EVA／木质素薄膜的制备与性能研究

研究了经造粒、吹塑成膜的乙烯醋酸乙烯酯共聚物（EVA）／木质素共混物的结构、热性能以及力学性能。热重分析表明木质素与EVA共混物的热稳定性比单一组分的高；差示扫描量热分析表明木质素与EVA的相容性好；傅里叶红外光谱分析表明木质素与EVA之间存在分子间氢键相互作用；扫描电子显微分析表明木质素含量对共混物形貌有明显的影响；力学性能测试表明木质素含量在30％（质量分数，下同）以内，共混物薄膜仍具有较好的力学性能，随着木质素含量的增加，共混物力学性能降低。     

尼龙6与低密度聚乙烯和乙烯—醋酸乙烯酯共聚物的共混物

本文研究了尼龙6(N_6)/低密度聚乙烯(LDPE)共混物的热和力学性能以乙烯—醋酸酯共聚物作为第三组分对N6/LDPE共混物性能的影响。共混物的拉伸强度和拉伸模量随LDPE含量的增加而降低,而断裂伸长率随LDPE含量的增加而增加。LDPE的加入可以改进N6均聚物的流动性能。热分析结果表明,共聚物中LDPE含量在10％以内,N6的熔化热和结晶度基本不变。LDPE在N6/LDPE/EVA其混物中比在N6/LDPE共混物中有较低的熔化热,但其熔点在实验误差范围内保持不变。     

改性Sb2O3协同十溴二苯乙烷阻燃LDPE/EVA的研究

采用熔融共混法制备了阻燃低密度聚乙烯/乙烯-醋酸乙烯共聚物(LDPE/EVA)复合材料,研究了表面有机化改性三氧化二锑(Sb2O3)与十溴二苯乙烷(DBDPE)在LDPE/EVA中的阻燃协效性,通过极限氧指数(LOI)、垂直燃烧等级(UL94)、力学性能和热稳定性等测试对复合材料进行研究。结果表明,DBDPE/Sb2O3复合阻燃剂对LDPE/EVA有良好的阻燃作用,经表面有机化改性的Sb2O3,较之未改性Sb2O3阻燃协效性增强,制品热稳定性提高,对力学性能影响较小。     

EVA对PP/EVA共混物力学性能的影响

将不同配比的聚丙烯(PP)和乙烯-乙酸乙烯共聚物(EVA)进行共混,测试了共混物的拉伸强度和冲击强度;用差示扫描量热法研究了共混物的结晶性能;用扫描电镜(SEM)二次电子成像系统分析了试样的断口形貌,研究了EVA含量对共混物力学性能的影响。结果表明:EVA的加入提高了EVA/PP共混体系的韧性,同时降低了PP的结晶度。     

相容剂对TPEE/LDPE共混材料的结构及性能影响研究

采用熔融挤出的方法将热塑性聚醚酯弹性体(TPEE)、低密度聚乙烯(LDPE)、乙烯醋酸乙烯共聚物(EVA)共混,固定EVA与TPEE质量比,制备了一系列不同TPEE含量的TPEE/LDPE共混物,研究了EVA对TPEE/LDPE共混物力学性能和形态变化的影响。结果表明当TPEE含量为10%时,相容剂EVA改性后的共混物力学性能最佳,拉伸强度为10.8MPa,断裂伸长率为508.5%;TPEE颗粒的尺寸更小,且分布更均匀。     

EVA对PMVS橡胶的增强改性

采用机械共混法制备了乙烯-醋酸乙烯酯共聚物(EVA)增强甲基乙烯基硅橡胶(PMVS),并对影响PMVS/EVA共混物力学性能的因素及体系的微观结构、热稳定性能进行了表征与分析.结果表明,当EVA用量相同时,醋酸乙烯酯(VA)质量分数对PMVS的力学性能有影响,其中,EVA630(VA质量分数为15%)最能有效地改善PMVS的强度; 随着EVA630用量的增加,PMVS/EVA共混物的拉伸强度先降后升,当EVA用量为40 份时,共混物的力学性能最佳;当EVA用量为40 份时,共混物的热稳定性能较好,SEM照片显示其微观形貌为双连续相结构.     

乙烯-醋酸乙烯酯共聚物对茂金属聚乙烯的改性研究

以添加不同比例的茂金属聚乙烯 (mLLDPE) /乙烯 醋酸乙烯酯 (EVA)共混物为研究对象 ,考察了EVA含量对mLLDPE/EVA共混物的力学性能、热性能、流变性能、动态力学性能和形态结构的影响。研究结果表明 ,EVA添加到mLLDPE中 ,增加了mLLDPE的剪切敏感度、降低了mLLDPE的熔融粘度、改善了mLLDPE的流动性和加工性 ;在一定的添加比例范围内mLLDPE和EVA具有很好的相容性 ,可以在改善mLLDPE加工性能、引入极性基团的同时又保持与纯mLLDPE相近的力学性能 ,但会导致共混物材料的刚性下降 ,柔性增加。热分析数据说明 ,mLLDPE/EVA共混体系中 ,在EVA含量较小时共混物存在大量共晶 ,与mLLDPE有很好的相容性 ,无论是熔融曲线还是降温曲线都只出现一个峰。当EVA含量增大时 ,mLLDPE/EVA共混物出现相分离 ,曲线出现双峰 ,但两峰值呈现靠近趋势 ,预示mLLDPE/EVA共混物中仍存在少量共结晶     

