2005年中国聚丙烯研发与应用论文题录(上半年)

等通道转角挤出制备自增强等规聚丙烯的结构与性能研究,聚丙烯发泡体系粘度预测模型的确立,PP／POE／纳米CaCO3复合材料流变性能的研究,PP／SBS／纳米CaCO3复合材料结构与性能研究,聚丙烯基杂化材料的动态力学性能与流变行为.     

等通道转角挤压加工中挤压温度对聚丙烯结构和性能的影响

在45℃至105℃挤压温度范围内对等规聚丙烯（iPP）进行等通道转角挤压，研究了挤压温度对iPP结构和性能的影响。结果表明：经过等通道转角挤压加工后，iPP晶粒明显细化并获得剪切取向变形，挤压温度的升高有利于iPP晶相取向的形成和结晶度增大。等通道转角挤压使iPP的透明性提高，65℃挤压后iPP透光率增幅最大，提高了21．3％；随着挤压温度的升高，iPP冲击强度和拉伸强度逐渐增加，105℃挤压后其冲击强度、拉伸强度分别比ECAE前提高了127％、38％。ECAE挤压后jPP表现出韧性延性拉伸断裂特征，断裂伸长率的增幅随挤压温度的升高而降低，45℃挤压后其增幅最大，达到1090％。     

等通道转角挤压制备自增强高密度聚乙烯的结构与性能研究

采用等通道转角挤压方法对高密度聚乙烯进行自增强挤压，研究和分析了挤压工艺条件与材料结构、性能之间的关系。利用扫描电镜、广角X-射线衍射、差示扫描量热分析等手段对材料结构进行了表征。结果表明，经过等通道转角挤压后，高密度聚乙烯的结晶度提高、晶粒细化、熔点升高，形成明显的取向结构，拉伸强度提高了23％。     

等通道转角挤压对等规聚丙烯性能的影响

在25 mm/min的挤压速度及25～105 ℃的挤压温度,了等通道转角挤压(ECAE)对等规聚丙烯(iPP)结晶结构和力学性能的影响.结果表明,ECAE可以细化iPP晶粒,并可使细化的晶粒发生取向;随着挤压温度的升高,iPP的拉伸强度、冲击强度、弯曲强度、弯曲模量逐渐增加,断裂伸长率逐渐降低;iPP在105 ℃挤压后,其拉伸强度、断裂伸长率、冲击强度和弯曲模量分别比ECAE前提高了38%,700%,750%,33%.     

等规聚丙烯/细菌纤维素复合材料的制备及性能研究

研究了马来酸酐接枝聚丙烯作为增容剂添加到等规聚丙烯/细菌纤维素复合材料中后材料的性能。结果表明:加入细菌纤维素后,复合材料的拉伸强度、拉伸模量、冲击强度明显提高;添加马来酸酐接枝聚丙烯后,前述力学性能的提高更为显著,但两种复合材料的断裂伸长率都有所降低;随着相容性的提高,复合材料的最大失重温度提高。扫描电镜和粒度分布分析结果表明,马来酸酐接枝聚丙烯能显著改善细菌纤维素与等规聚丙烯之间的界面相容性和分散性。     

PP及PP/HDPE复合材料的等通道转角挤压加工

研究了聚丙烯(PP)和PP／高密度聚乙烯(HDPE)复合材料在等通道转角挤压(ECAE)加工中的宏观形变情况。结果表明,PP长方形网格线形变成平行四边形,其形变角约40°,A路径的二次ECAE加工使试样的塑性形变加大,平行四边形的形变角减小到33°,C路径的二次ECAE加工使平行四边形形变恢复为与PP试样未ECAE加工前的长方形,表明采用不同的ECAE加工路径可获得不同形变结构的试样;最佳的ECAE挤出速率为3 mm／min,且挤出速率须保持恒定;PP／HDPE复合材料的ECAE加工性能除与复合材料的摩擦系数有关外,还与复合物的结构有关, 当HDPE用量在10％时,ECAE加工较容易,但当用量大于10％时,在挤出过程中容易发生开裂和破碎现象;PP／ HDPE复合材料的最佳ECAE加工挤出速率为2 mm／min,可挤性能最好的是PP／HDPE质量比为90／10的复合材料。     

