Intermittent compression molding

FIGURE 1.216 Mold example for a semicontinuous system (intermittent compression molding)... 

Profiles can be manufactured with static pressing units (autoclave, upper ram press) as well as with semicontinuous or continuous units. Semicontinuous systems, like intermittent compression molding, enable the manufacture of continuous profiles. A distinction has to be made if the profile is open or closed. Open continuous profiles like U-, and triple V-profiles, can be manufactured with simple molds whereas the manufacture of closed profiles (e.g., double 1-profile or rectangular hollow profile) can only be realized with an increased mold complexity. Figure 1.218 illustrates a profile mold for the manufacture of open double-V profiles. This mold consists of... 

In the intermittent contact mode phase images shown in Fig. 3.74 a clear contrast between the constituent phases can be observed both for the compression-molded hmsPP (panel a), as well as for the blown film (in the machine and transverse direction in panels band c, respectively). The soft EPR phase appears with dark phase contrast indicating that a substantial amount of energy is dissipated in this phase compared to the PP phase. The EPR particles measure 1 pm or smaller in diameter dispersed in the polypropylene matrix. The horizontal lines and the occasional vertical streaks in the images are artifacts of microtoming. 

Fig. 3.74 Intermittent contact mode AFM phase images obtained with an amplitude setpoint ratio of 0.5 on (a) compression molded high melt strength polypropylene and microtomed sections of hmsPP blown film in the (b) machine direction (MD), and (c) the transverse direction (TD). Reproduced with permission from [152]. Copyright 2002. Elsevier...

NaOH solution was added intermittently to maintain the pH between 10 and 11.5. The entire reaction mixture was then added to 500 ml of methanol. The precipitated pol5nner was filtered and dried obtained 8.35 g. This material was redissolved in CH2CI2, filtered to remove some NaCl, and reprecipitated by adding to methanol. The polymer was filtered and dried giving 7.6g of the block copolyformal-carbonate [nT = 0.66 dl/g DSC showed only one Tg, 120°C a compression molded plaque was flexible and essentially clear. The C-NlfR spectrum was in complete accord with the assigned structure showing a polyformal/polycarbonate ratio of 48 52 (theory, 49 51). 

FIGURE 1.218 Profile mold for continuous manufacturing of Double-V profiles on hot presses for intermittent compression... 

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