熔融共混色粉对滚塑级交联聚乙烯性能的影响

研究了熔融共混与物理干混着色对交联聚乙烯滚塑制品外观、热熔加工性能、产品力学性能和结晶性能的影响。采用旋转流变仪、光学显微镜、万能材料试验机、差示扫描量热仪分别表征了材料的熔融加工性能及交联度、制品的外观色泽、力学性能和结晶性能。结果表明:熔融共混法制得的交联聚乙烯滚塑制品外观色泽更亮丽,色粉微观分散更均一,内表面更光滑;熔融共混法添加一定量的色粉不会明显影响交联聚乙烯的熔体加工性能,但交联后熔体黏度有所降低;少量色粉在交联聚乙烯结晶过程中起到异相成核剂作用,提高了制品的结晶度,不仅对滚塑制品的缺口冲击性能影响极小,而且其弯曲模量有一定提高。     

滚塑用交联聚乙烯的结构与性能

采用凝胶渗透色谱、升温淋洗分级、差示扫描量热法等对自制滚塑用高密度交联聚乙烯(XLPE-100)和进口滚塑用高密度交联聚乙烯(XLPE-i)的分子结构、交联动力学以及交联后试样的力学性能等进行了对比。结果表明:与XLPE-i相比,XLPE-100的重均分子量略大,相对分子质量分布宽,结晶性能较好,交联反应活化能及起始交联温度较高,交联反应半交联时间短,具有较好的加工与成型性;XLPE-100交联后试样的弯曲模量、断裂拉伸应变以及缺口冲击强度高于XLPE-i,具有较好的力学性能。     

磨粉温度对交联聚乙烯滚塑加工性能及其力学性能的影响

考察了磨粉温度对自制滚塑级交联聚乙烯材料粉体特性和力学性能的影响,分析和比较了不同磨粉温度下粉体颗粒形貌、流动性、松装密度、粒径分布、流变特性、滚塑加工性能以及制品冲击强度、弯曲模量等,以筛选合适的磨粉温度区间。研究结果显示,随磨粉温度升高,粉体流动性提高、松装密度增加、颗粒形貌改善,滚塑加工性能逐渐提高;但冲击性能逐渐降低,流变测试的复数黏度及交联度逐渐下降。结合粉料的各项性能,选择磨粉温度在45~55℃,所制交联聚乙烯粉料兼具较高流动性(滚塑加工性能)、较优力学性能(使用性能)。     

滚塑成型PE-X交联度试验方法的探索

本公司生产的防腐龟甲衬里产品,就是利用滚塑成型法,将交联聚乙烯衬塑在钢制制品上,使之钢制品的高强度和交联聚乙烯的耐腐蚀性能得到互补。针对滚塑成型法生产的交联聚乙烯产品的交联度没有相应的实验方法,依据挤出法生产的交联聚乙烯产品交联度的检测方法对滚塑法成型的交联聚乙烯产品的交联度试验方法进行探索实验。     

防腐、耐磨滚塑复合钢管技术

介绍了滚塑技术、滚塑复合钢管的优点.阐述了交联型聚乙烯滚塑复合钢管、聚苯硫醚滚塑复合钢管、改性超高相对分子质量聚乙烯滚塑复合钢管的性能和特点.     

聚乙烯滚塑专用料的开发

利用Unipol气相流化床工艺装置进行聚乙烯滚塑专用料的研制开发,通过聚合工艺参数的调整,生产出聚乙烯滚塑专用料YLR-3505,并从常规物性、热行为、分子序列、相对分子质量及其分布、加工应用情况等几方面对YLR-3505和进口聚乙烯滚塑专用料样品进行分析表征.结果表明,YLR-3505聚乙烯滚塑专用料的综合力学性能、加工成型性及制品长期耐老化性能均类同于进口产品.     

