Joining of Specific Plastics

Table 7.10 lists common recommended surface treatments for plastic adherends. These treatments are necessary when plastics are to be joined with adhesives. Specific surface treatments for certain plastics and their effect on surface property characteristics are discussed in Sec. 7.6. Details regarding the surface treatment process parameters may also be found in ASTM D-2093 and various texts on adhesive bonding of plastics. An excellent source of information regarding prebond surface treatments is the suppher of the plastic resin that is being joined. 

The part assembly design addresses the ability to join/assemble the component parts. Where the components are assembled with adhesives, it is important to know the compatibility and strength of adhesion to dissimilar substrates, in addition to the chemical compatibility of the plastic with the specific adhesive and its constituents. If melt bonding methods, like ultrasonic, vibration, or spin-welding processes, are employed, thermal compatibility aspects have to be taken into account. The broad possibilities of mechanical assembly methods include snap fits, press fits, bolts, and threads. The material properties needed for each of these design calculations are listed in Table 11.9. 

Hollomon s ethos, combined with his ferocious energy and determination, and his sustained determination to recruit only the best researchers to join his group, over the next 15 years led to a sequence of remarkable innovations related to materials, including man-made diamond, high-quality thermal insulation, a vacuum circuit-breaker, products based on etched particle tracks in irradiated solids, polycarbonate plastic and, particularly, the Lucalox alumina envelope for a metal-vapour lamp. (Of course many managers besides Hollomon were involved.) A brilliant, detailed account of these innovations and the arrangements that made them possible was later written by Guy Suits and his successor as director, Arthur Bueche (Suits and Bueche 1967). Some of these specific episodes will feature later in this book, but it helps to reinforce the points made here about Hollomon s coneeption of broad research on materials if I point out that the invention of translucent alumina tubes for lamps was... 

Doublets. More worrying and harder to discern are the faked insect inclusions that have been carefully placed on a piece of amber and capped with plastic. Careful inspection will probably show joins, and the piece is likely to sink in salt water because it has a higher specific gravity (a measurement of the mass of a substance) than natural amber (see Tests ). Again, the insect species will most likely be extant. 

Aqueous desalter effluent contains sediments, oil, dissolved salts, and sulfides. It is treated initially by using an American Petroleum Institute (API) separator for residual oil removal and recovery (Fig. 18.9). Any oil droplets larger than about 150 p.m (0.15 mm) in diameter are collected as an oil phase, which is routed to the refinery slop oil stream to join any other off-specification liquid oil streams for reprocessing. Inclined plastic plates inserted into an oil-water separator of this type substantially increase the speed and... 

We wish to estimate the dynamics of a cold thermocouple probe suddenly placed in a hot flowing fluid stream for the purpose of temperature measurement. The probe consists of two dissimilar metal wires joined by soldering at the tip, and the wires are then encased in a metal sheath and the tip is finally coated with a bead of plastic to protect it from corrosion. Take the mass of the soldered tip plus plastic bead to be m, with specific heat Cp. Denote the transfer coefficient as h. 

The reader should consider the individual plastic supplier as the primary source of information on joining processes for specific types of plastic materials. Generally, this knowledge is readily available, because the plastic resin producers benefit by providing the most complete and up-to-date information on how their materials can reliably and economically produce commercial products. 

Resistance wire welding can be used on any plastic that can be joined effectively by heated tool welding. The process is typically applied to relatively large structures. Contacting the plastic resin manufacturer for details concerning the specific parameters of this process is recommended. 

The technology of plastic pipeline construction has become increasingly sophisticated. In particular, the increasing use of PE pressure pipes laid by no-dig methods and joined by fusion welds has stimulated an innovative approach and a wide range of companies is involved in providing specialist services. Some of these companies are associated with the pipe or fittings suppliers, others are relatively small companies that have developed around specific products. 

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