Sample Shrinkage Research Articles

Effect of Expanding Monomer on Carbon Fiber-Reinforced Epoxy Composites

Abstract : In this investigation it was confirmed that copolymerization of dinorbornene spiroothocarbonate (DNSOC) with expoxy can eliminate sample shrinkage and even produce sample expansion. To maximize control of shrinkage, it is important to bring epoxy to the gel stage before the DNSOC begins to copolymerize. Embedded single filament tensile test results were compared for samples containing DGEBA-epoxy cured with m-phenylene diamine (mPDA) with those for DNSOC-epoxy cured with m-phenylene diamene (mPDA) with those for DNSOC-epoxy samples cured with mPDA and BF3.diethylenetriamine for which BF3 was used to catalyze polymerization of the DNSOC. As compared with epoxy, the DNSOC sample showed ten-fold reductions in interfacial tensile stress, 10 C reduction in Tg, and 40% reduction in tensile strength. The tensile modulus was not reduced and the sample showed no shrinkage. No stress patterns were seen in the DNSOC-epoxy with a polarizing microscope. It is concluded that smaller amounts of DNSOC than 12% can be used to produce optimal effects on mechanical properties. (jes)

Laser ultrasonic monitoring of ceramic sintering

Noncontacting laser-ultrasonic measurements of the sintering of ceramics in real-time are described. Lasers are used for both generation and detection of ultrasonic waves propagating through the material. A pulsed laser generates the ultrasonic wave from thermoelastic absorption at the material surface. Detection is accomplished by a confocal Fabry–Perot interferometer, which is insensitive to the speckle nature of the scattered light from the sample surface and can obtain measurements from samples with rough or diffusely reflecting surfaces. The densification of the ceramic sample is determined by changes in the bulk longitudinal wave velocity and the sample shrinkage.

A comparison between acetone and dioxane and explanation of their role in water replacement in undisturbed soil samples

SUMMARYUndisturbed, moist samples from the A horizon of a swelling grey clay were treated with acetone or dioxane with or without para‐dichlorobenzene to replace soil water. They were then either impregnated with polyester resin whilst still solvent‐wet or after drying. Structural changes in samples treated with dioxane and then impregnated while solvent‐wet indicated little evidence of either disintegration or shrinkage resulting from the treatment. However, samples treated with acetone were prone to disintegration, but this was mitigated somewhat by the addition of para‐dichlorobenzene. Allowing either solvent to evaporate before impregnation caused shrinkage.X‐ray diffraction and infra‐red studies of treated clay separates indicated that dioxane prevented the marked swelling and potential dispersion found with acetone. It was concluded that dioxane breaks structural bonds within clay interlayers and between soil crumbs, thus limiting both collapse of clay minerals and sample shrinkage on drying. No changes to plasmic fabrics could be seen under a petrological microscope. Because of their appropriate size and shape, dioxane molecules could also enter clay interlayers so preventing marked shrink/swell movements. There is some indication that they may also form epoxide‐like compounds that themselves form structural ‘cements’.

The influence of deformation temperature under uniaxial stretching on the parameters of heat shrinkage of high density polyethylene

The influence of deformation temperature under uniaxial stretching on the nature of shrinkage stress and the change in linear dimensions of PE oriented samples during subsequent heating has been studied. It has been shown that thermal expansion of the material takes place in the initial stages of heating under orientation above the temperature of PE melting. Subsequent increase in temperature to that of PE melting causes the development of shrinkage stress and sample shrinkage. On orientation below the melting temperature, the heat expansion can be completely balanced, whereas sample shrinkage develops in the early stages of heating; high values of shrinkage stress are observed.

Grip for fatigue testing pure aluminium

A simple method of clamping pure aluminium for fatigue tests at cryogenic temperatures is described. Easily machined cylindrical specimens are aligned and held firmly by collet grips that counteract sample shrinkage during cooldown. Specimens are quickly mounted and removed after testing without distortion or thermal treatment 99.999% aluminium, aluminium alloys and copper were gripped successfully through tens of thousands of fully reversed tension-compression cycles at 295, 77 and 4.2 K.

Studies on the juvenile Japanese sea bass in the Chikugo estuary of Ariake Bay. III. Ecology of ascending larval and early juvenile Japanese sea bass in the Chikugo estuary.

