Neat thermoplastics

Figure 3.34. Neat thermoplastics 100 h creep modulus examples versus stress at20°C...

Figure 3.36. Neat thermoplastics 100h creep modulus examples versus stress at 65 5°C...

Neat thermoplastic polyethylenes have low moduli that involve high strains for moderate loading. Consequently, creep moduli are also low, the more so as the temperature rises, as we can see in Figures 4.3 ((a) and (b)) where creep moduli are displayed as a function of time, load and temperature. 

Inserts are often dedicated to specific plastic materials neat thermoplastics, neat and filled thermosets, reinforced plastics, composites, structural foams. .. 

Figures 6.3 to 6.6 compare the main mechanical and thermal properties of the main neat thermoplastics.

Figure 6.3. Neat thermoplastic matrices examples of unstressed continuous use temperatures...

Figure 6.4. Neat thermoplastic matrices examples ofHDTA (l.SMPa) (°C)...

Figure 6.9 shows examples of cost ratios (costs of short glass fibre reinforced thermoplas-tics/costs of the neat thermoplastics) versus costs of the neat grades. 

The dynamic mechanical thermal analysis also indicated molecular mixing of the two components. The Tg of the thermoplastic was lower than the composite, as determined from the inflection point of the E curve seen in Figures 13 1. The PEOX glass transition temperature appeared at 62°C, while that for PVP showed up at ll5°C. The discrepancy in the Tg of PVP had already been addressed. The Tg extrapolated from the DMTA thermogram was reported since no artifacts were to be introduced. The samples exemplified for all DMTA thermograms were processed in a normalized fashion. Any thermal or hygroscopic Influences were eliminated. Some water may be trapped in the neat thermoplastics but this was minimized since they are hot pressed at 150°C and stored under calcium... 

In Figure 4, the ratios of the maximum moduli measured for the blends and the neat thermoplastics are plotted versus the LCP content, for the different blends. For the correct interpretation of the data shown in Figure 4, it must be kept in mind that the values of the tensile moduli whose ratios are plotted in the figure are those measured on fibers prepared with the highest windup speeds that could be used for either the blends and the neat polymers. Thus, the ratio of the maximum tensile moduli accounts also for the orientation of the matrix, due to the filament attenuation induced by drawing. 

Ratio of the maximum tensile moduli measured for blend and neat thermoplastic fibers, as a function of the LCP content... 

Thermoplastic starch alone can be processed as a traditional plastic. Its sensitivity to humidity, however, makes it unsuitable for most of the applications (Fig. 3). Main use of neat thermoplastic starch is in soluble compostable foams (loose-filler, etc.) as a replacement for polystyrene. 

The heating element is sandwiched between the parts to be joined, referred to as the adherends. Thermoplastic materials used include neat thermoplastics and composites such as carbon fibers in a PEEK, polyarylsulfone (PAS), or polyetherimide (PEI) matrix. An interlayer thermoplastic material melts or softens below the melting point of the adherend, so that adherend degradation is minimized and mechanical performance of the joint is maintained. Insulators on the outermost ends of the weld stack complete the assembly. The weld stack can be autoclaved for consolidation. [ 9]-[94]... 

The rule of thumb ( ... the reinforcing effect is directly related to the viscosity decrease of the blends compared to the neat thermoplastics ) stated by Fekete et alP is intriguing but of course too simple and limited. There is a need for a more general theory or predictive model of LCP blends which would allow input of rheological parameters, parameters related to adhesion, orientability, degradation temperature, etc. and of course the cost of the components, and allow one to compare the expected material to commercially available grades of glass-filled thermoplastics, etc. 

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