纳米TiO_2表面接枝PAN及其对PP抗紫外老化性能的影响

采用细微乳液聚合法制备了基于共价键结合的纳米TiO2表面接枝聚丙烯腈(PAN)(纳米TiO2-g-PAN)复合抗紫外老化剂,将其与聚丙烯(PP)共混制备了PP/纳米TiO2-g-PAN复合材料。研究了纳米TiO2-g-PAN在PP中的分散情况及PP/纳米TiO2-g-PAN复合材料的抗紫外老化性能。傅立叶变换红外光谱、热失重、扫描电子显微镜和力学性能测试分析表明,PAN成功接枝到纳米TiO2表面,提高了纳米TiO2与PP的相容性及PP/纳米TiO2-gPAN复合材料的热稳定性能、力学性能和抗紫外老化性能。当纳米TiO2-g-PAN与PP配比为0.05时,PP/TiO2-gPAN复合材料的拉伸强度、冲击强度、拉伸强度保持率和冲击强度保持率分别为38.66 MPa,691.75 kJ/m2,63.49%和58.42%,综合力学性能最佳。     

PP/TiO_2(KH–560)-g-AN/复合材料抗老化性能

向聚丙烯(PP)内添加抗老化剂[TiO_2(KH–560)-g-AN]改善PP的抗老化性能。通过紫外可见光谱测试仪分析了TiO_2,KH–560,PAN,TiO_2(KH–560),TiO_2(KH–560)-g-AN紫外吸收效果,测定了在0,500,1 000,1 500,2 000,2 500 h老化时间下,PP/TiO_2(KH–560)和PP/TiO_2(KH–560)-g-AN复合材料的拉伸性能。结果表明,TiO_2,PP/KH–560,PAN,TiO_2(KH–560),TiO_2(KH–560)-g-AN都有较好的紫外吸收效果;PP/TiO_2(KH–560)和PP/TiO_2(KH–560)-g-AN复合材料的拉伸数据对比结果表明,当PP∶TiO_2(KH-560)-g-AN=100∶5时,PP的抗老化性能达到最好。     

PP/EPDM/纳米TiO_2复合材料的制备与热性能

采用熔融共混法制备了PP/EPDM/纳米TiO_2复合材料,并对其结晶行为和热稳定性进行了研究。通过Jeziorny法和莫志深模型对复合材料的非等温结晶动力学进行表征,并利用Kissinger法和Friedman法计算结晶活化能。结果表明,三元乙丙橡胶(EPDM)包裹在纳米TiO_2表面所形成的核壳结构虽然延缓了复合体系的结晶过程,但并没有影响PP基体的结晶能力。纳米TiO_2作为导热填料使复合材料的特征温度T_(5%)、T_(10%)、T_(max)比PP分别提高了33.34、21.55、7.92℃,说明纳米TiO_2能够增强体系的热导率,增加内部的热传导作用,从而有效地提高了基体的热稳定性。     

T_iO_2的表面处理及其在PP中的分散行为

选用硅烷偶联剂KH–570对TiO_2进行表面处理,并采用热失重分析、红外光谱分析、两相沉降测试、接触角测试等对其进行表征。结果表明,KH–570改性使纳米TiO_2由亲水性变为亲油性,在溶剂中有较好的分散稳定性,并且接触角提高到107°。将改性后TiO_2与聚丙烯(PP)基体通过熔融共混制成复合膜,并采用扫描电子显微镜、差示扫描量热法进行分析。结果表明,未改性TiO_2存在较大的团聚,而改性后的TiO_2在PP中分散比较均匀,说明表面处理提高了TiO_2与PP的相容性。此外纳米TiO_2的添加对结晶和熔融行为影响不大。     

