R. E. Fornes

Fourier transform infra-red spectroscopy of nylon-6 blends: binary blends with poly(methyl methacrylate) and ethylene vinyl ester/alcohol copolymer

Abstract Films of blends of nylon-6 with poly(methyl methacrylate), (PMMA) and poly(ethylene-vinyl alcohol) were cast from formic acid solutions and examined by Fourier transform infra-red spectroscopy. At high contents of nylon-6 the vinyl alcohol of the copolymer reacts with formic acid to form vinyl formate. In contrast, the films of 100% copolymer and of the 25 75 and 10 90 blends contained both the alcohol and the ester groups. The FT i.r. results indicate that there are specific interactions between the amide group on nylon-6 and the ester group of PMMA or the copolymer. Data are also presented which show that there are at least two amorphous phases - one miscible containing both the polymers and the other containing almost pure noncrystallizable component. The differences in the specific interactions in the two blend systems are largely due to the inversion of the ester group in the pendant chain.

Electron spin resonance study of a cured epoxy resin exposed to high-energy radiation

Abstract Tetraglycidyl-4,4′-diaminodiphenyl methane cured with 4,4′-diaminodiphenyl sulphone was irradiated with varying dosages of 0.5 MeV electrons and 1.17 and 1.33 MeV gamma rays and was studied using electron spin resonance. The radical concentration increases with increasing radiation dose and decays, at ambient temperature, in a way consistent with a model that assumes two simultaneous second-order reactions occurring in different zones.

Inorganic Content of Cotton Dusts, Trash, and Bracts

The exact etiological agents responsible for the biological effects of cotton dust are unidentified, but most investigators believe they are organic in nature. Inorganic compounds have not been considered as significant factors. However, cotton dusts, trash, and bracts have high inorganic contents (7–43% ash), as reported here; more importantly, aqueous extracts of the trash and bracts have inorganic contents as high as 65%, which means a significant amount (10–36%) of the inorganic compounds in trash or bract is water extractable. Elements present in the ash include: N2, Cl2, P, K, Ca, Mg, Mn, Cu, Zn, S, and O2. KCl and K2SO4 have been definitively identified. It is suggested that greater attention should be given to the inorganic nature of cotton dust in the etiology of byssinosis.

Chemical Composition of Cotton Dusts Part II : Analyses of Samples Collected in a Model Card Room

The ash and protein contents of Pneumafil (PN) trash samples collected in a model card room and of the aqueous extracts of these samples arc reported here. The average ash content of these samples is 12.5% (σ = 4.2%). The average ash content of the dried aqueous extracts of these samples is much higher than that of the raw samples (mean 36.9%, σ = 10.8%). The average protein content of these samples and their dried aqueous extracts are about the same (13.2 and 14.9%, respectively). Trash samples from cotton grown under dry, arid conditions tend to have relatively high inorganic contents. Steaming tends to reduce the inorganic fraction of both the raw samples and their dried aqueous extracts but has little effect on the protein content. Increasing the number of gin lint cleaning stages reduces the dust level in the card room but has little effect on the proximate chemical composition of the PN samples. The fraction of ash in the PN dust tends to increase as the grade of cotton improves. Respirable dust collected from an electrostatic precipitator and respirable dust separated from lint trash are shown to have very high inorganic contents (41.3 and 37.1%, respectively). The average ash content of five samples rollected on the vertical elutriator was 20.1%, a value close to the average ash content of leaf and bract samples.

