Relationships between Processing Parameters and the Foaming Performances of Polyethylene for Coaxial Cable Insulation

Coaxial cable is cable that transmits electrical energy and signal from the receiver devices to the antenna in the base station. Nowadays, as the telecommunication technology develops, demand for a high signal quality is required in the coaxial cable. In this cable, the electromagnetic signal passes through the insulation, which is usually composed of foamed high-density polyethylene (HDPE)/low-density polyethylene (LDPE) blend. To improve the dielectric properties of insulation and reduce the signal power loss (attenuation), it is necessary to increase the foaming rate of insulation. In this study, two types of foaming experiments were performed: batch type foaming and continuous extrusion foaming. The relationship between the foaming rate and the electrical properties of insulation was investigated in the batch type foaming process. Also, the effects of processing conditions, such as resin composition, die temperature, screw speed, and pressure drop rate of die on the foaming performances were studied in the continuous foaming extrusion for coaxial cable insulation.     

高性能LLDPE电缆护套的研制

采用扬子石化公司生产的LLDPEX基体树脂制备通信电缆用黑色LLDPE电缆护套料,研究了电缆护套料各组分选择、用量和加工工艺对其性能的影响,给出了成型电缆护套的工艺条件。结果表明,该电缆护套料的配方合理、加工工艺可行,性能达到了国家标准要求,尤其是拉伸强度、断裂伸长率、耐环境应力开裂等性能优异。该电缆护套料的加工性能可满足生产通信电缆外层护套的要求,生产的护套的各项指标均达到邮电部标准要求。     

热挤HDPE护套在桥梁缆索防护中的应用

选择热挤高密度聚乙烯(HDPE)护套对桥梁缆索索体进行防腐保护,介绍热挤HDPE护套的成型工艺及性能。结合工程实践,探讨热挤HDPE护套的成型缺陷及应用中的变色、老化和龟裂、破坏和修补、质量检验等问题,并提出了相应的解决措施。     

Coated metals compatible with PVC jackets for bonded sheath cable applications

Mechanical strength in the cable sheath is particularly valuable for both fiber optical and copper pair cable. By bonding a PVC jacket to a coated metal tape, a mechanically strong sheath construction is obtained. Changes in PVC jacket technologies have created the need for PVC compatible coated metals with greater tolerance for variations in PVC jacketing materials. This need has been met by the development of a variety of coated metals having thermoplastic coatings which adhere to PVC. As a consequence of this development, new cable sheath designs for use in a variety of applications, such as riser cable and direct buried cable destined for local area networks, are possible. These cables may utilize both copper conductors and/or optical fibers for signal transmission. Data will be provided in the paper to show the effects of extrusion process conditions on adhesion for a variety of PVC resins. The properties of a variety of coated metals—aluminum, copper, and steel—will be discussed. Data on environmental tests of adhesion will be presented. Relationships between adhesion, metal characteristics, jacket properties, and mechanical performance of the sheath will be discussed. Cable applications for the PVC compatible metals will be discussed. Data on the performance of the bonded sheath in riser cable and buried local area network cable will be presented. New cable applications where coated metals in the sheath can provide lightweight armoring will also be discussed.     

Effect of co-additives on the flame/smoke suppression properties of zinc borates

Two zinc borates are useful partial replacements for the antimony oxide flame retardant normally used to flame retard flexible PVC products. The effect of using various co-additives with zinc borates on the flame retardancy and smoke formation of a model flexible PVC cable jacket was evaluated in an attempt to further improve the properties of the formulation. The use of ammonium octamolybdate with the borates yields products with improved properties. Highly flame retarded formulations that yield low levels of smoke can be prepared by using alumina trihydrate or magnesium compounds as replacements for the usual calcium carbonate filler. Replacement of part of the phthalate ester plasticizer with brominated ester, a phosphate ester, or a brominated phosphate ester also results in formulations with oxygen values as high as 39.5 which produce lower levels of smoke.     

Development of potentially degradable materials for marine applications. III. Polyethylene-polyethylene oxide blends

The effect of a simulated marine environment on unstabilized polyethylene-polyethylene oxide blends, having varying polyethylene oxide content (up to 40% by weight), with or without a metal catalyst (e.g., cobalt (III) acetylacetonate) and a metal containing plasticizer (e.g., aluminum stearate), has been studied for 10 weeks exposure time. In the absence of metal catalyst and plasticizer, phase separation of polyethylene oxide was quite evident visually after melt mixing and subsequent regular compression molding of polyethylene-polyethylene oxide blends. However, these blends rendered better and uniform mixing in the presence of metal catalyst and plasticizer. Since polyethylene oxide is a water soluble component of the system, % weight loss increased significantly with increase in its content after exposure to brine. These blends have been further characterized by tensile properties, optical and scanning electron microscopy, and thermal analysis in order to monitor mechanical as well as morphological changes.     

