振动力场下PP增强管材的制备及性能研究

采用电磁动态塑化挤出机挤出聚丙烯（PP）管材,通过爆破压力测试、拉伸性能测试、差示扫描量热（DSC）分析和X射线衍射（XRD）分析研究了振动频率和振幅对PP管材结构与力学性能的影响。力学性能测试结果表明,振动挤出PP管材的周向强度有了显著提高,实现了管材的双向自增强。与稳态挤出的PP管材相比,振动挤出PP管材的爆破压力最大提高了27．03％,轴向拉伸屈服强度最大提高了7．3％。DSC分析和XRD分析表明,振动挤出的PP管材结晶度提高,熔点升高,结晶完善,晶粒变小,有利于管材力学性能的提高。     

微注塑与常规注塑等规聚丙烯的拉伸性能及微观结构对比研究

采用微注射成型和常规注射成型制备厚度分别为200μm和2400μm的等规聚丙烯(iPP)制品。通过拉伸测试和广角X射线衍射(WAXD)对微注塑制品和常规注塑制品的力学性能及微观结构进行对比。拉伸测试结果表明:微注塑制品的拉伸强度(46.53MPa)较常规注塑制品的(38.43MPa)增加17.41%,而断裂伸长率和断裂韧性却明显降低。广角X射线衍射测试结果表明:微注塑制品形成了高度取向结构、且结晶度大于常规注塑制品的,高的取向度和结晶度导致了微注塑制品较高的拉伸强度和较低的断裂伸长率及断裂韧性。     

α-成核剂对聚丙烯结晶性能和形态的影响

用差示扫描量热仪（DSC）、广角X射线衍射（WAXD）研究了不同含量的α-成核剂对聚丙烯的结晶行为和结晶形态的影响，用偏光显微镜观察了结晶尺寸大小的变化，测试了聚丙烯的力学性能，同时对聚丙烯的透光性也进行了表征。结果表明，添加少量α-成核剂提高了聚丙烯的结晶温度和结晶度。且随α-成核剂的添加，聚丙烯的球晶尺寸明显缩小，聚丙烯的拉伸强度也相应增强。当α-成核剂的质量分数为0．3%时，拉伸强度最大，薄片的透光性显著改善。     

α-成核剂对聚丙烯结晶性能和形态的影响

用差示扫描量热仪（DSC）、广角X射线衍射（WAXD）研究了不同含量的α成核剂对聚丙烯的结晶行为和结晶形态的影响，用偏光显微镜观察了结晶尺寸大小的变化，测试了聚丙烯的力学性能，同时对聚丙烯的透光性也进行了表征。结果表明，添加少量α-成核剂提高了聚丙烯的结晶温度和结晶度，且随α-成核剂的添加，聚丙烯的球晶尺寸明显缩小，聚丙烯的拉伸强度也相应增强。当α-成核剂的质量分数为0．3％时，拉伸强度最大，薄片的透光性显著改善。     

电磁动态注射机振动参数对PP力学性能的影响

采用电磁动态注射机注塑成型PP试样,并对其进行拉伸强度、冲击强度和DSC测试,探讨振动频率和振幅对制品力学性能的影响。结果表明:施加振动后,拉伸强度和冲击强度提高;熔点向高温漂移,有利于结晶完善程度的提高。对PP注塑料,电磁动态注塑成型时最佳的振动参数范围为f=3～9Hz,A=0 10mm～0 40mm。     

剑麻纤维增强聚丙烯复合材料的制备与性能研究

采用动态保压注塑成型技术(DPIM),通过在熔融共混体系中施加往复的剪切应力以改善剑麻纤维(SF)与聚丙烯(PP)复合材料的结构与性能。力学性能测试表明:动态保压获得的样品,拉伸强度与模量获得大幅度提高,但样品冲击性能有所下降。当剑麻纤维质量分数为30%时,动态复合材料的拉伸强度提高了23%。DSC结果表明:由于剑麻纤维充当了结晶成核点的作用,使得复合物的结晶温度提高。     

