舰船用辐射交联无卤阻燃电缆护套料的研究

应用γ射线辐射交联技术,制备出以乙烯－醋酸乙烯/茂金属聚烯烃弹性体/纳米级改性氢氧化铝（EVA/POE/ ATH）为基材的舰船用无卤阻燃电缆护套料,探讨了共混物配比、ATH的种类与用量以及辐射剂量对材料力学性能和阻燃性能的影响。结果表明,随着POE用量的增加,材料的拉伸强度和断裂伸长率增加,耐热老化性能提高,但硬度降低;纳米ATH的加入使材料具有较好的阻燃性能;材料的辐射交联工艺可弥补阻燃剂对材料力学性能的影响,在辐射剂量为80 kGy的条件下,采用EVA /POE/ATH ＝90/10/60（质量份数,下同）的共混体系可制备出综合性能优异的护套料。     

二次辐照对交联聚乙烯结构和性能的影响及其应用

研究了辐照对高密度聚乙烯(HDPE)、低密度聚乙烯(LDPE)、线型低密度聚乙烯(LLDPE)、乙烯-乙酸乙烯酯共聚物(EVA)及其共混物性能的影响。将辐照交联后的聚合物经扩张定型后再次辐照,考察了二次辐照对交联结构的影响,并利用二次辐照法制备了一种新型热收缩套管产品。结果表明:随着辐照剂量的增加,样品的凝胶含量增大,拉伸强度先增大后减小,而断裂伸长率则逐渐降低;二次辐照后,样品的形变回复率随着辐照剂量的增加显著降低;所制备的热收缩套管两端收缩率大、中间部分收缩率小,实现了同一制品不同部位收缩倍率的可控性,具有良好的应用前景。     

水合氧化铝阻燃EPDM/PP的性能研究

用氧指数测定和力学性能测定方法研究了水合氧化铝 ( ATH)的用量及粒径对共混物性能的影响。结果表明 ATH对 EPDM/ PP有一定的阻燃作用和消烟作用 ,但使其拉伸强度和断裂伸长率降低。随其用量增加和粒径变小 ,阻燃效果提高 ;粒径对阻燃性能的影响随用量增大影响也增大。少量使用 ATH时 ,粒径对拉伸强度影响不大 ,但对断裂伸长率影响明显 ;随用量增大 ,粒径对拉伸强度和断裂伸长率的影响也增大。     

硅烷交联无卤阻燃EVA的制备与性能

制备了硅烷接枝交联乙烯-醋酸乙烯酯共聚物(EVA)/氢氧化镁(MH)/氢氧化铝(ATH)复合材料。结果表明:过氧化二异丙苯引发硅烷接枝交联EVA的凝胶含量高于过氧化苯甲酰,硅烷接枝交联EVA的难易顺序为乙烯基三甲氧基硅烷乙烯基三乙氧基硅烷3-甲基丙烯酰氧基三甲氧基硅烷;阻燃剂用量一定时,交联阻燃EVA的拉伸强度和断裂伸长率都低于非交联阻燃EVA,二者的拉伸强度都随MH含量的增加而降低,LOI都随MH含量的增加先增加后降低,交联阻燃EVA的LOI比未交联的提高了约1%;MH阻燃的交联EVA热分解温度比纯EVA的提高了20～30℃,ATH阻燃的则降低了约5℃;ATH和MH具有协同效应,二者的最佳配比约为2:1。     

SBS/CPE共混物辐射效应研究

研究了不同辐照剂量下苯乙烯-丁二烯-苯乙烯嵌段聚合物（SBS）／氯化聚乙烯（CPE）共混物的动态流变性能及力学性能。结果表明：随着辐照剂量的增大，共混物的粘流活化能降低，温度敏感性减弱；共混物拉伸强度和断裂伸长率下降，凝胶含量增加。     

PP-硅橡胶-LLDPE三元共聚物的合成及性能研究

以聚丙烯(PP)为基体树脂,硅橡胶为增韧剂,线性低密度聚乙烯( LLDPE)为辅增韧剂,制备了一系列的PP/硅橡胶LLDPE的三元共聚物,考察了PP填充不同配比的硅橡胶共混物的力学性能.结果表明,随着硅胶含量不断的增加,样条的断裂伸长率,弹性模量,冲击强度逐渐增加,样条的拉伸强度随着硅胶的增加而逐渐减少;LLDPE的加入量为15％时,PP/硅橡胶/LLDPE的三元共混体系力学性能最佳;硅橡胶的加入量为20％时,PP/硅橡胶/LLDPE的三元共混体系具有良好的拉伸性能和冲击强度.     

