Polymeric material, characterization

Plastics testing encompasses the entire range of polymeric material characterizations, from chemical stmcture to material response to environmental effects. Whether the analysis or property testing is for quaUty control of a specific lot of plastic or for the determination of the material s response to long-term stress, a variety of test techniques is available for the researcher. 

A series of carboxyl containing bioerodible polymeric materials, characterized by modulated functionality and hydrophobic/hydrophilic balance, was prepared both on a lab-scale and in the pilot plant. Procedures were setup as amenable for scaled-up productions. Those materials displayed a high versatility to combine with proteins in different proportion and to provide hybrid bioerodible matrices without any adverse effect on protein structure and activity. 

The modification of lignins by chlorophosphazenes allows the formulation of polymeric materials characterized by ... 

Challa, V., Kuta, K., Lopina, S., Cheung, H.A. and von Meerwall, E. (2003) Microporosity ofbi-continuous nanoporous polymeric materials, characterized with restricted diffusion. Langmuir,... 

Semicrystalline Plastic - A plastic (polymeric) material characterized by localized regions of crystallinity. See also Amorphous Polymer. 

In the area of chemical sensors, thin polymer films are routinely used as coatings for the semi-selective sorption of chemical vapors. One sensor technology, the surface acoustic wave (SAW) device, has demonstrated excellent sensitivity as a vapor sensor when coated with films having appropriate solubility properties (2). To date, most sensor applications have utilized the extreme mass sensitivity of the devices. In this paper, we will examine the response mechanisms of the SAW sensor and demonstrate its sensitivity to changes in the elastic properties of the coating materials. Finally, we will discuss the significance of these results in terms of current sensor applications, and the advantages of the SAW for polymeric materials characterization. 

Epoxy resins are an important class of polymeric materials, characterized by the presence of more than one three-membered ring known as the epoxy, epoxide, oxirane, or ethoxyline group. 

Hydrogels, or water-containing gels, are polymeric materials characterized by both hydrophilicity and insolubility in water (121). Hydrogels that are capable of absorbing very large amounts of aqueous fluids are sometimes referred to as superwater adsorbents. 

The 3 approach has been demonstrated with diverse problem-solving illustrations of polymeric materials characterization. Detailed, validated information in the synthesis and processing of complex natural and synthetic polymeries is imperative, so that the final formulated products meet their infield performance requirements. Automated analytical and process instrumentation with preprogrammed methods and interpretive guides enable manufacturers to provide high quality products for the global marketplace. 

We shall follow the same approach as the last section, starting with an examination of the predicted behavior of a Voigt model in a creep experiment. We should not be surprised to discover that the model oversimplifies the behavior of actual polymeric materials. We shall continue to use a shear experiment as the basis for discussion, although a creep experiment could be carried out in either a tension or shear mode. Again we begin by assuming that the Hookean spring in the model is characterized by a modulus G, and the Newtonian dash-pot by a viscosity 77. ... 

The search for substances which quahfy for proposed applications has always been a driving force for the synthesis and characterization of new compounds. This is especially true in polymer chemistry, where it is the potential of polymers as engineering materials that often stimulates research. Polymeric materials frequently fail to be serviceable in engineering applications for one of the following reasons ... 

After a temptative structure-based classification of different kinds of polymorphism, a description of possible crystallization and interconversion conditions is presented. The influence on the polymorphic behavior of comonomeric units and of a second polymeric component in miscible blends is described for some polymer systems. It is also shown that other characterization techniques, besides diffraction techniques, can be useful in the study of polymorphism in polymers. Finally, some effects of polymorphism on the properties of polymeric materials are discussed. 

Although the diffraction techniques are unique in providing detailed information on the structural organization at the molecular level in the different crystalline forms, there are other characterization techniques which are sensitive to the chain conformation and in some cases to the chain packing, which can be used advantageously (and in some case more efficiently than diffraction techniques) in the recognition and quantification of the different polymorphs in polymeric materials. 

The present review shows how the microhardness technique can be used to elucidate the dependence of a variety of local deformational processes upon polymer texture and morphology. Microhardness is a rather elusive quantity, that is really a combination of other mechanical properties. It is most suitably defined in terms of the pyramid indentation test. Hardness is primarily taken as a measure of the irreversible deformation mechanisms which characterize a polymeric material, though it also involves elastic and time dependent effects which depend on microstructural details. In isotropic lamellar polymers a hardness depression from ideal values, due to the finite crystal thickness, occurs. The interlamellar non-crystalline layer introduces an additional weak component which contributes further to a lowering of the hardness value. Annealing effects and chemical etching are shown to produce, on the contrary, a significant hardening of the material. The prevalent mechanisms for plastic deformation are proposed. Anisotropy behaviour for several oriented materials is critically discussed. 

An important aspect concerning the surface indentation mechanism is the creep effect shown by polymeric materials i.e. the time dependent part of the plastic deformation of the polymer surface under the stress of the indenter14-16. The creep curves are characterized by a decreasing strain rate, which can be described by a time law of the form... 

E. A. Turi, Thermal Characterization of Polymeric Materials, Academic, New York, 1997, Chapter 5,... 

Then, the macromolecular characterization is necessary to obtain the molecular weight distribution of the polymeric material and the average molecular weights. For this purpose, the first important condition is to get a perfectly molecular soluble material which means to avoid aggregation and/or take off insoluble material. This point was previously discussed [12]. The polysaccharide must be isolated preferentially as a sodium salt form to be fully soluble in water or in presence of some NaCI used to screen electrostatic interactions. 

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