Organic Plastic Research Articles

Deformation and failure of angle-plied organic fiber-reinforced plastics in the 3D stress state

Tubular specimens of organic fiber-reinforced plastic (OFRP) are tested in tension under a high hydrostatic pressure of up to 300 MPa. The specimens are made by winding at an angle of ±60° to the generatrix. The experimental equipment and technique are described. The tests show the insignificant effect of hydrostatic pressure on the elastic properties and the failure mode of the OFRP. The hydrostatic pressure considerably affects the strength properties of the OFRP. The material strength increases almost twofold under a pressure of 300 MPa. The failure strains of the material increase significantly as well.

Effect of the surface structure of a composite material on spatio-polarization characteristics of reflected radiation

The polarization degree, rotation of the polarization plane, and strength indicatrix of radiation with a wavelength of 0.63 μreflected from the surface of a unidirectional superhigh-modular organic plastic are investigated.

Meetings of the Royal Botanical Society of The Netherlands

A new non-chemical method for the control of soilbome pathogens is being developed. This method involves the incorporation of green plant material into moist soil, directly followed by the application of a plastic tarp with a low permeability for oxygen for 12-15 weeks in summer and autumn. Results of field experiments in 4 consecutive years show that in this manner a strong reduction in the inoculum density of Fusarium oxysporum f. sp. asparagi and Verticillium dahliae (usually >90%) is achieved. No significant reduction was observed in treatments with organic material or plastic only. Following application of the plastic, the treated soil became anoxic rapidly and redox potential dropped gradually to values as low as —200 mV at a depth of 15 cm. Products of fermentative bacteria (e.g. organic acids, aldehydes, alcohols) that accumulate temporarily in the anoxic soil layer prior to the onset of methanogenesis are suggested to be responsible for the inactivation. These products can cause inactivation of fungal resting structures either by acting as a toxicant or by inducing germination followed by lysis. A simulation model was developed to describe organic matter decomposition and transport processes in treated soil. With this model it can be shown that key factors controlling the concentrations of fermentation products in treated soil are (1) the amount and quality of the organic matter; (2) the amount of available inorganic electron acceptors, such as oxygen, nitrate and reducible Fe oxides; (3) the initial biomass of methanogenic bacteria in the soil; and (4) soil temperature. Further research aims at obtaining more insight in the mechanism and dynamics of inactivation during the treatment since this will allow an efficient optimization of the control method.

THE USE OF SCINTILLATING FIBERS FOR CHARGED-PARTICLE TRACKING

▪ Abstract The demand for instrumentation capable of detecting and triggering on ionizing radiation in high-rate particle physics experiments at colliding-beam and fixed-target accelerator facilities and for spacecraft-borne instrumentation in astrophysics has led to the development of new tracking technologies. One of these, scintillating fiber tracking, combines the speed and efficiency of a scintillation detector with the flexibility and hermeticity afforded by fiber technology. A paradigm for a fiber-tracking detector that utilizes organic plastic fibers read out with visible-light photon counters is presented and critiqued. Alternate strategies are considered, and an overview of recent experimental applications is provided.

Notiz: Sulphate Rotator Phases in Polarised Light

Abstract Li2SO4 has a well defined high-conducting fee phase in the temperature range 577-860 °C, and LiNaSO4 a bcc phase in the range of 518-614 °C. Both salts were studied in polarised light during sequences going from melt, through the cubic phase into the "room temperature" phase, and back to the cubic phase. The two cubic sulphate phases are compared with organic plastic rotator phases, especially regarding the formation of vapour snakes.