HDPE/EVA二元共混物敏化辐射交联与性能

以三烯丙基异氰脲酸酯(TAIC)为交联敏化剂,采用电子束对高密度聚乙烯(HDPE)与乙烯-乙酸乙烯酯共聚物(EVA)的共混物进行辐射交联。研究了TAIC的敏化作用机理以及辐照剂量对共混物的力学性能、电学性能以及结晶度与交联度之间的相互关系。结果表明:TAIC对共混体系的交联反应具有敏化作用,可显著减小辐射剂量,共混物产生交联反应后可获得较高的凝胶含量;在辐射剂量120 kGy时,1%的TAIC即可使复合材料的拉伸强度提高了20%,断裂伸长率达到475.4%。此外,电子束辐射并未改变复合材料的晶型,随着辐射剂量的增加,复合材料的结晶温度、熔点、介电常数下降,共混物的介电损耗在120 kGy剂量下达到最佳。     

两类无卤阻燃体系对mPE树脂基体阻燃和力学性能的影响

以乙烯-辛烯共聚物(POE)及乙烯-醋酸乙烯酯共聚物(EVA)为增韧剂、马来酸酐接枝线型低密度聚乙烯(LLDPE-g-MAH)为增容剂,分别采用磷氮阻燃剂(PN)和纳米蒙脱土(nano-OMMT)、氢氧化铝(ATH)和氢氧化镁(MH)阻燃体系,利用双螺杆挤出和注射成型制备无卤阻燃茂金属聚乙烯(mPE)复合材料。测试并分析了PN/nano-OMMT/mPE、ATH/MH/mPE和PN/ATH/MH/mPE复合材料的热稳定性、阻燃和力学性能。结果表明,与mPE树脂基体相比,ATH/MH的热分解温度范围较大。PN/nano-OMMT的阻燃效率高于ATH/MH。当PN/nano-OMMT含量为50%时,PN/nano-OMMT/mPE的LOI为30.8%,垂直燃烧等级达到UL 94 V-0级;当ATH/MH含量由40%增大至70%时,mPE复合材料拉伸强度从10.86 MPa增大至12.48 MPa,断裂伸长率从539%下降至109%。在满足阻燃性能相同的条件下,PN/nano-OMMT/mPE的断裂伸长率高于ATH/MH/mPE,但拉伸强度较低。10%PN部分替代ATH/MH后,60%PN/...     

低密度聚乙烯/聚乳酸共混物性能的研究

利用熔融成型法制得不同聚乳酸(PLA)质量分数的低密度聚乙烯/聚乳酸(PE–LD/PLA)共混物,并对PE–LD/PLA共混物的结构和性能进行研究。结果表明,共混物中PLA相与PE–LD相之间没有发生化学反应,它是PLA与PE–LD的一种简单混合物。共混物中的PLA含量对其力学性能和亲水性均有很大影响。随着PLA含量的增加,共混物的断裂伸长率逐渐降低而拉伸强度和拉伸弹性模量逐渐增大,共混物的亲水性增加,且随着降解时间的增加,共混物的断裂伸长率轻微增加而拉伸强度和拉伸弹性模量小幅度降低,这些现象均与PLA是一种强度高但柔韧性较差的亲水性高分子材料有关。     

热塑性聚酯弹性体共混改性线性低密度聚乙烯

采用熔融共混法制备了线性低密度聚乙烯(LLDPE)/热塑性聚酯弹性体(TPEE)共混物,借助电子万能材料试验机、差示扫描量热仪等手段,研究了共混物的结晶行为和力学性能。结果表明,少量TPEE对LLDPE结晶的完善性有一定影响,LLDPE的结晶度稍有减小,断裂伸长率和拉伸强度均有提高。随着TPEE用量的增加,LLDPE的断裂伸长率和拉伸强度先升高后降低,当TPEE的质量分数在2%~3.5%时,分别有最大值851.1%和18.758MPa。     

