Comparison of thermal properties of crude by-product polyolefin wax, fractionated paraffin wax and their blend

The molecular weight and thermal properties of unfractionated by-product polyolefin wax (wax K) from a naphtha cracking unit, fractionated commercial paraffin wax (wax J) and their blend (wax M) were evaluated and were compared with each other using differential scanning calorimetry (DSC), normal and high-temperature gel permeation chromatography (GPC), and wide-angle X-ray diffraction (WAXD). Such properties as molecular weight distribution, melting temperature and degree of crystallization were altered by blending wax K with wax J. By blending with two parts of wax K and one part of wax J to prepare wax M, M _w of wax K was shifted, by half, to that of wax J in order to approach that of wax M, whereas the M _n of wax K remains almost unaltered to become that of wax M. In particular the effect of blending of wax K and wax J turned out co-crystallization for the sharper lower-melting-temperature endothermic peak of the blend, indicating narrower molecular distribution, than that of wax K at the melting temperature shifted even below that of wax J. The total degree of crystallinity for the blend, wax M, turns out less than that before blending wax K with wax J, which may be attributed to the effect of co-crystallization due to blending.     

含蜡原油管道清、防结蜡技术

在管道输送含蜡原油的过程中,由于原油的物性,即原油的内在因素,和外界环境因素的影响,输送过程中会产生操作上的问题,有时会严重影响生产的进行。本文针对目前我国原油输送管道所存在的含蜡问题,分析含蜡原油管线结蜡机理和影响因素,提出了常用于输油管道的清防蜡化学药剂。     

聚烯烃包覆石蜡相变材料的结构和初步热性能

分别以低密度聚乙烯（LDPE）和乙烯-辛烯共聚物（POE）为包覆材料,以石蜡为相变材料,制备了定形相变材料,采用SEM、DSC和流变性能对其进行分析表征。SEM电镜显示了两种不同的表面形貌;DSC测试表明石蜡加入量越多,潜热越大,POE/石蜡体系的潜热高于LDPE/石蜡体系;流变性能研究表明,石蜡的加入在固态时提高了基体的储能模量,对于LDPE/石蜡体系,LDPE为连续相;对于POE/石蜡体系,由于POE和石蜡熔融温度非常接近,分辨不出谁是连续相谁是分散相。     

Crosslink density and diffusion mechanisms in blend vulcanizates loaded with carbon black and paraffin wax

Results on blends containing different ingredients have revived the interest on the interaction parameter and crosslink density of structures that contain soft fillers. Composite blend of natural rubber and styrene butadiene rubber loaded with the percolation concentration of high abrasion furnace carbon black and different concentrations with paraffin wax were prepared. The applicability of the blends for liquid diffusion has been examined through the changes in the interaction parameter and the crosslink density at different temperatures. The transport mechanism through the vulcanized blends is governed by Fickian diffusion law at room temperatures and it becomes non‐Fickian at higher temperatures. The diffusion coefficients were calculated and found to have an activated behavior with temperature from which the activation energy was calculated. The change in entropy, enthalpy, and Gibbs free energy are also studied at different temperatures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

高含蜡原油聚烯烃降凝防蜡剂合成及性能评价

为了保障海上原油长距离管输低温流动安全,以丙烯酸十八酯、十八烯和苯乙烯为单体合成三元共聚物,以其为主剂合成聚烯烃降凝防蜡剂POOS,对三元共聚物的合成条件进行了优化,并对加剂前后原油流变性、析蜡特性、微观形态以及降凝防蜡效果进行评价。结果表明,共聚物优化合成工艺条件为：单体摩尔配比n(丙烯酸十八酯):n(十八烯):n(苯乙烯)=5:3:2,引发剂过氧化苯甲酰质量分数5 ‰,反应温度70 ℃,反应时间8 h。当POOS质量浓度为200 mg/L时,原油流变性与未加POOS原油相比变化明显,15 ℃下加剂前后屈服应力为50.3和2.95 Pa,屈服应力降幅94 %,析蜡温度由31.33 ℃降至24.94 ℃,凝点由25 ℃降至15 ℃,冷指测试防蜡率88 %,环道测试防蜡率83.7 %,微观分析蜡晶形态由针状转变为圆状结晶,析出分布不均匀,多个微小蜡晶聚集析出形成单个聚集体,加剂有效改善蜡晶分散形态,抑制网状结构形成,显著改善原油低温流动效果。     

石蜡乳液制备及性能研究

以高速分散器为乳化设备,58#工业级全精炼石蜡为原料制备了石蜡乳液.考察了乳化剂的组成及其HLB值,乳化剂用量,乳化温度,转速和乳化时间等因素对石蜡乳液性能的影响.结果表明,适宜的乳化工艺条件为:以Span80,K12和助乳化剂A为复配乳化剂,其HLB值为11,乳化剂用量为7％,乳化温度为85℃,转速为2×2 800 r/min,乳化时间为1min.     