近熔点挤出等规聚丙烯的微结构与力学性能的关系

分别在近熔点附近（167℃）和完全熔融温度（190℃）下挤出制备等规聚丙烯（iPP）片材。拉伸试验结果表明：在167℃挤出的iPP,其屈服强度比在190℃时挤出的提高了15.8%;拉伸强度和杨氏模量均有一定程度的提高。采用二维广角X射线衍射（2D-WAXD）、示差扫描量热法（DSC）和扫描电子显微镜（SEM）对微结构进行表征,并讨论了微结构与力学性能的关系。     

等规聚丙烯-丙烯酸接枝共聚

详细研究了等规聚丙烯细粒子在丙烯酸水溶液中,以过氧化苯甲酰为引发剂的液－固相接枝共聚反应和十氢化萘乙醇溶液对等规聚丙烯的膨化预处理作用,检测了等规聚丙烯－聚丙烯酸的某些性质,发现随接枝率提高,其吸湿性和碱性染料染色性均提高,熔点略有降低,但熔体流动性下降,按本研究获得的最佳膨化预处理条件和最佳接枝共聚反应条件,接枝产物等规聚丙烯－聚丙烯酸的接枝率可超过13％。     

新型聚烯烃包装材料

美国推出一种新型聚烯烃系列树脂新工艺、新添加剂 ,它具有高透明性等多种优异性能。例如等规聚丙烯及间规聚丙烯均聚物 ,其熔体流动速率为 2 .5 g/10min ,拉伸成型压力分别为 10 4 8.8MPa及 5 79.6MPa ,拉伸屈服压力分别为3176 0MPa及 2 4 15MPa,雾度分别为 5 8.7% ,15 .5 %。若把高透明度间规聚丙烯 (70 % )与常规聚丙烯均聚物 (30 % )共混。其清晰度将远远超过其他材料。特别适于要求高透明度的包装新型聚烯烃包装材料$扬子石油化工股份有限公司研究院@张云英…     

等规聚丙烯的深度氯化及其在涂料中的应用

采用溶液催化氯化工艺对等规聚丙烯（IPP）进行深度氯化，制得氯含量达52％～62％的氯化等规聚丙烯（CIPP）。该氯化等规聚丙烯可代替过氯乙烯、氯化橡胶用于各种防腐涂料，所得防腐蚀涂料具有良好的性能。     

Crystallization in blends of isotactic polypropylene with polyethylene-b-poly(ethylene-co-butylene)-b-polyethylene block copolymer

In this study, isothermal crystallization in blends of isotactic polypropylene (i-PP) with polyethylene-b-poly(ethylene-co-butylene)-b-polyethylene block copolymer (CEBC) was investigated using a polarized photometer, polarized microscope and differential scanning calorimeter. Half time of crystallizaiton (τ_1/2) is increasing with increasing CEBC content in i-PP/CEBC blends. Avrami index and rate constant of crystal growth decrease with increasing CEBC content in i-PP/CEBC blends. On the contrary, heat of fusion of i-PP crystal in the blends is almost constant against the variation of CEBC content in i-PP/CEBC blends. Hence, it is pointed out that blending i-PP with CEBC caused only retardation of rate of crystalline growth and change in mechanism of crystalline growth from three dimensional to two dimensional growth. Received: 19 May 1999/Revised version: 15 July 1999/Accepted: 19 July 1999     

High-resolution solid-state C nuclear magnetic resonance study of isotactic polypropylene polymorphs

