同向双螺杆捏合盘错列角对不相容体系共混物相态结构的影响

双螺杆挤出机螺杆构型对不相容体系共混物的相态结构有一定影响。将捏合块置于熔融段,通过改变捏合盘错列角,在熔融段末端位置进行在线取样,对所取试样(HDPE/PS共混物)应用扫描电子显微镜考察其相态结构,由此分析研究双螺杆挤出过程熔融段捏合盘错列角对不相容体系共混物相态结构的影响。结果表明:正向30°和反向60°错列角的捏合块元件具有较强的分散混合能力。     

同向双螺杆熔融段螺杆组合对共混物相态变化的影响

研究了双螺杆熔融段不同螺杆组合对模型聚合物共混体系HDPE/PS相态变化的影响。发现错列角为正向30°及正向60°的捏合块具有较好的输送能力,但不利于物料的熔融和混合;90°错列角捏合块对共混物具有很好的熔融和混合效果,其混合性能甚至优于反向30°捏合块,接近反向60°捏合块;及向螺纹元件对共混物相态变化影响显著。     

捏合盘错列角和厚度对聚丙烯降解的影响

研究了啮合同向双螺杆挤出机中具有不同捏合盘错列角、不同捏合盘厚度的螺杆构型的捏合块元件对造粒过程中聚丙烯（PP）降解的影响。结果表明,随着捏合盘错列角的增加和捏合盘厚度的增大,PP的降解加剧。     

啮合异向双螺杆挤出机中捏合块元件对PE-HD/PS不相容体系混合效果的研究

在常规啮合异向双螺杆上引入不同错列角和不同捏合盘厚度的捏合块元件,将其用于高密度聚乙烯/聚苯乙烯（PE-HD/PS）不相容体系的混合,观察混合体系的相态并分析分散相的粒径。结果表明,增加捏合块元件后啮合异向双螺杆挤出机的分散混合能力得到了提高;捏合块的错列角和捏合盘的厚度对PE-HD/PS不相容体系分散相PS的重均粒径和粒径分布指数有较大影响。     

螺杆组合对同向双螺杆挤出机能耗影响的研究

利用不同螺杆组合的双螺杆挤出机制备了超细碳酸钙填充聚丙烯试样,通过测量挤出机的功率来计算其能耗,并测试了试样的拉伸性能,研究了45°捏合盘厚度、塑化段捏合盘错列角、转子类螺纹元件位置及多组捏合盘连续排列形式对挤出机能耗和试样拉伸性能的影响。结果表明,45°捏合盘厚度为30 mm或45 mm、塑化段捏合盘错列角为30°或45°、转子类元件放在塑化混合段之后,均可在保持试样较高拉伸强度的条件下有效地降低挤出机能耗。多组捏合盘连续排列方式下的挤出机能耗并未大幅增加,可适用于需要高剪切物料的挤出生产。     

拉曼光谱成像研究PS/HDPE共混体系的相态结构

用拉曼光谱成像技术研究了双螺杆挤出机加工成型的PS/HDPE共混体系及其增容体系的相态结构分布。实验结果表明,当PS/HDPE共混体系不加增容剂时,体系发生严重的相分离,呈现"海-岛"状结构,相界面清晰可见。加入增容剂之后,分散相以不规整的形状"漂浮"或"包埋"分布在连续相中,这是因为增容剂能增加PS和HDPE之间的相互作用,降低了体系的相分离程度,改善体系的相容性。实验结论与扫描电子显微镜(SEM)研究基本一致,说明拉曼光谱成像可以用来研究聚合物共混体的相态结构分布。     

同向双螺杆捏合盘错列角对MAH接枝LDPE反应的影响

研究了同向双螺杆挤出机中,捏合盘错列角对马来酸酐(MAH)接枝低密度聚乙烯(LDPE)反应挤出过程的影响。对挤出沿程中的三个位置和挤出机出口处进行取样,从纯化后样品的红外谱图中可以证实MAH确实已经接枝到LDPE的分子链上。捏合盘错列角为120°的螺杆构型所对应的沿程样品的接枝率最大,挤出产物的熔体质量流动速率最小。     

