用于发泡成型的高熔体强度聚丙烯的研究

在同向双螺杆挤出机上,对聚丙烯(PP)进行硅烷交联,制得高熔体强度聚丙烯(HMSPP),然后制备高发泡倍率的PP制品。分析了改性剂用量对PP熔体流动速率、熔体黏度、熔体强度、凝胶含量、力学性能、热性能和发泡性能的影响。结果表明:自制HMSPP的熔体强度和熔体黏度分别是纯PP的5.01倍和1.52倍,力学性能和耐热性与纯PP相比均有较大提高,可用于成型高发泡倍率制品。     

高熔体强度聚丙烯的发泡性能研究

通过反应挤出法对聚丙烯(PP)进行硅烷接枝交联改性获得高熔体强度PP(HMSPP),并对HMSPP的发泡性能及影响因素进行了研究。结果表明,HMSPP具有良好的发泡性能,可以制备出高质量泡沫材料;随着HMSPP的熔体流动速率的降低,泡沫材料的密度和泡孔平均直径降低;随着HMSPP用量减少,HMSPP/PP泡沫材料的泡孔平均直径和密度增大,泡孔尺寸及分布的不均匀程度增加;发泡条件对泡沫结构具有一定的影响,最佳的发泡温度为185~190℃,螺杆转速为40~100r/min;随着口模厚度的增加,泡孔平均直径增加,材料密度下降,而材料内外层泡孔直径不均匀性增加。     

发泡高熔体强度聚丙烯研究进展

高熔体强度聚丙烯具有优异的物理机械性能,其发泡制品拥有广泛的用途。文章综述了制备高熔体强度聚丙烯的制备方法,主要有直接聚合法、辐射接枝交联法、硅烷接枝交联法等。硅烷接枝交联法成本适中、产品质量优异,是目前最有希望的改性技术。综述了发泡高熔体强度聚丙烯材料的应用。     

高熔体强度聚丙烯的开发及应用

综述了国内外高熔体强度聚丙烯的研究进展和应用前景，并简述了高熔体强度聚丙烯在挤出涂布和发泡等方面的应用。     

发泡用高熔体强度聚丙烯工业生产及其应用

概述了高熔体强度聚丙烯的性能特点及其国内外的发展状况;通过中国石化镇海炼化国产二代环管聚丙烯装置产出适合釜式发泡用高熔体强度聚丙烯,并对其发泡性能进行了表征,与同等进口料进行了性能比对。     

高熔体强度聚丙烯结晶行为及其发泡性能

在双螺杆挤出机上采用一步硅烷接枝交联法制得了高熔体强度聚丙烯,采用DSC、偏光显微镜研究高熔体强度聚丙烯的结晶行为、结晶结构和结晶形态.研究结果表明:高熔体强度聚丙烯的结晶温度明显增加,硅烷接枝交联促进了聚丙烯的异相成核,使晶粒细化,高熔体强度聚丙烯的发泡效果明显优于普通PP.     

高熔体强度聚丙烯发泡性能的研究

对高熔体强度聚丙烯进行发泡研究。在物理发泡和连续挤出成型工艺条件下,高熔体强度聚丙烯能发泡成圆柱形制品,而其在圆环形口模下吹胀成型时,发泡稳定性差,不能成型。实验分析得出热机械曲线中高弹态的温度范围太窄是产生这一现象的原因。     

聚丙烯高发泡材料

为提高聚丙烯(PP)的熔体强度,改善PP的发泡性能,用双螺杆挤出机对PP进行硅烷交联改性,制备出了高熔体强度聚丙烯(HMSPP)后,进行了模压法发泡的研究.结果表明:HMSPP随着引发剂含量的增加,改性PP的熔体强度提高;PP发泡材料的密度降低至0.118 g/cm3.发泡剂AC的用量及成核剂的含量对发泡材料的表观密度有很大影响,当发泡剂含量为2.5份、成核剂含量为1份时,得到的PP发泡板材密度降低,发泡倍率增大,泡孔均匀致密,力学性能较好.     

高熔体强度聚丙烯的研制

用过氧化物引发聚丙烯(PP)交联制备高熔体强度聚丙烯(HMSPP),研究了过氧化物的用量、反应温度、螺杆转速对HMSPP性能的影响。得到的HMSPP比普通PP的熔体强度提高约3倍。用所研制的HMSPP进行发泡实验,制得泡孔结构较均匀且闭孔的发泡制品。     

提高发泡聚丙烯熔体强度的研究进展

介绍了聚丙烯(PP)泡沫塑料的特点、国内外发展概况及其发泡研究中存在PP熔体强度较低的普遍问题。重点概述了提高PP熔体强度的4种方法,即采用高熔体强度PP、PP部分交联、PP共混改性及PP/无机物复合材料,并分别介绍了这4种方法的国内外研究进展、特点。指出PP化学交联及共混改性仍是今后PP发泡研究的重点及热点。     

高熔体强度PP的制备研究

用辐照法制备出了高熔体强度聚丙烯（PP）：对其物理机械性能、熔体强度、熔体拉伸粘度、粘垂等进行了测试，研究了辐照剂量、交联剂种类和浓度，辐照后PP的热处理条件等对制备高熔体强度PP的影响；并在此基础上，还制备出了发泡倍率为15倍以上的发泡PP。     

高熔体强度聚丙烯技术进展

高熔体强度聚丙烯(HMSPP)是聚丙烯改性的研究的重要产品之一。本文综述了高熔体强度聚丙烯的性能特点、制备方法、用途以及国内外研究和开发情况。     

Polydimethylsiloxane assisted supercritical CO2 foaming behavior of high melt strength polypropylene grafted with styrene