滚塑用V-0级阻燃交联聚乙烯的制备及其性能研究

利用十溴二苯乙烷(DBDPE)与三氧化二锑(Sb_2O_3)组成的卤锑阻燃剂对交联聚乙烯进行阻燃改性,研究了阻燃剂含量对交联聚乙烯材料阻燃性能的影响,材料含22.5%DBDPE和7.5%Sb_2O_3在UL94阻燃测试达到V-0等级。通过体系树脂熔体流动性的优化,可改善高填充量阻燃剂时材料的滚塑加工性能。实验室制备了滚塑用V-0级阻燃交联聚乙烯,并测试了材料的机械性能包括拉伸强度、弯曲模量和缺口冲击强度等。所制材料缺口冲击强度达到43 k J/m~2。SEM和EDS表征显示阻燃剂在体系内分散较均匀。     

滚塑加工现状与发展趋势

1 国外滚塑加工业发展概况 滚塑是一种塑料中空制品的加工方法,始于40年代,但由于受较慢的加工周期及所用材料等因素的限制,使其发展速度远低于其它塑料加工行业。近20年来,由于过程控制的改进和各种塑料粉料的出现,才使滚塑制品从单层向多层、从实心向发泡制品发展。 目前世界上约有1000家滚塑企业,2/3分布在欧美国家。滚塑制品的品种随国家和地区不同而有所差异,美国的滚塑制品有玩具、箱子、容器及汽车部件等,而欧洲的制品则主要是工业部件、农业用品、汽车部件及容器等。 可用于滚塑加工的塑料有聚烯烃、尼龙、聚碳酸酯、聚酯、E/VAC、ABS和PS等。60年代开发的粉料聚乙烯给滚塑     

几种新的滚塑成型树脂

介绍几种新型商品化或实验性的滚塑制品加工厂用树脂材料(包括聚乙烯和工程塑料),这些材料都具有较高的强度、韧性和可加工性能。可用于加工制造玩具乃至大型容器罐等制品。     

滚塑成型工艺对交联高密度聚乙烯低温冲击性能的影响

采用滚塑成型方法,研究了加工条件对交联高密度聚乙烯(XLPE)制品低温落锤冲击性能和微观结构的影响。结果表明,滚塑模具内部空气最高温度(PIAT)对XLPE的-40℃的冲击强度影响大,PIAT为212℃时,-40℃的冲击强度约1 J/mm,为脆性破坏,PIAT在228~263℃时,-40℃冲击强度基本没有变化,约为30 J/mm,为韧性破坏;非等温交联动力学以及交联和结晶数据分析表明,通过优化加工条件,使制品最内层充分交联进而获得较高的交联度,较低的结晶度,获得优异的低温落锤冲击强度。     

The effect of chemical crosslinking on the properties of Rotomolded high density polyethylene

In this study, high density polyethylene (HDPE) was combined with dicumyl peroxide (DCP) to produce crosslinked parts via rotational molding. The effect of DCP content (0.1–2.5 phr) on the crosslinking degree was investigated to determine its effect on the chemical, mechanical, physical, and thermal properties of HDPE. The gel content and crosslink density was found to increase with DCP content. These trends led to a reduction in the degree of crystallinity, melting, and crystallization temperature. Thermogravimetric analysis (TGA) showed that crosslinked HDPE (xHDPE) has higher thermal stability than the neat matrix in both air and nitrogen atmosphere. In addition, a direct relationship was observed between improved thermal resistance and higher impact strength. Finally, relationships between the tensile properties of xHDPE and the degree of crystallinity were observed, which were all controlled by the level of crosslinking. These results have the potential to advance the manufacturing of high performance materials suitable for a wide range of applications such as automotive parts, agricultural products, chemical storage tanks, large waste containers, and fuel tanks in general.     

