Injection-Molding Parameters

For the process of injecHon-molding the major thermal process parameters are  

Optimal values of these parameters are of great importance for the Hme between two consecutive injections, the so-called cycle time, which in turn determines the economic feasibility of the process. 

The injection process temperature is the temperature (or somefimes a range of temperatures), at which the mass is plasticized to such a degree that it may easily be injected from the heating cylinder into the mold. The choice of this temperature can depend on several factors, such as the type of polymer, the size and shape of the injected object, the maximum attainable pressure, and the mold temperature. The plasHcizing of the material takes place in an electrically heated cylinder, where a certain temperature profile of the wall can be imposed. This temperature range is generally determined experimentally for the type of material, the kind of product, and the type of the injection-molding machine [4]. 

The injection pressure (p ) is the pressure generated by the screw or the ram in the heating cylinder and it should be sufficiently high to press the plasticized mass from the cylinder into the mold, to fUl the cooled mold completely before the material solidifies. The maximum injection pressure is determined on the basis of the diameter (D) of screw or ram, an external diameter (d) of the hydraulic piston in the shove and retract system of the screw or ram, the pressure in the hydraulic system (pt), and the friction force (F) at screw shove [3]  

The friction forces can be redefined in terms of frictional pressure by  

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No microstructural differences between the mid and the core layers could be detected from comparison of the fracture surfaces (Figure 7c, d and 8c, d). The microstructures in these layers were better described as strips, and the average molecular orientations of the mid and the core layers were still parallel to the flow direction, in contrast with a relatively featureless core with little or no molecular orientation observed by other investigators Qj. The variations in the layered structures and the skin core phenomena observed in PECs could be correlated to the process history, the shapes of the specimens, the injection molding parameters, and the molecular structures of the polymers. 

A Plexus two-component reactive MMA adhesive system was able to resolve the problem for the OEM. The nature of the MMA adhesive means it is compatible with many types of thermoplastic regrind materials, and the adhesive does not need to be cut from the bonded part. Test data clearly showed that there were minimal effects on the injection molding parameters of the plastic and that there was minimal loss of properties when compared to the virgin material (see Figures 1 and 2). 

The Effects of Injection Molding Parameters on Color and Gloss 149... 

SF Xavier, D Tyagi, A Misra. Influence of injection-molding parameters on morphology and mechanical properties of glass fiber-reinforced polypropylene composites. Polymer Composites 3 88-96, 1982. 

Table 5.4. Injection molding parameters used for a two-level factorial experimental design ...

Since the formation of the nanotube network is strongly related to the flow of the melt, the electrical conductivity of injection molded parts can exhibit local variations [46]. Thus, next to the choice of the injection molding parameters, the electrical properties depend on the design parameters of the mold as gate position and shape, for instance. Such kind of investigations and the development of corresponding models are the topic of actual research activities. Some first results can be found in [67]. 

Villmow T, Pegel S, Potschke P and Wagenknecht U (2008) Influence of injection molding parameters on the electrical resistivity of polycarbonate filled with multi-walled carbon nanotubes. 

Figure 5.27 is from Composites Science and Technology, Vol. 68, 2008, Authors ViUmow T, Pegel S, POtschke P and Wagenknecht U, Title Influence of injection molding parameters on the electrical resistivity of polycarbonate filled with multi-walled carbon nanotubes, pp. 777-789, Copyright (2008), with permission from Elsevier Ltd. 

Tianjin P(3HB-4HB) and Tianan PHBV can be molded via injection molding. The temperature profile in the injection molding barrel is different than conventional thermoplastics with the hottest temperature at the first zone and the coolest temperature at the nozzle. PHAs can be exposed to a temperature range between 160°C and 190°C. PHAs viscosity is too large for injection molding at temperatures below 160°C. PHAs can thermally decompose at temperatures above 190 C. PHAs also require a heated mold to enhance crystallinity. The injection molding parameters for P(3HB-4HB) are displayed in Table 4.4. Injection molding process conditions are similar for PHBV. 

Typical Injection Molding Parameters for Mirel P(3HB-4HB) (MatWeb 2013)... 

Polylactic acid plastics should be dried with standard desiccant drying conditions of 4 hours at 45°C for amorphous PLA and of 2 hours at 60"C for crystalline PLA. Typical injection molding parameters for PLA are listed in Table 4.9 (NatureWorks 2012). 

Chen, M., Hsu, C., Huang, C Yang, W Chen, C., and Lin, K. (2007) Influence of injection molding parameters on one-stage injection stretch blow molding. SPE ANTEC Proceedings, 923-927. 

Influence of Injection Molding Parameters on One-stage Injection Stretch Blow... 

EFFECT OF INJECTION MOLDING PARAMETERS ON THE ELECTRICAL CONDUCTIVITY OF POLYCARBONATE/CARBON NANOTUBE... 

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