Thermoplastic materials problem solving

The use of GC/MS (gas chromatography/mass spectrometiy) in the thermoplastics problem solving area is outlined. GC/ MS is a hyphenated technique i.e. it combines the two techniques, chromatography and spectroscopy. In this procedure, a material is introduced into the GC, components are separated and sent to the MS where they ate ionised, and the resulting particles are separated by mass. The apphcations of GC/MS to solving complex problems are discussed through positive identification of base resins, contamination, odours and solvents. 

Manufacturing technique of thermoplastic materials causes difficulties for today, notably dispersion of silicate nanoparticles in monomer solution. To solve this problem it is necessary to develop the dispersion technique, which could be transferred from laboratory conditions into the industrial ones. 

In terms of structure, this chapter has been divided into sections dealing with each of the principal techniques in turn. Within each section there is a description of how the technique is used for the analysis of plastics and rubbers, a review of the application of the technique, the data that are obtained, and how it can be used in problem solving and compositional analysis work. Throughout the chapter the terms thermoplastic and its abbreviation, plastic, can be regarded as interchangeable. It is also the case that as thermoplastics and rubbers are members of the group of materials known as polymers, this word is often used in the chapter to refer to them as a single class. 

The brothers J.W. and J.S. Hyatt in the USA patented the first piston injection mold press in 1872, when they solved the problem of plasticizing a mixture of nitrocellulose and camphor. Much later a screw-injecting molding machine was designed. Nowadays screw injection molding is the most commonly used method for thermoplastic materials. 

The use of polyols such as pentaerythritol, mannitol, or sorbitol as classical char formers in intumescent formulations for thermoplastics is associated with migration and water solubility problems. Moreover, these additives are often not compatible with the polymeric matrix and the mechanical properties of the formulations are then very poor. Those problems can be solved (at least partially) by the synthesis of additives that concentrate the three intumescent FR elements in one material, as suggested by the pioneering work of Halpern.29 b-MAP (4) (melamine salt of 3,9-dihydroxy-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]-undecane-3,9-dioxide) and Melabis (5) (melamine salt of bis(l-oxo-2,6,7-trioxa-l-phosphabicyclo[2.2.2]octan-4-ylmethanol)phosphate) were synthesized from pentaerythritol (2), melamine (3), and phosphoryl trichloride (1) (Figure 6.4). They were found to be more effective to fire retard PP than standard halogen-antimony FR. 

Recycling of industrially produced material is important from the environmental point of view. For the recycling of materials bonded with adhesives, dismantlement of the products is necessary to separate them, although that is quite difficult. Therefore, a novel technique by which adherends can be dismantled easily has to be established. A conventional way to solve the problem is the use of thermoplastic adhesives because they soften at high temperature and joints bonded with them can be separated by applying small forces. Recently, a new kind of adhesive including thermally expansive microcapsuies has been proposed as an alternative method [1]. A joint bonded with such an adhesive can be dismantled by heating, as shown in Fig. 34.1. 

However, fluidized bed powder matrix application and derivative processes may solve these problems. Ideally, processors would like to see a material with the properties of polyetheretherketones (peek), poly(acrylene sulfides) (qv), polysul-fones, and similar engineering thermoplastics with melt viscosities below 1 Pa s (=cP). 

Using the same assumptions of the example solved in the Laplace domain (step input in pressure, elastic bulk modulus and Maxwell behavior in shear) with Eq. 9.58, the solution of the integral equation (Eq. 9.58) will yield the same results. (See homework problem 9.4). Since polymers are such that many Maxwell or Kelvin elements are needed to represent actual behavior, this example shown here is simplistic. However, such simple solutions can show trends in behavior and may give insight to the differences between thermosets and thermoplastics. The next section discusses briefly use of broadband material response functions for more physically realistic... 

Additionally, the adhesion of the nanofiber layer and support materials is another problem that needed to be solved to meet the requirement of post-processing of air filter media. Thus, a hot-press lamination process using a thermoplastic resin as glue was applied to improve the adhesion of the nanofiber layer onto the textile support. After 1,500 cycles of repeated compression and torsion, the PA-6 nanofiber layer was stiU firmly attached to the support, while mechanical damage is visible in some areas [32]. Recently, Guibo and co-workers [33] reported... 

The development of an alternative fabrication technique that would solve these issues would have commercial benefits. Researchers have demonstrated that embossing techniques offer solutions to many of the previously detailed problems [3]. Localized heating coupled with embossing has been demonstrated by many researchers to fabricate micro-features on thermoplastic substrates. However, this process produces undesired flash which must be removed with costly secondary operations [4]. Because the substrate is only locally heated, the material that is displaced during the embossing caimot be captured by the embossing tool to form a flat surface. It is possible to heat the entire surface of the substrate and reform the flash to a flat surface, but this is not desirable because it increases the heat input. 

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