注射温度对PP/微球发泡材料发泡行为及力学性能的影响

通过二次开模注塑成型的方法,在180～230℃的范围内制备PP/微球发泡材料,采用SEM、Image-pro图像处理软件对泡孔进行观察、统计和计算,并测试了发泡材料的力学性能,研究了注射温度对PP/微球发泡材料发泡行为及力学性能的影响规律。结果表明:当注射温度为200℃时,PP/微球发泡材料的发泡质量较理想,泡孔平均直径为32 m、泡孔密度为7.95×106个/cm3,同时获得理想的综合力学性能。     

The effect of a polypropylene skin on the structure and properties of PE/PP dual layer pressure pipe

A new and growing family of polyethylene (PE)‐based pressure pipes have a polypropylene (PP) skin. The effect of the PP skin on the structure and properties of the core PE pipe was investigated by comparing the skinned pipe with an uncoated pipe made from the same PE material and with the same dimensions. The annealing effect introduced by the skin changed the PE core pipe density profile across the wall thickness, increasing density in the PE core pipe near to its outer surface. The density at the bore of the coated and the uncoated pipe was similar. The melting temperature and enthalpy of melting data from DSC agreed with the density profile results. The melting temperature of PE core pipe material close to the PP skin increased with increasing skin thickness. Residual stress assessment indicated that, as the PP skin thickness increased, the PE core pipe had a lower level of overall residual stress in the hoop direction. Long‐term hydrostatic strength (LTHS) tests were carried out and showed a higher strength for the coated pipe than the uncoated one. The observed structural changes have been used to explain the relative strength of these two PE pipes. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

PP/微球复合材料的发泡行为及力学性能

选用PP(EPS30R)、PP(K9928)为基体材料,分别加入EK405、EK406微球母粒,在二次开模条件下制备微发泡PP/微球复合材料,研究不同特性树脂和微球母粒对PP/微球复合材料发泡行为及力学性能的影响规律。结果表明:微球母粒EK406适合于PP/膨胀微球复合材料的发泡,发泡倍率达12%,泡孔平均直径和泡孔密度分别为29.94μm、7.93×106个/cm3,能够获得泡孔细小、均匀而致密的微发泡聚丙烯材料。熔体指数低的PP材料适合于微球发泡,发泡质量较好,综合性能理想,拉伸和冲击强度分别为18.52 MPa、13.18 kJ/m2,比强度达到23.03。     

发泡剂BIH40对PP和LDPE化学发泡性能影响的研究

本文以BIH40作为发泡剂,使用注塑方法化学发泡成型制备了PP、LDPE发泡材料,探讨了发泡剂含量对PP和LDPE发泡制品的密度、拉伸强度、缺口冲击强度等力学性能的影响,并用扫描电子显微镜（SEM）观测了断面的泡孔形貌。实验结果表明,随着发泡剂含量的增加,发泡试样的拉伸强度、冲击强度、断裂伸长率和密度等与未发泡试样相比总体呈现下降趋势,LDPE的断裂伸长率在发泡剂含量为1.0%（重量百分比wt.）时较其他发泡组分有所增加,PP的冲击强度在发泡剂含量为0.5%（重量百分比wt.）时与其他发泡组分相比有所提高。综合实验测试结果显示,发泡剂含量在1.0%（重量百分比wt.）时所得到的发泡制品力学性能较好。     

微发泡PP/竹塑复合材料发泡行为及性能研究

采用注塑成型方法,在二次开模条件下制备微发泡聚丙烯(PP)/竹粉复合材料,分析了不同含量的竹粉对微发泡PP复合材料力学性能和发泡行为的影响。结果表明:随着竹粉用量的增加,泡孔平均直径逐渐减小,泡孔密度逐渐增加。竹粉用量为30%时,泡孔直径最小,为23.4μm,泡孔密度达到10.4×106个/cm3,具有理想的发泡效果。竹粉用量在20%时,发泡材料的冲击强度和纯PP基本相同,在性能不降低情况下,节约了原材料成本。     