螺杆构型对PP/PA6共混物性能和相态结构的影响

在啮合同向双螺杆挤出机中,研究了6种不同螺杆构型对聚丙烯/聚酰胺6（PP/PA6）共混物相态结构和性能的影响。结果表明,在熔融段设置拉伸型元件时,共混物的拉伸强度和冲击强度较大,而弯曲强度和流动性能则较小,分散相粒径较小且粒径分布更均匀;在熔融段设置剪切型元件、熔体输送段设置六棱柱（FTX）元件时,共混物的流动性能最好。     

双螺杆挤出共混物分散相粒子的分散和分布（Ⅱ）：捏合盘错列角的影响

采用同向啮合双螺杆挤出机的不同螺杆组合形式,研究了捏合错列角对双螺杆挤出聚合物共混物表层和内层分散相粒子粒径及其分布的影响。发现螺杆后段采用不同错列角的捏合盘,对于分散相粒子尺寸和分布状态都有明显影响。在塑化区多段式组合的后段采用剪切强、停留时间长的捏合盘(K45°、K60°),可有效地减小分散相粒子尺寸但分布状态不理想;使用 K30°的捏合盘时,分散相粒子分布状态最佳;整体两段式螺杆的前段混合段中设置 K45°捏合盘,有利于分散相含量较少情况下粒子的尺寸及分布的均匀性的提高。     

非对称同向双螺杆挤出机加工PP/HDPE/POE共混复合材料的研究

首先分别采用两种不同的同向双螺杆挤出机(新型非对称同向双螺杆挤出机以及传统双螺杆挤出机),制备了聚丙烯/高密度聚乙烯(PP/HDPE)共混复合材料,通过试样力学性能以及微观结构形貌对其加工过程进行了表征。然后采用新型非对称同向双螺杆挤出机进一步制备出了PP/聚烯烃弹性体(POE)、PP/HDPE/POE共混复合材料,分析了HDPE及POE用量对复合材料力学性能的影响,并采用扫描电子显微镜(SEM)观察了共混复合材料的表面微观结构形貌。结果表明:新型非对称同向双螺杆挤出机具备更好的分布、分散混合能力,所加工共混复合材料的分散相颗粒粒径分布更加集中,粒径也更小;HDPE和POE对PP有良好的协同增韧作用,当PP、HDPE、POE的质量比为68:17:15时,PP/HDPE/POE共混体系的综合性能最佳。     

Development of polymer blend morphology during compounding in a twin-screw extruder. Part III: Experimental procedure and preliminary results

Currently, selection of screw configurations as well as the operating conditions for compounding polymer blends with desired morphology in a co-rotating twinscrew extruder is an art based on experience. In this paper a quenching section of a twin-screw extruder is described. The section may replace any segment of the extruder barrel. It allows, on the one hand, a regular operation of the machine, and on the other, a rapid quenching and removal of blend specimens for morphology analysis from any place along the extruder barrel and at any time of the blending. The experimental observation of development during compounding of polymer blends enables verification and improvement of the theoretical model, aimed at predicting and controlling the size and polydispersity of the minor phase. Development of the predictive model for blend morphology will provide a valuable guide to the polymer processing industry. The preliminary data were collected using polystyrene/high density polyethylene (PS/HDPE) blends at low concentration of the dispersed phase, 5 wt% of either PS or HDPE. It was observed that the viscosity ratio, blend composition, screw configuration, temperature, throughput, and screw speed significantly influence the blend morphology.     

