著者

西嶋 清明 弘中 克彦

出版者

The Japan Society of Polymer Processing

雑誌

成形加工 (ISSN:09154027)

巻号頁・発行日

vol.5, no.9, pp.603-609, 1993-09-20 (Released:2009-11-18)

参考文献数

5

著者

瀬戸 雅宏 寺倉 祐二 佐々木 幹夫 山部 昌

出版者

The Japan Society of Polymer Processing

雑誌

成形加工 (ISSN:09154027)

巻号頁・発行日

vol.15, no.2, pp.148-154, 2003-02-20 (Released:2009-11-18)

参考文献数

11

被引用文献数

10 3

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The material properties within injection molded products may display a distribution or anisotropy due to the influence of the resin flow velocity distribution profile and the cooling rate during the injection molding process. As a result, the products may warp. From the standpoint of production efficiency, it is very important to predict such warpage prior to the injection molding process, and injection molding CAE tools are widely used at present to conduct warpage analyses.Warpage analysis techniques currently available do not provide sufficient accuracy because they cannot predict the distribution of material properties that occurs in the interior of injection molded products. This is especially true for thick injection molded products, which display a large distribution of material properties across their thicknesses. As that distribution is thought to affect warpage substantially, the accuracy of the warpage analysis presumably declines even further.In this research, a thick flat plate was injection molded from a medium density crystalline polyethylene material, and the distribution of the thermal expansion coefficient was measured along the thickness of the molded part. The molecular orientation ratio and crystallinity were also measured and their correlation was examined in order to investigate a method for predicting the thermal expansion coefficient distribution. The results revealed that the thermal expansion coefficient displayed a large variation and anisotropy in the thickness direction and that the distribution correlated with the crystallinity. Moreover, using the thermal expansion coefficient data obtained by these measurements, a material property database was created for use in conducting warpage analyses that take account of the distribution of material properties along the thickness of injection molded products. A multi-layer analysis model was then used in an effort to improve warpage analysis accuracy. The results indicated that warpage analysis accuracy was improved, which shows that a multi-layer model that takes account of the distribution of material properties is effective in conducting more accurate warpage analyses.

著者

北浦 達朗 久後 行平 西野 潤

出版者

The Japan Society of Polymer Processing

雑誌

成形加工 (ISSN:09154027)

巻号頁・発行日

vol.5, no.2, pp.134-142, 1993-02-20 (Released:2009-11-18)

参考文献数

26

被引用文献数

1 1

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溶融混練したビスフェノールAポリカーボネート(PC)/ポリエチレンテレフタレート(PET)ブレンドのモルフォロジーを,フーリエ変換赤外全反射分光法(FTIR ATR),顕微鏡フーリエ変換赤外分光法(顕微FTIR)および走査透過型電子顕微鏡(STEM)により解析した.FTIR ATRと顕微FTIR測定の結果,PCとPETに基づくカルボニル吸収ピーク位置は,PET組成の約20~50wt%で変化した.すなわち,相分離構造のドメインサイズが,PC/PETブレンドフィルムの断面の深さに依存して変化することが示唆された.また,STEM観察の結果からも,ドメインサイズがブレンドフィルム断面の内部から表面に近づくに従って小さくなり,表面近傍では逆に大きくなる傾向が認められた.またPETが50wt%以下の組成で,相分離構造の反転や相構造の乱れが観察された.STEMにより観察されたこれらの相分離構造は,FTIR ATRおよび顕微FTIR測定の結果から予想されたモルフォロジーと一致した.