聚丙烯/马来酸酐接枝聚丙烯/超细云母的界面增容及其断面形态研究

:针对 PP/云母相界面缺乏亲和力 ,云母对 PP力学性能改善不明显的缺陷 ,采用偶联剂KH- 570与 PP- g- MAH并用的技术对超细云母进行表面处理并与 PP共混增容。结果表明 ,云母能同时有效提高 PP的强度、模量、硬度和冲击强度。其中 ,由于 PP- g- MAH导致的界面强度提高和界面层厚度增加 ,使 KH- 570与 PP- g- MAH并用的 PP/PP- g- MAH/云母 - 4#材料比单用 KH- 570的PP/云母 - 4# 材料的改性效果更加明显。同时发现 ,云母对 PP的结晶过程具有较明显的成核作用 ,使改性 PP的结晶温度和熔融温度提高     

Characterization of PP/Mg(OH)2 and PP/Nanoclay Composites with Supercritical CO2 (scCO2)

In this article, supercritical carbon dioxide (scCO₂) is used to form a high density microcellular foam structure to reduce the polymer use and facilitate dispersion of Mg(OH)₂ and Nanoclay fillers. A twin-screw extruder system was used to predistribute the inorganic filler from the PP polymer, resulting composite PP/filler pellets. This followed by the use of a single-screw extruder wherein supercritical carbon dioxide is introduced in the formulation. Finally the resulting foam PP/filler/CO₂ pellets are injection molded into test samples. The structure and properties of the composites are characterized using a scanning electron microscopy (SEM), Differential scanning calorimetry (DSC), and density measurements. Furthermore, PP/Clay/Mg(OH)₂ polymer composites are subjected to examinations to obtain their yield and tensile strengths, elasticity modulus, % elongation, Izod impact strength, hardness, Heat deflection temperature (HDT), Vicat softening point and Melt flow index (MFI).     

PTT/PP共混物的性能研究

通过熔融共混制备了聚对苯二甲酸丙二酯/聚丙烯(PTT/PP=75/25)及其马来酸酐接枝PP(PP-g-MAH)增容共混物,研究了PTT/PP及其增容共混物的结晶性能、力学性能、流变性能和结晶形态。研究结果表明,PTT与PP共混能提高PP、PTT组分的结晶温度;对于增容共混物,随PP-g-MAH用量的增加,PP和PTT的结晶温度基本不变。加入PP使PTT拉伸强度降低,冲击强度提高;PP-g-MAH增容使共混物的拉伸和冲击强度都提高。增容共混物的熔体粘度明显降低,存在明显的剪切变稀现象,但熔体粘度与PP-g-MAH用量无关。在一定用量范围内,随PP-g-MAH用量的增加,PP分散相的尺寸变小。     

POE-g-MAH对SGF/POE/PP泡沫复合材料结构和性能的影响

采用型内二次发泡工艺制备马来酸酐接枝聚烯烃弹性体(POE-g-MAH)共混改性短玻璃纤维/聚烯烃弹性体/聚丙烯(SGF/POE/PP)泡沫复合材料,考察POE-g-MAH含量对复合材料泡孔形貌、微观结构和力学性能的影响.结果表明:少量POE-g-MAH的引入有利于降低平均泡孔和提高泡孔密度;同时POE、SGF与基体间的界面结合均得到了增强,SGF/POE/PP泡沫复合材料的冲击韧度和弯曲强度分别在POE-g-MAH的含量为5%和8%时达到最大值,而压缩强度则呈逐步下降的变化趋势.     

注塑工艺参数对微发泡PP/SiO2纳米复合材料发泡行为及力学性能的影响

用正交实验研究了喷嘴温度、注射压力、注射速度和冷却时间等工艺参数对化学发泡法制备的微发泡聚丙烯（PP）/SiO2纳米复合材料的泡孔平均直径和泡孔密度的影响,用Image-pro图像处理软件对复合材料的泡孔尺寸进行了观察和统计,并对其力学性能进行分析。结果表明,在PP中添加纳米SiO2后,喷嘴温度对发泡PP/SiO2纳米复合材料的发泡行为影响最大,其次为注射速度;实验范围内较理想的工艺参数为：喷嘴温度175 ℃、注射压力67.5 MPa、注射速度95 %、冷却时间35 s,在此工艺条件下获得了泡孔平均直径为15.71 m、泡孔密度9.8×106个/cm3的PP/纳米SiO2发泡复合材料,冲击强度达5.45 kJ/m2。     

