Structure glassy polymers

The high optical quality of these glassy polymer structures compares favorably with the propagation loss for devices fabricated in TiiLiNbO ( 0.1 dB/cm). In addition, Kurokawa et al investigated the use of selective photopolymerization to fabricate optical dividers and low loss couplers. 

Lately the mathematical apparatus of fractional integration and differentiation [58, 59] was used for fractal objects description, which is amorphous glassy polymers structure. It has been shown [60] that Kantor s set fractal dimension coincides with an integral fractional exponent, which indicates system states fraction, remaining during its entire evolution (in our case deformation). As it is known [61], Kantor s set ( dust ) is considered in onedimensional Euclidean space d = ) and therefore, its fractal dimension obey the condition d Euclidean spaces with d > 2 (d = 2, 3,. ..) the fractional part of fractal dimension should be taken as fractional exponent [62, 63] ... 

Let us consider two limiting cases of the adduced in Fig. 4.15 dependence at = 0 and 1.0, both at d = 3. In the first case (d = 2) the value dU = 0 or, as it follows from dU definition (the Eq. (4.31)), dW = dQ and polymer possesses an ideal elastic-plastic deformation. Within the frameworks of the fractal analysis d =2 means, that (p, = 1.0, that is, amorphous glassy polymer structure represents itself one gigantic cluster. However, as it has been shown above, the condition d =2 achievement for polymers is impossible in virtue of entropic tightness of chains, joining clusters, and therefore, d > 2 for real amorphous glassy polymers. This explains the experimental observation for the indicated polymers dU 0 or dW dQ [57], At Vg, =... 

A glassy polymers structure in the general case is multifiactal [85], for which the inequality is true [82, 84] ... 

Proceeding from the said above and also with appreciation of the known fact, that rubbers do not have to some extent clearly expressed yielding point the authors of Ref [73] proposed hypothesis, that glassy polymer structural state changed from multifiactal up to regular fiactal, that is, criterion (4.44) fulfillment, was the condition of its yielding state achievement. In other words, yielding in polymers is realized only in the case, if their structure is multifi actal, that is, if it submits to the inequality Eq. (4.45). 

Kozlov, G. V., Sanditov, D. S., Ovcharenko, N. (2001). The Plastic Deformation Energy and Amorphous Glassy Polymers Structure. Mater of Il-th Interdisciiplinaty Symposium Tractals and Apphed Synergetics FaAs-01 . Moscow, Publishers of MSOU, 81-83. 

Hence, the stated above results allow to give the following interpretation of critical temperatures and T of amorphous glassy polymers structure within the frameworks of solid body synergetics. These temperatures correspond to governing parameter (nanocluster contents) cp j critical values, at which reaching one of the main principles of synergetics is realized-sub-ordination principle, when a variables set is controlled by one (or several) variable, which is an order parameter. Let us also note reformations number m = 1 corresponds to structure formation mechanism particle-cluster [4, 5]. 

Thus, the Ref [27] results showed, that the obtained by EPR method natural nanocomposites (amorphous glassy polymers) structure characteristics corresponded completely to both the cluster model theoretical calculations and other authors estimations. In other words, EPR data are experimental confirmation of the cluster model of polymers amorphous state structure. 

For interactions nanoclusters - loosely packed matrix estimation within the range o T = 293- -373K the authors of Ref. [48] used the model of Witten-Sander clusters friction, stated in Ref. [46]. This model application is due to the circumstance, that amorphous glassy polymer structure can be presented as an indicated clusters large number set [47]. According to this model, Witten-Sander clusters generalized friction coefficient t can be written as follows [46] ... 

Bashorov, M. T, Kozlov, G. V., Mikitaev, A. K. (2009). A Nanoclusters Synergetics in Amorphous Glassy Polymers Structure. Inzhenemaya Fizika, N4,39-42. 

Crystalline structures have a much greater degree of molecular packing and the individual lamellae can be considered as almost impermeable so that diffusion can occur only in amorphous zones or through zones of imperfection. Hence crystalline polymers will tend to resist diffusion more than either rubbers or glassy polymers. 

When the stress that can be bom at the interface between two glassy polymers increases to the point that a craze can form then the toughness increases considerably as energy is now dissipated in forming and extending the craze structure. The most used model that describes the micro-mechanics of crazing failure was proposed by Brown [8] in a fairly simple and approximate form. This model has since been improved and extended by a number of authors. As the original form of the model is simple and physically intuitive it will be described first and then the improvements will be discussed. 

Water molecules combine the tendency to cluster, craze and plasticize the epoxy matrices with the characteristic of easily diffusion in the polymer1 10). The morphology of the thermoset may be adversaly influenced by the presence of the sorbed moisture. The diffusion of the water in glassy polymers able to link the penetrant molecules is, therefore, characterized by various mechanisms of sorption which may be isolated giving useful information on the polymer fine structure. 

The general principles of the structure of glassy polymers and their rubber-modified derivatives, and of the molecular and morphological parameters have been thoroughly investigated. 

An atactic structure is in both cases not crystallisable. Atactic PP is because of its glass-rubber transition temperature (Tg = -15 °C) rubbery and technically of no use. Isotactic PP is able to crystallise and can, therefore, be used in practice. For PS atacticity is no objection its properties as a glassy polymer are retained up to its Tg (95 °C). 

Regarding the effects of shear band structure on the fracture mode in glassy polymers, Wu and Li [170] concluded that when microshear bands propagate in a specimen cross section, a shear failure is produced with a very small overall de-... 

The reaction of curing the epoxy-amine system occurring in the diffusion-controlled mode has little or no effect on the topological structure of the polymer 74> and on its properties in the rubbery state. However, the diffusion control has an effect on the properties of glassy polymers 76 78). 

We shall conclude with some remarks on the structure of glassy polymers. If one frequently speaks of glass structures, this does not mean that there exists one definite glass structure similar to a crystal. In a macromolecular solid-e.g., the polystyrene-plasticizer system, entirely different glasses are obtainable, the macroscopic composition of which is always the same (8). In Figure 10 the full... 

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