Effects of sowing cowpea on properties of an irrigated Vertisol and growth and yield of succeeding cotton

The effects of sowing a break crop of cowpea on soil properties, nutrient uptake, growth, and yield of furrow-irrigated cotton were evaluated in a trial conducted from 1993 to 1995 in a Typic Haplustert (Vertisol) with high subsoil compaction in north-western New South Wales, Australia. The experimental treatments were cowpea (Vigna unguiculata Walp.)-cotton (Gossypium hirsutum L.), continuous cotton, and long-fallow cotton (cotton alternating annually with a bare fallow). Cotton was sown in all plots in 1994 with minimum tillage. Soil was sampled to a depth of 0.6 m in August 1993, May–June 1994, and April 1995. Soil properties evaluated were organic matter fractions, resilience (a measure of the self-mulching ability of the soil), plastic limit, strength (as cone resistance), shrinkage indices derived from shrinkage curves, exchangeable Ca, Mg, K, and Na, pH, nitrate-N, and electrical conductivity. Profile water content and water extraction, nutrient uptake, crop vegetative growth, cotton lint yield, and fibre quality were also quantified. Compared with fallowing, sowing either cotton or cowpea in 1993 decreased pH and aggregate size formed after puddling and drying, and increased soil organic matter and plastic limit. Cropping also increased exchangeable cations in the surface 0.3 m of the soil. Nitrate-N in the 0–0.15 m depth was 23% higher after cowpea than after fallow. Amelioration of soil compaction was quickest in the short-term where continuous cotton was sown, but was also observed with time in plots where cowpea was sown in 1993. In comparison with cowpea-cotton and long-fallow cotton, continuous cotton had the highest nutrient uptake. Growth of cotton sown after either fallow or cotton was greater than that of cotton sown after cowpea, with lint yield being highest in the previously fallowed plots. Lint fibre quality did not differ significantly between treatments. Overall, the benefits of sowing cowpea in terms of improvements in soil properties and crop yields were either small or negligible in comparison with fallowing or sowing cotton.

Michael Buonocore and the Eastman Dental Center: a historic perspective on sealants.

Dr. Michael Buonocore is known for his innovative research on the preparation of the enamel surface with a weak acid to enhance adhesion of an organic plastic chemical sealant and the polymerization in situ of a sealant with ultraviolet light. His co-workers at Eastman Dental Center aided and extended his research findings. The purpose of his original research was the development of a sealant to prevent occlusal caries on posterior teeth. However, the major impact of his work has been the development of adhesive restorative techniques. Although it has been demonstrated that (i) bacteria tend to die out and caries does not progress if early caries lesions are inadvertently sealed, (ii) sealant retention rates are favorable, and (iii) sealants are cost-effective, the use of sealants by the profession is still far short of early expectations.

The effect of magnetic field on the scintillation efficiency of organic scintillators

The fluorescence of different organic plastic and liquid scintillators has been measured as a function of magnetic fieldH up to 13 mT (milli tesla). In the case of NE213, NE230 and stilbene, the percentage change in scintillation efficiency ΔE(%) increases with increasingH till it becomes maximum at an optimum valueH m, and then it decreases with further increase inH. However, in the case of pamolene crystal ΔE(%)) increases monotonically withH throughout the magnetic field range referred to.

Experimental investigation of the deformability of fiberglass and organic plastics as a function of strain rate

The purpose of the present study is to investigate experimentally the effect of strain rate on the mechanical characteristics of unidirectional epoxy-base composite materials. Specifically, fiberglass and organic plastic in the form of tubular specimens with a 0 degree winding angle.

Long-time strength of a composite shell in a field of centrifugal forces

The article deals with a shell of revolution made of fibrous composite material that is subjected to the effect of centrifugal forces and contact pressure from the side of the flywheel rim. For investigating long-time resistance, an approach according to components is used: the shell is represented in the form of the combination of a jointly operating monotropic (filament) and an isotropic (binder) layer. The problem is solved with large deformations. In the solution the hereditary theory of creep and the energy criterion of long-time strength were used. The solution in time was carried out by the step method. A computer program for the numerical realization of the problem was prepared. An example is presented of the calculation of the change of the state of stress and strain and of the strength of the components of an organic plastic shell.

