Plastics temperature effects

Plastic Viscosity and Yield Point. Plastic viscosity and yield point measurements are obtained from a direct indicating viscometer. Due to the temperature effect on the flow properties of oil-base mud, the testing procedure is modified. The mud sample in the container is placed into a cup heater [23]. The heated viscometer cup provides flow property data under atmospheric pressure and bottomhole temperature. 

However, there are, as always, complications both Tb and temperature effect is of importance the continuing plastic deformation results locally in high heat dissipation, which, due to the low heat conduction of polymers, is not transported to the environment. An estimation of the local temperature increase can be made with ... 

Temperature Effect on Reinforced Plastics. Often, fibers and polymer matrix have different coefficients of thermal expansion. After painting the liquid coating flows... 

The chief problem is that plastic deformation effects at the crack tip usually obscure the process of surface formation. The work needed to propagate a crack is utilized not only to form two surfaces and to bend the cleaved material elastically but also for plastic deformation around the crack tip [16]. The energy needed for this plastic deformation is dissipated as heat. Hence the measured quantity, which is called the effective fracture surface tension yntts- is numerically larger than y. Reliable results can only be obtained at temperatures below 150 K when plasticity practically disappears 121,55]. 

Figure 23.3 Temperature effects on product phase yields for the feed size range 150-75 xm. (Copyright 2003 from Polymer-Plastics Technology and Engineering by A Karaduman, M. C. Kocak and A. Y. Bilgesu. Reproduced by permission of Taylor Francis, Inc., http //www.taylorandfrancis.com)...

In both explosives and propellants the materials are relatively non-porous. The binders and plasticizers used effectively fill the pore spaces. Pyrotechnics are porous and the heat transfer related to the hot gas permeation into the reactant material mixture becomes important. In many pyrotechnics no binders or plasticizers are used. The explosives and propellants have burning (or detonation) rates that depend on density, temperature, and pressure. However, the burning rates of pyrotechnics are, in addition, affected by porosity, particle sizes, purity, homogeneity (degree of mixing), and stoichiometry (fuel or oxidizer ratio). 

Mercury can also be lost after volatilisation, by adsorption and chemical reaction, as above. Adsorption is essentially a surface-area and temperature effect and so surface areas should be minimised. Absorption can be noticeable when plastic tubing is used for interconnections. Mercury is also lost if the release tube is heated excessively with vitreous silica this occurs at temperatures of around 900"C. 

Not only plastic but also cellulose contributes to free radical formation and adds their share to the system. Gellulose is degraded by temperature effects and UV light. 

Ho, K.-L.G. and Pometto, A.L. Ill (1999) Temperature effects on soil mineralization of polylactic acid plastic in laboratory respirometers. Journal of Environmental Polymer Degradation, 1, 101-108. Buchanan, C.M., Dorschel, D.D., Gardner, R.M. et al. (1995) Biodegradation of cellulose esters Composting of cellulose ester-diluent mixture. Journal of Macromolecular Science, Part A Pure and Applied Chemistry, A32,683-697. 

Thus, for a priori evaluation of plasticizer s effectiveness in decreasing the glass transition temperature of a polymer, it is desirable to estimate the thermodynamic compatibility of a polymer and a plasticizer using, for example, the concept of solubility parameters. " In the case when results suggest that polymer is compatible with plasticizer in the whole range of concentrations, it is possible to use one of the above given equations. 

Duthie X, Kentish S, Powell C, Nagai K, Qiao G, Stevens G. Operating temperature effects on the plasticization of polyimide gas separation membranes. J Membr Sci 2007 294(l-2) 40-9. 

Hilado, C. J., Huttlinger, P. A. Integration of temperature effects in toxicity of off-gases from plastics. J. Elastomers and Plastics, 13, 108 (1981)... 

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