In order to clarify the ecology with the river ascension of the larval and early juvenile Japanese sea bass Lateolabrax japonicus, larva net sampling and environmental observations were made in the Chikugo River estuary of Ariake Bay. A total of 3297 fish (SL, 10-24mm) was collected with 274 tows in 1981-1983.Preliminary notes on the ascending mechanism of the sea bass are given. In the vertical research across the river, the ascending sea bass larvae were concentrated near the bank, and the catch on flood tide is larger than on ebb tide both in the middle and near the bank of the river. The catch in the surface layer is more than that at the bottom (the ratio, 1:0.55).Comparative examination of yearly abundance and mean length was made, including results in mid 10-day of March during 1979-1983. There was a 10-fold difference in yearly abundance around the river mouth area. The range of yearly variation in the mean body length was more than 2mm.Ages and spawning season were determined from daily growth increments in the otoliths. One increment was formed each day after hatching. Spawning season extended from November to the next February, and the peak spawning was in January. The mean hatching date slightly changed each year. Estimated standard length was almost the same for sea bass of the same age (100 days after hatching). The sample shrinkage by preservation and percentage of water contents was also examined.

Effects of After-curing on the Properties of the Carbon-glass Composite

Effects of after-curing in the air and in N2 gas on properties of the carbon-glass fiber composite are described.The after-curing temperatures are 230, 250 and 300°C., and after-curing period is about 24 hours.After-cured composites are carbonized at 1000°C in coke powder. The heating rates are as follows: 5°C/min for the temperatures ranging from the room temperature to 200°C, 10°C/hr for temperature ranging from 200 to 280°C, 2.5°C/hr from 280 to 500°C, and 7.5°C/hr for temperature ranging from 500 to 1000°C.Two kinds of glass-cloth phenol resin laminates are used as the samples; resin content of the sample I is about 30%, and that of the sample II is about 51%.The effects of after-curing are as follows: No difference of the sample shrinkage by both after-curing and carbonization is observed between the specimen cured in the air and that in N2 gas at all after-curing tempera tures. Moreover, there is no significant difference of glass content, real density, bulk density, and porosity between these samples cured in different atmospheres. The weight loss by after-curing for the sample I in the air is smaller than that in N2 gas to 250°C, but for the sample II, no difference is observed.Flexural strength of the carbonized sample increases with the after-curing temperature . Flexural strength of the sample after-cured in the air is larger than that after-cured in N2 gas throughout the curing temperatures investigated.

Experimental control, subject selection, and problems of generalization in research with schizophrenic SS.

This report focuses on the severe reduction in sample size caused by the introduction of experimental controls in research with schizophrenic Ss and the limitations which this places on the generalizing of findings to the total population of schizophrenics. The selection procedures of a representative study were examined, and it was found that Ss meeting the selection criteria represented only 11.4% of the male schizophrenics in the hospital and 25.6% of all those meeting age and chronicity requirements. More detailed reporting of the degree of sample shrinkage and increased restraint in the generalizing of findings were recommended for studies using schizophrenic Ss.

Physical Growth from Birth to Maturity

RESEARCH on physical growth has been varied during the interval since the last review, but three major trends deserve mention. First, in exploring developmental aspects of growth there has been a continued emphasis upon longitudinal investigations of the same children thru time. This plan of research makes possible studies of individual variation in rate of development, and for a given sample size yields smaller standard errors for growth increment means than does the cross-sectional approach. Sample shrinkage, a major practical problem in longitudinal research, has been dealt with by workers at the Brush Foundation (63) by adding cases as needed and analyzing the data in terms of overlapping age groups arranged so as to permit splicing together the results for different stages of development. Second, there has been an emphasis upon the investigation of patterns of morphological variation among individuals, and of the relationships between physique, temperament, disease, and physical capacity. Interesting in this connection is the application of factor analysis to sets of anthropometric intercorrelations in an attempt to define mathematically the dimensions of growth and physical differentiation. Third, there has been an emphasis upon the integration of research findings from various sources. The last three years have perhaps produced fewer reports than heretofore on major investigations, but have been noteworthy for several comprehensive reviews including both published and unpublished findings on special topics (e.g., 15, 35, 37, 67, 73). These contributions have colligated and evaluated an extensive and scattered literature which the nonspecialist finds it difficult to correlate, owing to innumerable variations from study to study in sampling procedures and statistical treatments. However, these reviews suggest that much research effort would have been more productive had samples been more adequately selected and defined, and had anthropometric technics been applied in a more standardized fashion.

Accomplishments of the Regional Animal Research Laboratories

Accomplishments of the Regional Animal Research Laboratories