became diluents after their peak antiplasticizing action was reached. 

The carbon black plastic concentrates are often not prepared by the plastics processor. They may be purchased, from the pigment-black manufacturer in the form of chips, pellets, or powders. Black-plasticizer pastes (e.g., black/DOP pastes for tinting plastisols) and water- and solvent-based dispersions (e.g., for fiber manufacture) are also commercially available. 

The results obtained by addition of plasticizer vary with different polymers. In polyvinyl chloride, for example, plasticizer concentrations of 30 50% convert the hard, rigid resin to rubber-like products having remarkably high elastic recovery, while similar plasticizer concentrations in cellulose acetate produce tough but essentially rigid products. 

The effects of plasticizers has also been studied by PAL [64, 65]. The addition of a plasticizer to polymers generally has the effect of lowering the Tg, however in some cases an anti-plasticization can occur. Borek et al [65] have shown that the fraction of free volume in PVC polymers could be fit with a fourth order polynomial as a function of plasticizer concentration. The decrease in th Tg with increasing amount of plasticizer is attributed to this increase in the free volume of the polymers. 

Glycerol (plasticizer) concentration used in the hterature varied from 35 to 60g/100-g soy protein (35-39). A lower amount of plasticizer will cause drying out and cracking of the film. The intermolecular disulfide bonds resulting from the denaturing of protein and intermolecular interactions between the protein chain... 

Fig. 15 Influence of triethyl citrate plasticizer concentration on the force-deflection profile of Eudragit L 30 D-55 applied to tablet compacts ( ) 20% plasticizer ( ) 30% plasticizer. (From Ref...

Amighi, K. Moes, A. Influence of plasticizer concentration and storage conditions on the drug release rate from Eudragit RD30D fihn-coated sustained-release theophylline pellets. Fur. J. Pharm. Biopharm. 1996, 42 (1), 29-35. 

Table 3. Influence of filler and plasticizer concentration on physical mechanical parameters of composition HI.

The Tg values of SC films are shown in Figure 28.3. Increasing plasticizer concentration led to a significant reduction in Tg values in all SC films, the addition of GC decreased the Tg and the VC increased lightly the Tg. 

Lourdin, D., Coignard, L., Bizot, H., and Colonna, P. Influence of equilibrium relative humidity and plasticizer concentration on the water content and glass transition of starch materials. Polymer, 38, 5401,1997. 

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