Adhesive self-sufficiency

Phenolic adhesives continue to be the most significant adhesives for the production of weather-resistant wood products. The energy crisis of the seventies, the cost of phenol, and the inevitable decline in petroleum reserves have caused the wood industry to focus attention on obtaining adhesive self-sufficiency (1). This concern arises primarily from the questionable longterm availability of resins and secondarily from the economics of adhesive resin use. Ready availability of adhesive resins is critical to the manufacture of bonded wood products. In practical terms, this means that new adhesive systems are needed in which part, or perhaps all, of the petroleum-derived phenolic component is replaced... 

These are usually self-adhesive, precut, printed patterns on a substrate that are simply adhered to the surface of a product. Decals generally use a transparent plastic film while labels are usually on an opaque plastic, metallic and multilayer sandwich base. Labels of sufficient thickness are useful for hiding unavoidable appearance problems such as gate and sprue removal areas, sink marks, blushes, splays, and weld lines. 

Strip packages represent an alternative form of packaging for unit-dose medication. Strips can be produced from single- or multiple-ply laminated materials provided the two inner plies can be sealed by heat or pressure (e.g., cold self-adhesive seals). Materials can range from relatively permeable plies to those that incorporate a foil ply of sufficient thickness and effectiveness of seal so that an individual hermetic seal is produced for each dosage. Strip packages are produced at lower speeds and occupy greater volume than blisters. 

As previously stated, the rigid polyimides meet many of the requirements for microelectronics applications however, the presence of an ordered morphology, coupled with the lack of a softening transition results in extremely poor self-adhesion. Alternatively, thermally stable thermoplastics exhibit excellent self-adhesion, but often lack sufficiently high temperature dimensional stability and/or solubility and processability from common organic solvents. For instance, po-ly(phenylquinoxaline) (PPQ) has a T in the 370 °C range, thereby overcoming... 

Highly self-oligomerized 0.1 vol% APS solutions promote adhesion as do those with very low amounts of self-oligomerization. Formation of covalent Si—O bond with the mineral surface may not even be required to promote adhesion. Possibly, only hydrogen bonding or van der Waals interactions are sufficient. Such ideas have been discussed previously [6]. 

Attenuated Total Reflectance This method can be used to identify solid drugs but is only of use where relatively large amounts of compounds are available. The finely-ground sample is spread as a thin layer onto the sticky side of a piece of self-adhesive tape, and the tape is placed against the reflecting surface of the instrument with the sample side in contact. Sufficient sample is required to cover the surface of the tape completely, otherwise the spectrum of the tape will be recorded in addition to that of the sample. The technique is of use when the acid and salt forms need to be differentiated. 

Self-coloured materials such as plastics or anodized aluminium, and adhesive plastics film also had their limitations. There is therefore every reason to assume that oil-based paints will be here in the year 2000. Since the general natures of the mechanisms of autoxidation and polymerization were realized about 30 years ago there have been few significant scientific papers and these subjects are not current research items. Sufficient is now known to ensure the most effective use of the fatty oils in commercial paint products. 

The diffnsion theory of adhesion is basically a very simple concept, the original use of which is due to Voyutskii. He was concerned with the self-adhesion (antohesion) of nnvnlcanized (not cross-linked) rnbber (see also Rubber-based adhesives). He snggested that if two snch polymer surfaces are in sufficiently close contact, parts of the long-chain molecnles will diffuse across the interface. They will interpenetrate and eventnally the interface will disappear and the two parts will have become one. It is clear that, if this... 

The bonding is achieved by different methods. The hard component can contain undercuts where the rubber is anchored during its vulcanisation, a primer on the hard component or even using self-adhesive silicone rubber will give sufficient anchorage. 

However, at the same time it is possible to achieve sufficient bonding to steel without having problems with the self-adhesive silicone sticking to the mould, as is the case with conventional bonding agents for rubber to metal components. 

At the time of the release of the component from the mould, adhesion is at its weakest level. Therefore, in the case of self-adhesive or primer technology, it is essential to demould cautiously as, once silicone and substrate are separated, no adhesion will form again. In the case of self-adhesive LR, upon cooling and after sufficient storage and/or further heat treatment, adhesion will develop to its utmost extent. This will be explained further in Section 11.11.1. It is essential that the plastic material used for the moulding of the hard substrate solidifies quickly at a high mould temperature. 

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