Characterization of polymer fibers

Voelkel, A. Inverse gas chromatography characterization of polymers, fibers, modified silicas, and surfactants. CritRev. Anal. Chem. 22, (1991) 411. 

The viscoelastic behavior of polymer fibers is complex. Experimentally, it is important to perform simple laboratory tests from which information relevant to actual in-use conditions can be obtained. The viscoelastic characterization of polymer fibers often consists of condncting mechanical tests that are similar to those discussed in Chapter 15, but are modified so as to enable the observation of the time dependency of fibers response. Three most important viscoelastic tests are creep, stress relaxation, and dynamic mechanical testing. 

Microscopic techniques are extensively used to study the surface morphology of reinforcing fibers. The characterization of microstructure of polymer fibers provides an insight into stmcture-property relationship of the fiber. Microscopy techniques have been employed for the... 

Narkis, M., Chen, E. J. H. and Pipes, R. B., Review of methods for characterization of interfacial fiber-matrix interactions, Polym. Composites, 9, 245 (1988). 

A technique for the characterization of polymer crystallinity as a bulk material or around the stiff fibers/particulates in composites is based on WAXS. The WAXS method is actually more of a bulk analytical tool than a surface technique, but it has been developed mainly for monitoring crystallinity in thermoplastics and fiber composites made therefrom. 

The interaction of two substrates, the bond strength of adhesives are frequently measured by the peel test [76]. The results can often be related to the reversible work of adhesion. Due to its physical nature such a measurement is impossible to carry out for particulate filled polymers. Even interfacial shear strength widely applied for the characterization of matrix/fiber adhesion cannot be used in particulate filled polymers. Interfacial adhesion of the components is usually deduced indirectly from the mechanical properties of composites with the help of models describing composition dependence. Such models must also take into account interfacial interactions. 

There are several major areas of interfacial phenomena to which infrared spectroscopy has been applied that are not treated extensively in this volume. Most of these areas have established bodies of literature of their own. In many of these areas, the replacement of dispersive spectrometers by FT instruments has resulted in continued improvement in sensitivity, and in the interpretation of phenomena at the molecular level. Among these areas are the characterization of polymer surfaces with ATR (127-129) and diffuse reflectance (130) sampling techniques transmission IR studies of the surfaces of powdered samples with adsorbed gases (131-136) alumina(137.138). silica (139). and catalyst (140) surfaces diffuse reflectance studies of organo- modified mineral and glass fiber surfaces (141-143) metal overlayer enhanced ATR (144) and spectroelectrochemistry (145-149). 

Molecular weight characterization of modacrylic fibers is difficult because of the limited number of solvents available and inhomogeneties in composition between individual polymer chains that affect solution properties, particularly if the comonomers are ionic in character. Di-methylformamide and dimethylacetamide are suitable for measurement of molecular weight of polyacrylonitrile, but errors are introduced when copolymers are analyzed (126). Bortniak et al. (127) have analyzed modacrylic fibers quantitatively in microgram quantities by using pyrolysis gas chromatography. 

A further illustration of IGC as a source of data for acid/base characterization of polymers and of solid constituents of complex polymer systems, is given by Osmont and Schreiber (49), who rate the inherent acid/base interaction potentials of glass fiber surfaces and of polymers by a comparative index, based on the Drago acid/base concepts (SO). The interaction index is conveniently measured by IGC and is shown to differentiate clearly among untreated and variously silane-modified glass fiber surfaces. Conventional methods are used to determine adsorption isotherms for fiber-polymer pairs, and the IGC data ate used to demonstrate the relationship between acid/base interactions and the quantity of polymer retained at fiber surfaces. 

Yang, K.S. Cuculo, J.A. Formation and characterization of the fibers and films from mesophase solutions of cellulose in ammonia/ammonium thiocyanate solvent. Polymer 1992,33 (1), 170-174. 

Procedure proposed by Papirer et al. [28,37-39,53] was used in characterization of silicas, modified silicas, oxides and minerals. Authors of refs. [23-28,30,54] used this method for characterization of carbon fibers, solid polymers, i.e. conducting polypyrroles, polycarbonates and poly (dimethacrylates), respectively. Voelkel and Krysztafkiewicz [55] characterized silicas modified by organic compounds. 

Schultz J, Lavielle L. Interfacial properties of carbon fiber-epoxy matrix composites. In Lloyd DR, Ward TC, Schreiber HP, Pizana CC, eds. Inverse Gas Chromatography—Characterization of Polymers and Other Materials. Washington, DC American Chemical Society, 1989 185-202. de Boer JH. The Dynamic Character of Adsorption. 2d ed. Oxford Clarendon Press, 1968. 

The use of IR microscopy is still fairly new but appears to be a technique that will find increasing applications in the future. Some of its current applications include identification of polymer contaminants, imperfections in polymer films, and individual layers of laminated polymer sheets identification of tiny samples of fibers, paint, and explosives in criminalistics characterization of single fibers in the textile industry and identification of contaminants on electronic components. 

Surface morphology of the electrodeposited PPDOT-Et2 film observed by SEM is characterized as a random and highly porous network of polymer fibers, as shown in Figure 3.9. The polymer fiber size tends to depend on the total charge... 

