PP/PEG共混体系熔体流变性能研究

以聚乙二醇(PEG)为抗静电剂,在不同共混比例下与聚丙烯(PP)熔融挤出,用流变仪分析了PP/PEG二元共混体系的流变性能,并深入研究了剪切速率、温度、PEG含量等因素对共混体系熔体流变性能的影响。结果表明:PP/PEG共混体系为典型的假塑性流体;随着PEG含量的增加,非牛顿指数n先增大后减小;黏流活化能随PEG含量的增加而增加;结构黏度指数Δη则随PEG含量的增加先减小后增大,且在PEG含量为6%时达到极小值,此时共混体系的可纺性相对较好。     

mLLDPE及mLLDPE/LDPE共混物挤出加工性能的研究

使用双螺杆挤出机、单螺杆挤出机研究了mLLDPE及mLLDPE/LDPE共混物挤出表面、螺杆扭矩与喂料速度、螺杆转速之间的关系 ,并讨论了有机硅对mLLDPE/LDPE共混物挤出性能的影响     

mLLDPE及mLLDPE／LDPE共混物薄膜性能研究

研讨了茂金属线型低密度聚乙烯（ｍＬＬＤＰＥ）薄膜和ｍＬＬＤＰＥ与低密度聚乙烯（ＬＤＰＥ）共混物薄膜的物理性能和光学性能,并与传统的ＬＬＤＰＥ薄膜和ＬＬＤＰＥ／ＬＤＰＥ共混物薄膜进行了比较,表明ｍＬＬＤＰＥ薄膜和ｍＬＬＤＰＥ／ＬＤＰＥ共混物薄膜的性能优于传统的ＬＬＤＰＥ薄膜和ＬＬＤＰ／ＬＤＰＥ共混物薄膜,指出在ｍＬＬＤＰＥ中混合１０％ＬＤＰＥ,对薄膜性能影响不大。     

Melt Rheological Properties of PBT/ABAS/Mica Composites

Melt rheological properties of poly (butylene terephthlate) (PBT)/poly (acrylonitrile–butyl acrylate-styrene) terpolymer (ABAS)/mica composites were studied at 0.02 to 0.14 vol fraction (Φ_f) of mica at 518 K. The shear stress vs. shear rate plots was linear and the melts obeyed power law relation. The composites melts were shear thinning. Apparent melt viscosity decreased initially up to Φ_f = 0.07 the parameter increased with further increase in Φ_f. Melt elasticity viz. extrudate swell ratio also decreased up to Φ_f = 0.07 whereas the data increased at Φ_f > 0.07. Surface treatment of mica particles by zirconate coupling agent, NZ-97, brought about further modification of the rheological properties through enhanced interaction between the matrix and the dispersed phase.     

PP/Rosin Blends: Mechanical and Rheological Properties

Abstract

Melting mixtures of polypropylene (PP) and glycerol ester of hydrogenated rosin (ester gum) were prepared under select conditions using up to 50% of rosin. The addition of modified rosin on PP increased the elastic modulus which maximum value was observed in the 70/30 PP/ROSIN blend. The stress dropped monotonically with rosin content. Above 10% rosin, the elongation at yield diminished and reached a constant value. The elongation at break dropped abruptly above 10% of rosin. The density and hardness of blends increased with amount of rosin. The melt flow index of blends increased exponentially with the rosin content while the torque decreased monotonically with the composition and the processability was improved.     

Rheological and Mechanical Properties of LDPE/HDPE Blends

Melt rheology and mechanical properties of binary blend of low-density polyethylene (LDPE) and high-density polyethylene (HDPE) have been investigated. Four different wt fractions of blends containing LDPE/HDPE (20/80, 40/60, 60/40, and 80/20) were prepared. Cole-Cole plots [storage melt viscosity (η′) vs. loss melt viscosity (η″)] and relation between storage melt viscosity (η′) with frequency (ω) and blend composition were constructed. Miscibility of blends was established from rheological data. Impact strength of the blends increased with increasing LDPE concentration, whereas tensile strength shows the opposite trends. Percentages of the crystallinity of the blends were calculated by both the differential scanning calorimetry and wide-angle X-ray scattering methods, which show that the percentage of crystallinity decreased with increasing LDPE concentration, but the rate of crystallization of HDPE phase was unaffected.     

Anomalous Melt Rheological Properties of Unimodal-MWD HDPE Blends

The melt rheological behaviors in both linear and nonlinear regions were studied for binary blends of high-density polyethylenes (HDPEs) with unimodal molecular weight distribution (MWD). The surface distortion of the component resin with high-molecular-weight (HMW) and wide MWD through the capillary die could be alleviated with the addition of the component resin with low-molecular-weight (LMW) and narrow MWD. At the concentration of LMW component resin above 50 wt%, the negative deviation behavior (NDB) was observed in both the plots of dynamic storage modulus and complex viscosity versus the composition of the blends, furthermore, the Cole-Cole plot of the blend was below that of the pure LMW component, indicating the characteristics of immiscibility. However, the characteristic of homogeneity was revealed in the logG′～logG″ curves that possessed almost identical slopes for all the blends. The anomalous phenomena were attributed to the slow diffusion of HMW ingredients in the blends, which was aggravated by the inefficient stress transfer during melt blending at high concentration of LMW component.     

