Factors Affecting Durability

Figure 21 Factors affecting durability of adhesive joints.

For a hot water environment general guidance can be given for the desirable properties in good enamels. Five factors affecting enamel life are corrosiveness of contact liquor, design, operating conditions, life of sacrificial anode (if any) and the durability of the enamel coat. This implies that... 

The bioavailability of drugs from tablets can be markedly influenced by the rate and efficiency of the initial disintegration and dissolution process. Unfortunately, one is faced with a compromise situation — a structure that has both a durable structure prior to administration and the ability to readily break down when placed in the in vivo environment. One of the major factors affecting both these properties is the structure of the tablet, in particular its density (or porosity) and the pore structure. Study of the significance of such measurements and interpretation of the results is a relatively recent field of interest. 

The minimum thickness specification for an FML top liner covered with a layer of soil is 0.75 mm for an FML without a soil cover layer, the specification is 1.14 mm. An FML in a composite bottom liner system must be at least 0.75 mm thick. Even though these FML thicknesses meet U.S. EPA specifications, 0.75mm is not a suitable thickness for all FML materials. In fact, most FML materials installed at landfills are in the range of 1.50-2.50 mm in thickness. Other key factors affecting the selection of FML materials include chemical compatibility with waste leachate, aging and durability characteristics, stress and strain characteristics, ease of installation, and water vapor/ chemical permeation. 

These results have suggested that mineral dusts that are inert in a particulate form may have biological activity when they occur in a fibrous form. Factors affecting fiber toxicity include length, diameter, respirability resistance to chemical dissolution in biological fluids, and durability. "... 

It is difficult to compare the data published by different authors due to differences of strains, physiological conditions, organic substrates, durability of the process, and size and peculiarities of photobioreactors. However, an evaluation of the main factors affecting the specific rate of hydrogen photoproduction can be attempted. 

The cathodes are similarly corroded (chemically or electrochemically) as the anodes but metallurgical factors affect to a lesser degree, that is, the transformation is gradual [69]. However selective attack, such as from electrolyte impurities, often takes place and the production of a homogeneous surface layer of sub-products or crystal metallic impurities produce micro-cracks reducing the durability [70]. In addition, microbial factors produce cathode failure especially in the electrochemical treatment of wastewaters [71]. 

Some of the factors affecting the activity and durability of automotive emissions control catalysts were studied. It was found that at... 

Recently, the fluidized bed membrane reactor (FBMR) has also been examined from the scale-up and practical points of view. Key factors affecting the performance of a commercial FBMR were analysed and compared to corresponding factors in the PBMR. Challenges to the commercial viability of the FBMR were identified. A very important design parameter was determined to be the distribution of membrane area between the dense bed and the dilute phase. Key areas for commercial viability were mechanical stability of reactor internals, the durability of the membrane material, and the effect of gas withdrawal on fluidization. Thermal uniformity was identified as an advantageous property of the FBMR. 

Figure 6 shows the fatigue endurance of tire wall specimens from different tires as the functions of temperature. First, we observe that the fatigue endurance Is sensitively dependent on the temperature. At about 130 deg. C which Is the temperature range In the shoulder of these truck tires at 65 MPH, It Is seen that a temperature Increase of 10 deg. C reduces the number of cycles to failure by factor of two. These experiments show clearly that the tire shoulder temperature Is a critically important factor affecting the tire durability and that a lower... 

This article discusses briefly the use of adhesives on the construction site in the context of structural repair and reinforcement the requirements and practical dilficulties in the work on site with regtirds to the strength and durability of the rehabilitated timber structure and the consequent need for queility control. It also highlights the characteristics and requirements that must be fidfilled by structural adhesives and reinforcing materials factors affecting performance and durability of bonded joints tmd ways to improve adhesion and durability. Finally, it points out some research needs and future developments identified by the authors. 

Besides the environmental factors mentioned above, the materials involved in a structural joint also influence bond strength and durability. The factors in the material category include the adherends the adhesive the design of the joint absence of surface contamination (including contamination with wood extractives) stability of the adherend surface the ability of the adhesive to wet the surface, and entrapment of air/volatiles. Thus, the condition of the adhesive/adherend interface becomes a decisive factor affecting the initial bond strength as well as the long-term durability of the bonded joint [31]. 

Environmental Factors Affecting Strength and Durability of Rubber... 

The objectives of mixing additives with soil are to improve volume stability, strength and stress-strain properties, permeability and durability. In clay soils, swelling and shrinkage can be reduced. Good mixing of stabilizers with soil is the most important factor affecting the quality of results. Cement and lime are the two most commonly used additives. 

The discussion of heat durability in this section should make clear that this is a complex phenomenon. Embrittlement, retropolymerization, thermoplasticity, and the loss of adhesion are all factors affecting the adhesive s performance on metal surfaces. Based on the published state of the art, optimum cyanoacrylate heat durability could be achieved using a combination of a heat-resistant adhesion promoter, a crosslinking agent, and a plasticizer. The heat durability promoters discussed in this section are summarized in Table XI. 

In the discussion of factors affecting joint strength and durability, it was seen that the presence of water was responsible for many of the problems. Most bonded structures, if exposed to water or high humidity, will lose strength over a period of time and in extreme cases will fail completely. 

In the earlier chapters, various authors have provided basic issues regarding the mechanical and physical properties of composites. An issue that may not have been fully covered, which could be considered as an important factor affecting the durability of pipes and risers made of composite, is the issue of long-term durability of GFRP when in contact with an aqueous environment, especially in the presence of relatively high temperatures. GFRP pipes and risers are subjected to harsh environments the environments... 

The condition of the adhesive/adherend interface then becomes a decisive factor affecting the initial bond strength as well as the long-term durability of the bonded joint. 

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