Phase transitions in “plastic crystals”

The solid state phase transitions in certain organic molecular plastic crystals reversibly absorb large amounts of heat. These have potential applications for use in thermal energy storage. Pure plastic crystals undergo first order transformations but the binaries exhibit complex behavior. A phase diagram for two energetic materials, 2,2-dimethyl-1,3-propanediol (NPG) and 2-amino-2-methyl-1,3-propanediol (AMPL) plastic crystals is proposed. This diagram was determined by high temperature Guinier X-ray diffraction and differential scanning calorimetric methods. It is found that the AMPL rich binaries supercool and the high temperature phase can be triggered by straining the material to release an estimated amount of 50–53 cal g −1 at room temperature. The structure of the high temperature γ′ phase of AMPL is determined as body centered cubic with a lattice parameter 6.778 Å at 92 °C; which is much lower than that of 8.8381 Å at 46.5 °C for the face centered cubic γ phase of NPG. A eutectoid γ → α + β transformation occurs at 20 °C. In the AMPL rich mixtures heat is absorbed in the α + γ and α + γ′ regions over a wide temperature range. An interesting feature is that there are binary equilibria between the γ and γ′ phases, with molecular rotations. Some rather uncommon thermal contractions with abrupt changes of 28% are observed in γ and γ′ phases in heating AMPL-25 mol.% NPG binary mixture.

Effect of stress ratio on the fatigue strength of organic plastics

Experimental fatigue curves of a unidirectional organic plastic are obtained for a number of asymmetry factors and diagrams of the limiting cycle stresses are constructed for a load in the direction of the fibers and across the fibers, and for in-plane shear of a layer. The simplest methods of approximating the calculated diagrams are tested. It is shown that the method of layer-by-layer analysis of fatigue failure makes it possible to construct limiting-stress diagrams for a laminar oblique-ply composite with an accuracy acceptable for engineering calculations, proceeding from the same analysis as for an individual layer.

Use of elements of the mathematical theory of experiment planning to determine the mechanical characteristics of unidirectional organic plastic as a function of the technological parameters of winding

Use of elements of the mathematical theory of experiment planning to determine the mechanical characteristics of unidirectional organic plastic as a function of the technological parameters of winding

Investigation of the interaction of laser radiation with composite materials by infrared spectroscopy methods

A description is given of the method and apparatus for determination of the effective temperature and composition of a jet of products of the interaction of laser radiation with a glass-fiber-reinforced plastic and an organic plastic. Measurements are also possible of the temperature and emissivity of a target when it is exposed in atmospheric air to cw CO2 laser radiation with a flux density of 3 × 102 — 103 W/cm2. The products of damage to the glass-fiber-reinforced plastic consisted of particles of metal oxides with a diameter d32 = 2.3–3.5 μm and a volume concentration Cv = (0.06–0.25) × 10 − 4, and of molecular gases CO2, H2O, and HCl; the damage products of the organic plastic were conglomerates of soot particles with the diameter d32 = 1–1.8 μm and a volume concentration Cv = (0.4–0.9) × 10 − 4, and the same molecular gases. The target emissivity increased with time and reached 0.8–0.9.

Fatigue of laminated composites with various reinforcement systems. 2. Planar stress state and calculation model

1. The fatigue strength diagrams at up to 106 load cycles were obtained for the first time for a laminated organic plastic in the plane stress state, i.e., cophased loading with cyclic tension—compression and shearing. 2. The calculation based on the concept of ply failure and linear damage cumulation reflects accurately from the qualitative viewpoint the dependence of the fatigue strength of the laminated organic plastic, on the reinforcements system and the loading beam. 3. The assumption on the partial retention of the capacity of the ply to receive loading after failure and compression in the direction of the fibers results in better agreement with the experimental data in the plane stress state than the hypotheses on the complete reduction of the elastic constants to zero.

Properties of epoxy organic carbon plastics under conditions of thermohumid aging

1. The rate of moisture absorption depends on the volume content of organic plastic in hybrid CM, and it increases with increasing content. Hybrid composites with distributed layers of organic plastic have greater moisture absorption than composites with “block” reinforcement with equal content of SVM. 2. Thermohumid aging leads to impaired elastic and strength characteristics of organic carbon plastics, mainly on account of the sensitivity of the organic layers to these factors. 3. When hybrid CM are exposed to high temperatures and moisture, there are reversible effects (change of the vitrification temperature) as well as irreversible effects (incomplete restoration of mechanical characteristics in uniaxial quasistatic tension and in three-point bending).

