Injection mold temperature

Table 4. Injection-Molding Temperatures for Different Polyamides ...

Molding and injection Compression ratio Compression molding pressure (lbf/in. ) Compression molding temperature (°C) Injection molding pressure (Ibf/in. ) Injection molding temperature (°C) Molding qualities Mold (linear) shrinkage (in./in.) Specific volume (Ib )... 

The activated carbonyl of anhydrides can acylate alcohols or amines at the temperatures necessary for polymer processing. These reactions have been verified by HPLC using the polymer system described in Table 2. An examination of the HPLC chromatograms in Fig. 25 indicates that the phthalic anhydride peak (3.2 min) diminishes with increasing injection-molding temperatures and that two new peaks (4.6 and 6.9 min) increase in intensity. These new peaks corresponded to the half phthalate esters of 1,6-hexanediol and trans-... 

TABLE 2 Effect of Injection Molding Temperature on 3,9-Bis-(ethylidene-2,4,8,10-tetraoxaspiro[5,5]undecane), (75 25) 1,6-Hexanediol / trans - Cyclohexanedimethanol Polymer Compounded with 3 wt% Phthalic Anhydride and 7.5 wt% Cyclobenzaprine Hydrochloride (CBP)... 

The free acid devices were substantially free of acylation byproducts. Infared spectra shown in Fig. 26 supports the conclusion that as the injection-molding temperature increased, the phthalic anhydride content (1853, 1789, and 1777 cm l) decreased and the content of the corresponding half ester (1735 cm"l) increased. 

Figure 27 shows that the release rate of CBP from the polymer decreased with increasing injection-molding temperatures. Samples with decreased levels of phthalic anhydride and increased levels of the phthalate half ester erode at slower rates presumably because the phthalic acid (pKai = 2.9 and pKa2 = 5.5) is a stronger acid than its alkyl half ester (estimated pKa = 3.6) and because the concentration of acidic groups is reduced by the esterification reaction. 

FIGURE 27 Release of cyclobenzaprine hydrochloride (CBP) at 37 C and pH 7.4 from devices made at different injection-molding temperatures. Polymer prepared from 3,9-bis(ethylidene-2,4,8,10-tetra-oxaspiro[5,5]undecane) and a 25 75 mole ratio of trans-cyclohexane dimethanol and 1,6-hexanediol and contained 3 wt% phthalic anhydride and 7.5 wt% cyclobenzaprine hydrochloride (CBP). 

BPA polycarbonate becomes plastic at temperatures around 220°C, The viscosity decreases as the temperature increases, exhibiting Newtonian behavior, with the melt viscosity essentially independent of the shear rate, At the normal injection molding temperature of 270-3l5°C, the melt viscosity drops from 1.100 to 360 Pa j s (11.000 to 3,600 poise). Because the viscosity of polycarbonate can only be reduced by increasing the temperature, the ultimate limit on molecular weight is controlled by the processing conditions and the thermal stability of the polymer. 

Styron 686E (wt%) Robber (wt%) Compatibilizer (wt%) Injection molding temperature (°C) Dose (kGy) Izod value (kj/m2) Dela- mination... 

One of the growing areas for PAB blend applications under the hood is in electrical and electronic connectors and systems for power distribution and control. Such applications often require low melt viscosity at injection molding temperatures to fill the intricate tooling that may be designed for up to hundreds of individual electrical connections. Practical toughness is required for snap-fit of the connections. Furthermore, glass-reinforcement of these PAB s may be required to improve modulus and dimensional stability. Typical blends suitable for these applications include PBT/PC, PA/PPE and PPS/PEI. 

Some of the properties of injection-molded test bars of IV when R is phenyl and y is 0 to 0.5 are listed in Table 4. The polyester I.V. s were 2.5 to 3.5, and the injection-molding temperatures were 350 to 380°C, depending upon the I.V. In general, the mechanical properties are similar to those in Table 1, including the increase in flexural modulus when the homopolymer of phenylhydroquinone and terephthallc acid was modified. 

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