Individual polymer components

Thermal analysis of homopolymer samples are simpler than those of blends. Separate thermal analysis of individual polymer components are made before doing the same for a blend in order to get more accurate and proper information on thermal characteristics. 

One technical difficulty that does beset recycling is that in many applications a variety of polymers are employed together in a complex way. It therefore becomes essential to distinguish between the various types of polymer in order to separate them. One system proposed (but not yet introduced anywhere in the world) is for the individual polymer components of complex articles such as automobiles to be identified using computer-scannable bar codes on each individual polymer component. 

Tsuchida et al.223 reported that in aqueous solution, the ratio of the components of the system of PMAA-PVPo is 1 1 whereas Bekturov et al.223) found a ratio of 3 2. This discrepancy may be caused by the influence of the concentration, pH and molecular weight of individual polymer components... 

It is expected that the intermacromolecular complexes display entirely new physical and chemical characteristics different from those of the individual polymer components. So the following applications are, for example, considered membranes for dialysis, ultrafiltration, fuel cells and battery separators, wearing apparel, electrically conductive and antistatic coatings for textiles, medical and surgical prosthetic materials, environmental sensors or chemical detectors, and electrodes modified with specific polymers. 

The findings of Scholte and Derham et al. revealed that g for quasi-binary solutions ought to depend not only on T and (j>, but on at least one more variable. It is not evident whether, in the early 1970s, one had a clear recognition that this third variable should be the chain length distribution f P) or, to be equivalent, that g should depend on the concentrations of the individual polymer components ((/> ,, [Pg.307]

A polymer blend is considered miscible if the free energy of mixing is zero or negative. If two polymers are miscible, then their blend properties, such as the glass transition temperature (7 ), will be the average of the two individual polymer component proportions. This may not be desirable for many applications because such a blend will lose its elasticity at low temperatures and the upper use temperature will be lower than that of the plastic used. 

One objective of developing polymer blends is to obtain new materials with different properties to those of the individual polymer components. Natural... 

The functional biopolymer matrix in biominerals is a multicomponent mixture with the possibility of all kinds of interactions and this makes the analysis of the individual polymer components difficult. Also, the biomineralization proteins are often polydisperse, have a non-globular shape and multiple charges and post translational modifications, which further hampers the protein separation. It is even more difficult to reveal their function as they are not only present in a polymer mixture with the associated possibUity of polymer interactions, but are furthermore often only active for a certain time. For example, in calcified parts of crustacean cuticles, 33 different proteins have already been identified [ 153] so that it is difficult to reveal the fimctions of individual biomineralization polymers. 

Several points should be kept in mind in "designing" an aiqiropriate blend system. Fiist, the individual polymer components should be incompatible, leading to clean phase-separated domains for the encapsulant and continuous matrix. Second, the continuous phase component should have a Tg some 30 to 50 C above the expected rai e for the encapsulant phase 7//. Hiird, the continuous phase polymer support should be free of, or have relatively weak sub-7 transitions, particularly in the ranges where the encapsulant is expected to show its Tg and Tn transitions. Lasdy, the minor phase should be incorporated at levels of 25 wt% or less so that h remains intact as isolated spherical domains embedded in the continuous high Tg polymer supporting medium. 

In total, the aforementioned experiments clearly show that the historical view, in which individual polymer components in a miscible amorphous blend should exhibit identical glass transition (and therefore a-relaxation chain dynamics) properties, is not always true. Qualitatively, these experimental results support the self-concentration idea, in that individual polymer chain dynamics for the blend constituents should depend on the relative concentrations of each of the components in the blend, as discussed in References [28, 37] in which concentration dependent results were obtained based on variations in the amounts of each... 

Chapter 3 provides a brief review of recent developments in areas of amorphous polymer blends. Differential mixing, chain dynamics, and glass transition properties for individual polymer components in miscible binary blends, as well as new methods to experimentally acquire such information, are considered. Miscible blend dynamics and length scales of mixing of amorphous polymer blends are discussed. Amorphous biopolymer blends involving polymers obtained from renewable feedstocks is also briefly reviewed. 

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