PP/HDPE共混体系毛细管流变性能研究

用毛细管流变仪对以马来酸酐接枝聚丙烯(PP-g-MAH)为相容剂的聚丙烯/高密度聚乙烯(PP/HDPE)共混体系的流变性能进行研究。研究发现,PP/HDPE共混体系属于假塑性流体;随着剪切速率的增加,表观黏度下降;PP-g-MAH的加入降低了共混体系的表观黏度;HDPE与PP的非牛顿指数在低剪切速率区与适宜温度下适用于幂律方程的经验公式;HDPE与PP共混后,HDPE含量越低,体系出现壁面滑移的临界剪切速率越高,可加工性能越好。     

mPE弹性体/PP共混物的流变行为与力学性能

用茂金属聚乙烯弹性体（mPE)代替传统的弹性体,对聚丙烯（PP）进行增韧改性,绘制了不同配比mPE/PP共混物熔体的流变曲线,讨论了共混物的组成,切应力和剪切速率以及温度对熔体流变行为,熔体粘度的影响。测定了共混物熔全的非牛顿指数,熔体质量流动速率及力学性能,为mPE共混改性PP提供了理论依据。结果表明,mPE适用于PP的增韧改性,增韧效果取决于共混物中mPE的用量,当mPE质量分数达到25%-40%时,共混材料既有较高的拉伸强度和韧性,又有较好的加工性能,mPE/PP共混物熔体的假塑性流动随mPE用量的增加向更高切应力或更高剪切速率方向移动。     

Melting behavior and isothermal crystallization kinetics of PP/mLLDPE blends

The melting/crystallization behavior and isothermal crystallization kinetics of polypropylene (PP)/metallocene-catalyzed linear low density polyethylene (mLLDPE) blends were studied with differential scanning calorimetry (DSC). The results showed that PP and mLLDPE are partially miscible and interactions mainly exist between the mLLDPE chains and the PE segments in PP molecules. The isothermal crystallization kinetics of the blends was described with the Avrami equation. Values of the Avrami exponent indicated that crystallization nucleation of the blends is heterogeneous, the growth of spherulites is almost three-dimensional, and the crystallization mechanism of PP is not affected much by mLLDPE. The Avrami exponents of the blends are higher than that of pure PP, showing that the mLLDPE helps PP to form perfect spherulites. The crystallization rates of PP are decreased by mLLDPE because the crystallization temperature of PP was decreased by addition of mLLDPE and consequently the supercooling of the PP was correspondingly lower. The crystallization activation energy was estimated by the Friedman equation, and the result showed that the activation energy increased by a small degree by addition of mLLDPE, but changed little with increasing content of mLLDPE in the blends. The nucleation constant (K _g) was determined by the Hoffman–Lauritzen theory. Supported by the Science Foundation of Hebei University (2006Q13).     

PC/SAM-g-AEP共混物动态流变性能的研究

通过熔融共混的方法,制备了PC/SAM-g-AEP共混物。采用旋转流变仪、熔体流动速率仪测试其流变性能。结果表明:PC/SAM-g-AEP与纯PC均表现出假塑性流体的特性,PC/SAM-g-AEP熔体黏度大于纯PC;PC/SAM-g-AEP熔体黏度随着SAM-g-AEP含量的增加而下降,且PC/SAM-g-AEP体系黏度随SAM-g-AEP中AEP含量的增加也呈现出下降趋势。     

PP/有机改性蒙脱土纳米复合材料的性能

采用熔融插层法制备了聚丙烯/有机改性蒙脱土(PP/OMMT)纳米复合材料,研究了OMMT用量对PP基体力学性能和阻燃性能的影响,利用透射电镜(TEM)分析了OMMT在PP基体中的分散性。结果表明:OMMT的加入有助于提高PP基体的力学性能和阻燃性能;熔融插层法可以使PP的大分子链有效地插入OMMT的片层之间;随着OMMT用量的增加,其在PP基体中的分散性变差。     

聚丙烯及聚苯乙烯发泡体系熔体密度的研究

通过高压毛细管流变仪测量聚丙烯发泡体系的PVT关系,得到一定压力和温度下聚丙烯发泡体系的熔体密度,用于分析发泡体系的毛细管流变特性。与聚苯乙烯和高冲击强度聚苯乙烯发泡体系的熔体密度进行了对比,研究并分析了温度、压力、发泡剂及成核剂含量对发泡体系熔体密度的影响。结果表明:发泡体系的熔体密度均随压力的增大而提高,随温度的升高而降低;在发泡气体的临界压力处,发泡体系的熔体密度产生突变;高压下,发泡剂与成核剂含量对熔体密度的影响很小。     

