Nylon characterization methods

Both IR and Raman spectroscopies are vibrational spectroscopies that provide a unique identification of the substance, or a fingerprint. They are used extensively to determine the composition of materials as discussed by Koenig [3]. Lang et al. [4] showed that IR and Raman provided complementary information about the fibers. They comment that sample preparation is far easier for these methods than the traditional characterization methods based on the solubility of the fibers. In this mode, Raman is used to determine whether a film or fiber is nylon, polyester, polypropylene, cotton, wool, and so forth. Each type of material will have Raman bands specific to the type of polymer of which it is composed. If copolymers are present, the Raman spectra can be used to determine the ratio of comonomers. Many comonomers are strong Raman scatterers (aromatics, double and triple bonds, carbonyls, etc.). Others are weak Raman scatterers (NH, OH, etc.) and are better determined by IR. In either case, an appropriate calibration is required and the spectroscopist needs to make an educated selection between IR and Raman or perhaps use both. 

Standard Test Methods for Tire Yarns, Cords, and Woven Fabrics. ASTM standard D885M-94 includes test methods for characterizing tire cord twist, break strength, elongation at break, modulus, tenacity, work-to-break, toughness, stiffness, growth, and dip pickup for industrial filament yams made from organic base fibers, cords twisted from such yams, and fabrics woven from these cords that are produced specifically for use in the manufacture of pneumatic tires. These test methods apply to nylon, polyester, rayon, and aramid yams, tire cords, and woven fabrics. 

The surprising discovery that small oligo-P-peptides exhibit extraordinary tendencies to form stable secondary structures has led to rapid developments in the chemistry of these peptides. The earliest work in the field revolved around the synthesis of P-peptide polymers (the so-called nylon-3 derivatives). 2 Polymerization of P-amino acids led to polymers of undefined length. It was noted they could form stable structures but it proved impossible to gain any concrete information about the nature of those structures at that time. The developments in the synthesis of P-peptide oligomers of predefined length and advances in methods (i.e., NMR spectroscopy and X-ray crystallography) for the 3D characterization of such compounds has led to the discovery of new helical structures found to be adopted by a variety of P-peptides. I1,3-7 ... 

Test methods used to determine the uniformity of substrates are numerous and vary with the type of material. They are generally the same tests used to characterize the material or to determine its fundamental physical properties. Tests that are commonly employed are hardness, tensile strength, modulus, and surface characteristics such as roughness or contact angle with a standard liquid. Often a test similar to the nonvolatile test mentioned above is used to determine if there are any compounds in the substrate that are capable of out-gassing on exposure to elevated temperatures. Moisture content of certain hydroscopic polymers, such as nylon and polycarbonate, is also known to affect adhesion. 

Some of the areas where interfacial protein layers dominate the boundary chemistry are reviewed, and we introduce some nondestructive armlytical methods which can be used simultaneously and/or sequentially to detect and characterize the microscopic amounts of matter at protein or other substrates which spontaneously acquire protein conditioning films. Examples include collagen and gelatin, synthetic polypeptides, nylons, and the biomedically important surfaces of vessel grafts, skin, tissue, and blood. The importance of prerequisite adsorbed films of proteins during thrombus formation, cell adhesion, use of intrauterine contraceptives, development of dental adhesives, and prevention of maritime fouling is discussed. Specifics of protein adsorption at solid/liquid and gas/liquid interfaces are compared. 

Scanning electron microscopy (SEM) combined with energy dispersive X-ray (EDX) analysis could be used to physico-chemical characterization of SILMs [26]. This technique allows the characterization of the membrane surface morphology and the examination of the global chemical composition of the membranes and the distribution of the ILs within pores. Figure 11.2 shows examples of SEM micrographs of a plain nylon membrane and supported liquid membranes based on [bmim ][PF ] prepared by using the pressure method [26]. 

There are currently several methods for analysis of the amplified target DNA. For HIV-1, liquid hybridization with radioactively labeled probes is used (K12). Tests for HLA genes and sickle cell anemia utilize the reverse dot-blot format with a nylon membrane (S3). Each clinical research format has a well-characterized detection method defining the optimum probe concentration, the hybridization times and temperatures, as well as the concentrations of indicator reagents. Table 5 describes the optima and tolerances of a nonradioactive dot-blot assay that uses biotinylated probes and detection by a chemiluminescent substrate and a strepta-vidin-HRP conjugate. 

NMR, LD(low decoupling)/MAS NMR and PST(pulse saturation transfer)/MAS NMR methods [4, 5]. The CP/MAS method enhances the signal of the immobile component and, on the other hand, the LD/MAS and PST/MAS methods enhance the signal of the mobile component. These methods have been used to characterize the mobile and immobile components of nylon. 

For linear polyamides, the viscosity of dilute or moderately concentrated solution can be related closely to M . Thus, the molecular weight of polymer can be evaluated from i inh = ln reiA- This is usually measured at a concentration of 0.5 g of polymer in 100 ml of solvent, e.g., m-cresol. A typical value of T i h of nylon-6,6 is one forMn of about 15,000. Another method of characterization commonly used is to measure the relative viscosity (RV) of an 8.4% solution of polymer in 90% formic acid. Typical values of relative viscosity for nylon-6,6 are in the range of 30 to 70. An RV of 41 corresponds toMn of about 15,000, whereas an RV of 60 corresponds to about 19,000. Polymers in the lower range are used for textile yarns, and those in the higher range for industrial yarns. 

