Glass Transition Temperature and Thermal Stability

The polymers were synthesized by the standard NMP/K2CO3 procedure according to literature (10,11). Glass transition temperatures and thermal stability measurements (TGA) were performed on a Du Pont DSC 1090 instrument at heating rates of 10 and 5°C/min, respectively. Intrinsic viscosity measurements were determined using a Cannon- Ubbelhodhe dilation viscometer in NMP (25°C). 

Properties of polyamide-poly(ethylene terephthalate) mixtures have been evaluated with particular reference to viscosity, glass transition temperatures, and thermal stability studies. 

Due to the curing nature of modified PPO, substantial resistance to halogenated solvents can be achieved and the increase of epoxide molar content also enhanced the thermal curing reaction and resulted in a significant increase in both glass transition temperature and thermal stability. 

The ring-opening metathesis polymerization of norbomene monomers functionalized with arene complexes of cyclopentadienyliron has been reported using Grubbs catalyst. These polymerization reactions proceeded rapidly to produce the corresponding polynorbomenes (32 and 33). It was found that the incorporation of bulkier aromatic groups in the sidechains of these materials increased their glass transition temperatures and thermal stability. 

Glass Transition Temperature and Thermal Stability of Phosphorus-Containing Siliconized Epoxy Resin... 

There are also important differences in the nature of the polymer backbone formed by these processes. Olefin addition reactions lead to polymer chains containing aliphatic carbon as the backbone. Most step-growth reactions instead form polymer chains or rings containing heteroatoms (noncarbon atoms) in addition to aliphatic carbon in the backbone. The presence of heteratoms can provide remarkable enhancements in polymer performance and often leads to polymers with higher glass transition temperatures and thermal stability leading to such properties as conductivity or electroluminescence. 

Polyorganoslloxanes are probably the most widely used and studied class of "seml-lnorganlc polymers. There are a variety of Interesting and useful properties exhibited by these materials that make them worthy of study. For example, they exhibit high lubricity, low glass transition temperatures, good thermal stability, high gas permeability, unique surface properties, and low toxicity (1 ). 

The trimerization reaction of the polyfunctional cyanates is catalyzed by zinc or manganese octoate, copper carboxylates, and acetylacetonate metal chelates with a synergistic effect when the catalyst is mixed with 4-nonylphenol [21]. The final cure or postcure temperature depends on the glass transition temperature of the tridimensional network. This means that the semi-solid biscyanate 88 is cured at 180-195 C (Tg 192°C) while the biscyanate 85 is cured at 250-300°C (Tg 290°C). However, the maximum cure temperature can be reduced to 120°C in the former example by adding 6-10% of 4-nonylphenol. When compared to epoxies, cyanate esters have higher glass transition temperatures, better thermal stability, and improved dielectric properties. Cyanate esters have been primarily developed... 

The most commonly used siloxane modifiers are those having phenyl, trifluoro-propyl and cyanopropyl substituents. Introduction of phenyl units into the polydimethylsiloxane backbone either in the form of methylphenylsiloxane or diphenyl-siloxane increases the thermal and oxidative stability, glass transition temperature and the organic solubility characteristics of the resulting copolymers. At low levels (5-10 percent by weight) of incorporation, bulky phenyl groups also break up the regularity of polydimethylsiloxane chains and inhibit the crystallization (Tc... 

A,A -di(/>-dimethylamino-benzyl) derivatives of di(imidazolidinylidene)gold(i) salts were polymerized into polyimides by condensation with arene-tetracarboxylic anhydrides. The products are tough, but flexible, and have high glass transition temperatures and high thermal stability. Yellow films of the materials are transparent above 365 nm.279... 

This is very useful for generating modulus versus temperature data on rubber compounds. The effects of temperature on this important material property can be obtained over a wide temperature range (typically -150 to +200 °C), along with the glass transition temperature and information on thermal stability. 

In order to select materials that will maintain acceptable mechanical characteristics and dimensional stability one must be aware of both the normal and extreme thermal operating environments to which a product will be subjected. TS plastics have specific thermal conditions when compared to TPs that have various factors to consider which influence the product s performance and processing capabilities. TPs properties and processes are influenced by their thermal characteristics such as melt temperature (Tm), glass-transition temperature (Tg), dimensional stability, thermal conductivity, specific heat, thermal diffusivity, heat capacity, coefficient of thermal expansion, and decomposition (Td) Table 1.2 also provides some of these data on different plastics. There is a maximum temperature or, to be more precise, a maximum time-to-temperature relationship for all materials preceding loss of performance or decomposition. Data presented for different plastics in Figure 1.5 show 50% retention of mechanical and physical properties obtainable at room temperature, with plastics exposure and testing at elevated temperatures. 

Nuyken has optimized indan formation of diisopropenylbenzene to prepare polyindans with both high glass transition temperatures and high thermal stability [Eq. (94)] [291]. 

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