UHMWPE改性PPB和PPR的力学性能研究

研究了超高相对分子质量聚乙烯(UHMWPE)增韧改性的嵌段共聚聚丙烯(PPB)／UHMWPE和无规共聚聚丙烯(PPR)／UHMWPE的力学性能,采用红外光谱和扫描电镜对PPB,PPR和共混物的内部结构进行了分析。结果表明,UH- MWPE可以增韧PPB和PPR,PPB／UHMWPE断裂行为呈现网络结构破坏特征,而PPR／UHMWPE则发生脆-韧转变。     

嵌段共聚聚丙烯/无规共聚聚丙烯共混材料的制备及性能

通过熔融共混的方式制备嵌段共聚聚丙烯(PPB)和无规共聚聚丙烯(PPR)共混材料。研究PPB和PPR相对含量对共混材料的加工性能、结晶性能、动态热力学性能、力学性能的影响。结果表明:随着PPB含量的增加,共混材料的熔体流动速率升高,加工流动性得到提高。共混材料只有一个玻璃化转变温度,且结晶温度和熔融温度与PPB含量呈线性关系,说明PPB与PPR具有较好的相容性。随着PPB含量的增加,共混材料的低温损耗峰强度增加,球晶尺寸变小,常温和低温冲击强度增加。PPB含量为50份时,在-40℃附近出现明显的低温损耗峰,常温和低温冲击强度较纯PPR分别提升98.5%和48.2%。PPB含量为10份时,共混材料的弯曲强度和弯曲模量较纯PPR分别降低18.9%和18.8%;PPB含量超过50份时,共混材料的弯曲强度和弯曲模量高于纯PPR。     

不同结构聚丙烯的紫外光降解研究

研究了均聚聚丙烯(PPH)、嵌段共聚聚丙烯(PPB)、无规共聚聚丙烯(PPR)的耐紫外光性能。结果表明,这3种PP中,经过黑板温度为(65±3)℃、光强为0.51 W/m2@340nm时连续辐照400h后,PPB的耐紫外光性能较好,在体视显微镜照片中,并没有出现裂纹;PPH在紫外光辐照前后以α晶型为主,复合少量β晶型,PPB在紫外光辐照前只有α晶型,辐照后出现β晶型,然而PPR在紫外光辐照前后均只出现α晶型。     

不同种类聚丙烯加速老化性能对比

采用差示扫描量热仪及热重分析仪对无规共聚聚丙烯（PPR）、均聚聚丙烯（PPH）和嵌段共聚聚丙烯（PPB）进行原位热氧加速老化特性研究,分析了老化温度对PPR,PPB,PPH熔点和热稳定性能的影响,并采用傅里叶变换红外光谱仪探究了老化温度与分子结构的关系。结果表明：随着热氧老化温度的上升,试样的老化作用逐渐加剧,总体氧化稳定性变差。在典型供应热水70℃条件下,PPR的使用寿命远大于PPB和PPH,说明PPB和PPH不适用于作为热水管材的材料。     

PPH/PPB共混体系的性能与表征

研究了均聚聚丙烯(PPH)和嵌段共聚聚丙烯(PPB)共混体系的力学性能,探讨了共混比对材料性能的影响,并用差示扫描量热仪(DSC)、傅里叶红外光谱仪(FTIR)、扫描电子显微镜(SEM)和偏光显微镜(POM)等对共混物的结晶行为和微观结构进行研究。结果表明:PPH/PPB共混物的韧性相比于PPH大幅度提高,同时耐热性和刚性有一定下降,PPH/PPB在质量比为50/50至30/70之间综合性能最好。     

聚丙烯结构与光降解研究进展

主要论述了均聚聚丙烯(PPH)、嵌段共聚聚丙烯(PPB)和无规共聚聚丙烯(PPR)的结构和特点。重点介绍了聚丙烯(PP)在氧气、氮气和含有光敏剂时的紫外光降解机理及紫外光降解研究进展。     