Foamable high melt strength polypropylene (HMSPP) was prepared by grafting styrene (St) onto polypropylene (PP) and simultaneously introducing polydimethylsiloxane (PDMS) through?a?one-step?melt extrusion process. The effect of PDMS viscosity on the foaming behavior of HMSPP was systematically investigated using supercritical CO₂ as the foaming agent. The results show that the addition of PDMS has little effect on the grafting reaction of St and HMSPP exhibits enhanced elastic response and obvious strain hardening effect. Though the CO₂ solubility of HMSPP with PDMS (PDMS-HMSPP) is lower than that of HMSPP without PDMS, especially for PDMS with low viscosity, the PDMS-HMSPP foams exhibit narrow cell size distribution and high cell density. The fracture morphology of PDMS-HMSPP shows that PDMS with low viscosity disperses more easily and uniformly in HMSPP matrix, leading to form small domains during the extrusion process. These small domains act as bubble nucleation sites and thus may be responsible for the improved foaming performance of HMSPP.     

高熔体强度聚丙烯树脂的结构与性能

采用差示扫描量热法、傅里叶变换红外光谱、毛细管流变、熔体拉伸等方法,从结晶性、黏弹性及物理机械性能等方面对高熔体强度聚丙烯(HMSPP)树脂进行结构表征与性能分析。结果表明:HMSPP树脂具备较高的弯曲模量,同时具备优异的抗熔垂能力和更宽的加工温度;拉伸黏度随拉伸速率的增大而增大,呈现出HMSPP应变硬化这一明显行为,使得熔体在热成型过程中具有均匀变形的自我调节能力,从而克服普通聚丙烯在热成型加工中的严重熔垂问题;含有较长接枝链段的HMSPP树脂在刚性、熔体强度、结晶性能等方面均优于普通聚丙烯。     

我国高熔体强度聚丙烯生产技术进展

综述了国内高熔体强度聚丙烯(HMSPP)的生产技术。射线辐照法所制HMSPP可在常温条件下进行,纯度较高,但无法精确控制HMSPP的结构,生产成本较高;直接聚合法可通过改变外给电子体种类及加入量、聚合工艺条件等得到具有支化结构的HMSPP,其具有良好的拉伸性能和耐热性能,但催化剂及聚合工艺条件的研发周期长;化学交联改性法可减少凝胶含量,降低单体用量,但反应温度较高时,聚丙烯易发生降解;共混改性法制备的共混物中各树脂间的协同效应和化学反应性好,但会影响HMSPP的力学性能;反应挤出法工艺稳定,操作简单,适合工业化连续化生产,但各树脂在掺混时会降低HMSPP的力学性能,且各相间的相容性差。     

高熔体强度聚丙烯的研究应用进展

通用聚丙烯（PP）由于熔体强度低和加工温度范围较窄,因而在挤出发泡、挤出涂布和热成型等条件下难以加工成型,所以限制了通用聚丙烯的应用领域。高熔体强度聚丙烯（HMSPP）具有较高的熔体强度和优异的物理机械性能,因此拓宽了聚丙烯的应用范围。文章综述了国内外高熔体强度聚丙烯的性能特点、制备方法、研究进展和应用现状。     

Preparation of polypropylene with high melt strength by wet reaction blending of lignin

In this paper, the melt strength of polypropylene is shown to be significantly improved by lignin-cooperative construction of heterophase network structure and the evolution mechanism of lignin on the topology of polypropylene is investigated. Electron paramagnetic resonance (EPR) analysis shows that the free radicals generated by polypropylene irradiation can remain active for 2 weeks; rheological studies show that lignin promotes the formation of heterogeneous network structures in polypropylene, and its melt is characterized by long-chain branching. Phase angle-complex modulus, complex viscosity-complex modulus, Han's, and Cole–Cole curves are used to analyze the liquid–solid transformation, and the results indicate that the enhanced interfacial action is due to the formation of the heterogeneous network structures. The mechanical properties show that the impact strength is increased by 1.8 times due to the synergistic effect of lignin and acrylamide. SEM shows the formation of a fibrous network structure around the lignin, which undergoes interfacial yielding, improving the interfacial interaction between the components.     

反应挤出制备高熔体强度PP

采用反应挤出方法制备高熔体强度聚丙烯,通过凝胶渗透色谱仪、差示扫描量热仪、偏光显微镜等研究了改性产品的结构与性能,并进行挤出发泡应用实验。结果表明：采用特殊的过氧化物引发剂和支化促进剂,与聚丙烯基础树脂共混后通过双螺杆挤出机熔融连续反应挤出,可以直接制备具有长链支化结构的聚丙烯,熔体强度提高300％;挤出发泡试样泡孔均匀,发泡倍率达到50倍,具有较好的可发性能。     

Structure of blown film from blends of polyethylene and high melt strength polypropylene

The structure of blown film processed from linear low density polyethylene blended with up to 30 wt[percnt] of a high melt strength polypropylene (hmsPP) was examined using primarily atomic force microscopy and wide angle X-ray scattering. The study focused on two polyethylene resins with the same density: a conventional Ziegler-Natta catalyzed linear low density polyethylene (znPE) and a blend of a Ziegler-Natta catalyzed and a metallocene catalyzed linear low density polyethylene (zn/mPE). Parallel characterization was performed on blown film of the hmsPP and blown film of each of the polyethylene resins. In films of the blends, the hmsPP was well-dispersed in the polyethylene matrix as elongated domains. In the domains, the hmsPP crystallized as planar row-nucleated structures with the long axis of the lamellae perpendicular to the extrusion direction. Row-nucleated hmsPP lamellae provided a template for epitaxial crystallization of polyethylene lamellae. The 42° angle of the lattice match imparted a characteristic herringbone texture to the polyethylene. Blending with hmsPP increased the tensile modulus and strength of polyethylene film without significantly affecting the ultimate elongation.