石蜡的国内外市场

石蜡在国际市场上相对稳定，预计２０００年的需求量为３５０万ｔ，价格仍将维持在目前的水平。１９９５年我国石蜡的产量为８４．５万ｔ，预计２０００年国内需求量约６０万ｔ，出口量将达５０万ｔ     

聚烯烃塑料与液体石蜡共热解工艺研究

利用热重分析仪(TGA)研究了低密度聚乙烯(LDPE)、液体石蜡(LP)及LDPE/LP共混物的热解特性,探讨了LDPE与LP在热解过程中的相互作用,进一步根据Coats-Redfern方法进行了反应动力学研究。结果表明,LDPE、LP及LDPE/LP共混物热解过程均符合一级反应动力学,LDPE/LP共热解反应活化能显著低于LDPE单独热解。为了验证LDPE和LP之间的协同效应,利用高压反应釜分别对LDPE、LP及LDPE/LP的共混物进行了热解研究。结果表明,LDPE与LDPE/LP共混物热解所得气体产物与液体产物组分相似,气体产物多为C_1～C_4的烷烃和烯烃,液体产物多为C_5～C_(23)的正构烷烃;LDPE/LP共热解所得液体产物中轻质烷烃组分(C_5～C_9)含量显著高于LDPE和LP单独热解,证实了LDPE和LP之间的协同作用。LP的加入改善了热解过程中的传质传热,抑制了LDPE单独热解时因局部过热而引起的结焦现象,促进了液体产物的轻质化。     

聚烯烃塑料与液体石蜡共热解工艺研究

利用热重分析仪(TGA)研究了低密度聚乙烯(LDPE)、液体石蜡(LP)及LDPE/LP共混物的热解特性,探讨了LDPE与LP在热解过程中的相互作用,进一步根据Coats-Redfern方法进行了反应动力学研究。结果表明,LDPE、LP及LDPE/LP共混物热解过程均符合一级反应动力学,LDPE/LP共热解反应活化能显著低于LDPE单独热解。为了验证LDPE和LP之间的协同效应,利用高压反应釜分别对LDPE、LP及LDPE/LP的共混物进行了热解研究。结果表明,LDPE与LDPE/LP共混物热解所得气体产物与液体产物组分相似,气体产物多为C_1～C_4的烷烃和烯烃,液体产物多为C_5～C_(23)的正构烷烃;LDPE/LP共热解所得液体产物中轻质烷烃组分(C_5～C_9)含量显著高于LDPE和LP单独热解,证实了LDPE和LP之间的协同作用。LP的加入改善了热解过程中的传质传热,抑制了LDPE单独热解时因局部过热而引起的结焦现象,促进了液体产物的轻质化。     

Preparation of highly pure and crystalline carbon nanotubes and their infiltration by paraffin wax

Carbon nanotubes (CNTs) of ultrahigh purity and high crystallinity, which could be used for the encapsulation of nanoscaled materials, were fabricated by the heat treatment of disordered CNT-encapsulated In–Sn nanowires at temperatures lower than 1800 °C in H₂ under vacuum conditions (pressure of approximately 1 Pa). The results showed that nearly 100% of the encapsulated In–Sn alloy was removed at 1800 °C, and as much as 99.99% of it at 1600 °C. The prepared CNTs were also filled with paraffin wax. A vacuum-based infiltration–purification process proved effective for fabricating the CNT–paraffin hybrid structures at a high filling yield, which was confirmed by thermograms and TEM observations.     

Surface properties of EPDM,silicone rubber,and their blend during aging

Surface energy of EPDM, silicone rubber, and their 50 : 50 (by weight) blend during aging was determined by contact angle measurement using water and formamide as the probe liquids. The surface energy increases initially with aging time. The results are explained on the basis of the polar component of the surface energy. Blending offers a good degree of protection toward aging of EPDM rubber. The generation of polar groups during aging is confirmed by IR and ESCA investigations. © 1995 John Wiley & Sons, Inc.     

Surface and interface characterization of chlorinated polyolefin coated thermoplastic polyolefin

Laser scanning confocal fluorescence microscopy measurements were performed on thermoplastic polyolefin (TPO) substrates that were coated with chlorinated polyolefin (CPO). The TPO investigated was a blend of high modulus polypropylene with an ethylene-butene copolymer (EBR9) containing 9 wt% butene. The CPO was a maleated chlorinated polypropylene containign 20 wt% Cl. The purpose of these experiments was to obtain detailed mechanistic information about the CPO-TPO interaction. To achieve acceptable contrast in these measurements, a fluorescent dye was covalently attached to a small portion of the CPO. Solvent wiping of the TPO substrates with isopropyl alcohol followed by xylenes prior to coating with CPO increased the mean roughness of the TPO surface by more than 100 nm; but it had a much larger effect on the roughness of the (several micrometers) CPO-TPO interface after coating. The EBR component of the TPO was shown to be exclusively responsible for the roughness increase. We also found evidence of a diffuse interface between the CPO and ERB components that was localized to sites in which the EBR was present at the TPO surface.     