An extensive discussion of all the important aspects and methods of characterization of physical and mechanical properties of fibers is outside the scope of this chapter. Corresponding information can be found in more comprehensive treatises [331,332]. Some typical properties of nylon-6,6, nylon-6, nylon-11, nylon-6,11 and nylon-6,12 are listed in Table 2.5 and Table 2.6. 

As an example, the application of the CID (B/E) method to the structure elucidation of mass peaks generated in the DPMS of poly-)5-propiolactam (Nylon 3) is illustrat. The pyrolysis mass spectra of Nylon 3 are characterized by a series of peaks at m/z 71 + n71 which can be assigned to cyclic lactams, formed by an intramolecular exchange process, or to open chain oligomers formed through a 8-hydrogen transfer reaction (Scheme 5.1). 

Differential scanning calorimetry (DSC) is one of the routine methods used in polymer characterization and improves the knowledge of the microphase structure with other complementary methods. Lu et al. [149] investigated nonisothermal crystallization processes of Nylon/EVM (ethylene-vinyl acetate rubbers) blend using DSC and they found out that EVM rubber could act as heterogeneous nuclei acting more effective in Nylon/... 

The acid and base values of the surface functional groups of the samples were determined by Boehm s titration method [50]. To determine the acid value, O.lg of the sample was added to 100 ml of 0.1 M NaOH solution and the mixture was shaken for 24 h. The solution was then filtered through a membrane filter (pore size = 0.24 pm, nylon) and titrated with 0.1 M HCl. Likewise, the base value was determined by the reverse titration of the acid value. The specific surface areas (Sbet. [51]) of the samples were determined by gas adsorption. Physical adsorption of gases was used to characterize the CBs support, and the adsorbate used was N2 at 77 K with automated adsorption apparatus (Micromeritics, ASAP 2400). Prior to adsorption measurements, the samples were outgassed at 298 K for 6 h to obtain a residual pressure of less than 10 torr in high vacuum. To analyze the functional groups of CBs, the treated CBs were subjected to infrared (IR) spectroscopy (FTS-165 spectrometer, Bio-Rad Co.). 

In this section, we discuss the identification process and the chemical structures of polymers as obtained from their infrared and Raman spectra. Many polymers have common features, and it is convenient to segregate polymers into groups, such that the characterization of the polymers in a group can be discussed together. A popular method for classifying polymers is by their modes of application. For instance, some polymers, such as polyvinyl acetate, polystyrene, and nylons, are classified as thermoplastics, while urea, melamine, and epoxide resins are classified as thermosets or thermosetting resins. In this chapter we will use a different approach to classify the polymers, based on their similarity of chemical structure. This enables us to utilize the correlation between the functional groups of polymers and their characteristic infrared and Raman frequencies. 

Novel polyimide-g-nylon 6 and nylon 6- polyiniide-] nylon 6 copolymers were synthesized by polycondensation and subsequent anionic, ring-opening polymerization methods. The graft and triblock copolymer structures were characterized with FTIR, GPC, selective extractions, DSC,TGA, tensile test and DMA. The effective reinforcement of nylon 6 with the incorporation of only a few wt% polyimide was demonstrated by the sigmOcant improvements in the copolymers thermal and mechanical properties, and chemical resistance. 

Near-infrared (NIR) spectroscopy has been found to be a useful technique to characterize raw materials and finished textile products, and NIR methods and techniques continue to find increasingly diverse and wide-ranging quantitative and qualitative applications in the textile industry. Quantitative analyses determine the amount (or quantity) of the property/species of interest in a substance or material. Qualitative analyses can be used to either identify a specific species or subsfance present in a material (i.e., coating on a fiber), the type of material itself (i.e., cotton, nylon, or polyester), or the quality of the material. NIR quantitative and qualitative methods allow the user to rapidly, accurately, and precisely monitor key chemical, physical, and morphological properties of textile fibers, yarns, fabrics, and chemical textile auxiliaries. Chemical properties are specific chemical species or groups present in the material (i.e., CH, OH, NH) that result in NIR spectral absorbencies at distinctive... 

Applications showing the range of microscopy techniques and specimen preparation methods used on commercial impact polymers will be described. Changes in polymer morphology are expected upon addition of an elastomer for instance, such addition is expected to cause a decrease in the spherulite size as the elastomer domains can act as nucleating sites [219]. This has been observed for many polymers including modified nylon [220]. Characterization of an EPDM impact modified nylon 6,6 has been... 

In vitro reconstituted models of the BBB from different mammalian species have been used since the late 1970s. However, their comparison is difficult because of the different species and methods used for isolation, culture, coculture, and characterization of the models. Lundquist et al. (2002) confirmed that the epithelial cells might not represent a valid and reliable in vitro BBB model, because results obtained on epithelial monolayers correlated poorly with in vivo BBB permeability values. Bowman et al. (1983) introduced the first in vitro BBB filter model. The insert was made of nylon mesh and polycarbonate tubing, and bovine brain endothelial cells were seated on it for stud5ung the effect of calcium-free medium and osmotic shock on sucrose flux. Since then, a variety of... 

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