Study of the electrical properties of flame retardant poly(vinylchloride) using positron annihilation lifetime spectroscopy

Since the large fire at the Brown Ferry cable plant which occurred at noon on March 22, 1975 in Alabama, attention has been given to the use of flame retardant cable in buildings to meet fire safety requirements. Flame retardants are used in wire and cable applications to prevent the conversion of an electric spark into fire and subsequently to prevent the spread of fire throughout a structure along the wiring. There are many substances used as flame retardants in wires and cables. In Egypt, Multi‐Purpose Reactor insulation and jacket cables have been constructed from a flame retardant substance, poly(vinylchloride) (PVC). In the present work, elemental and X‐ray fluorescence analyses have been performed to determine the composition of PVC in the jacket cable samples. In addition, the conductivity (σ), permittivity (?′), and dielectric loss (?″) as well as positron annihilation lifetime (PAL) are measured in the temperature range 30 to 140 °C. It is found that the amount of chlorine in the flame‐retardant PVC (FRPVC) jacket cable is significantly higher (5%) than the conventional PVC jacket cable. Inverse relationships between σ and free volume size and fractions (V, f) through the temperature range are obtained. However, a distinct positive relationship between σ and I₂ above 100°C is found. The results of PAL and electrical measurements indicate that FRPVC has good electrical insulation properties below 100°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 638–644, 2005     

塑化剂对玉米醇溶蛋白膜表面及机械性质的影响

研究了塑化剂种类(甘油、油酸和聚乙二醇)、用量对玉米醇溶蛋白(zein)膜表面和机械特性的影响及塑化剂对zein成膜液黏度、成膜后表面形貌、水分吸附特性的影响。结果表明:含油酸的成膜液黏度最大,含甘油的成膜液黏度最小,成膜后表面呈现不同的形貌图;蛋白膜的水分吸附特性与塑化剂亲水性变化趋势一致,随甘油、聚乙二醇和油酸顺序而下降;油酸和聚乙二醇塑化的zein膜的表观接触角随塑化剂含量的增加而增加,甘油膜却呈相反趋势;蛋白膜表面润湿动力学可用指数方程模型表征,动态接触角变化速率表现为甘油膜聚乙二醇膜油酸膜;随塑化剂含量增加,聚乙二醇蛋白膜抗拉强度(TS值)下降,延伸率(EB值)却急剧增加,甘油和油酸蛋白膜的TS值和EB值具有相同的变化趋势但效果不明显。     

耐环境应力开裂的PE电（光）缆护套料的研制

从结构、组成、工艺3个方面阐述了导致黑色LDPE电(光)缆护套料的开裂机理,从而针对性地提出了改进其耐环境应力开裂的具体方法。采用双螺杆挤出机组制备护套料新工艺所制得的电(光)缆护套料的环境应力开裂性能及其他性能指标均达到或超过国家标准要求。     

Improvement of flame-retardant properties of insulated wires by radiation crosslinking

Electric wires coated with polyethylene insulation crosslinked by a chemical method (gel fraction = 80%) and a jacket of self-extinguishing resin were produced. The jacket was crosslinked by irradiation with γ rays or accelerated electrons. Flame retardant properties of the wire improved by γ-ray induced crosslinking up to ～60% gel fraction in the jacket. Beyond this point, however, the flame resistance rapidly decreased with increasing gel fraction. The flame resistance was also improved by irradiation with electrons, but the extent of the improvement was strongly dependent on the energy of incident electrons. This fact was attributed to the difference in the distribution of energy dissipation, i.e., crosslinks formed in the jacket. By introducing a double layer structure to the jacket, in which the inner layer adjacent to the polyethylene insulation was crosslinked more densely than the outer layer, the wires were markedly improved in resistance to flame and heat deformation.     

PVA@tea tree oil-emulsion core–shell microfiber membranes for extending the shelf life of fruits

In this work, a temperature-regulating and antimicrobial–antioxidant fiber membrane was fabricated using coaxial electrospinning technology. The tea tree oil (TTO) emulsion used as the core solution, polyvinyl alcohol (PVA) as the shell solution for coaxial electrospinning, has been demonstrated. Compared with the original PVA fibers, the average diameter of the fibers is increased after coaxial electrospinning, and the diameter increases with the core flow rate. The diameters corresponding to core flow rates of 0.05, 0.1, and 0.15 mL/h are 561, 597, and 849 nm, respectively. Via in vitro release experiment demonstrated that the quantity of TTO released from the composite membrane increased with the elevation of temperature. The inclusions TTO and polyethylene glycol give the film excellent antibacterial–antioxidant properties and a delayed thermal response. More intriguingly, core–shell fiber membranes containing TTO in the core part are effective in slowing down the formation of oxidation spots on the surface of banana compared with pure PVA membranes. Seven days after wrapping bananas with different membranes, the surface of banana in pure PVA film was full of oxidized spots, whereas banana in PVA core–shell fibers showed only one obvious spot.     

Parameter Design of a Coaxial Cable Insulation Manufacturing Process Using Axiomatic Design and the Taguchi Method

In modern industries, the development of communication mediums requires high-frequency communication networks in which signal reduction by dielectric loss is increased. Accordingly, the need for an insulator with low permittivity also has grown, making the production of highly foamed insulators now necessary. Considering the mechanical and electrical properties of such insulators, benefits can be seen in multiresponse problems with higher densities of uniform-specific cell size.

