Study on high⁃pressure water penetration behavior of square cross⁃sectional pipes based on short⁃glass⁃fiber⁃reinforced polypropylene

doi:10.19491/j.issn.1001-9278.2022.02.013

Abstract

Abstract:

A square cross?sectional pipe was injection?molded through an overflow water?assisted injection molding method using short?glass?fiber?reinforced polypropylene as a raw material. The effects of process parameters such as melt injection temperature， water injection delay time and water injection pressure on the macro phenomenon were investigated， and the penetration behavior of high?pressure water in the square pipe was analyzed. The results indicated that with an increase in melt injection temperature， the residual wall thickness of the right?angle side and the inclined side of the square tube tended to decrease. However， when the temperature was too high， the pipe tended to shrink， and the hollow area of the pipe section was increased. The shape of the cross section was consistent with the shape of the high?pressure water penetration front， presenting an ellipse shape. However， the roundness of the cross section decreased gradually. The residual wall thickness of the pipe decreased with an increase in water injection pressure， and the hollow area of the cross section increased. With an increase in the water injection pressure， the shape of the cross section was gradually consistent with the cavity structure， presenting a rectangle shape. When the injection delay time increased， the residual wall thickness of the pipe tended to increase， the hollow section became smaller， and the pipe section was consistent with the penetration front of high?pressure water， presenting an ellipse shape. Compared to the other two parameters， the injection delay time showed less influence on the square pipe， and there was little influence on the circumference ratio roundness of the cross?section.

Key words: square tube, short?glass?fiber?reinforced polypropylene, water?assisted injection molding, penetration behavior of high?pressure water

CLC Number:

TQ320.66

HUANG Wei, LIU Hesheng, HUANG Xingyuan, ZHANG Wei, KUANG Tangqing, CHEN Zhongshi. Study on high⁃pressure water penetration behavior of square cross⁃sectional pipes based on short⁃glass⁃fiber⁃reinforced polypropylene[J]. China Plastics, 2022, 36(2): 82-88.

Figures/Tables 10

性能	测试标准	测试结果
密度/g·cm^-3	ISO 1183	0.960
熔体流动速率（230 ℃/2.16 kg）/g·10 min^-1	ISO 1133	7.0
拉伸应力（断裂）/MPa	ISO 527⁃2⁃2018	38.0
弯曲模量/MPa	ISO 178	2 000
悬臂梁缺口冲击强度（23 ℃）/kJ·m^-2	ISO 180	11

Tab.1. Property parameters of the experimental material

Fig.1. Picture of the mold

熔体温度/ ℃	注水压力/MPa	注水延迟时间/s
210	4	0
230	6	1
250	8	3
270	10	5

Tab.2. Experimental parameters of OWAIM

Fig.2. Schematic diagram of the sample

Fig.3. Effect of melt temperature on residual wall thickness

Fig.4. Cross section shape at P5 at different melt temperature

Fig.5. Effect of injection pressure on residual wall thickness

Fig.6. Cross section shape at P5 under different injection pressure

Fig.7. Effect of injection delay time on residual wall thickness

Fig.8. Cross section shape at P5 under different injection delay time

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