纳米TiO_2填充聚丙烯复合材料中β-成核及结晶行为研究

基于CaCO_3与庚二酸反应可得到具有高效β-成核作用的庚二酸钙(Ca PA)的原理,采用负载法和直接添加法制备了高β晶含量的聚丙烯(PP)/TiO_2复合材料,并对复合体系的成核及结晶行为进行了研究。结果表明:纳米TiO_2对PP具有显著的异相成核作用,可显著提高PP结晶温度,诱导PP形成α晶。纳米TiO_2经乙酸钙溶液处理及高温处理后,可在粒子表层形成CaCO_3,将其引入PP,能使PP的结晶温度明显提高,但与未经处理的TiO_2相比,其对PP的成核作用有所下降。采用负载法并未能使纳米TiO_2对PP具有显著的β-成核作用,仅在其用量较少时形成少量的β晶。在TiO_2(经乙酸钙溶液处理)填充PP复合体系中直接加入0.1%的Ca PA,可得到高β晶含量的PP/TiO_2复合材料,当乙酸钙溶液浓度在0.5%~5%之间时,复合材料的β晶含量可达50%以上。因此,可通过乙酸钙溶液处理减弱纳米TiO_2的异相成核作用,同时加入高效β-成核剂,从而制得高β晶含量的PP/TiO_2复合材料。     

改性纳米TiO_2的制备及其对聚丙烯的改性研究

用溶胶-凝胶法制备纳米二氧化钛(TiO_2),并用硅烷偶联剂γ-甲基丙烯酰氧基丙基三甲氧基硅烷(CG570)和油酸(OA)对其进行表面改性,提高了其亲油性;将改性TiO_2对聚丙烯(PP)进行共混改性制备得到PP复合材料。分别研究改性剂类型和CG570-TiO_2用量对PP复合材料力学性能、耐热性能和结晶性能的影响。研究表明,CG570-TiO_2对PP共混改性效果相对较好;当CG570-TiO_2的用量为3%时,PP复合材料的综合性能最佳;相比于纯PP,其热分解温度、结晶温度和力学性能均有所提高,其中冲击强度提高了35%。     

硅烷偶联剂改性纳米TiO_2[TiO_2(M)]/PP及TiO_2(M)-g-AN/PP复合材料老化性能的比较

本文采用三种硅烷偶联剂分别改性纳米TiO_2[TiO_2(M)],产物分别为TiO_2(KH-560)、TiO_2(KH-570)、TiO_2(AC-70),在此基础上将TiO_2(M)与丙烯腈进行自由基聚合反应[TiO_2(M)-g-AN],产物分别为TiO_2(KH-560)-g-AN、TiO_2(KH-570)-g-AN、TiO_2(AC-70)-g-AN。将TiO_2(KH-560)/PP、TiO_2(KH-570)/PP、TiO_2(AC-70)/PP、TiO_2(KH-560)-g-AN/PP、TiO_2(KH-570)-g-AN/PP、TiO_2(AC-70)-g-AN/PP复合材料进行老化,并比较它们的力学性能。     

RGO/In_2S_3复合修饰TiO_2纳米管阵列及其光催化应用

采用脉冲电沉积法将In_2S_3纳米粒子沉积在TiO_2纳米管阵列(NTs)上,得到In_2S_3–TiO_2 NTs。然后通过脉冲电沉积法将石墨烯薄膜修饰在In_2S_3–TiO_2 NTs上,制备出RGO/In_2S_3–TiO_2 NTs复合材料。通过光电流测试和2,4-二氯苯氧乙酸(2,4-D)降解试验表征了RGO/In_2S_3–TiO_2 NTs的光电性能和光催化性能。结果表明:相对于纯TiO_2 NTs,RGO/In_2S_3–TiO_2 NTs复合材料的光生电子-空穴对的复合率更低,对可见光的吸收更强。光催化180 min后,RGO/In_2S_3–TiO_2 NTs复合材料对2,4-D的降解效率高达93.36%,重复使用5次后仍有90.70%。     

N,N,N',N'–四(2–羟丙基)己二酰胺固化剂的合成及应用性能研究

采用己二酸二甲酯和二异丙醇胺为主要原料合成了N,N,N',N'–四(2–羟丙基)己二酰胺固化剂,借助液相、红外光谱对产品进行了表征.并对比研究了N,N,N',N'–四(2–羟丙基)己二酰胺作为固化剂产品与市售固化剂EMS-1260、HAA、TGIC产品在耐黄变、低温固化、耐老化等方面的应用性能.     

