矿物填料对改性聚丙烯熔接痕强度的影响

研究了滑石粉、碳酸钙、硅灰石、云母粉、硫酸钡、玻璃纤维六种矿物填料类型、粒径和含量对填充改性聚丙烯复合材料熔接痕强度、普通拉伸屈服强度和强度保持率的影响。结果表明:球型结构的矿物填充聚丙烯熔接痕强度和强度保持率最高;同一种矿物填充时,小粒径比大粒径的矿物填充聚丙烯的熔接痕强度和强度保持率高;同一种矿物填充时,矿物含量越高,熔接痕强度和强度保持率越低。     

聚丙烯／尼龙6原位复合材料的形态与表面,界面特性

以聚丙烯为基体、尼龙６为分散相共混得到分散相成纤的原位复合材料。显微形态观察发现在考察的浓度范围内微纤的直径基本与分散相含量无关。提高拉伸作用和增大剪切作用使微纤变细。当分散相含量越大，纤维数目越多时，水在复合材料表面的接触角越小，材料的吸水率越高。     

聚丙烯/锡氟磷酸盐玻璃复合材料的结构与性能

锡氟磷酸盐玻璃(Pglass)具有较低的玻璃化转变温度,在常规聚合物加工温度窗口内具有熔融流动性,是一种新型的无机类聚合物玻璃。本文采用双螺杆挤出机制备了聚丙烯(PP)/Pglass有机聚合物/无机玻璃复合材料,并对其相形貌、界面性能、流动性能、结晶性能、力学性能和热稳定性能进行了研究。结果表明:Pglass以微米级颗粒分散在PP基体中,且两相之间界面明显、相容性较差。Pglass的添加使复合材料的熔体剪切粘度降低。Pglass的存在促进了基体PP的结晶。复合材料的弹性模量随着Pglass含量的增加而增加。Pglass提高了复合材料的热稳定性。     

POE改性高熔指聚丙烯性能研究

采用聚烯烃弹性体(POE)对高熔指聚丙烯(PP)进行共混改性,研究了弹性体POE的含量对高熔指PP的力学性能、流动性和成型收缩率的影响规律。结果表明:随着弹性体POE含量的增加,共混材料的悬臂梁缺口冲击强度增大,断裂拉伸应变增大,弯曲强度、弯曲模量降低,拉伸强度降低,流动性变差,收缩率减小。     

聚丙烯/硫酸钡复合体系的界面相互作用与流变性质和结晶行为的关系

制备了一系列具有不同界面状态的聚丙烯 (PP) 硫酸钡 (BaSO4)复合体 .PP BaSO4的界面分别用硅烷、硬脂酸、马来酸酐接枝聚丙烯 (PP g MAH)改性 .研究表明 ,填充体系的熔体粘度和熔体弹性均高于基体 .以硅烷和PP g MAH进行界面改性后 ,PP BaSO4的界面相互作用加强 ,导致复合体系中的熔体粘度和熔体弹性进一步提高 ,同时BaSO4对PP的成核活性提高 .填料用硬脂酸处理后 ,硬脂酸能够在填料粒子表面上形成一个包覆层 ,使粒子与PP的亲和性改善 .同时该包覆层具有润滑作用 ,使得复合体系的熔体粘度和熔体弹性下降 ,并使得该体系中BaSO4的成核活性低于硅烷和处理的体系 .本文探讨了由复合体系的熔体粘度定量比较填充复合体系中聚合物 填料界面相互作用的方法 ,讨论了界面改性对复合体系流变性质和结晶行为影响的机理     

α-烯烃基甲基二氯硅烷调控丙烯多相共聚制备高熔体强度高抗冲聚丙烯

作为最重要的热塑性高分子材料之一,聚丙烯在材料力学性能上的缺陷主要表现为冲击韧性尤其是低温韧性差,在熔体加工中的缺陷主要表现为熔体强度低,如何综合改善这两方面的性能是丙烯聚合和聚丙烯结构设计研究的重要问题.本文利用α-烯烃基甲基二氯硅烷调控丙烯多相共聚,在聚合反应完成后通过对聚合物进行水解处理,在共聚物中产生长链支化结构,制备了同时具有高熔体强度和高冲击韧性的新型聚丙烯.共聚物的凝胶渗透色谱(GPC)和熔体流变学测试结果均表明长链支化结构的存在,而试样断面扫描电镜(SEM)则清楚给出其以聚丙烯为基体和以乙丙无规共聚物橡胶(EPR)为分散相的相分离形态.共聚物在拉伸流变测试中表现出高熔体强度和显著的应变强化效应,在力学性能测试中显现出高缺口冲击强度.     

