Improvement in Processability for Injection Molding of Bisphenol-A Polycarbonate by Addition of Low-Density Polyethylene

Abstract

The rheological properties and processability at injection molding were studied for bisphenol-A polycarbonate (PC) that was modified by low-density polyethylene (LDPE) having a low shear viscosity. The LDPE addition significantly decreased the steady-state shear viscosity, especially in the high shear rate region. The decrease did not originate from slippage on the die wall but due to interfacial slippage between the PC and dispersed LDPE droplets that deformed to the flow direction to a great extent. As a result of the viscosity decrease, injection pressure largely decreased from 150 to 110 MPa with the addition only 5 wt.% of LDPE. The enhanced flowability also reduced the warpage of the molded product significantly, demonstrating that the processability at injection molding was improved by the addition of LDPE.

Anomalous Postprocessing Dimensional Change of Injection-Molded Products Composed of Poly(lactic acid) and Poly(vinyl alcohol)

“…In general, the critical capillary number of an immiscible polymer blend with sea–island structure is significantly large under shear flow, when the viscosity of dispersions is much lower than that of the continuous phase. For such a system, dispersed droplets tend to be deformed affinely without breakup during flow, as summarized in previous studies. , In fact, in-site fiber formation was reported using a low-viscosity dispersion by several researchers. − Also in this study, the shear flow markedly deformed the dispersed PVAL droplets.…”

Antiplasticizing effect of triethyl citrate on an isosorbide-based polycarbonate

“…However, its high Tg often results in poor owability during injection molding, as is well known for bisphenol-A polycarbonate. Although novel techniques for decreasing the shear viscosity in the high shear rate region have recently been proposed [9][10][11][12], three methods have generally been adopted: (1) decreasing the molecular weight [13][14][15], (2) addition of a plasticizer [13][14][15], and (3) wall slippage, which is also known as "super extrusion" [16][17][18][19][20]. Among these, the addition of a plasticizer is known to decrease the Tg, which is undesirable in many scenarios.…”