Polymers thermal analysis curves

Figure shows the Differential thermal analysis curve for poly (ethylene terephthalate). The lower crystalline melting range in the specimen of figure below can be attributed to impurities present in the polymer. 

Fig. 5.9. Differential thermal analysis curve of a liquid crystalline polymer with flexible spacers in the main chain IPoiy(oxy-2,2 -dimethylazoxybenzene-4,4 -diyloxydodecanedioyl)]. Heating at 50 K/min after cooling at 50 K/min. LC glass transition at 290 K. Crystallization of the mesophase at T,. = 345 K. Disordering transition at = 385 K. Transition to the isotropic phase Ti = 420 K, ASi = 9.8 J/(K mol). Drawn after Ref.

Figure 1.6 Differential thermal analysis curves for high-density Hisex 5000. Upper curve, in air lower curve, in a nitrogen atmosphere. Reproduced with permission from S. Irgashi and H. Kambe, Polymer Preprints, 1964, 5, 333. 1964, American Chemical Society [3]...

This handbook is designed to provide general information on the basic principles of TA and a variety of its applications. It is composed of two 1915 parts. Part I deals with information on the transition, reaction and characteristic parameters of substances. It introduces general principles, data 1919 treatment, experimental procedures and data analysis. Part II presents about 1000 typical 1945 thermal analysis curves, with brief explanations, for a wide variety of materials, such as polymers, 1960s foods, woods, minerals, explosives, inorganic compounds, and their coupled simultaneous 1964 curves. TA charts have been contributed by Institutes and Universities in China. Part III cites 1965 various data tables relating to thermal analysis. 

Thermal Analysis Curves of Polymers Sample Phenolic resin. 

In the next three figures a short summary of the fusion behavior of some examples of polymers is given. In Fig. 4.31 a series of results for crystals of poly(oxymethylene) of various degrees of perfection are illustrated. Figure 4.31 A shows the differential thermal analysis curves on melting of extended chain crystals of poly(oxymethylene). These crystals are large, close to... 

The definition of polymer thermal stabiUty is not simple owing to the number of measurement techniques, desired properties, and factors that affect each (time, heating rate, atmosphere, etc). The easiest evaluation of thermal stabiUty is by the temperature at which a certain weight loss occurs as observed by thermogravimetric analysis (tga). Early work assigned a 7% loss as the point of stabiUty more recentiy a 10% value or the extrapolated break in the tga curve has been used. A more reaUstic view is to compare weight loss vs time at constant temperature, and better yet is to evaluate property retention time at temperature one set of criteria has been 177°C for 30,000 h, or 240°C for 1000 h, or 538°C for 1 h, or 816°C for 5 min (1). 

Melting temperatures of as-polymerized powders are high, ie, 198—205°C as measured by differential thermal analysis (dta) or hot-stage microscopy (76). Two peaks are usually observed in dta curves a small lower temperature peak and the main melting peak. The small peak seems to be related to polymer crystallized by precipitation rather than during polymerization. 

The physical properties of the acid- and ion-containing polymers are quite interesting. The storage moduli vs. temperature behavior (Figure 8) was determined by dynamic mechanical thermal analysis (DMTA) for the PS-PIBMA diblock precursor, the polystyrene diblock ionomer and the poly(styrene)-b-poly(isobutyl methacrylate-co-methacrylic acid) diblock. The last two samples were obtained by the KC>2 hydrolysis approach. It is important to note that these three curves are offset for clarity, i.e. the modulus of the precursor is not necessarily higher than the ionomer. In particular, one should note the same Tg of the polystyrene block before and after ionomer formation, and the extension of the rubbery plateau past 200°C. In contrast, flow occurred in... 

Figure 4. Thermogravimetric analysis of polymer VII (upper curve) with derivative (lower curve) showing two distinct thermal degradations.

Many different test methods can be used to study polymers and their physical changes with temperature. These studies are called thermal analysis. Two important types of thermal analysis are called differential scanning calorimetry (DSC) and differential thermal analysis (DTA). DSC is a technique in which heat flow away from a polymer is measured as a function of temperature or time. In DTA the temperature difference between a reference and a sample is measured as a function of temperature or time. A typical DTA curve easily shows both Tg and T . 

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