振动塑化挤出对聚烯烃片材性能的影响

利用塑料电磁塑化挤出机挤出聚烯烃片材，系统研究了挤出机螺杆轴向振动对聚乙烯挤出制品结构与性能的影响。采用DSC对挤出试样的结晶结构及形态进行分析。结果表明，振动塑化挤出使聚合物挤出试样结晶度提高，结晶完善，晶片之间的连接分子数量增加，因而制品的力学性能有所提高，特别在横向上表现明显。在适当的振动条件下，高密度聚乙烯（HDPE）试样的横向拉伸强度和冲击强度分别从22．68MPa和12．7kJ／m^2提高到了25．55MPa和23．5kJ／m^2；而聚丙烯（PP）试样横向拉伸强度和冲击强度则分别提高了20％和64％。     

聚丙烯接枝马来酸酐增容聚氨酯/聚丙烯复合体系

采用热塑性聚氨酯(TPU)对聚丙烯(PP)进行增韧改性,选取TPU/PP质量分数比10/90的配方添加聚丙烯接枝马来酸酐(MAH-g-PP)进行增容改性.通过拉伸测试、冲击测试表征力学性能,差示扫描量热仪(DSC)、X射线衍射(WAXD)表征结晶性能,动态流变测试表征TPU和PP的相容性.结果 显示,TPU对PP有明显...     

溢流槽对微注塑成型β-iPP制品微观结构及性能影响

利用微注塑成型技术制备不同含量β成核剂改性等规聚丙烯(β-iPP)制品,研究注射模具型腔末端所增设溢流槽对β-iPP制品的影响。通过实验手段对微注射制品进行微观结构和性能进行了表征分析,考察了β成核剂和溢流槽的引入对β-iPP制品微观结晶结构及力学性能的影响。从研究结果可知:在微注射模具型腔末端引入溢流槽能够使iPP制品的剪切层厚度增大、串晶数量增多及拉伸强度显著提高;含有溢流槽制品的拉伸强度随β成核剂含量增加而增大。     

液压脉振注塑PP/CaCO3的结构与力学性能

采用自制的液压脉振式动态注塑机在不同浇口条件下注射成型聚丙烯(PP)/CaCO3复合材料,通过拉伸及冲击性能测试、扫描电镜(SEM)分析和差示扫描量热(DSC)分析研究了PP/CaCO3复合材料的结构与力学性能.研究表明,浇口尺寸对振动效应有影响,浇口截面尺寸越大,振动效应越大;相对于小浇口,中、大浇口条件下动态注射成型复合材料的拉伸强度、冲击强度均有明显的提高l液压脉振有利于CaCO3在PP中的分散.相对于小浇口,大浇口条件下动态注射成型PP/CaCO3复合材料中的CaCO3分布更均匀,同时复合材料熔点更高,结晶度更高,这些均有助于提高复合材料的力学性能.     

Effect of melt vibration on structure and mechanical properties of HDPE/nano-CaCO3 blend

Melt vibration technology was used to prepare injection sample of HDPE/nano-CaCO₃ blend, whose mechanical properties were improved significantly. Compared with conventional injection molding, the enhancements of the tensile strength and impact strength of the sample molded by vibration injection molding were 41.2 and 43.2%, respectively. According to the SEM, WAXD, and DSC measurement, it was found that a much better dispersion of nano-CaCO₃ in sample was achieved by vibration injection molding. Moreover, crystal orientation degree of matrix HDPE increased under the effect of melt vibration. The crystallinity degree of HDPE in vibration sample increased by 5.5% compared with conventional one. The improvement of mechanical properties of HDPE/nano-CaCO₃ blend prepared by low-frequency vibration injection molding attributes to the even distribution of nano-CaCO₃ particles and the orientation of HDPE crystals and increase of crystallinity degree under the influence of melt vibration.     

