共交联VMQ/POE共混物的热致形状记忆行为研究

将甲基乙烯基硅橡胶(VMQ)与乙烯-辛烯共聚物(POE)进行机械共混和化学交联,制得具有热响应形状记忆特性的共交联VMQ/POE共混物,其形状记忆性能由交联、结晶、熔融所决定,其中交联程度对结晶和熔融有显著的影响。将着重分析交联剂对共混物的硫化特性以及热学、拉伸和弯曲形状记忆性能的影响规律。结果表明:添加交联剂的共混物胶料的硫化曲线呈现出焦烧、热硫化、平坦硫化等典型硫化特征,且胶料的交联速率和凝胶率均随交联剂用量增加而呈现增大的趋势。在相同的拉伸应力载荷下,随着交联剂用量的增加,共混物的最大应变值和固定率逐渐减小,而回复率先增大后减小;共混物的循环拉伸形状记忆稳定性较好,最大应变和固定率变化较小,而回复率有明显的增大。在相同的弯曲应力作用下,共混物的固定角度、回复角度、回复速度均随交联剂用量增加而呈现出增大的趋势。对比发现,当交联剂添加份数为0.5~1.0内,共混物具有较为理想的拉伸和弯曲形状记忆性能。

SUPER POLYOLEFIN BLENDS ACHIEVED VIA DYNAMIC PACKING INJECTION MOLDING:MORPHOLOGY AND PROPERTIES

As a long-term project aimed at developing super polyolefin blends, in this paper we summarize our work on themechanical reinforcement and phase morphology of polyolefin blends achieved by dynamic packing injection molding(DPIM). The main feature of this technology is that the specimen is forced to move repeatedly in the model by two pistonsthat move reversibly with the same frequency during cooling, which results in preferential orientation of the dispersed phaseas well as the matrix. The typical morphology of samples obtained via DPIM is a shear-induced morphology with a core inthe center, an oriented zone surrounding the core and a skin layer in the cross-section areas. Shear-induced phase dissolutionat a higher shear rate but phase separation at low shear rates is evident from AFM examination of LLDPE/PP (50/50) blends.The super polyolefin blends having high modulus (1.9-2.2 GPa), high tensile strength (100-120 MPa) and high impactstrength (6 times as that of pure HDPE) have been prepared by controlling the phase separation, molecular orientation andcrystal morphology.

Application of prodigiosin as a colorant for polyolefines

Serratia marcescens strain 9986 is a producer of prodigiosin used as a dye of polyolefines (polyethylene, ultratene). The biosynthesis of pigment was closely connected with controlled growth parameters. A prodigiosin yield 0.2 - 0.4 mg per l of culture medium in the batch culture under aerobic conditions was obtained. Prodigiosin was extracted from crude biomass treated by 0.1% of sodium dodecyl sulfate (SDS). This novel elaborated stage is necessary for thermostability a dye in polymer. The consumption of prodigiosin preparation is more economical in the technology of the coloration of polyolefines. The elaborated method has been manufactured for dyeing polyethylene by biological pigment-articles of the common use corresponding to the technological standard.

Ionomer Toughened Polyolefine

The morphology and properties of HDPE blends with Zn-SEPDM and GR were studied through SEM and mechanical property test. The results show that as Zn-SEPDM/GR content amounts to 20%, the blend becomes an IPN in structure, and that a rather high impact and tensile strength of HDPE may be obtained after blending. The antistatic effect, the softening point,and HDT of the blend are higher as compared to HDPE/Zn-SEPDM/ZnSt (zinc stearate).The effect of Zn-SEPDM on the compatibility the morphology and properties of IPP blends were studied by DSC, TEM and mechanical properties test. The results show that as Zn-SEPDM content exceeds 20%. Zn-SEPDM in the blend becomes continuous and an abrupt change in impact strength is incurred there from. Owing to the incorporation of ionic groups into EPDM.the strong interactions betWeen the chains make both the impact and the tensile strength of IPP remarkably higher

Ni-catalyzed carbon–carbon bonds cleavage of mixed polyolefin plastics waste

The inert carbon–carbon(C–C) bonds cleavage is a main bottleneck in the chemical upcycling of recalcitrant polyolefin plastics waste. Here we develop an efficient strategy to catalyze the complete cleavage of C–C bonds in mixed polyolefin plastics over non-noble metal catalysts under mild conditions. The nickelbased catalyst involving Ni_(2)Al_(3) phase enables the direct transformation of mixed polyolefin plastics into natural gas, and the gas carbon yield reaches up to 89.6%. Reaction pathway investigation reveals that natural gas comes from the stepwise catalytic cleavage of C–C bonds in polypropylene, and the catalyst prefers catalytic cleavage of terminal C–C bond in the side-chain with the low energy barrier.Additionally, our developed approach is evaluated by the technical economic analysis for an economically competitive production process.

