Effects of plasticizers

The calibration graph for the probe using a strength machine, has been shown in Fig. 7 It can be observed that the dependence of indications of the device of Wirotest type on the loading is linear within the proportionality limit scope. After unloading the indications do not return to zero, but show own stress caused in effect of plastic deformation of the tested sample... 

Environmental Effects of Plasticizers. Measurement of the effect of phthalates on environmental species is difficult because standard test methods are not designed to deal with poorly water-soluble substances. Eor this reason a number of early studies are flawed and their results should be disregarded in favor of more recent investigations where these difficulties have been overcome. 

The effect of plasticizers and temperature on the permeabiUty of small molecules in a typical vinyUdene chloride copolymer has been studied thoroughly. The oxygen permeabiUty doubles with the addition of about 1.7 parts per hundred resin (phr) of common plasticizers, or a temperature increase of 8°C (91). The effects of temperature and plasticizer on the permeabiUty are shown in Figure 4. The moisture (water) vapor transmission rate (MVTR or WVTR) doubles with the addition of about 3.5 phr of common plasticizers (92). The dependence of the WVTR on temperature is a Htde more comphcated. WVTR is commonly reported at a constant difference in relative humidity and not at a constant partial pressure difference. WVTR is a mixed term that increases with increasing temperature because both the fundamental permeabiUty and the fundamental partial pressure at constant relative humidity increase. Carbon dioxide permeabiUty doubles with the addition of about 1.8 phr of common plasticizers, or a temperature increase of 7°C (93). 

In some cases, plasticization of a PSA may be detrimental to its performance. A well-known example is the deterioration of the performance of an adhesive applied to plasticized PVC. Migration of the plasticizer from the flexible vinyl into the PSA often softens the adhesive to the point where it fails cohesively from the vinyl, leaving sticky residue behind during removal of the adhesive-coated article from the substrate. One way to address this detrimental effect of plasticizer migration is to formulate an already plasticized PSA, perhaps because a better balance exists between the plasticizer in the PVC substrate and the PSA in contact with it [101]. 

In the preparation and processing of ionomers, plasticizers may be added to reduce viscosity at elevated temperatures and to permit easier processing. These plasticizers have an effect, as well, on the mechanical properties, both in the rubbery state and in the glassy state these effects depend on the composition of the ionomer, the polar or nonpolar nature of the plasticizer and on the concentration. Many studies have been carried out on plasticized ionomers and on the influence of plasticizer on viscoelastic and relaxation behavior and a review of this subject has been given 119]. However, there is still relatively little information on effects of plasticizer type and concentration on specific mechanical properties of ionomers in the glassy state or solid state. 

Table 18.18 Summary of vapour corrosion effects of plastics...

Tliere is another type of application where the damping effect of plastic structures can be used to advantage. It has a long although not obvious history. The early airplanes used doped fabric as the covering for wings and other aerodynamic surfaces. The dope was cellulose nitrate and later cellulose acetate that is a damping type of plastic. Conse-... 

Humphery, LX-10-1 A High-Energy Plastic-Bonded Explosive , Univ Calif, UCRL-51629 (1974) 75) U. Deisenroth, Effect of Plastic... 

Ljungberg, N. and Wesslen, B. 2002. The effects of plasticizers on the dynamic mechanical and thermal properties of polyjlactic add). Journal of Applied Polymer Science 86 1227-1234. 

The role of plastics in municipal solid waste combustion is discussed, and in particular, their fuel characteristics. Details are given of a state-of-art municipal solid waste combustor and the effects of plastics on the different combustion stages. In addition, the contribution of plastics to the total output spread over the various emission paths of solids, liquids and gases, is also assessed. 

Cadogan DF, Papez M, Poppe AC, Scheubel J (1993) An assessment of the release, occurrence and possible effect of plasticizers in the environment. Prog Rubber Plast Techol 10 1-19... 

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.

VII. Effects of Crystallinity and Morphology Vin. Effects of Plasticizers and Copolymerization... 

However, the results do not necessarily reflect the fastness to overlacquering in actual application, because overprint varnishes may contain other solvents as well. Besides, a series of additional factors such as the effect of plasticizers, uneven flow of the pigmented lacquer, etc., play a role in pigment performance. The fastness to overlacquering is therefore most realistically determined in actual application. 

Tirosh J. (1973). The effect of plasticity and crack blunting on the stress distribution in orthotropic composite materials. ASME Trans. J. Appl. Mech. 40, 785-790. 

The effect of plasticizers has been explained by the lubricity, gel, and free volume theories. The lubricity theory states that the plasticizer acts as an internal lubricant and permits the... 

Rodriguez, M., Osels, J., Ziani, K., Mate , J. 1. (2006). Combined effect of plasticizers and surfactants on the physical properties of starch based edible films. Food Research International, 39, 840-846. 

Jain, G.C. Joshi, S.C. (1991) Effects of plasticizer di-(2-ethyl hexyl) phthalate (DEHP) on reproductive function of mice. Z. Angew. ZooL, 4, 465 70... 

Thompson, R. B., Smith, J. F., and Lee, S. S. (1990b). Effects of plastic deformation on the inference of stress and texture from the velocities of ultrasonic plate modes. In Review of progress in quantitative nondestructive evaluation, Vol. 9 (ed. D. O. Thompson and D. E. Chimenti), pp. 1773-80. Plenum Press, New York. [252]... 

Sometimes, the relationship between two variables is obscured by the presence of a third variable which may of may not be related to the other two. In order to clarify the relationship, we may want to remove or account for the effect of the third variable. For example, we may want to find the effect of plasticizer viscosity on the hardness of a resin-plasticizer mix. But some plasticizers are more efficient than others, and this factor may obscure the relationship. What we are really looking for is some way of separating out these effects. For example, in the simpler linear correlation study, we Came up with an equation of the form... 

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. 

Figure 13. Effect of plasticizer content on creep rate or unstressed expansion of polystyrene during irradiation at 23.5°C.

Machinists have learned through experience, and are certainly well aware, that machining plastics is profitable. While machining plastics is not particularly burdensome, there are specific considerations that must be followed when machining plastics. Because plastics have a much lower deflection temperature than metals if too great a heat build up is allowed, the plastic may tend to gum tooling. Plastics are more resilient than metals when close tolerance is required. The operator must compensate for the resilience effect of plastic. 

Plasticization is the process in which the plasticizer molecules neutralize the secondary valence bonds, known as van der Waal s force between the polymer molecules. It increases the mobility of the polymer chains and reduces the crystallinity. These phenomena become evident in reduced modulus or stiffness, increased elongation and flexibility, and lowering of the brittle or softening temperature of the plasticized product. The effect of plasticizers on polymers is the subject of the first chapter by E. H. Immergut and H. F. Mark. 

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). 

Nuclear Magnetic Resonance (NMR). One of the newest physical methods, which has been applied successfully to study the effect of plasticizers on Tg, is nuclear magnetic resonance (20). 

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