Mechanical properties and morphology of polypropylene‐calcium carbonate nanocomposites prepared by dynamic packing injection molding

In this article, dynamic packing injection molding (DPIM) technology was used to prepare injection samples of Polypropylene‐Calcium Carbonate (PP/CaCO₃) nanocomposites. Through DPIM, the mechanical properties of PP/nano‐CaCO₃ samples were improved significantly. Compared with conventional injection molding (CIM), the enhancement of the tensile strength and impact strength of the samples molded by DPIM was 39 and 144%, respectively. In addition, the tensile strength and impact strength of the PP/nano‐CaCO₃ composites molded by DPIM increase by 21 and 514%, respectively compared with those of pure PP through CIM. According to the SEM, WAXD, DSC measurement, it could be found that a much better dispersion of nano‐CaCO₃ in samples was achieved by DPIM. Moreover, γcrystal is found in the shear layer of the DPIM samples. The crystallinity of PP matrix in DPIM sample increases by 22.76% compared with that of conventional sample. The improvement of mechanical properties of PP/nano‐CaCO₃ composites prepared by DPIM attributes to the even distribution of nano‐CaCO₃ particles and the morphology change of PP matrix under the influence of dynamic shear stress. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of vibration parameters of electromagnetic dynamic plastics injection molding machine on mechanical properties of polypropylene samples

Dynamic injection processing experiments have been carried out on polypropylene using the self‐made electromagnetic dynamic plastics injection molding machine, and the effects of the vibration force field on mechanical properties of molding samples are studied, namely, the influence of vibration frequency and vibration amplitude on the mechanical properties of samples are researched by using tensile testing, impact testing, differential scanning calorimeter (DSC) and scanning electronic micrograph (SEM) techniques. The results show that the tensile strength and impact strength are both enhanced and the melting point shifts toward the higher temperature, which facilitates the perfection of crystal. The best vibration parameters for processing polypropylene using electromagnetic dynamic plastics injection molding machine are that frequency is from 3 to 9 Hz and amplitude is from 0.1 to 0.4 mm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 972–976, 2006     

Mechanical Properties and Crystal Structure of HDPE Induced by Small Amount of High-molecular-weight and Low-molecular-weight Polyethylene under Shear Stress Produced by Dynamic Packing Injection Molding

In order to better understand the effect of small amount of both high-molecular-weight polyethylene (HMWPE) and low-molecular-weight polyethylene (LMWPE) on the mechanical properties and crystal morphology under the shear stress field, the dynamic packing injection molding (DPIM) was used to prepare the oriented pure polyethylene samples and its blends ones with different contents of HMWPE and LMWPE. The experiment substantiated that the further improvement of tensile strength and impact stength along the flow direction (MD) of HDPE/HMWPE/LMWPE samples was achieved, while the tensile strength along the transverse direction (TD) still substantially exceeded that of conventional molding. When the contents of HMWPE and LMWPE were respectively 8% in blends, the tensile strength in both flow and transverse directions of the samples were highly enhanced, with improvements from 27.75 MPa to 115.43 MPa (about 316%), in MD and from 23MPa to 32.74 MPa (about 42.34%), in TD; besides the impact strength was improved from 21.55 KJ/m² to 72.6 KJ/m² (about 236.89%), in MD but decreased from 17 KJ/m² to 6.92 KJ/m² in TD. The obtained samples were characterized via DSC, WAXD and SEM. For HDPE/HMWPE/LMWPE, the shish-kebab structure which is composed of stretched chains (shish) and lamellae (kebab) was seen in the oriented region of DPIM samples and the spherulites existed in the oriented region of SPIM samples. Furthermore, the appropriate amount HMWPE and LMWPE (about 8%, respectively) blended into mixture can improve the thickness and the length of lamellae, and the degree of crystallinity in shear region by DPIM which were approved by DSC and SEM, at the same time, it can also enhance the intensity of orientation of lamellae in shear region confirmed by SEM and WAXD. The reason of improvement of mechanical properties is the existence of these thicker, longer and more orientated lamellae in shear region.     

Structure and Properties of Vibrating Extruded High-Density Polyethylene Sheet

Summary The effect of vibration frequency and vibration amplitude on the microstructure and mechanical properties of high-density polyethylene (HDPE) sheets, obtained through electromagnetic dynamic plasticating extruder, were studied systematically. The mechanical properties, characterized by tensile and impact strengths, have been tested along the flowing and transverse directions (MD&TD). The mechanical tests show that the tensile strength and impact toughness, especially in TD, were much improved under the reciprocating axial vibration. Differential scanning calorimetry (DSC), scanning electron microcopy (SEM) and wide angle X-ray diffraction (WAXD) were executed to analyze the microstructure of the samples. The results indicate that the vibration extrudate has higher crystallinity, perfect crystallite, and strong inter-spherulite ties, which account for enhancement of the mechanical properties of sheets, compared to conventional static extrusion.     

