Polymethyl methacrylate thermal conductivity

For amorphous polymers, the increase in thermal conductivity in the direction of the draw is usually not higher than two. Figure 2.4 [24] presents the thermal conductivity in the directions parallel and perpendicular to the draw for high density polyethylene, polypropylene, and polymethyl methacrylate. A simple relation exists between the anisotropic and the isotropic thermal conductivity [39], This relation is written as... 

TEMPERATURE DEPENDENCE OF THE THERMAL CONDUCTIVITY OF AMORPHOUS POLYMERS. POLYMETHYL METHACRYLATE. 

EFFECTS OF POLYMER CHAIN ORIENTATION UPON THE THERMAL CONDUCTIVITY OF POLYMETHYL METHACRYLATE AT LIQUID NITROGEN TEMPERATURES. M.S. THESIS GALSTAN G N NAVAL POSTGRADUATE SCHOOL MONTEREY CALIFORNIA DDC... 

Recent developments have been in the area of microthermal analysis using thermal conductivity with thermal diffiisivity signals or AFM to visualize specific areas or domains in the material and perform localized thermal analysis studies (183,184). Relaxational behavior over time and temperature is related to changes in free volume of the material. Positron annihilation lifetime spectroscopy (PALS) measurements of positron lifetimes and intensities are used to estimate both hole sizes and free volume within primarily amorphous phases of polymers. These data are used in measurement of thermal transitions (185,186) structural relaxation including molecular motions (187-189), and effects of additives (190), molecular weight variation (191), and degree of crystallinity (192). It has been used in combination with DSC to analyze the range of miscibility of polymethyl methacrylate poly(ethylene oxide) blends (193). 

For polymethyl methacrylate, the T au and n values can be obtained from the rheological data presented by Westover [86]. Density and thermal conductivity... 

Dos Santos and Gregorio [48] measnred the thermal conductivity of polyamide 6,6, polymethyl methacrylate, rigid polyvinyl chloride ether, and polyurethane foam. 

Other polymers for which thermal conductivity data are available include polyamide 6,6, polypropylene, polymethyl methacrylate, rigid polyvinyl chloride, cellular polyethylene [58], polyvinylidene fluoride [59], polyvinylidene difluoride-ceramic composite [60], polyethylene [61], and polyamide films [61]. 

Wohitjen and Dessy [106, 107] described a surface acoustic wave (SAW) device for conducting a thermomechanical analysis measurement of the on polyethylene terephthalate, polytetrafluoroethylene bisphenol A, polysulfone, polycarbonate, and polymethyl methacrylate. There are several factors that distinguish the SAW device as a useful monitor of polymer T. The device is very sensitive, thereby permitting very small samples to be used. Preparation and mounting of the sample are simple and rapid. The device is quite rugged and possesses a small thermal mass, which permits fairly rapid temperature changes to be made. 

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