凹凸棒石/弹性体协同改性无规共聚聚丙烯性能

以无规共聚聚丙烯(PP–R)为基料,采用纳米凹凸棒石(APT)和聚烯烃弹性体(POE)协同改性,通过熔融共混法制备出PP–R/POE/APT三元复合材料,研究了APT和POE对PP–R材料的协同改性效果。升温淋洗分级检测结果表明,单纯添加弹性体POE对PP–R进行改性,增加了室温下可溶物的含量,让PP–R复合材料中的分子链分布更加均匀,进而能够增强PP–R材料在室温下的抗冲击性能。结晶性能测试结果表明,APT与弹性体POE协同改性效果比单纯添加弹性体POE的效果明显;添加了2% APT纳米粒子和20% POE弹性体组合后,提高了材料的熔融温度与结晶温度,同时细化了PP–R中的α晶型,有利于提高材料的韧性。     

金红石型TiO2对聚丙烯纤维紫外光降解的影响

分析了聚丙烯(PP)／金红石型二氧化钛(TiO2)共混纤维在人工加速紫外光降解中断裂伸长率、断裂强度、质量损失和表面形态的变化,与PP纤维进行对比,研究了纳米级和微米级金红石型TiO2对共混纤维光降解的影响。结果表明,在紫外光照射下,共混纤维中金红石型TiO2的含量越高,PP纤维断裂伸长率、断裂强度的降低和质量损失速率就越快;同时由扫描电镜照片发现,经紫外光照射120 h后,纤维表面损伤程度也随着TiO2添加量的增多而加深。纳米级和微米级金红石型TiO2都对PP的光氧化降解具有一定的催化作用,而且其含量越高,催化作用越强,但纳米级TiO2的催化作用比微米级TiO2大。     

溶胶-凝胶法制备TiO2/PMMA纳米复合材料的研究

通过溶胶-凝胶法制备了TiO2溶胶,与聚甲基丙烯酸甲酯(PMMA)进行杂化处理制得了TiO2/PMMA纳米复合材料.并将不同量的溶胶与几种不同摩尔质量的PMMA进行复合,得到多种样品.通过透射电镜(TEM)、红外光谱(FTIR)、紫外-可见光谱(UV-Vis)、热失重(TGA)分析研究了TiO2/PMMA纳米复合材料的结构和性能,从而由溶胶含量、PMMA摩尔质量等不同因素对复合材料性质产生的影响作出了解释.结果表明当溶胶含量为1％、PMMA的摩尔质量较低(37.3万g/mol)时,TiO2微粒在聚合物中的分散性较好,粒径较均一,TiO2的加入使得材料的抗紫外线性和热稳定性都有所提高.     

Comparative effect of metallocene and Ziegler‐Natta polypropylene on the exfoliation of montmorillonite and hectorite clays to obtain nanocomposites

The present study was carried out on the effect of molecular weight and polydispersity of polypropylene (PP) obtained via Ziegler‐Natta or metallocene catalysis on the formation of nanocomposites with montmorillonite and mineral and synthetic hectorite. The formation of the nanocomposites was achieved by the melt‐mix method. X‐ray diffraction, transmission electron microscopy, and analysis of mechanical properties showed that, using PP obtained via metallocene catalysis (polydispersity ～ 2), it is possible to achieve improved formation of nanocomposites compared with PP obtained via Ziegler‐Natta catalysis (polydispersity ～ 4). It was also found that the molecular weight of the PP affects the tendency toward clay exfoliation and consequently the properties of the nanocomposites. Montmorillonite type clay was evaluated at 1%, 3%, and 5% by weight in the nanocomposite. The nanocomposite with 1 wt % clay was found to have better mechanical properties compared with the nanocomposite containing 3 wt % and 5 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 698–706, 2007     

中熔均聚聚丙烯1100N流变性能研究

借助旋转流变仪、毛细管流变仪等研究了中熔均聚聚丙烯(PP1100N)及PP1120,PPV30G的熔体流变性能。结果表明,PP1100N与对比试样的流变性能略有差异,3种试样均具有良好的加工流动性。PP1100N相对分子量最大;PPV30G居中;PP1120相对分子量最小。PP1100N和PPV30G的挤出胀大直径变化相差不大,PP1120的挤出胀大直径变化相对较小,3种试样在挤出胀大实验中均未出现试样熔体破裂现象。     