注塑条件对长玻纤增强聚丙烯性能影响研究

利用熔融浸渍装置,采用长玻纤(LGF)增强双马来酰亚胺等改性的聚丙烯(PP),制备了LGF增强PP复合材料。研究了在螺杆转速为80～250 r/min、背压为8～10 MPa的注塑条件下,复合材料的纤维长度、力学性能与热变形温度的变化。在研究范围内,注塑工艺参数的变化对复合材料的弯曲强度和热变形温度没有明显的影响,但随着螺杆转速的提高,纤维长度下降,所得复合材料的冲击强度先降低后升高。     

聚乳酸/聚丙烯/淀粉复合材料的制备及性能研究

采用模压成型制备了聚乳酸(PLA)/聚丙烯(PP)和PLA/PP/淀粉两种复合材料.主要研究了复合材料的热性能、力学性能和降解性能.结果表明:对于PLA/PP复合材料而言,复合材料的熔融温度先增加后降低,结晶度随PLA的含量增加而变大,而且出现了结晶双峰.力学性能相较与纯PLA,断裂伸长率明显提高,拉伸强度有所下降,最...     

硅烷偶联剂改性云母粉在微孔发泡PP中的应用

通过硅烷偶联剂改性的云母粉,以不同含量加入聚丙烯(PP)中,制备微发泡PP/云母粉复合材料;通过相容性和分散性分析了改性与未改性云母粉微发泡PP复合材料发泡行为和力学行为的影响规律。结果表明:改性云母粉的微发泡PP复合材料泡孔直径明显减小,泡孔密度增大;抗拉强度和冲击强度都得到提高。     

EOC-g-MAH共混增韧SGF/PP泡沫复合材料的制备及力学性能

采用型内二次发泡工艺制备了马来酸酐接枝乙烯-1-辛烯共聚物(EOC-g-MAH)共混增韧短玻璃纤维(SGF)/聚丙烯(PP)泡沫复合材料,考察了EOC-g-MAH含量对复合材料的泡孔形貌、微观结构和力学性能的影响。结果表明,EOC-g-MAH的引入改善了泡沫体的发泡效果,平均孔径减小约35%,泡孔密度提高近4倍且分布均匀。SGF与基体间的界面结合得到显著增强,且EOC-g-MAH在SGF表面形成了颗粒黏附结构,大幅提高了SGF/PP泡沫复合材料的冲击韧度,并在质量分数为8%时达到最大值,增幅为77%。随着EOC-g-MAH质量分数的增加,SGF/PP泡沫复合材料的抗弯强度先增加后降低,而压缩强度则呈近似线性下降的变化趋势。     

发泡工艺对超临界CO2／PP微孔发泡泡孔形态的影响

研究了超临界CO2／PP微孔发泡过程中发泡温度和饱和压力对结晶性聚合物PP泡孔形态的影响。结果表明，温度对泡孔形态影响很大，温度升高，熔体黏度和表面张力降低，泡孔变大，泡孔密度减小。与发泡温度相比，CO2饱和压力对泡孔结构的影响较小。压力太低，CO2的溶解度小，泡孔壁太厚，泡孔分布不均匀。随着压力升高，CO2的溶解度增加，熔体黏度减小，所以泡孔直径和泡孔密度都增加，泡孔壁变薄。     

新型发泡剂制备PP微泡材料与性能研究

采用注塑法制备了PP微泡材料,并研究了发泡剂种类和用量对性能的影响。结果表明:新型发泡剂RS3000发泡效果明显优于AC和NaHCO₃;随着发泡剂用量的增加,拉伸强度和断裂伸长率逐渐降低,冲击强度先增加减小,密度则是先降低后增加;当发泡剂RS3000用量为0.5份时,性能最佳:拉伸强度20.4MPa、断裂伸长率564%、冲击强度50.6kJ/m²、密度0.879g/cm³。     

Lightweight and High Impact Polypropylene Foam Fabricated via Ultra-Low Gas Pressure Injection Molding

