Physical structure of polymers

We have already discussed the possibility of changes in fractional free-volume being related to the physical structure of polymers. To show this in greater detail, a special study was made102. Hie viscoelastic properties and relaxation time spectra were studied in a filled system where a powder of hardened epoxy resin was used as the filler and the same epoxy resin as the matrix. Thus the system was identical from the chemical point of view, the only difference being in die method of preparation. 

Langer R, Peppas NA. Chemical and physical structure of polymers as carriers for controlled release of bioactive agents a review. Rev Macromol Chem Phys 1983 C23 61-126. 

The chemical structure of macromolecular compounds should be independent of the method of synthesis, at least in the ideal case. Part I is thus concerned with the chemical and physical structure of polymers. 

Spectroscopic studies at variable temperatures have become an important tool for the characterization of the physical structure of polymers. Especially in combination with thermoanalytical DTA or DSC measurements short-time spectroscopic FTIR investigations in controlled heating or cooling experiments provide a detailed picture of the structural changes as a function of temperature. Any variations of spectroscopic parameters such as intensity, wavenumber position and band shape directly reflect the temperature dependence of the vibrational behaviour of the investigated polymer as a consequence of changes in the inter- and intramolecular interactions and the state of order The vibrational spectra of polymers recorded in selected... 

The analogy between polymer chains and spaghetti is a useful one in examining the physical structure of polymers. As everyone knows. 

In combination with full-spectrum multivariate analysis methods and developments in fibre-optic technology NIR has gained great importance especially for chemical quality assurance but also for automatic reaction process confiol of polymers, in a rational and economical manner [272,278]. Although multiple component quantitations are now routinely being performed, NIRS is not an easy to use technique. Each specific application needs to be calibrated. The complex relation between chemical and physical structure of polymers can easily lead to misinterpretations by uncritical use. Clearly, NIRS is not a technique suitable for analysis of competitor products beyond the training set. 

Mechanochemical processes can induce modifications in both the chemical and physical structure of polymers. Changes in melt rheology and solid mechanics can also result. The more important variations that can occur... 

The results obtained show that stabilizer injection causes a significant (over two times) deceleration of thermal oxidation in LCP. Of interest is the effect of additives on polymer morphology, determined during studying stabilized and non-stabilized samples (before and after thermal oxidation in air) by the X-ray difiraction analysis. It is found that crystalline reflex is preserved in stabilized polymers, whereas it disappears in non-stabilized samples. The stabilization effect on the physical structure of polymers was not studied well with respect to chemistry of degradation processes. Only complex consideration of the problem (chemistry + change of physical permolecular structure) may cause the increase of thermal stability of prepared product and extension of the material lifetime in articles. 

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