私密直播全婐app免费大渔直播,国产av成人无码免费视频,男女同房做爰全过程高潮,国产精品自产拍在线观看

相關鏈接
聯系方式
  • 通信地址:加拿大魁北克省蒙特利爾
  • 郵編:無
  • 電話:(514) 848-2424 ext.5611
  • 傳真:
  • Email:zhibin.ye@concordia.ca
當前位置:> 首頁 > 論文著作 > 正文
Chain-topology-controlled hyperbranched polyethylene as effective polymer processing aid (PPA) for extrusion of a metallocene linear-low-density polyethylene (mLLDPE)
作者:J. Wang, M. Kontopoulou, Z. Ye*, R. Subramanian, S. Zhu
關鍵字:Chain-Topology, PPA, mLLDPE
論文來源:期刊
具體來源:Journal of Rheology
發表時間:2008年
Hyperbranched polymers have recently received extensive interest for applications as polymer processing aids (PPAs). In this work, we present the first study on the performance of novel hyperbranched polyethylene as a processing aid for a metallocene linear-low-density polyethylene (mLLDPE). Moreover, we investigated for the first time the unique role that chain topology plays in determining the efficiency of the polymers as PPA. Two polymers of drastically different chain topologies, a hyperbranched polyethylene (HBPE) and a linear branched polyethylene (LBPE) having a linear chain topology, were prepared by ethylene polymerization using chain walking Pd-diimine catalysis. The performances of these two polymers of different chain topologies in improving the processability of the mLLDPE were investigated and compared by using two-step capillary extrusion experiments, including constant-shear testing at 200s?1200s?1 and shear-rate sweep testing. For comparison purposes, a commercial fluoropolymer-based PPA, Viton Free Flow Z100, together with a polyethylene wax sample, were also evaluated for their performances. It was found that, at a concentration 3wt%, the presence of HBPE in mLLDPE significantly reduced the apparent shear stress, improved extrudate surface morphology, and postponed the onset shear rate for sharkskin instability. However, LBPE did not improve the processability of mLLDPE and it worked merely as a plasticizer, slightly reducing the viscosity of polymer melts. Morphology studies conducted on the cross sections of the blends showed that chain topology greatly affected the polymer additive’s miscibility with mLLDPE; the mLLDPE/HBPE blend was a phase-separated system, whereas LBPE appeared to be miscible with mLLDPE. The hyperbranched polymer, HBPE, forms phase-separated droplets, which can migrate to the die surface and form a lubricating layer promoting extrudate slippage. By identifying the effect of chain topology on the polymers’ performance, this work may provide a chain-topology guideline for designing polymer-based processing aids.
主站蜘蛛池模板: 峨眉山市| 鄂伦春自治旗| 唐山市| 应城市| 兴文县| 读书| 龙井市| 安化县| 西充县| 合作市| 鄂托克前旗| 沁阳市| 天门市| 德惠市| 甘肃省| 五华县| 肇州县| 嘉峪关市| 临清市| 温宿县| 汝州市| 永平县| 江山市| 凤山县| 定襄县| 雅江县| 太白县| 庆安县| 柳江县| 乃东县| 普兰店市| 堆龙德庆县| 万全县| 竹山县| 宾阳县| 息烽县| 崇州市| 申扎县| 兴海县| 平泉县| 昆山市|