Molecular Orientation in Polycarbonate Induced by Cooling Stresses

Wimberger-Friedl, R.

doi:10.3139/217.960373

Cited by 13 publications

(7 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Kim [5], Despa et al [6], and Wimberger-Friedl [7] found that the mold temperature must be above the softening temperature to mold microchannels with a high-aspect ratio. Kim [5] also found that the filling percentages in microchannels are less than 10% if the mold temperature is less than 90°C for HDPE, whose melting temperature is 125°C.…”

Section: Effects Of Injection Speed Mold Temperature and Materialsmentioning

confidence: 99%

“…for x* Յ 0.001 7.541 ϩ 6.874͑1000x*͒ Ϫ0.488 e Ϫ245x* for x* Ͼ 0.001 (7) where x* is the dimensionless axial distance from the entrance, which is defined as:…”

Section: Numerical Analysismentioning

confidence: 99%

“…It should be pointed out that the heat transfer coefficients calculated from Eqs. [5][6][7][8][9] have been converted to the heat transfer coefficients defined by Eq. 4, i.e.…”

Section: Numerical Analysismentioning

confidence: 99%

See 2 more Smart Citations

Experimental and numerical studies of injection molding with microfeatures

Lee

et al. 2005

Polym. Eng. Sci.

View full text Add to dashboard Cite

Injection molding with microstructures was investigated both experimentally and theoretically. A series of injection molding experiments with PP and PMMA was carried out in a long and a short rectangular mold containing microchannels with the thickness of either 50 or 100 m and an aspect ratio of 5. The filling lengths in the microchannels were affected by injection speed, mold temperature, and channel location. A high injection speed or high mold temperature resulted in a longer filling length. The filling length in the microchannels decreased as the filling time in the main flow region increased. All filling lengths can be merged into a single curve vs. Fourier number based on the microchannel thickness. Comparison was also made between the experimental measurements and numerical simulation. The mold/melt heat transfer coefficient was found to be a critical factor in determining the filling lengths. The local heat transfer coefficient provided a much better agreement than a constant heat transfer coefficient. POLYM. ENG. SCI., 45:866 -875, 2005.

show abstract

Section: Effects Of Injection Speed Mold Temperature and Materialsmentioning

confidence: 99%

“…for x* Յ 0.001 7.541 ϩ 6.874͑1000x*͒ Ϫ0.488 e Ϫ245x* for x* Ͼ 0.001 (7) where x* is the dimensionless axial distance from the entrance, which is defined as:…”

Section: Numerical Analysismentioning

confidence: 99%

See 1 more Smart Citation

Experimental and numerical studies of injection molding with microfeatures

Lee

et al. 2005

Polym. Eng. Sci.

View full text Add to dashboard Cite

show abstract

“…Several authors have reported that increasing mold temperature and injection velocity improves the replication of microfeatures [6][7][8][9][10][11][12][13][14]. However, only limited quantitative data exists on how the mold temperature and the injection velocity influence replication.…”

Section: Introductionmentioning

confidence: 99%

Injection molding of a diffractive optical element

Tofteberg

Amédro

Andreassen

2008

Polymer Engineering & Sci

View full text Add to dashboard Cite

The injection molding of a microfeatured component, a diffractive optical element, was studied. The component has a wave‐like pattern on the surface, with amplitude 0.5 μm and wavelength 3 μm. Two different polymers were used: a polymethylmethacrylate and an ethylene‐norbornene copolymer (cyclic olefin copolymer). The topography was investigated using white light interferometry (WLI), atomic force microscopy (AFM), and scanning electron microscopy (SEM). A new WLI‐based technique is proposed for rapid quantification of the replication of periodic surface patterns. This technique gives almost the same information regarding the degree of replication as AFM but can be performed much faster. Quantitative data on the degree of replication as function of processing conditions are presented. At optimal conditions, almost perfect replication is obtained using both materials. At suboptimal conditions, it is observed that the degree of replication increases with increasing injection velocity and increasing mold temperature, with similar characteristics for both materials. The difference in replication quality between the two materials seems to be related to the different temperature dependencies of the viscosities. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

show abstract

“…Because of the different thermomechanical history the melt undergoes, the injection-molded parts often show a hierarchical multilayered structure through the thickness [1][2][3][4][5][6][7][8][9]. For the universal semicrystalline polymer, Polypropylene (PP), this layered structure has been widely studied with its heterogeneous crystallization because of the shear and temperature gradient [10][11][12][13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Structure and property of injection‐molded polypropylene along the flow direction

et al. 2009

Polymer Engineering & Sci

View full text Add to dashboard Cite

The structure and mechanical properties of injectionmolded polypropylene along the flow direction were investigated in this article. A remarkable difference was found in morphology and mechanical properties of the injection-molded parts along the flow direction. The three-layered structure (namely the skin, subskin, and core layer) showed a gradient distribution along the flow direction. The IR and WAXD results showed that the orientation of the subskin layer in the gate part is much higher than that in the far part. DSC analysis results indicated that the two parts (gate part and far part) of injection-molded bar has the same degree of crystallinity that should not be responsible for the mechanical difference of the two parts. According to the measurement of residual internal stress, there is large difference between the gate part and far part, which is the main reason leading to the difference of impact behavior. The annealing treatment eliminated the internal stress, so the mechanical difference between the two parts decreased and the fracture type of the far part changed from brittle to ductile. POLYM. ENG. SCI., 49:703-712, 2009. ª

show abstract

Molecular Orientation in Polycarbonate Induced by Cooling Stresses

Cited by 13 publications

References 18 publications

Experimental and numerical studies of injection molding with microfeatures

Experimental and numerical studies of injection molding with microfeatures

Injection molding of a diffractive optical element

Structure and property of injection‐molded polypropylene along the flow direction

Contact Info

Product

Resources

About