著者

堤 菁

出版者

The Japan Society of Polymer Processing

雑誌

成形加工 (ISSN:09154027)

巻号頁・発行日

vol.2, no.4, pp.331-335, 1990

著者

亀田 隆夫 高橋 辰宏 小山 清人

出版者

The Japan Society of Polymer Processing

雑誌

成形加工 (ISSN:09154027)

巻号頁・発行日

vol.17, no.8, pp.571-579, 2005-08-20

参考文献数

15

被引用文献数

1

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The precise measurement of three dimensional shrinkage at different locations within molded parts is seldom reported. In this research, we compared the measured shrinkage (relating the difference between the dimensions of the metal mold and the resultant molded plastic parts) with calculations based on PVT measurements for parts made from AS and ABS resins. With increasing packing pressure, the shrinkage was minimized in the normal direction (ND) more than in the melt flow (MF) and transverse (TD) directions. The ND shrinkage was proportional to the volume shrinkage, while those of the other directions were proportional to less than the 1/3 power of volume shrinkage. The TD shrinkage was larger than the MD shrinkage. With increasing packing pressure, the gate seal time increased for ABS, but hardly changed for AS. The molecular orientation, obtained from birefringence measurements, increased with packing pressure.

著者

亀田 隆夫 高橋 辰宏 小山 清人

出版者

The Japan Society of Polymer Processing

雑誌

成形加工 (ISSN:09154027)

巻号頁・発行日

vol.17, no.5, pp.342-348, 2005-05-20

参考文献数

15

被引用文献数

1 1

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The size of the dependence of the shrinkage anisotropy in different locations of injection molded parts is not frequently reported (shrinkage calculated by comparing the actual plastic parts to the metal mold, while anisotropy refers to differences in the melt flow (MD) and the transverse (TD) directions). In this study, the effects of packing pressure (from 20 to 100MPa) in the injection molding process on the shrinkage anisotropy at two positions in a molded part were investigated in two ABS resins. The shrinkage anisotropy decreased as a function of packing pressure at both locations, although at different rates. It was found that the shrinkage anisotropy at these two positions was quite similar at around 60MPa. It was also found that the screw head moved forward (backward) at pressures higher (lower) than 60MPa. At a packing pressure of 60MPa the screw head position was almost constant during the packing process in a plunger type injection molding machine where the polymer melt can hardly flow backwards.<br>In order to get further insight into the causes of the shrinkage anisotropy, birefringence measurements were performed with a transparent ABS resin. The measured birefringence at the two locations of the injection molded part were in good agreement with the respective shrinkage anisotropy values. Moreover, the packing pressure dependence seen in the shrinkage anisotropy was found to be similar for that of birefringence. It was demonstrated that a difference in molecular orientation in the two directions (MD and TD), caused the shrinkage anisotropy, and that the ratio of molecular orientation difference becomes almost identical at the two locations at around 60MPa of packing pressure.

著者

佐藤 貞雄 斉藤 工 大柳 康

出版者

The Japan Society of Polymer Processing

雑誌

成形加工 (ISSN:09154027)

巻号頁・発行日

vol.4, no.1, pp.55-61, 1992

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In order to determine the thermal conductivity of molten polymers with greater accuracy, we improved the measurement device proposed in our previous paper. The accuracy of measurement of the improved device was within ±2.5∼3%. This improvied device was used to investigate experimentally the effects of molecular structure and polymer temperature dependence on the thermal conductivity of liquid crystalline polymers (LCP), and general-purpose polymers (GPP). The results showed that both of the thermal conductivity of LCP and GPP increased with raising of polymer temperature, while the thermal conductivity of LCP is 1.2∼1.7 times larger than that of GPP. The measured results also showed that thermal conductivity of LCP excepting LCP-XD 138 is influenced by the molecular structure. Namely, the thermal conductivity of III type-LCP which has flexible structure is 40% larger than that of the I type-LCP which has rigid structure. Furthermore, using a relation between the thermal conductivity and the thermal diffusivity <i>a</i> (=<i>v</i>·λ/<i>C_p</i>, where <i>v</i>: specific volume, λ: thermal conductivity, <i>C_p</i>: specific heat), the temperature dependence of the thermal diffusivity of the GPP was examined and the thermal properties which dominate the behavior of those thermal diffusivity were discussed. The thermal diffusivity shows various behavior in accordance with raising of temperature. The temperature dependence of the thermal diffusivity is dominated by that of thermal conductivity in PC, PMMA and PA-6, by that of specific heat in PP, respectively. For all of these GPPs, the density change due to polymer temperature has little effect on the thermal diffusivity.