PPH/PPB/NAP-71共混体系结构与性能研究

研究了添加刚性成核剂(NAP-71)的均聚聚丙烯/嵌段共聚聚丙烯(PPH/PPB)共混体系的力学性能,探讨了共混比对该材料性能的影响。并采用差示扫描量热法(DSC)、傅里叶红外光谱技术(FTIR)、扫描电子显微镜(SEM)和偏光显微镜(POM)等手段对PPH/PPB/NAP-71共混物的结晶行为和微观结构进行了研究。结果表明:成核剂改性的PPH/PPB共混物的韧性相比于添加了成核剂的PPH大幅度提高,而材料的耐热性变化不大,刚性则略有下降;当PPH/PPB/NAP-71共混物的共混比为70/30/0.2时,材料具有最佳综合力学性能,其冲击强度、断裂伸长率、弯曲强度和弯曲模量分别达到61.8 k J/m2、180%、52.3 MPa和1 976 MPa。     

无机填料对不同结构聚丙烯耐紫外光性能的影响

采用熔融共混法研究了滑石粉、绢云母和碳酸钙分别对均聚聚丙烯(PPH)、嵌段共聚聚丙烯(PPB)、无规共聚聚丙烯(PPR)耐紫外光降解性能的影响,并通过色差分析、体视显微镜、傅里叶变换红外光谱等表征其微观结构和宏观性能。结果表明:PPB/无机填料复合材料的耐紫外光性能最好;与片层的滑石粉和绢云母相比,碳酸钙与聚丙烯基体的界面黏接性较差;PPH/绢云母、PPB/绢云母、PPR/绢云母的羰基指数分别为0.11,0.14,0.02;相较于其他两种无机填料,PPR/绢云母复合材料的羰基指数最小、耐紫外光性能较好。     

刚性成核剂对不同结构聚丙烯性能的影响

在均聚聚丙烯(PPH)、无规共聚聚丙烯(PPR)和嵌段共聚聚丙烯(PPB)中分别加入刚性成核剂,研究其对聚丙烯(PP)结构与性能的影响。利用电子万能试验机、差示扫描量热仪(DSC)、傅立叶红外光谱仪(FT-IR)和偏光显微镜(POM)等表征手段对改性PP的力学性能、微观结构和结晶性能进行了研究。结果表明,刚性成核剂有细化球晶和加快结晶速率的作用;同时能有效提高PP的弯曲模量、冲击强度、热变形温度;添加0.2份刚性成核剂的PPH和PPB以及添加0.3份刚性成核剂PPR的综合性能最佳。     

一种挤出级聚丙烯材料的制备

采用毛管流变仪分析均聚聚丙烯(PPH)、助剂偏氟乙烯和六氟丙烯共聚物[P(VdF-HFP)]、高密度聚乙烯(HDPE)对共聚聚丙烯(PPB)黏度变化的影响。结果表明:PPB中加入PPH、P(VdF-HFP)、HDPE可以减轻挤出时发生畸变,同时PPB的物理性能并无明显变化。     

Study on Mechanical Properties and Crystallization Behavior of Polypropylene and Its Blends Modified by β Crystalline Form Nucleating Agent

The influence of β crystalline form nucleating agent (β nucleator) on the mechanical properties of homo-polymerized polypropylene (PPH), random-copolymerized polypropylene (PPR), block-copolymerized polypropylene (PPB), and PPH/PPR/PPB blends was studied. Polarized optical microscopy (POM), differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD) were used to characterize the crystalline morphology and behavior. The results indicated that α crystalline form of polypropylene (PP) had transformed to β crystalline form by adding 0.5% β nucleator; in the meantime, the toughness of PP and its blends was enhanced. That is, 0.5% β nucleator helped to improve the notched impact strength of PPH, PPR, and PPH/PPR/PPB blends by 130%, 40%, and 40%, respectively, without losing the tensile strength and flexural strength.     