High-resolution ¹³C nuclear magnetic resonance spectra are reported for three solid samples of isotactic polypropylene (i-PP): (i) the -crystalline form (monoclinic), (ii) the β-crystalline form (hexagonal), and (iii) the mesomorphic or smectic form of i-PP. These spectra were obtained using magic angle spinning, high-power proton dipolar-decoupling and cross-polarization techniques, and for the β- and smectic forms of i-PP constitute the first reported high-resolution solid-state spectra. The spectrum of the -crystalline form shows well resolved splittings (1 ppm) of the methyl and methylene carbon resonances, as was reported previously by Bunn et al. These splittings are absent in the spectra observed for the β- and smectic forms of i-PP. Based on a comparison of the chemical shifts and T₁ relaxation times observed for the carbon resonances in these three forms of solid i-PP, we reach the following conclusions: (i) i-PP adopts the same 3₁ helical conformation in each crystalline polymorph, (ii) the packing of i-PP helices in the β-form crystal is closer to the more distant of the two interhelical packings in the -crystalline form, and (iii) the local packings of 3₁ helices are very similar in the β- and smectic forms of i-PP.     

生物降解材料聚（DL）-乳酸剪切变形强韧化研究

研究了等通道转角挤压技术对生物降解材料聚（DL）-乳酸（PDLLA）的增强、增韧。探讨了挤压温度、挤压次数对PDLLA性能的影响。实验表明，随挤压次数增加，材料强韧性提高；挤压温度对材料性能影响明显。经过2次挤压后，PDLLA的弯曲强度由83．3MPa增加到178．7MPa；原始试样弯曲断口呈脆性断裂，强韧化挤压后，断口呈典型韧性断裂特征，强韧性明显提高。扫描电镜观察表明，断口有大量纤维尾端，呈明显纤维化。广角X射线衍射和差示扫描量热分析表明，随挤压次数增加，PDLLA玻璃化转变温度提高，结构更趋稳定。     

Ultrasonic oscillations induced morphology and property development of polypropylene/montmorillonite nanocomposites

Polypropylene/montmorillonite nanocomposites (PPCNs) with 3% organophilic montmorillonite (OMMT) content were prepared via ultrasonic extrusion. The objective of present study was to investigate the effects of ultrasonic oscillations in processing on the morphology and property development of PPCNs. XRD and TEM results confirmed the intercalated structure of OMMT in conventional nanocomposite (without ultrasonic treatment) and ultrasonicated nanocomposite, but ultrasonic oscillations could make silicate layers finely dispersed and a little exfoliated. According to SEM, the OMMT particles were evenly and finely dispersed in the ultrasonicated nanocomposite via ultrasonic oscillations, and the aggregation size of clay particles was about 100 nm, which is less than that in conventional nanocomposite. The crystalline dimension, crystalline morphology and the growth rate of crystallization in PPCNs were investigated by DSC and PLM, it was found that the OMMT particles and ultrasonic oscillations played an important role in the nucleation rate, crystallization temperature and spherulite size of PP matrix in nanocomposites. Compared with conventional nanocomposite, the mechanical properties of the ultrasonicated nanocomposite increased due to the improved dispersion of OMMT and diminished spherulite size. The thermal stability and the rheological behavior of PP and its nanocomposites were both studied by thermogravimetry and high pressure rheometer, respectively.     

Using synchrotron FTIR spectroscopy to determine secondary structure changes and distribution in thermoplastic protein

Blood meal is a high protein, low value by‐product of the meat processing industry that can be converted into a thermoplastic material by extrusion with a combination of a surfactant, urea, a reducing agent, water, and plasticiser. Changes in protein structure after each processing step (mixing with additives, extrusion, injection molding, and conditioning) were explored using synchrotron FTIR microspectroscopy. Blood meal particles were found to have higher β‐sheet content around the perimeter with a randomly structured core. α‐Helices were either located near the core or were evenly distributed throughout the particle. Structural rearrangement consistent with consolidation into a thermoplastic was seen after extrusion with processing additives, resulting in reduced α‐helices and increased β‐sheets. Including triethylene glycol as a plasticiser reduced α‐helices and β‐sheets in all processing steps. At all processing stages, regions with increased β‐sheets could be identified suggesting blood meal‐based thermoplastics should be considered as a semicrystalline polymer where clusters of crystalline regions are distributed throughout the disordered material. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The Effect of Rotational Extrusion on the Structure and Properties of HDPE Pipes

