机械工程学报
機械工程學報
궤계공정학보
Journal of Mechanical Engineering
2015年
20期
79-85
,共7页
超声外场%微尺度通道%聚合物熔体%黏性耗散%试验测量
超聲外場%微呎度通道%聚閤物鎔體%黏性耗散%試驗測量
초성외장%미척도통도%취합물용체%점성모산%시험측량
ultrasonic field%micro-scale channel%polymer melts%viscous dissipation%experimental measurement
针对聚合物熔体在微尺度通道中流动时的黏性耗散效应对其流动行为的影响，通过自行构建的带有温度传感器和超声振子的微注塑成型试验系统，采用单因素成型试验方法，对聚丙烯(Polypropylene, PP)和高密度聚乙烯(High-density polyethylene, HDPE)两种聚合物材料在不同工艺参数和超声外场作用下，流经矩形截面微通道时由黏性耗散效应引起的通道出口熔体温升进行试验测量。结果表明，微通道中熔体的黏性耗散效应随注射速度的增加而增强，随入口熔体温度和模具温度的升高而减弱；与不加超声振动相比，施加超声振动使两种材料的微通道出口熔体温升值明显升高；但材料自身的微观分子结构及其热物理性能不同，其温升增幅差别较大。试验注射速度下，施加超声振动比不加超声振动时的PP熔体温升增幅高出34.7%，而HDPE熔体的温升增幅则高达71.7%。当超声频率和工艺参数一定时，增大超声功率使PP熔体的微通道出口温升增加了24.8%，HDPE熔体的温升增加了83.6%。可见施加超声外场作用能使微通道中聚合物熔体的黏性耗散效应明显增强。
針對聚閤物鎔體在微呎度通道中流動時的黏性耗散效應對其流動行為的影響，通過自行構建的帶有溫度傳感器和超聲振子的微註塑成型試驗繫統，採用單因素成型試驗方法，對聚丙烯(Polypropylene, PP)和高密度聚乙烯(High-density polyethylene, HDPE)兩種聚閤物材料在不同工藝參數和超聲外場作用下，流經矩形截麵微通道時由黏性耗散效應引起的通道齣口鎔體溫升進行試驗測量。結果錶明，微通道中鎔體的黏性耗散效應隨註射速度的增加而增彊，隨入口鎔體溫度和模具溫度的升高而減弱；與不加超聲振動相比，施加超聲振動使兩種材料的微通道齣口鎔體溫升值明顯升高；但材料自身的微觀分子結構及其熱物理性能不同，其溫升增幅差彆較大。試驗註射速度下，施加超聲振動比不加超聲振動時的PP鎔體溫升增幅高齣34.7%，而HDPE鎔體的溫升增幅則高達71.7%。噹超聲頻率和工藝參數一定時，增大超聲功率使PP鎔體的微通道齣口溫升增加瞭24.8%，HDPE鎔體的溫升增加瞭83.6%。可見施加超聲外場作用能使微通道中聚閤物鎔體的黏性耗散效應明顯增彊。
침대취합물용체재미척도통도중류동시적점성모산효응대기류동행위적영향，통과자행구건적대유온도전감기화초성진자적미주소성형시험계통，채용단인소성형시험방법，대취병희(Polypropylene, PP)화고밀도취을희(High-density polyethylene, HDPE)량충취합물재료재불동공예삼수화초성외장작용하，류경구형절면미통도시유점성모산효응인기적통도출구용체온승진행시험측량。결과표명，미통도중용체적점성모산효응수주사속도적증가이증강，수입구용체온도화모구온도적승고이감약；여불가초성진동상비，시가초성진동사량충재료적미통도출구용체온승치명현승고；단재료자신적미관분자결구급기열물이성능불동，기온승증폭차별교대。시험주사속도하，시가초성진동비불가초성진동시적PP용체온승증폭고출34.7%，이HDPE용체적온승증폭칙고체71.7%。당초성빈솔화공예삼수일정시，증대초성공솔사PP용체적미통도출구온승증가료24.8%，HDPE용체적온승증가료83.6%。가견시가초성외장작용능사미통도중취합물용체적점성모산효응명현증강。
For viscous dissipation effect of the polymer melts flowing in micro-scale channel on their flow performance. The micro-injection molding experimental system with temperature sensors and ultrasonic field are designed. The temperature rises at the outlet of the rectangular cross-section micro-channel caused by viscous dissipation at different process parameters and ultrasonic power changes are investigated, using polypropylene(PP) and high-density polyethylene(HDPE) two polymer melts by the single factor molding experiments. The results show that the viscous dissipation effect of the polymer melts flowing in micro-scale channels is enhanced with the increase of injection rate, while it can be weakened by the rise of inlet melts temperature and mold temperature and the outlet temperature rise of the two materials with ultrasonic vibration can be significantly higher than that without ultrasonic vibration.However, their temperature increases vary greatly for microscopic molecular structures of different materials and their thermo-physical properties.PP melt temperature increase applying ultrasonic vibration is 34.7% higher than that without ultrasonic vibration at the set injection speed, while it is 71.7% for HDPE. But the under a certain ultrasonic frequency and process parameter, increasing the ultrasonic power make PP melt temperature increase by 24.8%, while it is 83.6% for HDPE. It’s obvious that the viscous dissipation effects of polymer melts flowing the micro channel can be enhanced by applying ultrasonic field.