两步法硅烷交联聚乙烯及其制品加工

介绍两步法硅烷交联聚乙烯粒料的制备和性能,研究了交联聚乙烯管材成型设备结构的选择,结果表明,和普通三段式、屏障混炼头或盘式混炼头制螺杆相比,分离型螺杆是优先选用的设备;生产中应加强对A、B材料的防护和按照规程进行处理;硅烷交联HDPE管的使用寿命可长达50年,两步法在接枝率、交联度、管材成型速度和物料存放时间方面优于一步法。     

过氧化物交联聚乙烯热收缩管成型研究

简要介绍了聚乙烯高能辐射交联、硅烷化学交联和过氧化物化学交联,给出了交联前后分子结构变化的示意图,说明3种交联方法所得到的交联聚乙烯分子结构十分接近,在性能上基本没有差别。采用最新的过氧化物交联配方,并给出详细的生产工艺,使用最新研制的具有自主知识产权的活塞式挤出机加工成型交联聚乙烯热收缩管坯,并用自制的扩管装置扩张成型热收缩管。针对试验结果,对产品的凝胶率、力学物理性能和电性能进行了讨论,并比较了辐射交联、硅烷交联和过氧化物交联3种交联生产工艺在设备投资成本、产品质量控制、能耗、交联反应时间、产品的实际交联度和产品的表面质量等方面的优劣。     

Zur Verfestigung von Schüttgütern – Mikroprozesse und Kinetikmodelle

Storage tanks are important elements of a self-operating closed processing system. The reliability and availability of storage equipment essentially depends on the flow behaviour of particulate solids in storage containers. A wide residence time distribution (i.e. too long a storage time at rest) in silos, bunkers or transportation containers, respectively, can lead to the hazardous problem of so-called “time consolidation” of particulate solids. During this hardening process, solid bridges are forming with resulting solidification and solid properties of bulk material. In principle, there are four main physico-chemical effects in bulk materials storing and handling which can produce solid briding between the particle contacts due to crystallisation, chemical reactions, solidification of high-viscous bonding agents and sintering. Generally, new adhesion force based models are presented to describe the consolidation kinetics of particulate solids. Preliminary solutions of kinetic model equations are discussed and compared with new test results and practical conclusions are drawn concerning the reliable processing, storage and transportation of bulk materials.     

Design and performance evaluation of multilayer packaging films for blister packaging applications

Five multilayer packaging film structures consisting of amorphous poly(ethylene terephthalate) (APET), low‐density polyethylene (LDPE), polypropylene (PP), and acrylonitrile/methyl acrylate copolymer (Barex) films [i.e., APET/polyethylene (PE), APET/PP, APET/PE + UV inhibitor, APET/PP/PE, and APET/Barex/PP] for blister packaging applications were designed and produced. Blister containers with APET/PE and APET/Barex/PP structures were prepared, and their optical, mechanical, barrier (O₂, CO₂, and H₂O), physical, and product/package compatibility performance properties were evaluated. Package/product compatibility with simulants (soy sauce and sunscreen skin cream) at 37.8°C was evaluated for 3, 7, 14, and 28 days in the multilayer films and the blister containers. APET/Barex/PP film showed significantly better O₂ and CO₂ barrier performance than the other four film structures. The UV inhibitor had no significant effect on the barrier properties in the APET/PE film structure. All of the film structures showed high enough elastic storage modulus values to be applied to blister packaging in a broad range of temperatures between ?45 and 80°C. The glass‐transition temperature of APET, which was responsible for the elastic modulus of the multilayer structure, decreased after the samples were exposed to the skin cream. This decrease may have been due to the sorption of the skin cream's active ingredients, such as ethylhexyl methoxycinnamate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

液氢储运技术及标准化

液氢作为一种高效的储氢方式,其应用前景十分广阔,但储运技术相对落后、储运环节标准化的缺失限制了液氢产业的快速发展。本文介绍了液氢特性及发展现状,对液氢存储容器类型和运输方式进行对比分析,调研了液氢国内外相关标准现状,并讨论了液氢产业发展对标准体系的迫切需求,阐述了液氢储运技术的难点和未来发展方向,并对液氢储运标准体系的建立进行展望。分析表明,减少液氢储罐的蒸发率、有效降低储运设备成本将是液氢储运技术未来重要的发展方向,液氢储运技术的发展需要建立健全的标准体系,液化天然气相关标准体系对液氢储运标准化具有重要的参考意义。     