Vinyl acetate content and electron beam irradiation directed alteration of structure,morphology, and associated properties of EVA/EPDM blends

A series of ethylene vinyl acetate/ethylene–propylene diene elastomer (EVA/EPDM) blends with four types of EVAs with various vinyl acetate (VA) content, are prepared without and with crosslinker, trimethylol propane triacrylate (TMPTA). These are irradiated by electron beam (EB). As the VA content increases, the gel content, i.e., degree of crosslinking of EVA/EPDM blends, is increased. With increase in VA content, the modulus and tensile strength are decreased but elongation at break is increased due to increase in amorphousness. On EB irradiation, modulus and tensile strengths are increased but at the cost of elongation at break. Crystallinities of all blends are decreased with increase in VA and EB crosslinking. The thermal stability of EVA/EPDM blend is decreased with increase in VA content but increased after EB irradiation. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) show that with increase in VA content the miscibility of two polymers keeps on increasing, which even become more after EB irradiation. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43468.     

Effects of irradiation on the mechanical,electrical, and flammability properties of (low‐density polyethylene)/(ethylene‐[vinyl acetate] copolymer) blends containing alumina trihydrate

Alumina trihydrate (ATH) was added to (low‐density polyethylene)/(ethylene‐[vinyl acetate] copolymer) blends (LPEs) to enhance their flame resistance. The addition of substantial amounts of ATH has been known to have deleterious effects on the mechanical properties of such blends. Hence, electron beam irradiation was used to improve the mechanical properties of our ATH‐filled LPE specimens. The specimens were irradiated at 50 to 150 kGy before being cut into specified shapes for analysis. The increase in the irradiation dosage increased the gel content as a result of the formation of crosslinked networks. Also, the flame resistance of the LPE blends was enhanced by increasing both the loading level of ATH and the irradiation dosage. However, a high ATH loading level reduced tensile strength and elongation at break. Nevertheless, the electron beam irradiation maintained the tensile strength and elongation of the ATH‐filled blends. In addition, a higher content of ATH in the LPE blends showed reactive interaction with irradiation effects. A higher amount of ATH reduced the electrical resistivity of the blends, but analysis of their surface and volume resistivity showed that the electrical resistance of the ATH‐filled LPE blends could be improved by electron beam irradiation in the range of 50 to 150 kGy. J. VINYL ADDIT. TECHNOL., 20:91–98, 2014. © 2014 Society of Plastics Engineers     

Effect of electron beam irradiation and vinyl acetate content on the physicochemical properties of LDPE/EVA blends

The radiation‐induced crosslinking, compatibility, and surface modification of low density polyethylene/ethylene vinyl acetate blends (LDPE/EVA) were investigated. The structural and physical properties were characterized in terms of gel content, hot set, mechanical properties, contact angle, and surface free energy. The highest crosslink density was obtained at 20 wt % of EVA. Gel content of LDPE/EVA blends was increased with increasing irradiation dose, vinyl acetate (VA), and EVA contents. The hot set results are consistent with the gel content data. Mechanical testing showed that the tensile strength of samples increased with increasing irradiation dose up to 180 kGy, whereas the elongation at break was decreased with increasing irradiation dose. Contact angle measurements showed that the surface hydrophillicity of LDPE blend was increased with increasing irradiation dose and contents of both VA and EVA. The surface free energy was greatly dependent on irradiation dose and content of both VA and EVA. The total surface free energies of different LDPE formulations were in the range 17.25–32.51 mN/m, in which the polar (^pσ) and disperse (^dσ_s) values were within the range 16.52–26.6 and 0.9–5.91 mN/m, respectively. In conclusion, electron beam irradiation and blending LDPE with EVA improved the wettability or adhesion properties of LDPE/EVA blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Studies on Linear Low-Density Polyethylene Functionalized by Ultraviolet Irradiation and Its Compatibilization

