Bonding Agent Reliability

The FMEA concept was developed in the mid 1960s in the aerospace industry. It was then taken up by sectors of the North American automotive industry and soon 

Occurrence of failure Because of product design and the ISO 9001 manufacturing procedures this is seen as being remote hence a rating of 1. 

Severity of failure If the product did not perform as designed then the failure could cause serious injury or death, i.e., catastrophic failure, hence a rating of 10. 

Detection of failure Because of the physical properties of a liquid coupled with product testing of a large number of molecular components the probability of a defect reaching the customer is remote, hence a rating of 1. 

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These factors all favour materials such as composite resins, which exploit the growing technical knowledge of adhesion and the improved performance of bonding agents for their success. Current materials available for bonding are formulated with the aim of providing reliable adhesive bonds that are, in principle, capable of lasting for many... 

Under normal conditions on repair sites it seems likely that a more reliable bond can be achieved by using a bond coat rather than by relying on any natural bond between fresh and hardened Portland cement concretes(2). However, bonding agents for use on site must be tolerant of site conditions, be reliable and cannot be selected solely on the basis of slant shear results. The bonding performance of carefully applied SBR and acrylic latex/cement slurry coats appears to be similar to that of epoxy resin bonding aids(14). However, other factors such as open time, barrier coat effects and cost may affect the final choice. 

Correct viscosity of the applied bonding agent must be controlled by methods other than those used with solvent-based systems. Cup or rotary viscosity testers are not reliable methods of determining viscosity of emulsions. Hydrometer testing of specific gravity is a more reliable way of measuring viscosity and hence controlling deposited film thickness. 

Surface treatment which follows cutting may attempt to modify or remove the smear layer, in order to ensure that a uniform and reliable surface is left behind. It may also remove the smear plugs, thus opening the tubules and allowing the bonding agent to penetrate the tooth... 

Diols are applied on a multimilhon ton scale as antifreezing agents and polyester monomers (ethylene and propylene glycol) [58]. In addition, they are starting materials for various fine chemicals. Intimately coimected with the epoxidation-hydrolysis process, dihydroxylation of C=C double bonds constitutes a shorter and more atom-efficient route to 1,2-diols. Although considerable advancements in the field of biomimetic nonheme complexes have been achieved in recent years, still osmium complexes remain the most efficient and reliable catalysts for dihydroxylation of olefins (reviews [59]). 

The data in Table 6.4 have been developed from many years of practical experience. It provides information on the suitable types of coupling agents differentiated by the organic portion of the molecule. In polymers which are not reactive, such as polyethylene, polypropylene, etc., adhesion is built up by hydrogen bond formation. Methaciylosilanes provide this effect with these materials. Experimental work is always recommended to evaluate each combination of coupling agent, substrate, and polymer. So many diverse factors are involved that theoretical predictions are not always reliable. 

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