Foamed materials play an important role in a lightweight design. Foam injection molding (FIM) is an advanced and convenient way to fabricate lightweight structural materials. Recently, a new foam injection molding machine is developed, which only needs ultra-low gas pressure to fabricate microcellular foam. As a universal plastic, polypropylene (PP) is widely used due to its good mechanical properties. But after foaming, the toughness of the PP tends to decrease. Herein, a lightweight and high-impact polypropylene foam is fabricated via the new FIM technology with an ultra-low nitrogen pressure of 6.5 MPa. PP/polyolefin elastomer (POE) foam with a tiny cell size of 4.13 µm and high cell density of 2.7 × 10⁹  cm⁻³ is successfully obtained. Owing to the superior cellular structure, compared with the pure PP foam, after adding the POE component, the maximum impact performance is increased by 465%. In this work, an easy-to-industrialized method for preparing lightweight and high-impact injection-molded PP foams are presented.     

加工参数及配方对PP/LLDPE共混物泡孔形态的影响

采用高压毛细管流变仪对不同含量碳酸钙(CaCO3)的聚丙烯/线型低密度聚乙烯(PP/LLDPE)共混物的流变性能进行了表征;并利用自制的实验装置,在不同发泡温度和饱和压力下,对共混物进行了超临界CO2模拟挤出发泡实验研究。结果表明:使用高熔体强度聚丙(烯HMSPP)发泡可以获得较好的泡孔形态;添加成核剂CaCO3可以使发泡试样的泡孔结构更加规则,泡孔分布更加均匀;随着CaCO3含量的增加,共混物的稠度上升,非牛顿指数降低,当CaCO3含量为3%时,共混物的发泡效果较好;130℃为最佳发泡温度,此时发泡试样的结构完整尺,寸均匀;随着饱和压力的增加发,泡试样的泡孔密度也有所提高。     

Studies on blends of high‐density polyethylene and polypropylene produced by oscillating shear stress field

Tensile strength and morphology of blends of high‐density polyethylene (HDPE) and polypropylene (PP) obtained by oscillating packing injection molding were investigated via Universal Testing Machine, DSC, and SAXS. Tensile strength is greatly enhanced from 24.5 MPa to more than 90 MPa for pure HDPE and for blends with PP content less than 10 wt %. There exists a sharp decrease of tensile strength when PP content is more than 10 wt %. The shear‐induced morphologies with core in the center, oriented zone surrounding the core and skin layer are observed in the cross‐section areas of the samples. Interestingly, a sharp decrease of oriented zone is seen when PP content is more than 10 wt %, associated with the sharp decrease of tensile strength. DSC result shows double melting peaks with a high‐temperature melting peak that is not present in the endotherm obtained from the central core and obtained from the samples by static packing injection molding, which indicates the existence of shish‐kebab structure in the oriented zone. However, there is no difference of crystallinity between the samples by oscillating and by static packing injection molding. SAXS was used to analyze the complicated morphologies induced by shear stress, and results show that the crystal thickness could be greatly increased under shear stress. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 58–63, 2002     

PP/纳米Al_2O_3复合材料及其发泡材料的制备与表征

用PP与纳米Al_2O_3熔融共混法制备复合材料,再用超临界CO_2间歇发泡法制备发泡材料,并对材料的结晶行为、力学性能、发泡行为和导热性能进行研究。结果表明,纳米Al_2O_3能提高复合材料的结晶和熔融温度,但会降低PP链段运动能力,当纳米Al_2O_3含量为7%时,复合材料的结晶度由纯PP的28.10%降至24.46%;纳米Al_2O_3具有刚性粒子的增强增韧协同效果,当纳米Al_2O_3含量为5%时,纳米Al_2O_3的骨架效应使得复合材料的拉伸强度达到33.9 MPa,继续提高其含量后复合材料的拉伸强度略微下降。由于纳米Al_2O_3的刚性粒子增韧效果,当纳米Al_2O_3含量达到7%时,复合材料的冲击强度可达到5.26 k J/m2。纳米Al_2O_3起到异相泡孔成核剂作用,加入5%的纳米Al_2O_3后,发泡材料的泡孔密度提高至2.18×107个/cm3,其热导率在纳米Al_2O_3含量为7%时达到0.107 W/(m·K)。