Changes In Durability Research Articles

Microfocus small angle X-ray scattering reveals structural features in archaeological bone samples: detection of changes in bone mineral habit and size.

Microfocus X-ray scattering provides a powerful nondestructive technique capable of providing important information about the size, habit, and arrangement of mineral crystals in bone. The technique is capable of probing textural differences in a sample at a micron scale resolution. The study presented here involved the analysis of a number of archaeological bones by microfocus X-ray scattering at the ESRF Grenoble in order to determine local changes in mineral durability. The results showed that regions of bone with a modified microscopic morphology contained a greater dispersion of crystal shape when compared with more intact regions and control contemporary bone samples, but the crystal thickness values showed similar consistency. We speculate that the persistence of collagen in the archaeological bone may allow diagenetic remodeling of bone in terms of crystallite shape but defines the size of remodelled crystallites. The ability to detect such local changes in texture has wide potential for determining crystal characteristics in healthy and diseased bone samples.

Monitoring the changing state of a polymeric coating resin during synthesis, cure and use

Essential to 'intelligent manufacturing' and 'smart materials' is the ability to monitor the state of a polymer coating resin as it is synthesized in a reactor, as it cures during application and as it ages during use in the field. Important aspects of this sensor monitoring capability are: in situ, on-line measurement; that the signal output be related to the relevant processing and use properties; sensitivity with long-term reliability in a manufacturing and field environment. This paper addresses the ability of in situ dielectric sensor measurements to monitor the state and progress of batch reactor resin polymerization both in the laboratory and in an industrial ICI pilot plant, the cure of a coating during application, and the changes in physical properties or durability of the polymer during use in the field.

Fatigue Behavior of Aramid Nonwoven Fabrics Under Hot-Press Conditions

We set out to find the most suitable design for heat-resistant nonwoven fabrics to be used as components of laminated cushion materials. The changes in mechanical prop erties and durability of a nonwoven fabric subjected to repeated hot-press fatiguing treatments depend on the properties of the fiber material and the structure of the non woven. In this paper, we focus on fiber fineness, one of the material properties, and discuss its influence on the mechanical properties of nonwoven fabrics after hot-press fatiguing. We find that a nonwoven made of fine fibers has a higher tensile breaking strength and a higher tensile modulus than those made of larger diameter fibers. The nonwovens we prepared have the same fabric basis weight with different fiber diam eters. Accordingly, the finer fiber nonwoven has a larger number of component fibers than those of larger diameter fibers, and the degree of fiber entanglement in the finer fiber nonwoven is higher because the number of fibers caught by the needle is greater when the fibers are finer. Tensile breaking strength is proportional to the degree of fiber entanglement, so the finer fiber nonwoven has a higher tensile breaking strength. However, this strength decreases after too many fatiguing treatment cycles, probably due to the deterioration of the fiber material (Nomex). As regards compressive behav ior, the finer fiber nonwoven has a lower compressive strain and a higher modulus than those of the larger diameter fibers. These tensile and compressive properties are closely related to the nonwoven's fiber packing factor.

Apparent and Genuine Affluence

The twentieth century rise in energy consumption appears to be due more to rises in affluence than changes in energy technology. This conclusion is disputed by suggesting that the rise in energy consumption is due not to a genuine rise in affluence, but to the use of energy to produce goods and services that only compensate for the poorer character of new products and the environment within which they function. This thesis is examined using data on durability of products, and a measure of affluence that takes account of changes in the socioeconomic environment. These data indicate that changes in the environment can partly explain the rise in energy consumption, whereas changes in durability have had little if any effect.

Product Durability and Market Structure: Some Evidence

CHANGES in product durability disturb existing supply and demand relationships. Whether they occur ultimately depends on expected profits and, therefore, on the degree of competition among sellers. In competitive markets the firm is constrained by the actions of other producers. Being slow to introduce an innovation may force it to leave the industry as consumers turn to the improved products of competitors. Will the monopolist, who faces no such immediate constraints, produce a different quality of product from that which would emerge from competitive markets? Specifically, will product durability be different under alternative industry structures? If so, will monopoly, competition, or some monopolistically competitive structure produce the 'better' product? The 'conventional' view, associated most closely with the work of Martin [28], Kleiman and Ophir [22], Levhari and Srinivasan [24] and Schmalensee [45], asserts that monopolistic firms are likely to shorten product life from that obtainable under competition. The counter or 'revisionist' position, argued most convincingly by Swan [48, 49], states that monopolistic firms will not reduce product durability but instead will extract the monopoly toll by charging higher prices for fewer units of the optimum, competitive durability. Although Swan's 'revisionist' formulation successfully overturned the 'conventional' view, given the latter's assumptions, the assumptions themselves have become central to the continuing debate. In short, under various assumptions both competition and monopoly have been singled out as providing the most congenial environment for reductions in durability.1

Storage of dried grass wafers: Moisture relationships, safe storage periods and changes in durability

The behaviour in store of milled and wafered S23 Ryegrass, S48 Timothy and Eynsford Lucerne was studied: A storage trial was carried out at 21°C and 5 r.h. levels from 67–90% on milled and whole dried wafers with and without the addition of a binding agent and/or fungus inhibitor (propionic acid). The addition of propionic acid (33% by weight of 99% solution) had a marked effect, no mould was present at 80% r.h. after 440 days compared with less than 20 days for untreated material. A complementary study established moisture content/r.h. equilibrium relationships. The hysteresis lag between wetting and drying curves was less than 2% at 70% r.h. and curves were similar for three crops studied. Changes in the durability of wafers manufactured with and without the addition of a binding agent, were recorded over a period of 9 months. Where a binding agent was included, wafers were more durable and consistent in manufacture than corresponding untreated wafers. The durability of all wafers declined slightly over the period.