Effects Of Injection Molding Conditions Research Articles

Effect of Injection Molding Conditions of Effective Surface Properties of F-theta Lens

Effect of Injection Molding Conditions of Effective Surface Properties of F-theta Lens

Effect of Injection Molding Conditions on Crystalline Structure and Electrical Resistivity of PP/MWCNT Nanocomposites.

Polypropylene (PP) / multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by melt-mixing and used to manufacture samples by injection molding. The effect of processing conditions on the crystallinity and electrical resistivity was studied. Accordingly, samples were produced varying the mold temperature and injection rate, and the DC electrical resistivity was measured. The morphology of MWCNT clusters was studied by optical and electron microscopy, while X-ray diffraction was used to study the role of the crystalline structure of PP. As a result, an anisotropic electrical behavior induced by the process was observed, which is further influenced by the injection molding processing condition. It was demonstrated that a reduction of electrical resistivity can be obtained by increasing mold temperature and injection rate, which was associated to the formation of the γ-phase and the related inter-cluster morphology of the MWCNT conductive network.

Effects of Injection Molding Conditions on Replication, Birefringence and Optical Property of Microscopic V-groove Structures for Polycarbonate

Effects of Injection Molding Conditions on Replication, Birefringence and Optical Property of Microscopic V-groove Structures for Polycarbonate

Effects of Interfacial Structure and Molding Condition on the Injection Welding Strength of Polyamide

The effects of injection-molding conditions and interfacial structures on the shear welding strength of polyamide material were investigated and the following main results have been obtained. (1) Variations of the first injection-molding speed and temperature exert an influence on the welding strength when the secondary injection-molding temperature T2 is low (below T2=265°C), but the influence vanishes when T2 is higher than 285°C. (2) Under any first injection-molding condition, the welding strength intensifies with the increase of secondary injection-molding temperature, and the highest welding strength reaches 45 MPa, which is almost the same as that of the non-welding base material. (3) It greatly influnences the welding strength that a trans-crystal which is perpendicular to the welding interface is formed in secondery molding. When T2 is higher that 285°C the trans-crystal layer is formed in the whole welding interface and a stable high welding strength may be obtained. Above results show that it is possible to obtain a high shear welding strength close to that of base material by controlling welding conditions in the injection welding method applied in the present research.

Effects of injection-molding conditions on the gloss and color of pigmented polypropylene

The effects of processing conditions on appearance characteristics of injection-molded mineral-filled polypropylene (compounded with pigments giving differing intensities of a beige color) have been studied; characteristics studied included gloss, color, and texture. A mold cavity embossed with smooth, fine, and coarse surface patterns was used. In-mold rheology and gate-seal analysis were used to select the filling and postfilling processing parameters. Interest was focused on the effects of filling rate, holding pressure, and mold temperature on the appearance characteristics, and a significant influence of these processing conditions on the gloss and color was found. For all the surface patterns examined, a better replication of the mold texture was obtained with a low melt viscosity at a high shear rate (high injection speed or short injection time) and a high mold temperature. This gave a higher gloss in the smooth surface regions and a lower gloss in the textured regions. An increase in the holding pressure had an effect similar to but smaller than increasing the filling rate or mold temperature. The gloss (or surface topography) had a significant effect on the color; an increase in gloss was associated with an increase in the color coordinate b* and a decrease in the lightness L*. POLYM. ENG. SCI. 45:1557–1567, 2005. © 2005 Society of Plastics Engineers

The Effect of Injection Molding Conditions on the Mechanical Properties of an In Situ Composite

Abstract The effect of processing conditions on the mechanical properties of an injection molded polypropylene/liquid crystalline polymer (PP/LCP) blend was studied. The LCP consisted of a copolymer based on poly(ethylene terephthalate) and poly-(hydroxybenzoic acid). Two PP matrices were used to vary the viscosity ratio of the blend. It was found that the highest flexural moduli were obtained for blends with the PP matrix that provided the highest viscosity ratios (closest to unity). These optimal properties were obtained only at one processing temperature, 250°C. At this temperature, the storage (G′) and loss moduli (G″) of the neat LCP were approximately equivalent. The optimal properties at temperatures where G′ ∼ G″ is in agreement with a prior study of another PP/co-polyester LCP blend [15]. Futhermore, the optimal properties were sensitive to the filling time. This was related to heat transfer via the Graetz number. For thinner molds, higher properties are obtained over a broad range of Graetz numbers (temperatures) while for thicker molds higher properties are obtained only at lower Graetz numbers (temperatures). The dependence of the flexural modulus on the Graetz number was related to the ability to deform the LCP at the advancing front and the ability to freeze the morphology possibly even before cessation of flow.