Diffusion Characteristics and Removal of Cyclohexane in Polyolefin Elastomer Melt

The diffusion coefficient of volatiles in polymer solutions is a crucial parameter to describe the mass transfer efficiency and ability of volatiles.In this research,polyolefin elastomer(POE)was used as a polymer,and cyclohexane was used as a volatile.A gravimetric analysis was applied to measure the diffusion coefficient of cyclohexane in POE.The devolatilization rate of the POE-cyclohexane system under different conditions was measured.The effects of temperature,film sample thickness,and initial concentration of volatiles on the devolatilization rate were discussed.Based on the devolatilization rate data,the average diffusion coefficient of cyclohexane in POE was obtained by fitting with a mathematical model.The experimental results indicate that the devolatilization rate increased with increasing temperature and initial concentration of volatiles,but it decreased with increasing sample thickness.As the thickness increased,the overall diffusion resistance increased.As the temperature increased,the molecular movement increased,resulting in the increase of average diffusion coefficient.The relationship between the diffusion coefficient of the POE-cyclohexane system and temperature follows the Arrhenius law.The diffusion activation energy E=6201.73 J/mol,and the pre-exponential factor of the diffusion coefficient D0=2.64×10^(-10) m^(2)/s.This work can provide basic data for exploring the devolatilization of POE polymers and serves as a useful reference for enhancing the effect of devolatilization.

FILLED POLYOLEFIN COMPOSITES PREPARED FROM IN-SITU POLYMERIZATION VIA A CATALYST-SUPPORTED APPROACH——Ⅰ.MORPHOLOGY OF PE IN CARBON BLACK(CB)/PE IN-SITU COMPOSITES

The morphology of PE in the in-situ CB/PE composites prepared from in-situ polymerization via a catalyst-supported approach was studied by DSC. It is found that both the melting peak temperature and crystallinity of the PE shelldecrease as filler level increases. The unexpected phenomena are ascribed to the strong interaction between PE and CB andthe very high specific area of CB. It is suggested that the lamellar thickness should be well correlated to the PE shell thickness. A two-layer PE model is successfully used to explain the experiment results.

HIGH VISCOUS STRESS OF ORIENTED POLYOLEFINS UNDER UNIAXIAL TENSILE DEFORMATION

In this communication, by means of stress relaxation experiments, the viscous stress at various strains during tensile deformation of oriented polyolefin samples including high density polyethylene （HDPE）, linear low density polyethylene （LLDPE） and isotactic polypropylene （iPP）, has been determined. The viscous stress in the oriented samples takes up to 50%-70% of the total stress, which is unusually high compared with their isotropic counterparts. The unusual high viscous stress was discussed based on mainly the existence of shish structure in oriented polyolefins, which could enhance the inter-lamella coupling significantly.

UNUSUAL CRYSTALLIZATION AND MELTING PROCESSES OF AN OPTICALLY ACTIVE POLYOLEFIN:ISOTACTIC POLY((S)-4-METHYL-HEXENE-1)

Polyolefins that bear a chiral side chain(typically an isobutyl group)experience a so-called macromolecularamplification of chirality:the chiral side-chain induces a slight preference for either tg or tg(?) main chain conformation.Thisslight conformational bias is amplified cooperatively along the chain,and results in preferred chirality of the main chainhelical conformations.As a result,these polymers display a liquid-crystal(LC)phase both in solution and,in the melt as atransient phase on the way to crystallization.The existence of two processes(melt-LC and LC-crystal transitions)results inunconventional behaviors that were first analyzed by Pino and collaborators back in 1975.These polymers also offer a meansto test the structural consequences of recently introduced crystallization schemes.These schemes postulate the formation of atransient liquid-crystal phase as a general scheme for polymer crystallization.