High density polyethylene (HDPE) pipes were prepared using a novel rotational extrusion processing system. The experimental results showed that the hoop stress exerted by either mandrel rotation or die rotation could have the macromolecular chains oriented in hoop direction and alter the crystallization behavior of HDPE during rotational extrusion, resulting in forming transcrystals with larger crystalline size, thicker lamellae, higher Tm. Therefore, the mechanical properties of HDPE pipes were greatly improved in hoop direction, which was attributed to the changes of the crystalline morphology and the molecular orientation under the action of the hoop stress field.     

Effect of PVC resins on multi-screw pipe extrusion

The increased use of multi-screw (twin) extruders by pipe producers brought on this study of available PVC homopolymer “pipe grade” resins. Basic tests on resin were examined via a “Correlation Matrix” computer program. Highly significant test data were determined to be internal pore volume and centrifuge plasticizer adsorption. Additional compound evaluation proceeded via torque rheometer followed by twin-screw extrusion. Significant resin test values affecting extrusion properties are inherent viscosity, apparent bulk density, porosity uniformity and melt viscosity. The work shows that the compounder should know resin properties in order to benefit from processing equipment developments.     

Mechanical properties of thermoplastic waxy maize starch

The properties of thermoplastic amylopectin materials were investigated by stress-strain and relaxation measurements as a function of water content and crystallinity. Granular waxy maize starch was plasticized by extrusion with water and glycerol. The materials are amorphous after processing. The sharp fall in modulus at a water content of 10% is characteristic of a glass to rubber transition of an amorphous polymer. The materials are brittle below their glass transition temperature with a modulus of approximately 1000 MPa and an elongation of less than 20%. The amorphous rubbery materials are soft and weak with moduli of 0–10 MPa and tensile strengths of 0–2 MPa. The materials are viscoelastic, show plastic flow, and form a highly entangled polymer matrix, resulting in high values of elongation (500%), due to the high amylopectin molecular mass. Above glass transition temperature the amylopectin forms inter- and intramolecular double helices, crystallizing in a B-type crystal. The initial increase in modulus, tensile strength, and relaxation time is the result of the lower mobility of the amylopectin molecules and the reinforcement of the network by physical crosslinking. The drastic reduction of the elongation and the formation of cracks is the result of intramolecular crystallization. At crystalline junction zones the internal stress is increased and the interaction between molecules is reduced. © 1996 John Wiley & Sons, Inc.     

Effect of the inner wall cooling rate on the structure and properties of a polyethylene pipe extruded at a high rotation speed

A novel rotation extrusion processing system was self‐designed to prepare high‐performance polyethylene (PE) pipes. In this study, during the extrusion of the PE pipes at a high mandrel rotation speed, compressed air, as a cooling medium, was introduced through their interior to achieve the quick cooling of the inner wall and the effects of the inner wall cooling rate on the microstructure and mechanical properties of the obtained PE pipes were investigated. The experimental results showed that in contrast to conventional extrusion, the molecular orientation deviated from the axial direction under a high mandrel rotation speed and was fixed by the inner wall cooling; with increasing cooling rate, the orientation degree also increased. On the other hand, cooling promoted the augmentation of spherulites. So when the cooling rate reached a certain high point, the effect of cooling on the formation of spherulites was stronger than that on the fixation of the orientation. A much higher cooling rate decreased the orientation degree, which was closely related to the performance of the PE pipe. As a result, there was an optimal cooling rate of the inner wall during the rotation extrusion for better performance of the PE pipe. When the cooling rate was 1.5°C/s, the hoop strength of the PE pipe produced by the novel extrusion method increased from the original 24.1 MPa up to 37.1 MPa without a decrease in the axial strength, and the pipe's crack initiation time increased from 27 to 70 h. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011