UHMWPE/聚烯烃共混物的性能及其熔融纺丝研究

将超高相对分子质量聚乙烯(UHMWPE)与共混组分聚烯烃(PB)按一定质量比计量,并加入质量分数为0.3%的抗氧剂1010,在双螺杆挤出机上共混造粒,研究了PB的用量对UHMWPE/PB共混物熔点和流变性能的影响;采用实验室熔融纺丝装置对UHMWPE/PB共混物进行纺丝,拉伸得到UHMWPE/PB共混纤维,研究了共混纤维的形貌、结晶性能和力学性能。结果表明:在共混温度为230~290℃时,UHMWPE/PB共混物可实现宏观上均匀共混;共混物具有介于两共混组分熔点之间的单一熔点,共混物熔点随UHMWPE含量的提高而提高;共混物熔体属假塑性流体,270~320℃条件下,随UHMWPE含量的增加,UHMWPE/PB共混物结构黏度指数逐渐增加,黏流活化能逐渐减小,共混物的熔体黏度对温度不敏感;当UHMWPE/PB质量比为1∶1,纺丝温度为310℃时,共混物具有良好的可纺性,经过19倍的后拉伸,所获得的UHMWPE/PB共混纤维直径为45μm,断裂强度可达16.4 c N/dtex,初始模量约190.0 c N/dtex。     

Dynamic rheological study of paraffin wax and its organoclay nanocomposites

Dynamic rheological data for paraffin wax and its organoclay nanocomposites are reported. Dynamic mechanical analysis of paraffin wax for temperatures ranging from ?40 to 55°C showed a decrease of several orders of magnitude in the dynamic moduli and a significant shift toward viscous behavior, which resulted from the occurrence of two solid–solid phase transitions. In both the crystalline and mesophase regions, the dispersion of organoclay platelets in paraffin wax via ultrasonication increased the storage modulus, whereas the effect on the loss modulus was temperature‐dependent. The melt rheology data of the wax–clay nanocomposites at 70°C showed that the complex viscosities increased monotonically with clay addition and demonstrated shear‐thinning behavior for frequencies between 0.1 and 100 rad/s. The complex viscosity versus angular frequency data were well fit by a power‐law function for which the shear‐thinning exponent provides a gauge for the extent of clay exfoliation. The nanocomposites exhibited low‐frequency solid behavior, which indicated good exfoliation of the organoclay in the wax matrix. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Bleeding of cement pastes containing paraffin wax emulsions and clays

Bleeding properties were studied in cement pastes containing a number of different paraffin wax emulsions and clays. Bentonite suspensions and wax emulsions which were unstable in the presence of cement paste filtrate, reduced bleeding rates and capacities more effectively than kaolin suspensions or stable wax emulsions. Additions of calcium lignosulphonate diminished the efficiency with which wax emulsions and bentonite reduced bleeding in cement pastes.     

石蜡中下游产品开发与应用

介绍了国内外石蜡和特种蜡、专用蜡的生产情况 ,列出了各行业对石蜡特性的要求 ,简要介绍了石油蜡中下游产品的开发途径以及我国与发达国家之间的差距     

特种乳化石蜡的制备及应用进展

介绍了我国石蜡生产现状及石蜡乳化方法,并根据我国石蜡乳化工艺现状,总结了特种乳化石蜡制备工艺环节影响因素及最佳操作条件。立足于我国石蜡市场现状,综述了特种乳化石蜡在汽车制造业、农业、陶瓷工业等行业中的用途及其发展路线和市场前景。     

Swelling and electrical properties of rubber vulcanizates loaded with paraffin wax

The influence of the concentration of paraffin wax on the penetration rate, P, and the average diffusion coefficient, D, of kerosene in an SBR–NR composite and also on the coefficient of viscosity were investigated. All decreased with the addition of wax. Also, the effect of the concentration of paraffin wax on both the current–voltage characteristics and the temperature dependence of the dc electrical conductivity were studied. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3169–3177, 2001     

Phase morphology and compatibilization mechanism in ternary polymer blend systems of polyethylene terephthalate,polyolefin rubber,and ionomer

The phase morphology and the mechanism of the compatibilization in ternary blends of PET/EBM (ethylene buten rubber)/ionomer (partially neutralized ethylene and methyl methacrylic acid copolymer, EMAA) are examined. Applying the repulsion idea in random copolymer, the ionomer was selected as an encapsulating agent to compatibilize PET/EBM blend. As anticipated, the ionomer can encapsulate EBM in PET matrix and effectively compatibilize PET and EBM. The results of droplet sandwich experiments verified that the actual driving force for the encapsulation is wettability. In addition, this wettablility was found to be realized by the contribution of the polar and nonpolar units in the ionomer: The polar units decrease the interfacial tension between PET and the ionomer, and the nonpolar units decrease that between EBM and the ionomer. The metal ions in the ionomer have little influence on the wettability, and consequently EMAA can encapsulate EBM even when unneutralized. The efficiency of the compatibilization, on the other hand, is not determined by the wettability only, and the metal ions play an important role. EMAA can effectively compatibilize EBM and PET only when neutralized. This compatibilization effectiveness of the ionomer is supposedly due to the strong interaction between PET and the metal ions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1567–1576, 2004