A METHOD TO QUANTIFY CRAZING DEFORMATION BY TENSILE TESTS FOR POLYSTYRENE/POLYOLEFIN ELASTOMER IMMISCIBLE BLENDS

A method to quantify crazing deformations by tensile tests for polystyrene （PS） and polyolefin elastomer （POE） blends was investigated. The toughness of PS/POE blends, reflected by the Charpy impact strength, increased with the content of POE. SEM micrographs showed the poor compatibility between PS and POE. In simple tensile tests, it is very easy to achieve the ratio of crazing deformation, i.e. K by measuring the size changes of samples. The K values decreased with increasing the content of POE, and the deformations of PS/POE blends were dominated by crazing. The plots of the change of volume （△V） against longitudinal variation （△I） showed a linear relationship, and the slope of lines decreased with the content of POE. Measuring samples at the tensile velocities of 5 mm/min, 50 mm/min, and 500 mm/min respectively, the K values kept unchanged for each PS/POE blends.

A Greener Approach for Synthesis of Functionalized Polyolefins by Introducing Reactive Functionality into Ethylene Copolymers

Recent successful examples for synthesis of new polyolefins containing (polar) functionalities by adopting the approaches by controlled incorporation of reactive functionalities (and the subsequent introduction of polar functionalities under mild conditions) by coordination polymerization in the presence of transition metal complex catalysts have been described. Related methods (such as direct copolymerization of olefin with polar monomer using living radical or coordination insertion methods) have also been demonstrated for comparison. Our recent efforts for precise synthesis of polyolefins containing polar functionalities by efficient incorporation of reactive functionality by copolymerization of ethylene with nonconjugateddiene (1,7-octadiene, vinylcyclohexene etc.) or divinyl-biphenyl using nonbridged half-titanocene [ex. Cp’TiCl2(O-2,6-iPr2C6H3), Cp’ = C5Me5, tBuC5H4 etc.] catalysts have been introduced.

Catalytic Cracking of Polyolefins in the Molten Phase——Basic Study for the Process Development of Waste Plastics Liquefaction

The cracking of polyolefins, especially polyethylene in the molten state was effectively catalyzed by the powdery spent FCC （Fluid Catalytic Cracking） catalyst which was dispersed in it. The activation energy of the catalytic cracking of polyethylene was about 74 kJ/mol. The cracked product was naphtha and middle distillate as the major product and gaseous hydrocarbon （C1-C4） as the minor product while little heavy oil was produced. The chemical compositions of the product were： aromatic hydrocarbons, isoparaffins and branched olefins, whereas that of the non-catalyzed products were： n-olefins and n-paraffins with minor amount of dienes with increasing the process time. Additionally, the product pattern shifted from naphtha rich product to kerosene and gas-oil rich product. However, any catalytic product showed low fluid point （〈 -10 ℃）, while that of the non-catalyzed product was as high as 40 ℃. Catalyst could process, more than 100 times by weight of polyethylene with fairly small amount （- 30 wt%） of coke deposition. Spent catalyst gave higher hydrocarbons while fresh catalyst gave gaseous product as the major product. Other polyolefins such as polypropylene and polystyrene were tested on same catalyst to show that their reactivity is higher than that of polyethylene and gave the aliphatic products, alkyl benzenes and C6-C9 iso-paraffins as the major product. Product pattern of the cracked product suggested that the reaction proceeded via the primary reactions making paraffins and olefins which were followed by the isomerization, secondary cracking, aromatization and hydrogen transfer which based on the carbenium ion mechanism.

Development Scenario of China Polyolefin Industry in 2009 and Its Prospect During Twelfth Five-year-plan Period

The development situation of the polyolefin industry during the first four years of the Elevemth Five-year-plan was reviewed.Domestic supply and demand of polyolefins at the period of the Twelfth Five-year-plan were analyzed and predicted.It was pointed out that production capacity of polyolefin in China will be increased significantly and market demand will keep a steady growth.Large-scale industrial equipment of polyolefin will be developed to meet the increasing demand.

聚烯烃在锂离子电池隔膜领域的应用进展

隔膜是锂离子电池的重要组成部分之一,它的性能直接决定了锂离子电池的安全性能、使用寿命和电化学性能等。聚烯烃微孔膜凭借电化学性能优异、价格低廉等优势成为锂离子电池隔膜市场的主流。在隔膜减薄化趋势下,超高分子量聚乙烯隔膜独特的性能优势成为聚烯烃微孔膜中最具竞争力的产品。介绍了锂离子电池隔膜的工作原理及性能要求,聚烯烃锂离子电池隔膜的制备方法,包括湿法、干法、静电纺丝等制备工艺;阐述了锂离子电池隔膜专用料的性能要求和研发进展,生产超高分子量聚乙烯的催化剂以及聚烯烃隔膜改性的研究进展。