聚丙烯/石墨导电纳米复合材料的制备与性能

用溶液插层及其与熔体混合相结合的母料熔体混合 (MMM)方法制备了聚丙烯 (PP) 马来酸酐接枝聚丙烯 (gPP) 膨胀石墨 (EG) (gPP EG =3 2wt)导电纳米复合材料 ,其室温逾渗阀值 (c)分别为 6wt%和 8wt % ,明显低于直接熔体混合制得复合材料和PP EG对照材料的c=11wt%和 12wt% .增加gPP含量 (Cg)能提高复合材料的电导率 (σ) ,例如对于MMM法制备的复合材料 ,固定PP gPP =1 1wt时 ,c 降为 7wt% ;保持EG含量 =9wt%时 ,σ在Cg>30wt %后跃升 7个数量级以上 .通过TEM、SEM和OM观察 ,从制备方法、EG和gPP含量影响复合材料形态和微结构的角度 ,分析说明了出现上述差异和现象的原因 .     

丁醛等离子体处理填料对填充聚烯烃熔体流变性的影响

用毛细管流变仪研究了经丁醛等离子体处理的云母粉填充高密度聚乙烯熔体(160℃)和聚丙烯熔体(180℃)的流变性。数据表明,处理削弱填充聚烯烃熔体流动的非牛顿性,熔体流动非牛顿指数随等离子体处理时间的延长而增大;处理降低填充聚烯烃熔体在低切变速率下的表观粘度,提高其在高切变速率下的表观粘度,发生转变的临界切变速率对填充聚乙烯和聚丙烯分别为150S~(-1)和50S~(-1)。扫描电镜观察熔体形态证实,处理对熔体粘度的复杂影响,是处理改善填料在熔体中的分散性和提高填料与基体界面结合力两者综合作用的结果。     

聚丙烯/纳米级金红石型二氧化钛/聚烯烃弹性体复合材料的抗老化性能研究

采用TEM和UV-Vis等测试手段表征了金红石型纳米级TiO2和体相TiO2的性能特征;通过熔融共混法分别制备了PP/纳米级TiO2/POE和PP/体相TiO2/POE复合材料,采用GB/T16422·2-1999所述的塑料实验室光源暴露实验方法,用氙灯气候试验机对纯PP和复合材料进行28天人工加速老化.结果表明,二氧化钛粒子在PP/POE基体中分散性良好,而纳米粒子对PP/POE基体具有增韧作用;改性后的两类复合材料均具有优异的抗老化性能,而PP/(1·0wt%)纳米级TiO2/POE复合材料的抗老化性能更加优异,其加速老化28天后的无缺口冲击强度达到80·45kJ·m-2,比纯PP提高4倍多,而同期加速老化28天后的PP/(1·0wt%)体相TiO2/POE复合材料的无缺口冲击强度只有47·88kJ·m-2;对纯PP老化过程中的羰基指数和冲击性能的变化情况进行了分析,发现二者近似成线性关系,其相关系数r在0·9以上.     

高熔体强度聚丙烯的制备与表征*

高熔体强度聚丙烯（HMSPP）相比于普通聚丙烯具有优越的综合性能,其良好的加工性能使其具有广阔的应用前景,并成为许多国家近年来竞相开发的热点。本文从HMSPP的结构特点、制备方法、性能测试等方面总结了近年来的研究进展,着重介绍了反应器合成长链支化型高熔体强度聚丙烯（LCB-HMSPP）的方法以及其结构表征,并在总结国内外现状的基础上展望了高熔体强度聚丙烯的发展前景。     

磨盘碾磨力场作用下聚丙烯/石墨体系中聚丙烯晶态结构的变化

通过磨盘碾磨制备了PP 石墨复合粉末 .用FT IR ,XRD和DSC表征了磨盘剪切力场作用下 ,PP 石墨体系中 ,聚丙烯结构与性能的变化 .结果表明 ,磨盘碾磨使PP有序结构破坏 ,分子链断裂并与石墨的表面官能团之间发生了固相力化学反应 ,导致其结晶度降低 (由 5 7 2 %降低到 2 6 4%) ,晶面间距增大 ( ( 0 1 0 )面由 0 62 3nm增加到 0 63 2nnm) ,晶粒尺寸减小 (由 1 2 83nm减小到 6 48nm) ,这些变化 ,在热压成型的非等温过程中部分得到恢复 ,且α 晶的 ( 0 40 )面生长有择优性 ,其XRD强度大大超过 ( 0 1 0 )面 ,微晶尺寸更大 .同时发现 ,在PP 石墨复合粉末和复合材料中 ,α 单斜晶部分地转化为γ 三斜晶 ,在PP 石墨复合材料中 ,γ 三斜晶占 3 4 8%.     