Summary Some groups containing oxygen such as C-O, C-OH and C=O were introduced onto the molecular chains of linear low-density polyethylene (LLDPE) through ultraviolet irradiation in air. The concentration of these groups containing oxygen increased with increasing irradiation time. After irradiation, the molecular weight of the LLDPE decreased, and its distribution widened. It was found that the gelation occurred after the LLDPE was irradiated for 12 h, and the gel content increased with increasing irradiation time. The crystal shape and space of the crystalline plane for irradiated LLDPE remained. Compared with those of LLDPE, the melt flow index, tensile strength and elongation at break of the irradiated LLDPE decreased, but its hydrophilicity increased and its toughness retained good. The polyamide 66 (PA66)/LLDPE/irradiated LLDPE blends were prepared by blending a small percentage of irradiated LLDPE with PA66. The melting temperature and crystallinity of both the LLDPE and PA66 components in the blends decreased with increasing irradiation time. The compatibility, dispersion and interfacial interaction between PA66 and LLDPE were improved after blending. With the addition of 5% LLDPE irradiated for 36 h, the tensile strength, bending strength and notched impact strength of the blends was enhanced from 48.3 MPa, 64.8 MPa and 30.8 J/m to 57.4 MPa, 71.5 MPa and 101.2 J/m, respectively.     

White Rice Husk Ash Filled Natural Rubber/Linear Low Density Polyethylene Blends

Abstract

Natural rubber (NR)/Linear low density polyethylene (LLDPE) blends were prepared using an internal mixer at 150°C and a rotor speed of 55 rpm. The tensile strength, tensile modulus and hardness increase with increasing LLDPE content whereas elongation at break and mass swell show decreasing trend. With 30/70 (W/W) NR/LLDPE blends, the increasing white rice husk ash (WRHA) loading also increases the tensile modulus and hardness but reduced the tensile strength, elongation at break, and mass swell.     

The Role of Selectively Located Commercial Graphene Nanoplatelets in the Electrical Properties,Morphology, and Stability of EVA/LLDPE Blends

Graphene nanoplatelets (GN) produced on a large scale by mechanochemical exfoliation of graphite are incorporated in a co‐continuous ethylene‐vinyl acetate/linear low‐density polyethylene (EVA/LLDPE) blend. Two different processing routes are chosen to selectively place GN in the EVA phase or force its migration to the EVA/LLDPE interface. The results show a drastic decrease in the electrical percolation threshold when the blends are compared to the respective single‐polymer composites. Even with the presence of agglomerates, GN particles are able to migrate to the blend interface and stabilize the morphology and hence the electrical properties. Annealing the insulating samples at processing temperatures causes a drastic increase in conductivity due to continued GN migration and blend morphology coarsening. Semi‐conductive samples, in which a more robust GN network is already established during processing, present no change in morphology but a slight increase in conductivity during annealing. The mechanical performance of the materials is also evaluated and some of the blends with GN present similar elongation at break as pure EVA, but with increased tensile modulus and tensile strength. The electrical performance at different working temperatures shows that the EVA/LLDPE/GN composites are good candidates to act as a semi‐conductive screen material in power cables or as anti‐static materials in electronic devices.     

辐射交联LDPE/EVA混合体系泡沫片材性能的研究

辐射交联LDPE/EVA混合体系泡沫片材表观光滑、柔软,手感好,表观密度较小,材料具有优异的力学性能,较高的拉伸强度、断裂伸长率和撕裂强度。进一步研究了产生宏观性能差异的原因是辐射交联LDPE/EVA混合体系泡沫片材制备成型工艺的特殊性,体系的交联度对制品性能影响很大。通过凝胶分析知道交联度与辐照剂量、LDPE树脂的物理性能和EVA树脂在混合体系的含量有关。此外,LDPE树脂的物理性能和EVA在混合体系的含量对材料宏观性能也有影响。     

PP/LLDPE交联共混物的力学性能研究

采用两步交联加工法制备出具有优良力学性能的PP／LLDPE共混物。实验表明：当m(PP)／m(LLDPE)／m(SBS)／m(交联剂)为80／20／10／3时，交联共混物的冲击强度、拉伸强度和断裂伸长率分别达到466．3J／m、27．1MPa和715．1％，比未交联的共混物分别提高262％、8．28％和115％；交联作用的存在使共混物的脆韧转变点明显提前；随交联剂用量的增加，共混物的力学性能不断提高，但增大趋势逐渐变小。