UHMWPE改性PP共混物的力学性能

研究了UHMWPE型号及UHMWPE的用量对PP材料力学性能的影响。结果表明:在PPH/PPR/PPB为60/20/20时分别加入UHMWPE2401和UHMWPE2402,可起到增强增韧的效果,在开炼机上制试样UHMWPE2402的效果要好于UHMWPE2401,注射制样为UHMWPE2401好于UHMWPE2402;随UHMWPE含量的增加,PPH/PPR/PPB共混物的缺口冲击强度大体呈直线上升趋势,在UHMWPE2401为20份时,达到29 4kJ/m2。     

Enhanced crystallization of the γ‐form of propylene–ethylene copolymer in its miscible blends with propylene homopolymer

BACKGROUND: How to promote the formation of the γ‐form in a certain propylene‐ethylene copolymer (PPR) under atmospheric conditions is significant for theoretical considerations and practical applications. Taking the epitaxial relationship between the α‐form and γ‐form into account, it is expected that incorporation of some extrinsic α‐crystals, developed by propylene homopolymer (PPH), can enhance the crystallization of the γ‐form of the PPR component in PPR/PPH blends. RESULTS: The PPH component in the blends first crystallizes from the melt, and its melting point and crystal growth rate decrease with increasing PPR fraction. On the other hand, first‐formed α‐crystals of the PPH component can induce the lateral growth of PPR chains on themselves, indicated by sheaf‐like crystal morphology and positive birefringence, which is in turn responsible for enhanced crystallization of the γ‐form of the PPR component. CONCLUSION: Crystalline/crystalline PPH/PPR blends are miscible and the crystallization of the γ‐form of the PPR component is largely enhanced due to the heterogeneous nucleation from the α‐crystals first developed by the PPH component. Our findings could provide an effective way in practice to obtain isotactic polypropylene copolymers rich in γ‐form. Copyright © 2009 Society of Chemical Industry     

SSA热分级技术在表征IPC各组分相互作用中的应用

对典型抗冲共聚聚丙烯(IPC)进行了溶剂分级,分级出三组分,即乙烯-丙烯无规共聚物(EPR)、乙烯-丙烯嵌段共聚物(EbP)、丙烯均聚物(PPH)。通过连续自成核与退火(SSA)热分级技术分析了IPC,EbP/EPR,EbP/PPH二元非共混物和溶液共混物的结晶行为。采用扫描电子显微镜观察了PPH/EPR二元、PPH/EPR/EbP三元溶液共混物的冲击断面。结果表明:SSA热分级技术对分析IPC及其分级出的各级分的异质性具有较好的分辨效果;EbP和PPH组分易形成共晶,而EPR对EbP的结晶起到了稀释和弱化作用,从而证明EbP和PPH,EbP和EPR之间均存在相互作用;PPH/EPR溶液共混物中加入EbP后,冲击断面出现韧性断裂,说明EbP起到了增容PPH基体和分散相EPR的作用。     

废胶粉/聚丙烯接枝物共混材料的制备与性能

采用熔融接枝法分别制备了高强度和高熔体流动速率的聚丙烯接枝马来酸酐共聚物,以改善聚丙烯与胶粉间的界面相容性,提高废胶粉/聚丙烯接枝物共混材料的力学性能和流动性.力学性能测试结果表明,随着废胶粉用量的增加,废胶粉/聚丙烯接枝物共混材料的拉伸性能下降,扯断伸长率和缺口冲击强度均增大,熔体流动速率减小,流动性变差.由热重分析...     