In this paper, we describe the applicability of a highly foamed polyolefin extrusion process to the manufacturing of insulation for coaxial cable. Moreover, a combination of axiomatic design and the Taguchi method was utilized for solving the multiresponse problem. Through this technique, we propose a new method for optimizing multiresponse problems. Development of manufacturing processes for insulating coaxial cable, and responses for each process variable, become possible with this method.     

输电母线专用PVC塑料的试制

以PVC树脂、耐高温增塑剂为主要原料,以PE—C为改性剂,试制出扁铜线挤出包覆的输电母线专用料,其氧指数不小于32％,各项性能符合GB 8815—88《电线电缆用软PVC塑料》中J-105和JGD-70要求,制成的输电母线其PVC塑料包覆层符合GB12706,1—91《额定电压为35kV及以下铜芯、铝芯塑料绝缘电力电缆》中PVC/A类要求。     

Determination of PVC cable insulation degradation

Assessing the degradation of electrical cable insulation is an important feature in extending plant life. The older generating stations are extensively wired with PVC insulated cables, and procedures have been developed to assess degradation using micro specimens in a manner that does not destroy the function of the cable. Material degradation of accelerated aged specimens was systematically monitored by measuring melting or glass transition temperatures ( Tg ), gel content, infrared peroxide absorbance, relative hardness, and plasticizer loss. The shift in the Tg or the characteristic melting peak predicted the maximum exposure temperature of the PVC. The peroxide absorbance and gel content measurements were sensitive indicators of degradation. The relative hardness as measured by thermo-mechanical analyzer (TMA) penetration distance and plasticizer content decreased as the material aged. The results obtained on micro specimens were related to the ultimate elongation values, which have been the traditional measure of degradation.     

提高PVC电缆料电绝缘性能的研究

通过研究增塑剂和绝缘改进剂与PVC电缆绝缘料体积电阻率、介电常数和介质损耗角之间的关系 ,建立了增塑剂和绝缘改进剂含量与电性能之间的关系曲线 ,从而确定了可满足程控交换机应用的、具有良好电性能的PVC电缆料配方     

柔性塑料保温管及其生产技术

柔性塑料保温管是由介质管、保温层、夹克管构成的复合型保温管,采用薄壁钢、软铜或交联聚乙烯这类具有柔韧性的材料作为介质管,同样采用具有高度柔韧性的聚氨酯泡沫保温层和聚乙烯夹克管,通过连续法生产工艺技术生产出性能优良,符合使用要求的柔性复合保温管。     

增塑剂对PVC电缆料电性能的影响

介绍了DBP、TPP、DOP、TOTM、TCP、DIDP及M－50等增塑剂在不同用量时对PVC电缆科电性能的影响：随着增剂用量的增加,PVC电缆料的电性能一般呈下降趋势。实验发现TOTM和TCP两种增剂的电性能较优,其最佳用量为35－40份。     

低挥发环保增塑剂对苯二甲酸二（2⁃丙基庚）酯的应用研究

以对苯二甲酸和2?丙基庚醇为原料,在钛酸异丙酯为催化剂的条件下制备对苯二甲酸二（2?丙基庚）酯（DPHTP）,并将DPHTP作为增塑剂用于制备聚氯乙烯（PVC）柔性薄膜,与市售DOP和DOTP进行应用性能的比较。通过傅里叶变换红外光谱和核磁共振氢谱对产物进行结构分析;通过热失重分析、拉伸测试、耐迁移测试和耐挥发性测试等比较DPHTP、DOP以及DOTP增塑的PVC薄膜在力学性能等方面的差异。结果表明,相比DOP和DOTP,DPHTP具有更低的挥发性,其增塑的薄膜有着更优异的热稳定性以及更高的体积电阻率;其中,DPHTP的加热减量为0.031 90 %,DPHTP增塑的薄膜的热失重5 %的温度为272 ℃,体积电阻率为6.5×10⁹ Ω·m;DPHTP具有更低的挥发性且可以赋予PVC材料优异的电绝缘性能,在包装材料和电线电缆行业具有广阔的开发前景。     

低烟无卤阻燃电缆护套用乙烯－丙烯酸酯弹性体胶料

以乙烯－丙烯酸酯弹性体为主体材料，用过氧化物硫化，填充氢氧化铝。硅烷偶联剂处理的锻烧陶土、ＬＥＥ白滑粉及超细滑石粉等，制成了低烟无卤阻燃电缆护套用胶料，其成品电缆的技术指标可以满足ＧＢ９３３１，ＧＢ１２６６６，ＩＥＣ５０２（１９９４）等标准的要求。     

橡胶型氯化聚乙烯在电缆料行业的开发及应用

简要概述了氯化聚乙烯橡胶在电缆料行业中的应用及其相对于氯丁橡胶和氯磺化橡胶的性能及成本优势。对电缆料行业中氯化聚乙烯的技术开发现状进行了概述,包括生产工艺、生产设备、生产原料及电缆料配方设计。同时对氯化聚乙烯橡胶的应用前景及应用技术发展思路也进行了简要说明。