Long-Term Thermal Performance

C. J. Hilado,/ Cell Plast. 3(4), 161 (1967) I. R. ShanMand, The Effect of Cell Structure on the Buate of Foam Aging International Workshop on Long Term Thermal Performance of CeUular Plastics, SPI, Canada, Oct. 1989. 

This technique reduces testing times significantly and provides reUable results for >20 years material. The values plotted in Figure 2 (25) are an illustration of the viabiUty of this technique as a means to provide reaUstic long-term thermal performance values (21). 

This long-term thermal performance of a material is tested alongside a second, control, material which already has an established RTI and which exhibits a good performance. Such a control is necessary because thermal degradation characteristics are sensitive to variables in the testing programme. Since the control material will also be affected by the same unique combination of these factors during the tests, there is a valid basis for comparison of test and control materials. 

M. Bomberg and M. Kumaran, Procedures to Predict Long-term Thermal Performance of Boardstock Foam Insulations, International Report, No.694 NRC-CNRC, National Research Council of Canada, Ottawa, Ontario, Canada, 1995. 

Baetens, R., Jelle, B.P., Gustavsen, A., and Roels, R. (2010) Long-term thermal performance of vacuum insulation panels by dynamic climate simulations. Proceedings of 1st Central European Symposium on Building Physics, Cracow, Poland, September 13-15, 2010,... 

Polyimides are high-performance technical polymers mainly used for their short- and long-term thermal stability. 

Ammonia synthesis catalysts have traditionally been based on iron and have been made by the reduction of magnetite (Fe304). The difference between different commercially available products lies in optimized levels of metal oxide promoters that are included within the magnetite structure. These metal oxides promote activity and improve the thermal stability of the catalyst. Typical promoters are alumina (AI2O3X potassium oxide (K2O), and calcium oxide (CaO). The interactions between the many components in the catalyst can radically affect 1) the initial reducibility, 2) the level of catalyst activity that is achieved, 3) the long-term catalyst performance and 4) the long-term catalyst stability204. 

Phenolic antioxidants are well known for being melt processing stabilizers as well as long-term thermal stabilizers. In the chemiluminescence measurements on the polyethylene films under oxygen (Fig. 3.3), the antioxidant effect of the phenols is clear when these induction times are compared with those of the free additive polyethylene film (0.73 h) (Table 3.2). The results showed that the structure of the phenolic moiety will be a cmcial factor influencing the stabilization performance. 

Since most stabilizers react in more than one way and combinations of additives are required to prepare stabilized polypropylene fiber, these materials are better discussed in accord with the function they perform for polypropylene rather than the mechanism by which they function. When making fibers, stabilizers are added to polypropylene to (1) provide melt extrusion stability (2) provide long-term thermal stability at normal use temperatures and (3) provide stability to exposure to UV light (sunlight). The degree to which these stabilizers effectively accomplish their objectives without introducing other objectionable effects, such as yellowing, determines the value of the resultant fiber product. 

This section is organized as follows the basic physical characteristics are introduced, followed by discussions of uniaxial room temperature mechanical properties, the effect of long term thermal exposure, creep behavior, notch sensitivity, and fatigue performance. The significantly different off-axis, matrix-dominated properties are described in the final section. 

Good long-term thermal stabilizer performance... 

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