Analysis of the Iosipescu shear test as applied to unidirectional carbon-fibre reinforced composites

Intralaminar shear properties of unidirectional carbon-fibre reinforced epoxy and PEEK composites were investigated using the Iosipescu shear test. The apparent shear strength and shear moduli were measured using specimens with two different fibre orientations. Finite element analysis was applied to determine the stress distribution within the Iosipescu specimen. Using numerical correction factors to account for the non-uniform shear stress distribution in the gauge-section of Iosipescu specimens, the actual shear moduli were established. The Iosipescu shear test also provided a reasonable estimate of the shear strength.     

A high speed push-pull analog memory using transfluxors

A two-transfluxor analog memory is described. It uses single coincident-current pulses on separate signal and bais windings to store a flux level analogous to the input signal sample in about 10 μs. An additional winding senses the set flux level and permits further linearization of the storage characteristic by means of negative feedback.     

Radioimmunoassay of iodinated tobramycin

A radioimmunoassay for tobramycin was developed using antisera from rabbits injected with a tobramycin-bovine serum albumin conjugate. The antibody had a relatively high affinity for (125)I-labeled tobramycin (1.6 x 10(9) liters/mol), thus indicating little interference in immunoreactivity by iodination. The radioimmunoassay was highly specific, and only minor cross-reaction occurred with other aminoglycoside antibiotics. The radioimmunoassay was also more sensitive than previously published tobramycin assays (minimum sensitivity, 280 pg), and there was a significant correlation (P < 0.05) with both the radioenzymatic and microbiological assays.     

Multifunctional cotton fabric: Antimicrobial and durable press

2‐Amino‐2‐methyl‐1‐propanol (AMP) was coated onto cotton fabric with 1,2,3,4‐butanetetracarboxylic acid (BTCA) as a crosslinking agent to simultaneously impart antimicrobial and durable‐press functionalities. The coatings were characterized and confirmed by attenuated total reflectance–IR and thermogravimetric analysis. The coated fabrics were rendered biocidal upon exposure to dilute household bleach, and the chlorinated swatches exhibited about 6 log reductions of Escherichia coli O157:H7 and Staphylococcus aureus within 5 min of contact time. A concentration of 1.5 wt % AMP was sufficient to produce this biocidal efficacy. Increasing the BTCA content of the coating improved the wrinkle recovery angle. The coatings were very stable toward repeated laundering, and they exhibited sufficient halogen storage stabilities for industrial applications. A photolytic decomposition was observed when the coatings were exposed to UVA light. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Airlaid nonwoven panels for use as structural thermal insulation

Thermal-bonded airlaid nonwoven webs consisting of fiber glass and polyester bicomponent fibers were manufactured, and then multilayer webs were formed into composite panels using compression molding technique. The consolidation process was optimized and the effect of bulk density on air permeabilites, mechanical properties, and thermal resistance was studied. Increasing binder amount and bulk density improved the flexural and tensile strength. Thermal resistance of the panels were found to be very dependent on the bulk density such that the resistance increased exponentially with an initial increase in density, then leveled off and decreased linearly with further increment in density. Depending on the composition and bulk density, the panels provided thermal resistance between 0.52 and 0.88 Km²/W, tensile strength between 2 and 7 MPa, and flexural strength between 600 and 3500 kPa. The findings revealed that airlaid nonwoven panels can be designed to use as structural thermal insulation materials in constructions.     

Influence of coupling agents on material behaviour of glass flake reinforced polypropylene

This paper presents a study evaluating the effects of aminosilane and titanate coupling agents on the material properties of glass flake reinforced polypropylene and compares the results with pure polypropylene and untreated glass flake reinforced polypropylene. Tensile and flexural properties, impact resistance and residual stresses are strongly dependent on the type and level of coupling agent employed, whereas changes in melt-crystallisation and crystalline content of the polypropylene in the composite materials was minimal. Glass flakes modified with aminosilane gave higher stiffness and strength than the titanate treatment. Thermal expansion hysteresis provided an indication of the relative levels of residual stresses in the polymeric materials, which was verified using the layer removal method for determining residual stress distributions. Ultrasonic velocity measurements conducted on the composite materials before and after exposure to sub-zero temperatures proved useful in assessing the effectiveness of the various surface treatments in promoting interfacial adhesion.