Fatigue of laminated composites with various reinforcement systems. 1. Experimental results

1. We obtained the fatigue diagrams of the unidirectional organic plastic in asymmetric tension and compression under various angles to the reinforcement direction at 106 cycles. The fatigue coefficients in tension vary from 0.35 to 0.54, in compression from 0.42 to 0.72. 2. The mechanisms of failure of the unidirectional organic plastics in static and cyclic loading are identical. 3. It was shown that the linear and quadratic strength criteria of the Coulomb-Mohr types can be used to calculate the static and fatigue strength of the unidirectional organic plastic in uniaxial tension and compression. 4. The fatigue diagrams of the laminated organic plastic were determined on the tubular specimens in asymmetric tensile and compressive loading at 106 cycles. The values of the fatigue coefficients in tensile loading vary from 0.17 to 0.49, in compressive loading from 0.39 to 0.71. 5. The fatigue strength of the laminated organic plastics in asymmetric tension and compression can be evaluated on the basis of the correlation dependence between the values of the proportionality limit on the static deformation curves and the fatigue strength of finite life determined previously for the glass textolites.

Static and fatigue strength of unidirectional composites under the combined effect of shear stress and transverse tension-compression stresses

1. Experiments were conducted on the tubular specimens into the strength of the unidirectional glass-reinforced plastic under the combined effect of the shear stresses and transverse tension-compression stresses. 2. The fatigue strength of the unidirectional organic plastic in uniaxial and biaxial asymmetric cyclic loading in the σ2 ∼ τ12 stress plane was examined by means of experiment. 3. The results show that Hashin's quadratic criterion can be used to describe the static and fatigue strength of the unidirectional composites under the combined effect of the shear stresses and transverse tension-compression stresses.

Synkinematic microscopy of transparent polycrystals

Deformation of weak, polycrystalline materials in thin section, on the stage of a petrographic microscope, offers insight into the origin of optical microstructures similar to microstructures in naturally deformed rocks. Sample materials used to date include several soft minerals (ice, carnallite, bischofite, nitratite) and various organic plastic materials. They can be simple-sheared or pure-sheared at temperatures to 300°C, at a variety of strain rates, using relatively simple and inexpensive apparatus. The complete microstructural evolution can be recorded photographically, along with the complete kinematic history. Research applications have focussed on dynamic recrystallization, and progress has been made towards understanding how the average grain size is maintained constant in steady-state recrystallization flow. Records have been obtained of the development of various crystal-plastic microstructures and of lattice reorientation trajectories during flow. Teaching applications have begun to be developed, and several videotapes are available. Future technical developments are expected to permit stress measurement or control during experiments, and synkinematic recording of lattice reorientation. Numerous research areas invite attention. These include investigation of the microstructural developments that precede faulting, the behaviour of deforming crystal-melt systems, and the behaviour of dynamically reactive, multi-phase systems.

EFFECT OF HEATING ON SOME PHYSICAL AND CHEMICAL PARAMETERS RELATED TO SOIL AGGREGATION AND ERODIBILITY

To clarify the effect of the heat wave that accompanies the passage of a fire on some physicochemical parameters related to soil erodibility, we subjected two soils, classified as a sandy loam and a silty clay, to an artificial heating in controlled conditions. The heating program was arranged according to the true thermal reactions occurring in the soils previously detected by differential thermal analysis. Heating up to 220°C had only little effect on organic matter content, particle-size distribution, and plastic and liquid limits. Beyond this value the organic matter was burned up, the soils lost their plasticity, and the textural sand fraction increased. The aggregate stability of both soils increased continuously also when the generally acknowledged cementing agents, such as the gel forms, the organic matter, and the organometallic cements, were destroyed. This means that heating promotes new forms of cementation in which iron and aluminum are involved in a process very similar to soil laterization. The porosity of the sandy loam soil decreased continuously, as the heating increased, the clearest evidence of this being in correspondence of the dehydration of the gel forms; on the contrary, the porosity of the silty clay soil increased up to 460°C. At this temperature the porosity sharply decreased, because the heating produced the loss of the OH groups from the clay materials and the internal structure of the clays collapsed.