螺杆构型对PA6/PE-LD共混体系性能的影响

在啮合同向双螺杆挤出机中,研究了熔体输送段分布混合元件和分散混合元件先后布置、交错/集中布置以及不同元件相同布置方式对聚酰胺6/低密度聚乙烯（PA6/PE-LD）共混体系性能的影响。结果表明,混合元件交错布置的螺杆构型混合能力优于混合元件集中布置的螺杆构型的混合能力;交错布置的螺杆构型获得的共混体系力学性能也优于混合元件集中布置的螺杆构型获得的共混体系的力学性能。     

同向旋转双螺杆挤出机捏合区的速度分布

应用多普勒激光测速计测量同向旋转双螺杆挤出机捏合区域的速度分布。在９０ｒ／ｍｉｎ的转速下,测量了两螺杆捏合区中推力区和阻力区熔体的轴向速度和法和速度。     

Analysis of mixing during melt-melt blending in twin screw extruders using reactive polymer tracers

Mixing during melt-melt blending of segregated polypropylene melt streams in a co-rotating twin screw extruder was experimentally investigated. The mixing limited reaction between two polymer reactive tracers, which are terminally functionalized polyolefin oligomers, was used to determine the mixing performance of a kneading block section. The selected functional groups were succinic anhydride and a primary amine, and Fourier-Transform Infrared Spectrometry (FT-IR) was used to determine the anhydride conversion. In the absence of interfacial tension, the reaction conversion was directly related to the amount of interfacial area generated. Experiments were completed to study the effects of operating conditions, kneading block design, and polymer material properties. The screw speed effect was observed to be non-linear because of competing contributions from shear rate, residence time, channel fill, and viscous heating. The mixing performance of kneading blocks backed by a reverse conveying element was observed to follow the trend of: forward > reverse > neutral. For each kneading block design, the mixing performance decreased with an increase in polymer viscosity.     

Ultrasonic improvement of weld line strength of injection‐molded polystyrene and polystyrene/polyethylene blend parts

The effect of melt temperature, ultrasonic oscillations, and induced ultrasonic oscillations modes on weld line strength of polystyrene (PS) and polystyrene/polyethylene (PS/HDPE) (90/10) blend was investigated. The results show that the increase of melt temperature is beneficial to the increase of weld line strength of PS and PS/HDPE blend. Compared with PS, the increase of melt temperature can greatly enhance the strength of PS/HDPE blends. For PS, the presence of ultrasonic oscillations can enhance the weld line strength of PS at different melt temperatures. But for PS/HDPE blends, the presence of ultrasonic oscillations can improve the weld line strength when the melt temperature is 230°C, but when the melt temperature is 195°C, the induced ultrasonic oscillations hardly enhance the weld line strength. Compared with Mode I (ultrasonic oscillations were induced into the mold at the whole process of injection molding), the induced ultrasonic oscillations as Mode II (ultrasonic oscillations were induced into the mold after injection mold filling) is more effective at increasing the weld line strength of PS and PS/HDPE blends. The mechanism for ultrasonic improvement of weld line strength was also studied. POLYM. ENG. SCI., 45:1666–1672, 2005. © 2005 Society of Plastics Engineers     

Effects of the addition of a liquid crystalline copolyester to polystyrenes on blending torque and mechanical properties of blends

Blending of polystyrenes (PS) with a thermotropic liquid crystalline polymer (LCP) was performed by using a continuous corotating twin screw extruder. The influence of LCP content on the blending process was studied by changing the barrel heater temperature and the screw speed. The torque of screw shafts, generated during the blending process, was influenced by LCP content and its influence was not simple. The torque generated during the blending process was not directly related to the apparent melt viscosity of blends. Further, the effects of the matrix viscosity on the morphology and mechanical properties of the PS/LCP blends were studied using three grades of PS as matrix resins. It was found that the size of the LCP dispersed phase decreased with increasing matrix viscosity. Consequently, the mechanical properties of the PS/LCP blend were improved. © 1993 John Wiley & Sons, Inc.     

双螺杆捏合机理及其捏合段设计

定性分析了捏合段的混合及输送机理，讨论了捏合块错列角、螺棱间隙、捏合块头数、螺杆转速等因素对混合质量及输送能力的影响，并由此提出了一些捏合段设计时应注意的问题。