Study of the effect of organic clay on the shear‐induced crystallization of high‐density polyethylene through dynamic‐packing injection molding

Organic nanoparticles as heterogeneous nucleators have a great effect on the crystallization of polymer matrices in nanocomposite systems, and the effect will be enhanced under shear flow. A home‐made dynamic‐packing injection molding (DPIM) device was developed to explore the effect of organic clay on the shear‐induced crystallization of high‐density polyethylene (HDPE). Differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD) and scanning electron microscopy (SEM) were used to characterize the flow‐induced crystalline structure of HDPE/clay nanocomposite injection moldings. It was found that higher crystallinity and thicker crystal planes which contribute to the improvement of mechanical properties were achieved in HDPE/clay nanocomposite samples prepared by DPIM. DSC results clearly showed that an increase of about 16% in crystallinity was achieved in dynamic HDPE/clay nanocomposite samples compared with traditional unfilled HDPE samples. WAXD confirmed that dynamic HDPE/clay nanocomposite samples had maximum crystal sizes at the (110) and (200) planes of 335 and 305 Å, respectively. SEM images indicated that the arrangement of crystalline structures in dynamic HDPE/clay samples was altered slightly compared with unfilled HDPE samples prepared using the same processing parameters. The results showed that organic clay was beneficial for increasing crystallinity and crystal size in the HDPE/clay nanocomposite system under shear flow. Meanwhile the arrangement of crystalline structures was insignificantly affected by the organic clay, and the preferred regular arrangement of lamellae could still be formed in the dynamic HDPE/clay nanocomposite system. Copyright © 2010 Society of Chemical Industry     

流动场下含β成核剂的玻璃纤维增强聚丙烯复合材料结构与性能研究

采用普通注射成型和动态保压注射成型分别制备了不同玻璃纤维（GF）含量和β成核剂含量的等规聚丙烯（iPP）复合材料,测试了复合材料的力学性能,并采用二维广角X射线衍射、扫描电子显微镜和二维小角X射线散射研究了复合材料的iPP分子链取向、GF取向及结晶性能。结果表明,在动态保压注射成型条件下,GF含量为30 %（质量分数,下同）、β成核剂含量为0.2 %时,复合材料具有最优异的综合性能,拉伸强度为58.52 MPa,冲击强度为9.26 kJ/m2,这是由于在流动场下含GF与β成核剂的复合材料形成了"皮刚芯韧"类竹子的仿生结构。     

注射工艺条件对抗冲共聚聚丙烯力学性能的影响

用注塑成型方法制备了抗冲嵌段共聚聚丙(烯PP-B)试样,研究了工艺条件的改变对PP-B力学性能的影响。结果表明:注射速率和模具温度与PP-B弯曲强度、弯曲模量成正相关,而与冲击强度、拉伸强度的关系较为复杂;模具温度的升高有利于结晶度的提高,PP-B刚性上升,韧性下降;注射速率改变引起的剪切、拉伸流动使熔体发生取向流动,从而使沿取向方向上的强度升高,垂直取向方向上的强度降低;保压压力对PP-B性能的影响主要是通过熔体非晶部分在保压阶段的分子定向作用来实现的,随着保压时间的延长,PP-B塑件密度提高缺,陷减少拉,伸强度弯、曲模量呈增大趋势。     

HDPE在少量HMWPE和剪切应力双重诱导作用下结构与性能的关系

将少量高分子量聚乙烯(HMWPE)和动态剪切应力场同时引入到高密度聚乙烯(HDPE)的注射成型过程中,在双重诱导的作用下制备了性能良好的聚合物材料,其拉伸强度和缺口冲击强度都有大幅度提高;同时通过形态表征(差示扫描量热、广角X射线衍射、扫描电子显微镜分析)对增强增韧的机理进行了探讨。