PP/TiO2纳米复合材料耐老化性能的研究

用纳米TiO2与聚丙烯(PP)共混制得PP／TiO2纳米复合材料，研究了PP／TiO2纳米复合材料的耐老化性能，分析了红外图谱和微观结构。结果表明，PP／TiO2纳米复合材料的耐老化性能较PP有较大程度提高，其微观结构和力学性能也有所改善，且纳米TiO2用量越大，改善效果越明显。     

Control of molecular weight distribution for polypropylene obtained by commercial Ziegler–Natta catalyst: effect of temperature

Polymerization of propylene was carried out by using MgCl₂-supported TiCl₄ catalyst in conjunction with triethylaluminium (TEA) as cocatalyst. The effect of polymerization temperature on polymerization of propylene was investigated. The catalyst activity was influenced by the polymerization temperature significantly and the maximum activity of the catalyst was obtained at 40 °C. With increasing the polymerization temperature, the molecular weight of polypropylene (PP) drastically decreased, while the polydispersity index (PDI) increased. The effect of the two-stepwise polymerization procedure on the molecular weight and molecular weight distribution of PP was studied and the broad PDI of PP was obtained. It was also found that the PDI of PP could be controlled for propylene polymerization through regulation of polymerization temperature. Among the whole experimental cases, the M _w of PP was controlled from 14.5 × 10⁴ to 75.2 × 10⁴ g/mol and the PDI could be controlled from 4.7 to 10.2.     

PP/TiO2纳米复合材料的研制及其抗老化机理分析

制备了聚丙烯(PP)／TiO2纳米复合材料,用氙灯耐气候试验机对该复合材料进行人工加速老化试验。采用紫外一可见光光谱法分析了纳米TiO2等粉体材料的紫外吸收性能;分析了PP／TiO2纳米复合材料的红外光谱并探讨了抗老化机理;对比研究了纯PP和PP／TiO2纳米复合材料老化期间力学性能的变化规律。结果表明,纳米TiO2能赋予PP优异的耐候性能,延长制品的户外使用寿命。     

聚丙烯硬弹性膜的挤出流延工艺及拉伸成孔性

以某进口均聚聚丙烯(PP)(PP1)为原料,通过挤出流延工艺制备了PP1硬弹性膜并在130℃下对其进行热处理,研究了挤出温度、流延辊转速及温度、热处理温度和时间等工艺参数对PP1硬弹性膜弹性回复率的影响,得到了最佳工艺条件,即挤出温度为195℃、流延辊温度及转速分别为90℃,26 r/min,热处理温度和时间分别为145℃,30 min。将该工艺应用于分子量及其分布与PP1基本相似的国产PP(PP2),发现由此工艺制备的PP2硬弹性膜的弹性回复率可达94.6%,与PP1硬弹性膜相差不大。通过冷热单向拉伸将PP1和PP2硬弹性膜制备成微孔膜,发现两者具有相似且优异的微孔结构。在此基础上,通过扫描电子显微镜研究了冷热拉伸工艺参数对PP2微孔膜拉伸成孔性的影响。结果表明,当冷拉伸倍数为15%,热拉伸倍数为100%,冷热拉伸速率均为50 mm/min时,制备的PP2微孔膜形成了完整规则的多孔结构。     

Influence of recycling and contamination on structure and transport properties of polypropylene

In this work the effect of three processing cycles on the physical properties of polypropylene (PP) was studied and related to the changes in the structure (molecular weight, molecular weight distribution, morphology) occurring during recycling. In order to simulate both the use and the recycling process of PP in the laboratory, PP pellets were contaminated with three model substances and submitted to three cycles of processing by injection molding. The bars for testing were produced from virgin and recycled polymers. The amount of degradation occurring during the reprocessing was estimated by means of viscosity and gel permeation chromatography measurements. Differential scanning calorimetry and scanning electron microscopy analyses were performed to investigate the crystallization behavior and the morphology of virgin and recycled PP. In order to obtain information on the structural organization and mobility of the amorphous phase, a dynamic mechanical thermal analysis and measurements of the transport properties were carried out. The results obtained were attributed to the different structural organization of the bars in relation to the number of processing cycles and contamination. Part of the work was focused on the recyclability of PP for food packaging applications, considering the residual contamination and migrational behavior after repeated processing cycles. In particular, the relationships existing between reprocessing, the residual amounts of contaminants, and the migrational behavior were investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1768–1778, 2003