TPV及PP-g-MAH对回收PET的改性研究

以马来酸酐接枝聚丙烯(PP-g-MAH)为相容剂,回收聚对苯二甲酸乙二醇酯(rPET)为基体材料,动态硫化热塑性弹性体(TPV)为增韧材料,制备了rPET/TPV/PP-g-MAH共混物。用SEM、DMA及DSC分析了TPV及PP-g-MAH对rPET断面结构、储能模量和结晶性能的影响,并测试了共混物的力学性能。结果表明:加入9.95%TPV后,rPET/TPV共混物的熔融温度下降了2.33℃,结晶温度提高了2.82℃,断裂伸长率及缺口冲击强度明显提高,弯曲强度和拉伸强度略有下降;加入PP-g-MAH后,TPV球状粒子嵌入rPET基体材料中,共混物的相容性提高,储能模量明显增大,刚性增强,弯曲强度和拉伸强度有所提高;与纯rPET相比,含1.8%PP-g-MAH的rPET/TPV/PP-g-MAH共混物的断裂伸长率提高了129.06%,缺口冲击强度提高了47.02%。     

Mechanically Strong and Ductile Polypropylene/Poly(ethylene-co-octene) Blends Prepared Through Multistretched Extrusion: Morphological Evolution,Toughening, and Reinforcing Mechanism

In this paper, polypropylene matrix with densely stacked shish-kebab crystalline structure and dispersed poly(ethylene-co-octene) phase with micro/nanofibers were formed simultaneously in polypropylene/poly(ethylene-co-octene) blends through multistretched extrusion. The as-obtained highly oriented and densely stacked shish-kebab crystalline structure can provide blends with greatly enhanced tensile yield strength. The as-formed poly(ethylene-co-octene) micro/nanofibers can toughen polypropylene matrix effectively through deflecting the crack, which is different from the toughening mechanism in polypropylene/poly(ethylene-co-octene) blends filled with spherical poly(ethylene-co-octene) particles. Compared with that of conventional polypropylene/poly(ethylene-co-octene) blends, the tensile yield strength of multistretched blends increased approximately 300%, while the notched impact strength declined slightly.     

Fracture toughness of modified polypropylene/poly(styrene‐ran‐butadiene) blends

Fracture toughness of polypropylene (PP)/poly(styrene‐ran‐butadiene) rubber (SBR) blends as a function of concentration of maleic anhydride (MA) in the maleated polypropylene (MAPP) compatibilizer was investigated under uniaxial static and impact loading conditions. The addition of MAPP to the unmodified PP/rubber blend enhanced the tensile modulus and yield stress as well as the Charpy impact strength. The maximum values were recorded at 1.0 wt% grafted MA in the compatibilizer. V‐shaped blunt‐notched specimens exhibited typical ductile behavior and no breakage of the specimens occurred during the impact fracture tests. Sharp‐notched specimens of uncompatibilized and low‐content MA blends broke in a semibrittle manner, supported by a rapid crack propagation process. Increasing MA content in the blends led to semibrittle‐to‐ductile transition characterized by stable crack propagation. Fracture mechanics experiments, supplemented by scanning electron microscopy (SEM), were also employed to obtain a better understanding of the fracture and deformation behavior. Copyright © 2005 Society of Chemical Industry     

剪切作用下POE-g-MAH和PP-g-MAH对PA1010/PP共混物的增容作用

采用熔融共混的方法制备了聚酰胺1010/聚丙烯（PA1010/PP）共混物,通过扫描电镜、力学性能和差示扫描量热等方法研究了剪切作用下马来酸酐接枝乙烯-辛烯共聚物（POE-g-MAH）和马来酸酐接枝聚丙烯（PP-g-MAH）对PA1010/PP共混物的增容作用。结果表明,同样条件下,PP-g-MAH增容体系的相区尺寸较小,相界面更模糊,PP相的结晶温度和结晶度明显提高,共混物的拉伸强度和冲击强度均高于非增容体系。而POE-g-MAH增容体系的相区尺寸相对较大,PP相的结晶温度和结晶度明显降低,共混物只有冲击强度明显高于非增容体系,拉伸强度略低于非增容体系。