Rolling Circle Amplification on Biotin-Streptavidin Complexes Immobilized to Activated Cyclic Polyolefin Surfaces

Cyclic polyolefin (COP) is an inexpensive hydrophobic material with low auto-fluorescence, high light transmittance and thermal stability, broad chemical resistance and no non-specific protein binding. Here, the hydrophobic alkane COP was modified to have carbonyl functionalities through oxygen plasma and chemical etching treatments to increase usefulness for chemical and biochemical applications. Then, biotin-hydrazide was used to create biotinylated surfaces that bound streptavidin. A biotinylated target oligonucleotide was subsequently bound to the immobilized biotin-streptavidin and ligation mediated rolling circle amplification-based (L-RCA) SNP detection was demonstrated.

基于分子动力学方法研究乙烯-丁烯共聚物的传热性质

建立了乙烯α-丁烯共聚物的物理模型,采用分子动力学方法分析了不同丁烯含量和丁烯嵌段分布对乙烯-丁烯共聚物的传热性质。结果表明,选用聚合单体数为60的乙烯-丁烯分子链模型可有效地反映聚烯烃弹性体的真实性质且计算量适中。随着丁烯摩尔分数由20%增加至80%,共聚物的热导率由0.2783 W/(m·K)逐渐下降至0.1728 W/(m·K)。此外,随着丁烯嵌段数越大,共聚物由嵌段共聚更多地转变为无规共聚的形式,其热导率降低,声子振动态密度由高频分量逐渐地转变为低频分量。

HTPO内穿插管输油工况下的性能退化规律

为了研究耐高温聚烯烃(HTPO)内穿插管在输油工况下的性能退化规律,采用煤油介质模拟输油工况,比较管材在不同温度(20~80℃)和浸泡时间(0~7周)下的质量、密度、结构成分、微观形貌、热稳定性、力学性能的变化规律,研究发现,HTPO管材仅在空气中加热时,主要发生热氧化,随着温度升高,质量和密度无明显变化,热稳定性略有下降,碳氧基团吸收峰增强,材料表面出现细小裂纹,屈服强度和弹性模量分别降低了8.15%和13.12%。当管材在20℃浸泡1周时,由于煤油介质的溶胀作用,出现了C=C溶胀吸收峰和C=O伸缩振动峰,材料表面呈沟壑状,屈服强度和弹性模量分别降低3.11%和7.93%。随着温度升高和浸泡时间延长,管材氧化降解程度增大,煤油溶胀作用加剧,80℃浸泡7周时,试样质量增加10.4%,C=C峰和C=O峰的强度增强,材料表面出现蚀刻现象,屈服强度和弹性模量降低38.75%和75.51%,热稳定性显著下降。

塑料再生工艺及再生塑料在包装领域的应用研究进展

综述了塑料再生工艺及再生塑料在包装领域的应用研究进展。使用Rh/Nb2O5催化剂催化聚烯烃氢解可以得到液态油品和低碳烷烃气;加入合成助剂可以改善再生聚乙烯的阻燃性能和抗老化性能;加入由烷基三乙氧基硅烷、马来酸酐等组成的预混合液制备的改性再生聚乙烯冲击强度提高;将二元醇和天冬氨酸酯的混合物与多异氰酸酯单体反应,再加入氨基化聚对苯二甲酸乙二酯(PET)微粉,得到改性再生PET发泡材料。采用异氰酸丙基三乙氧基硅烷对再生PET进行化学改性,制备的改性PET可用于制造包装袋;加入含多孔二氧化硅的爽滑剂吸附母粒制备的再生聚乙烯包装袋可以解决爽滑剂白色粉末对被包装物造成污染的问题。

内给电子体对BCNX系列催化剂性能的影响

考察了内给电子体对BCNX系列催化剂性能的影响,并与参比催化剂进行对比。实验结果表明,醚类化合物作为内给电子体时,制得的BCNX系列催化剂的聚合活性和氢调敏感性较高,其中9,9-二甲氧基甲基芴使得催化剂具有较高的立构定向性;邻苯二甲酸酯类化合物作为内给电子体时,制得的BCNX系列催化剂整体性能均衡,聚合活性、立构定向性及氢调敏感性均较参比催化剂显著提升;二醇酯类化合物作为内给电子体时,制得的BCNX系列催化剂除聚合活性有所提升外,其他性能无显著变化。