Effect of molding parameters on the properties of PP/PP sandwich injection moldings

The basic characteristics of a sandwich injection molded product depend on the properties of the respective resins that comprise the skin and core layers, and the skin/core resin volume ratio. The characteristics of the core layer resin and the skin/core ratio in particular may vary depending on the injection molding conditions. This report considers the influences that the molding conditions such as injection speed, cylinder temperature, and mold temperature confer on the mechanical properties of the sandwich moldings. The study employed, skin/core resin combinations involving similar and dissimilar materials i.e. homopolymer PP/homopolymer PP and homopolymer PP/copolymer PP, respectively. It was demonstrated that core cylinder temperature and mold temperature could be used to adjust the mechanical properties of sandwich injection moldings. In the case of single material sandwich moldings, injection speed seemed to play no significant role, even though it was clearly demonstrated that core volume increases with injection speed. However, core injection speed plays a significant role in the dual material system by lowering or increasing the mechanical strength of moldings as the case may be. Thus, the dormant or active role of injection speed depending on the material system has been highlighted.     

Synthesis of Chain-End Functionalized PP and Applications in Exfoliated PP/Clay Nanocomposites

This paper summarizes our research to the preparation of chain-end functionalized isotactic polypropylene (i-PP) having a terminal functional group, such as an OH and an NH₂. The chemistry involves metallocene-mediated propylene polymerization using the rac-Me₂Si[2-Me-4-Ph(Ind)]₂ZrCl₂/MAO complex in the presence of styrene derivatives (St-f) and hydrogen, which serve as the chain transfer agents. The molecular weight of the resulting i-PP polymers with terminal OH or NH₂ groups (i.e., PP-t-OH and PP-t-NH₂) are inversely proportional to the molar ratio of [St-f]/[propylene]. Despite the extremely low concentration of functional groups, the high molecular weight NH₃⁺-terminated PP (PP-t-NH₃⁺) exhibits a distinctive advantage over other functional PP polymers containing side chain functional groups or long functional blocks. The terminal hydrophilic NH₃⁺ cation, with good mobility and reactivity, effectively ion-exchanges the cations (Li⁺, Na⁺, etc.) located between the clay interlayers, and anchors the PP chain to the clay surfaces. On the other hand, the remaining rest of the unperturbed, end-tethered, high molecular weight PP tail exfoliates the clay layers. This exfoliated structure is maintained even after further mixing of the PP-bearing platelets with pure, neat PP polymers.     

Isothermal crystallization kinetics of PP in PP/Mg(OH)2 composites

The crystallization and melting behavior of PP/Mg(OH)₂ composites was investigated, and the crystallization kinetic parameters and thermal characteristics were investigated according to the Avrami method. Optical polarizing microscope (POM) analysis suggested that the presence of Mg(OH)₂ particles gave rise to an increase in the number of nuclei and a decrease in PP spherulitic size. The Avrami exponent n of the PP and composites increased with increasing crystallization temperature, and markedly deceased with the addition of low Mg(OH)₂ content. A significant increase in crystallization kinetic constant, and a decrease in crystallization half time of PP were observed in the presence of Mg(OH)₂ particles, indicating a heterogeneous nucleating effect of Mg(OH)₂ upon crystallization of PP. The melting temperature and equilibrium melting temperature of PP in the composites decreased with increasing the Mg(OH)₂ content, which is directly related to the size of the PP crystals. The difference of PP melting enthalpies in the PP and composites demonstrated that the presence of Mg(OH)₂ can effectively enhance the crystalline of PP. The crystallization thermodynamics of PP and composites were studied according to the Hoffman theory. Surface free energy of PP chain folding for crystallization of PP/Mg(OH)₂ composites was lower than that of PP, confirming the heterogeneous nucleation effect of Mg(OH)₂. However, the evaluation of the nucleation activation energy of PP suggested the presence of a large amount of Mg(OH)₂ particles in the PP matrix reduced the mobility of PP segments and restricted the development of PP nucleation. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1914–1923, 2005     

