Polymers Searching

RAPRA free Internet search engine. The number of plastic-related web sites is increasing exponentially, yet searching for relevant information is often laborious and costly. During 1999 RAPRA Technology Ltd., the UK-based plastics and rubber consultancy, launched what is believed to be the first free Internet search engine focused exclusively in the plastics industry. It is called Polymer Search on the Internet (PSI). It is accessible at www.polymersearch.com. Companies involved in any plastic-related activity are invited to submit their web-site address for free inclusion on PSI. RAPRA Technology s USA office is in Charlotte, NC (tel. 704-571-4005). 

Herz M (1991) Polymer searching in different databases. J Chem Inf Comput Sci 31 469 75... 

Hydro Polymers Searching for a More Sustainable PVC, Environmental Expert.com, http // www.environmental-center.com/articles/articlel358/articlel358.htm. 

The more fully systematic lUPAC rules were adapted for the highly ordered alphabetical CA indexes. Most common names and special rules for some classes of substances were discontinued in 1972. Names used in the previous CA indexes as well as trivial names used in the literature have been retained as cross-references in the CA Index Guide and in the CAS database, and are available for polymer searching and retrieval. For each identifiable substance, a rigid order of precedence of chemical functions and compound classes is followed to determine first the preferred index heading parent, and then a single preferred name. 

Thus polymer structures represented on paper or stored in a database as ideal or theoretical representations are frequently not true representations of actual polymer structures. Before September 2002 all these problems and questions posed significant difficulties for the average polymer searcher. The following sections discuss what has been achieved to date in terms of organizing polymer structures and nomenclature, and of facilitating polymer searching. 

CAS. Enhanced Polymer Searching in Registry , STNotes No. 30, July 2002. Available on the world wide web at http //www.cas.org/ONLINE/STN/STNOTES/stnotes30.pdf... 

Woodruff and co-workers introduced the expert system PAIRS [67], a program that is able to analyze IR spectra in the same manner as a spectroscopist would. Chalmers and co-workers [68] used an approach for automated interpretation of Fourier Transform Raman spectra of complex polymers. Andreev and Argirov developed the expert system EXPIRS [69] for the interpretation of IR spectra. EXPIRS provides a hierarchical organization of the characteristic groups that are recognized by peak detection in discrete ames. Penchev et al. [70] recently introduced a computer system that performs searches in spectral libraries and systematic analysis of mixture spectra. It is able to classify IR spectra with the aid of linear discriminant analysis, artificial neural networks, and the method of fe-nearest neighbors. 

This is a fairly reasonable way to describe man-made amorphous polymers, which had not been given time to anneal. For polymers that form very quickly, a quick Monte Carlo search on addition can insert an amount of nonoptimal randomness, as is expected in the physical system. 

Conformation search techniques can be used to find very-low-energy conformations, which are most relevant to polymers that will be given a long annealing time. 

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 ... 

Copolymeis of ethylene [74-85-1] and tetiafluoioethylene [116-14-3] (ETFE) have been alaboiatory curiosity for more than 40 years. These polymers were studied in connection with a search for a melt-fabricable PTFE resin (1 5) interest in them fell with the discovery of TFE—HFP (FEP) copolymers (6). In the 1960s, however, it became evident that a melt-fabricable fluorocarbon resin was needed with higher strength and stiffness than those of PTFE resins. Earlier studies indicated that TFE—ethylene copolymers [11939-51 -6] might have the right combination of properties. Subsequent research efforts (7) led to the introduction of modified ethylene—tetrafluoroethylene polymer [25038-71-5] (Tefzel) by E. I. du Pont de Nemours Co., Inc, in 1970. 

Nuclear Magnetic Resonance Spectroscopy. Bmker s database, designed for use with its spectrophotometers, contains 20,000 C-nmr and H-nmr, as weU as a combined nmr-ms database (66). Sadder Laboratories markets a PC-based system that can search its coUection of 30,000 C-nmr spectra by substmcture as weU as by peak assignments and by fiiU spectmm (64). Other databases include one by Varian and a CD-ROM system containing polymer spectra produced by Tsukuba University, Japan. CSEARCH, a system developed at the University of Vieima by Robien, searches a database of almost 16,000 C-nmr. Molecular Design Limited (MDL) has adapted the Robien database to be searched in the MACCS and ISIS graphical display and search environment (63). Projects are under way to link the MDL system with the Sadder Hbrary and its unique search capabiHties. 

The wide range of soHd lubricants can generally be classified as either inorganic compounds or organic polymers, both commonly used in a bonded coating on a matching substrate, plus chemical conversion coatings and metal films. Since solid-film lubricants often suffer from poor wear resistance and inabihty to self-heal any breaks in the film, search continues for improved compositions. 

During the eady development of polycarbonates, many bisphenols were investigated for potential useftil products. Some of these monomers and polymers are hsted in Table 3. Despite this intensive search, however, no homopolycarbonates other than that of BPA have been produced. Copolymers and blends, on the other hand, have been quite successhil. Blends of polycarbonate with ABS and with poly(butylene terephthalate) (PBT in particular have shown significant growth since the mid-1980s. 

Epichlorohydrin. Commercial polyester elastomers include both the homopolymer and the copolymer of epichl orohydrin with ethylene oxide. The very polar chloromethyl groups create basic resistance to oil for these polymers, and they have been extensively used in fuel lines however, the desire for lower fuel permeation is causing a search to be made for other polymers (10) (see Elastomers, synthetic-polyethers). 

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