Chemical Composition of Cotton Dusts Part I: Analyses of Cotton Plant Parts, Gin Trash, and Weed Samples

Cotton plant parts are thought to be a major source of dust generated during cotton processing. Their chemical composition is important with regards to identifying the causal agents of byssinosis. Reported here are the ash and protein contents of cotton bract, leaf, stem, burr, and gin trash samples and of their dried aqueous extracts. The average ash contents of the above samples are 18.0, 16.6, 7.2, 7.5, and 19.1%, respectively. Significantly, the average inorganic contents of dried aqueous extracts are from two to five times higher than those of the raw samples.. The average protein contents of the above samples are 12.5, 17.4, 8.6, 5.7, and 13.6%, respectively. The average protein contents of the dried aqueous extracts of bract, leaf, and gin trash samples are about the same as the raw samples. The protein of the dried aqueous extracts of stem and burr increases markedly compared to the raw samples (from 8.6 to 21.3% and 5.7 to 15.5%, respectively). Ash and protein contents of several weed samples have been analyzed, and their extracts are approximately the same as stem and burr samples. The fraction of each sample that is extractable by water is about the same (ca. 13%) for all plant parts, gin trash samples, and weed samples investigated in this study.

Radiation Effects on Graphite Fiber Reinforced Composites

The effects of radiation on graphite fiber reinforced composites, particularly those using an epoxy matrix, are reviewed. Specifically, it is concluded that there is no catastrophic deterioration of mechanical properties for doses up to thousands of Mrad, provided the irradiation occurs in an oxygen-free environment.

Effects of 0.5‐MeV electrons on the interlaminar shear and flexural strength properties of graphite fiber composites

Composite samples of graphite fibers in both an epoxy matrix and a polyimide matrix have been prepared with different fiber arrangements and irradiated with 0.5‐MeV electrons up to 104 Mrad. Interlaminar shear strengths decreases significantly with radiation dosage while little change was observed in the flexural strengths and moduli. The results indicate that radiation causes significant degradation at the interface but not much change in the fiber or matrix.

An Analysis of the Mechanical Behavior of Triaxial Fabrics and the Equivalency of Conventional Fabrics

The results are presented of an earlier analysis of a triaxial fabric by extension of the classical results of Peirce and Grosberg. Using the geometrical model of this earlier work, a theoretical analysis is presented in which the work necessary to deform the fabric is approximated by the change in strain energy in the constituent threads. The relationship between triaxial and conventional fabrics is discussed in the context of equivalency. The relationships among triaxial, plain, and leno fabrics are discussed. Using a specially constructed biaxial test fixture, fabric moduli predicted in earlier work are experimentally verified. In addition, equivalent weight conventional fabrics, both plain and leno, are compared with a triaxial fabric through ball burst and tear testing. The study shows that, although both conventional fabrics can be thought of as equivalent to the triaxial fabric, in reality no conventional equivalent exists.

The Effect of Near-Ultraviolet Radiation on the Morphology of Nylon 66

Nylon 66 yarn was exposed to near-ultraviolet radiation in a dry oxygen atmosphere for exposure periods up to 240 hr. Dye take-up, viscosity, and density measurements, DSC thermograms, and wideline nmr spectroscopy were employed to assess the effects of the irradiation. Measureable changes were observed with each analytical technique. It was concluded that exposure of nylon 66 to the above conditions caused considerable chain scission in the defect regions, there was no detectable crosslinking, and the newly freed chain ends relaxed resulting in a more highly ordered fiber structure.

The Isolation of Cotton Plant Components by High-Performance Liquid Chromatography

The use of high-performance liquid chromatography (HPLC) to separate components of extracts of cotton bracts is described. A chloroform extract of the aqueous extract of the bracts and an ethanol extract of the dried aqueous extracts were used. The facile separation of 1,7-dihydroxy-4-isopropyl-1,6-dimethyl-2(1H)-naphthalenone (lacinilene C), its 7 methyl ether, and β-sitosterol from the chloroform extract, and 7-hydroxy-6-methoxycoumarin (scopoletin), cinnamic acid, and hydroxy cinnamic acid from the ethanol extract illustrate the capability of HPLC to separate the complex mixture of compounds in cotton plant parts. Preliminary separations by preparative thin-layer chromatography gave several major bands, but the HPL chromatograms showed that each band contains the same compounds, though in varying concentration, demonstrating the higher resolution of HPLC. Scopoletin was a major component in both extracts. Cinnamic and hydroxy cinnamic acids were identified by GC/MS. The other compounds were identified by pmr spectroscopy.