同质异构交联法对再生聚乙烯的改性研究

通过硅烷交联法制备了交联聚乙烯（PE）,并将其加入到水选废旧塑料薄膜再生PE颗粒中进行改性研究。通过扫描电子显微镜（SEM）对再生料冲击样条的断口进行观察,研究了交联料用量对再生PE的力学性能和加工流动性的影响;用差示扫描量热法（DSC）和X射线衍射法(XRD)研究了当交联料添加量为15份时,再生料结晶性能与交联度的关系。结果表明,添加了交联料的再生料的聚集态结构发生了变化,形成了“同质异构分散结构”,该结构会使再生料的拉伸强度和冲击强度大幅提升,而断裂伸长率和熔体流动速率则有一定程度的下降;当交联料的添加量为15份时,材料具有最佳的综合性能,且当添加量为15份、交联度为33.5 %时,再生料的结晶性能最好。     

Permeation barrier properties of polyethylene/modified blends of polyamide and polyvinylalcohol containers against methanol/gasoline fuels

One commercial grade of polyamide and/or polyvinylalcohol resins were modified by a compatibilizer precursor to make various compositions of modified polyamide (MPA) and/or modified blends of polyamide/polyvinylalcohol (MPAPVA) through reactive extrusion. Good methanol/gasoline fuel permeation resistance together with clearly defined MPAPVA and MPA laminar structures were found on containers blow‐molded from the blends of polyethylene PE/MPAPVA and PE/MPA, respectively. The compositions of MPAPVA and MPA resins were found to exhibit a significant influence on the methanol/gasoline fuel permeation resistance and morphology of PE/MPAPVA and PE/MPA containers, respectively. Possible mechanisms are proposed to explain these interesting phenomena. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2158–2169, 1999     

Effect of zone drawing accompanied with crosslinking on the structure and properties of ultrahigh molecular weight polyethylene gel film

To enhance the thermal properties of ultrahigh molecular weight (UHMW) (viscosity-average molecular weight of 6 × 10⁶) polyethylene (PE) gel film, this was crosslinked by dicumyl peroxide (DCP) during a high-temperature zone drawing, which is effective to orient film. Through a series of experiments, it turned out that crosslinking actualized by an optimum amount of DCP and high-temperature zone drawing technique caused significant changes in the structure and properties of UHMW PE gel film. That is, crosslinking increased storage modulus of UHMW PE gel film at 25°C, resulting in improving thermal properties of the film. On the contrary, the crosslinking effect played a hindering role in raising the draw ratio of UHMW PE gel film. Maximum storage modulus of 165 GPa at 25°C could be obtained at the draw ratio of 324 of uncrosslinked homo-PE gel film. In the case of crosslinked PE gel film, the highest storage modulus at 25°C reached 65 GPa at maximum draw ratio of 150. Crosslinked film exhibited high modulus, even at 190°C, to some extent, while uncrosslinked homo-PE gel film was molten completely at 150°C. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1583–1590, 1997     

Effect of Acidic and Basic Solutions on Electron Beam Irradiated Epoxy Nanocomposites Containing Nanoclay,CaCO3 and TiO2 Nanoparticles

High chemical resistance is the main prerequisites for materials that are intended to be utilized in usages such as chemicals storage containers production. Nanocomposites of epoxy resin containing nanoclay, CaCO₃ and TiO₂ nanoparticles were prepared and their chemical resistance was studied. Moreover, the effect of electron beam irradiation was explored. TEM micrographs proved the dispersion of nano-size particles in the polymeric matrix. XRD patterns showed an exfoliated structure for nanocomposite containing 1 % nanoclay and intercalated structures for nanocomposites with higher nanoclay contents. SEM showed the pits that appeared in epoxy/nanoclay structure due to chemical corrosion. Weight loss measurements revealed that an addition of 1 % nanoclay to the epoxy matrix is effective for improving the chemical properties of the polymer. Desirable effect of 100 kGy irradiation on chemical resistance properties of the samples was also observed in both acidic and basic environments.