紫外光辐照聚丙烯及其应用研究

通过红外光谱，热分析及熔体流动速率的研究了紫外光辐照对聚丙烯的化学结构和物理性能的影响。结果表明：在紫外光辐照下ＰＰ发生了快速光氧化，分子链中引入了ＣＯＯＨ，Ｃ－ＯＨ，Ｃ＝Ｏ等极性在团；紫外光强为６８μＷ／ｃｍ＾２时，辐照对ＰＰ分子量影响较小，紫外光强为１３０μＷ／ｃｍ＾２时，辐照可引起ＰＰ明显的光降解。     

动态硫化EPDM／PP共混体系中PP相的结晶度及晶体结构的研究

研究了动态硫化ＥＰＤＭ／ＰＰ共混物中ＰＰ相的结晶度及晶体结构,同时讨论了制备工艺条件以共混物中ＰＰ相的结晶度和晶体结构的影响。结果表明：在动态硫化ＥＰＤＭ／ＰＰ共混物中,硫化的ＥＰＤＭ的分子键没有穿入ＰＰ的晶区,ＰＰ的结晶度随ＥＰＤＭ含量的增加而下降。提高共混温度,加入软化剂或碳黑均使共混物中ＰＰ的结晶度降低,共混时间１５ｍｉｎ时,共混物中ＰＰ相的结晶度最低,但ＰＰ的晶格不受制备工艺条件的影响。     

The effect of organoclay and graphene on the crystallization of PP in ABS/PP blends

In the present research, the isothermal and non-isothermal crystallization of polypropylene (PP) phase in PP-rich poly(acrylonitrile–butadiene–styrene)/polypropylene (ABS/PP) blends was studied. The effect of nanofillers’ incorporation and specialty of organically modified montmorillonite (OMMT) and graphene, into the prepared blends on the isothermal and non-isothermal crystallization of PP phase, were investigated. Moreover, kinetic study of their isothermal crystallization process was carried out, by applying the Avrami equation. The addition of ABS to the PP matrix increased the crystallization rate of PP at 130 °C. The incorporation of OMMT in pure PP accelerated slightly the crystallization process, whereas in ABS/PP blends, it seemed to retard crystallization, due to interactions between ABS phase and organoclay. The incorporation of graphene in pure PP accelerated impressively its isothermal crystallization, while the addition of ABS in graphene/PP nanocomposite slowed down the crystallization rate of PP. The effect of ABS and nanofillers, separately or in combination, on the crystallization of PP phase was reflected on the kinetic parameters of the Avrami equation. Regarding the non-isothermal crystallization, ABS/PP blends presented higher crystallization temperature (T _c) compared to pure PP. The organoclay reinforcement did not have any obvious effect on this temperature, whereas graphene caused significant increase, acting as nucleating agent. The presence of ABS to PP increased the concentration of the β-crystalline phase, reaching its maximum value at 30 mass% ABS content. The organoclay decreased the β-PP in ABS/PP blends, whereas graphene eliminated it.     

反应性单体改性PP/PS共混物结晶与熔融行为

制备了三种反应性单体和两种PP接枝物改性的PP／PS共混物,用DSC研究了改性PP／PS共混物的结晶与熔融行为。结果表明：PS的加入提高了PP的结晶温度,两种接枝物的加入进一步提高共混物中PP的结晶温度,少量反应性单体对结晶温度影响不大,但高用量时则明显提高共混物的结晶温度;外加接枝物或者反应性单体对共混物中PP的熔融温度影响不大,但是熔融峰形与结晶温度高低有关。     

Solid‐state modification of polypropylene (PP): grafting of styrene on atactic PP

Grafting of unsaturated vinyl monomers onto polypropylene (PP) is a convenient route to develop new polymeric materials with synergistic properties. Particular attention must be paid to the formation of graft copolymer relative to the formation of homopolymer, since the final properties are dependent both on the dispersion of the new polymer into the iPP matrix, which is controlled by the degree of grafting, as well as on the chemical nature of the in‐situ formed polymer chains. In the present work the grafting reaction of styrene on atactic PP (aPP), considered as good model system for the more studied solid‐state modification of isotactic PP (iPP), has been investigated in the presence of two different radical initiators in order to get a first insight into the grafting reactions onto PP. Several grafting reactions were carried out by changing the chemical compositions of the starting polymerization mixture, whose homogeneity was accurately investigated by Raman spectroscopy. Infrared‐spectroscopy (FT‐IR) was used for qualitative and quantitative characterization of the reaction product. A quantitative separation procedure, based on the concept of selective solvent extraction, has been established which enables the determination of the grafting efficiency (Φ) as well as the exact chemical composition of the final product. Finally, all products were characterized by means of Differential Scanning Calorimetry (DSC) in order to study their thermal behaviour.