相容剂对rPET/mLLDPE共混物性能的影响

以回收聚对苯二甲酸乙二醇酯(rPET)为基体材料,茂金属线型低密度聚乙烯(mLLDPE)为共混材料,马来酸酐接枝线型低密度聚乙烯(LLDPE-g-MAH)、丙烯酸酯复合接枝苯乙烯-丁二烯弹性体为相容剂,制备了rPET/mLLDPE共混物。采用DSC和SEM分析了相容剂对共混物结晶性能及断面结构的影响,并检测了共混物的力学性能。结果表明:mLLDPE的加入使得rPET/mLLDPE共混物的熔体结晶峰向右移动,结晶温度提高了29.03℃;相容剂的加入使得共混物中rPET的玻璃化转变温度向低温方向移动,rPET与mLLDPE相容性增强;含3%LLDPE-g-MAH的rPET/mLLDPE共混物中,MAH基团与rPET中的羟基发生接枝反应,相界面模糊,rPET与mLLDPE界面黏结力增强,与纯rPET相比,其断裂伸长率提高了93.73%,缺口冲击强度提高了54.6%。     

PP/玻璃微珠复合材料的流变性能

制备了聚丙烯/玻璃微珠复合材料,在温度为175～225℃和载荷为1.2～12.5kg的条件下,应用熔体流动速率仪考察了填料粒径、剪切速率、载荷及温度等对复合材料熔体流变特性的影响。结果表明:熔体的剪切流动服从幂律定律;熔体的表观黏度对温度的依赖性符合Arrhenius方程;表观黏度随剪切速率和剪切应力的增加而下降;挤出胀大比随温度的升高而下降,随剪切应力和剪切速率的增大而增大。在此基础上,预测了第一法向应力差,发现其随剪切速率的增大而增大。     

聚丙烯/蒙脱土纳米复合材料的流变性能研究

制备了MMT/MgCl2/TiCl4插层催化剂,并通过原位聚合的方法制得聚丙烯/蒙脱土纳米复合材料。测试了聚丙烯/蒙脱土复合材料在不同温度及不同蒙脱土含量下的流变性能。结果表明:不同蒙脱土含量的聚丙烯复合材料,其表观黏度随剪切速率的增大而减小,剪切应力随剪切速率的增大而增大。符合流体切变稀释的性质,该性质有利于复合材料的成型加工。     

抗冲共聚聚丙烯2500H熔体流变行为研究

采用熔体流动速率仪、螺旋流动长度测试模具、毛细管流变仪和旋转流变仪等仪器,研究了抗冲共聚聚丙烯2500H及对比牌号K8303和3015的熔体流变行为。结果表明,2500H具有较大的分子量和较窄的分子量分布,即分子量大小依次为2500H3015K8303,分子量分布宽窄依次为K830330152500H。当剪切速率为700 s-1时,3015挤出胀大过程出现螺旋畸变现象,而2500H和K8303均未出现熔体螺纹畸变现象。三个样品的熔体流动速率从大到小依次为K830330152500H,其中K8303样品具有更高的熔体流动性。     

Preparation and Properties of PB-1/PP Blends

Crystallization behavior, dynamic mechanical properties, mechanical properties and rheological properties of isotactic polybutene-1/polypropylene (PB-1/PP) blends prepared by melt-blending the two components through Brabender extruder were mainly studied via POM, DSC, DMA, capillary rheometer and so on, respectively. The results indicated that after adding PP in PB-1: size of the spherical crystal and degree of crystallization of PB-1 in the blends decreased, its melt temperature and crystallization temperature unchanged; tensile property of the blends was decreased, but impact and flexural properties were improved; change of the melt viscosity of the blends with the shear rate was more sensitive than pure PB-1.     

聚乳酸/氯化钠共混物的流变性能

利用动态流变仪和毛细管流变仪,分别测试了聚乳酸(PLA)及PLA/NaCl(70/30)共混物的复数黏度和剪切黏度,得到了两种熔体的非牛顿指数(n)和流动活化能(ΔEη)。结果表明:PLA熔体的n随温度的升高以斜率为0.002线性地增大,而PLA/NaCl(70/30)共混物熔体的n随温度的升高以斜率为-0.01线性地减小;在剪切速率为1s-1时,PLA熔体的ΔEη为135.92kJ/mol,PLA/NaCl(70/30)共混物熔体的ΔEη为119.57kJ/mol,表明PLA熔体的黏度对温度的敏感性比PLA/NaCl(70/30)共混物熔体的黏度对温度的敏感性高。     

纳米SiO_2对聚丙烯/环氧树脂共混物性能的影响

采用熔融共混法制备了聚丙烯(PP)/环氧树脂(EP)共混物,研究了纳米SiO2对共混物性能的影响。结果表明:与纯PP相比,PP/EP共混物的冲击强度、断裂伸长率及黏度降低,弯曲模量增大;在PP/EP共混物中加入纳米SiO2后,共混物弯曲模量和冲击强度明显提高;将硅烷偶联剂KH550改性的纳米SiO2(SiO2-KH550)添加到共混物中,在EP为17%、SiO2-KH550为7%时,共混物的弯曲模量比纯PP提高了64%;EP降低了PP的结晶温度。