Sacks, M.D., A.A. Morrone, G.W. Scheiffele, and M. Saleem. 1995. Characterization of polymer-derived silicon carbide fibers with low oxygen content, near-stoichiometric composition and improved thermomechanical stability. Ceramic Engineering and Science Proceedings 16(4) 25-35. ... 

DAVID WILSON is a research specialist with 3M and has more than 10 years of research and development experience in the synthesis of new ceramic fibers using sol-gel techniques and is the inventor of the Nextel 610 and Nextel 720 ceramic fibers. His experience includes the development of novel fiber precursor formulations, continuous fiber processing, and characterization of ceramic fibers at room and elevated temperatures. Current research activities include preceramic polymer-derived SiC fibers and MOCVD coating and composite fabrication for the Mullite Matrix Composite Consortium Program. Mr. Wilson holds four patents and is the author of several publications. 

J. George, M.S. Sreekala, S. Thomas, A review on interfaee modification and characterization of natural fiber reinforced plastic composites. Polym. Eng. Sei. 41(9), 1471-1485 (2001)... 

M. Narkis, E.J.H. Chen, R.B. Pipes, "Review of methods for characterization of interfacial fiber-matrix interactions". Polymer Composites 9 (4), 245-251 (1988). Proceedings of the first International Conference on Interfacial Phenomena in Composite Materials - IPCM 89 , Sheffield (UK), September 5-7,1989. Controlled Interphases in Composite Materials , (Proceedings of the third International Conference on Composite Interfaces, Cleveland (Ohio, USA), May 21-24, 1990), Ed. by H. Ishida, Elsevier (N.Y., Amsterdam, London), 1990. Composite Science and Technology, 42 (1-3), 1991. 

In summary, there are a number of microscopic/spectroscopic experimental techniques, of which only a limited number have been discussed above, which are readily adaptable to the characterization of polymer/metal, fiber/matrix, and composite/composite adhesion. Indeed, basic questions in adhesion science such as the mechanism of adhesion, bond durability and the composition of failure surfaces, can be addressed experimentally today with increasing confidence due to the availability of these techniques. The author and his associates have summarized (6,11-13,22,25,2634,36-62) the results of the application of surface analysis to polymer/metal, fiber/matrix, and composite/composite adhesion on systems stuped at Virginia Tech. 

There are many techniques for probing the chemical and physical properties of a solid surface to predict the tending of organic polymers to solid surfaces. The electronic structure of solid surfaces has been studied by measuring the thermodynamic interaction of the solid surface with simple liquids of known molecular structure. Experimental techniques for measuring the thermocfynamic interaction between solid and liquid include contact angle measurement, calorimetry, and gas chromatography. Some of these techniques are discussed below. Specific techniques related to characterization of carbon fiber surfaces are also discussed. 

John MJ, Anandjiwala RD (2008) Recent developments in chemical modification and characterization of natural fiber-reinforced composites. Polym Compos 29 187-207 Joshy MK, Mathew Lovely J (2006) Rani studies on short isora fibre-reinforced polyester composites. Compos Interfaces 13(4—6) 377-390 Kicinska-Jakubowska A, Bogacz E (2009) Private sources of INEMP... 

Schirp A et al (2006) Production and characterization of natural fiber-reinforced thermoplastic composites using wheat straw modified with the fungus Pleurotus ostreatus. J Appl Polym Sci 102(6) 5191-5201... 

Borysiak S et al (2005) Method of preparation of board composites. Poland Patent No 190,405 George J, Sreekala MS, Thomas S (2001) A review on interface modification and characterization of natural fiber reinforced plastic ctnnposites. Polym Eng Sci 41 1471 Bledzki AK, Reihmane S, Gassan J (1998) Thermoplastics reinforced with wood fillers a literature review. Polym Plast Technol Eng 37 451-468... 

Hepworth DG, Hobson RN, Bruce DM, Farrent JW (2000) The use of unretted hemp fibre in composite manufacture. Compos A 31 1279-1283 Idicula M, Boudenne A, Umadevi L, Ibos L, Candau Y, Thomas S (2006) Thermophysical properties of natural fibre reinforced polyester composites. Compos Sci Technol 66 2719-2725 Ioffe R, Andersons J, Wallstrom L (2003) Strength and adhesimt characteristics of elementary flax fibers with different surface treatments. Compos A 34 603-612 John MJ, Anandjiwala RD (2008) Recent developments in chemical modification and characterization of natural fiber-reinforced composites. Polym Compos 29 187-207 John MJ, Anandjiwala RD, Thomas S (2009) Hybrid cranposites. In Thomas S, Pothan LA (eds) Natural fiber reinforced polymer composites macro to nanoscale. Old City, Philadelphia, pp 315-328... 

Tudu P (2009) Processing and characterization of natural fiber reinforced polymer composites a thesis submitted in partial fulfillment of the requirements for the degree of bachelor of technology in mechanical Engineering. Department of mechanical engineering National institute of technology, Rourkela, India, pp 1-52... 

M.J. John, and R.D. Anandjiwala, Recent developments in chemical modification and characterization of natural fiber-reinforced composites. Polym. Compos. 29,187-207 (2008). 

A.C. Karmaker, and G. Hinrichsen, Processing and characterization of jute fiber reinforced thermoplastic polymers. Polym. Plast. Technol. Eng. 30,609-629 (1991). 

---