针状微胶囊Mg(OH)_2/EVA纳米复合材料的制备及性能研究

将自制针状微胶囊纳米氢氧化(镁Mg(OH)2)与乙烯-乙酸乙烯共聚(物EVA)经双螺杆挤出机熔融共混挤出造粒,然后利用注射机制成针状微胶囊Mg(OH)2/EVA纳米复合材料,对其力学性能、热稳定性和流变性能进行了研究。结果表明:纳米Mg(OH)2用量为4%时,复合材料的拉伸强度最大,加工流动性较好;在低温区时,纳米Mg(OH)2含量对复合材料的热稳定性能几乎没有影响,在高温区时,纳米Mg(OH)2的加入使其热稳定性略有提高。     

聚合物/磺酸掺杂煤基聚苯胺复合物的制备研究

选择十二烷基苯磺酸(DBSA)原位掺杂煤基聚苯胺(CBP-DBSA)为导电填料,采用熔融共混技术成功制备了乙烯-醋酸乙烯酯共聚物/CBP-DBSA(EVA/CBP-DBSA)复合物及低密度聚乙烯/CBP-DBSA(LDPE/CBP-DB-SA)复合物。探讨了CBP-DBSA含量、聚合物化学结构对电导率、力学性能的影响,并借助SEM、FTIR、TG测试手段,研究了复合物的结构与性能。结果表明:随着CBP-DBSA含量增加,复合物电导率呈上升趋势,并渐趋平缓;而其力学性能逐渐下降。与LDPE/CBP-DBSA相比而言,EVA/CBP-DBSA的导电逾渗阈值较低,为7%,且电导率较高、力学性能受损较小。CBP-DBSA质量分数为15%时,EVA/CBP-DBSA复合物的拉伸强度为21.08MPa,断裂伸长率为278.38%,电导率达到7.56×10-9S/cm。EVA与CBP-DBSA的氢键作用可改善两相的界面亲和力,EVA是与CBP-DBSA共混制备抗静电材料较好的匹配基体。     

乙烯—醋酸乙烯酸共聚物对茂金属聚乙烯的改性研究

以添加不同比例的茂金属聚乙烯（mLLDPE）/乙烯-醋酸乙烯酯（EVA）共混物为研究对象，考察了EVA含量对mLLDPE/EVA共混物的力学性能，热性能，流变性能，动态力学性能和形态结构的影响，研究结果表明，EVA添加到mLLDPE中，增加了mLLDPE的剪切敏感度，降低了mLLDPE的熔融粘度，改善了mLLDPE的流动性和加工性，在一定的添加比例范围内mLLDPE和EVA具有很好的相容性，可以在改善mLLDPE加工性能，引入极性基团的同时又保持与纯mLLDPE相近的力学性能，但会导致共混物材料的刚性下降，柔性增加，热分析数据说明，mLLDPE/EVA共混体系中，在EVA含量较小时共混物存在大量共晶，与mLLDPE有很好的相容性，无论是熔融曲线还是降温曲线都只出现一个峰，当EVA含量增大时，mLLDPE/EVA共混物出现相分离，曲线出现双峰，但两峰值呈现靠近趋势，预示mLLDPE/EVA共混物中仍存在少量共结晶。     

Experimental investigation on the abrasive wear behavior of nanoclay‐filled EVA/LDPE composites

The article presents the results of experimental investigation on three‐body abrasive wear behavior of nanoclay‐filled EVA/LDPE (NC‐EVA/LDPE) composites. NC‐EVA/LDPE composites with and without compatibilizer were prepared by Brabender Co‐Twin extruder (Make: CMEI, Model: 16CME, SPL) and poly(ethylene‐co‐glycidyl methacrylate) was used as the compatibilizer. The mechanical properties were evaluated using Universal testing machine. In three‐body wear tests, silica sand particles of size 200–250 μm were used as dry and loose abrasives. Three‐body abrasive wear studies were carried out using dry sand/rubber wheel abrasion test rig. The effect of abrading distance on the abrasive wear behavior of neat EVA, EVA/LDPE, and NC‐EVA/LDPE composites was reported. The results showed that the wear volume loss is increased with increase in abrading distance and the specific wear rate decreased with increase in abrading distance. However, the presence of nanoclay filler in EVA/LDPE composite showed a promising trend. Abrasive wear volume of the composites was correlated with mechanical properties such as hardness, tensile strength, and percentage elongation. However, higher weight percentage of LDPE in EVA increased the wear rate. The results indicate that NC‐EVA/LDPE with compatibilizer composite exhibits good abrasive wear resistance compared with NC‐EVA/LDPE without compatibilizer. Attempts to explain these differing trends are made in this work by analyzing the features observed on the worn surface samples by employing scanning electron microscopy (SEM). POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Oxygen permeability and the mechanical and thermal properties of (low‐density polyethylene)/poly (ethylene‐co‐vinyl acetate)/organoclay blown film nanocomposites

Various (low‐density polyethylene)/poly(ethylene‐co‐vinyl acetate) (LDPE/EVA) nanocomposites containing organoclay were prepared by one‐ and two‐step procedures through melt blending. The resultant nanocomposites were then processed via the film blowing method. From the morphological point of view, X‐ray diffraction and optical microscopy studies revealed that although a prevalent intercalated morphology was evident in the absence of EVA, a remarkable increase of organoclay interlayer spacing occurred in the EVA‐containing systems. The advantages of the addition of EVA to the LDPE/organoclay nanocomposites were confirmed in terms of oxygen barrier properties. In other words, the oxygen transmission rates of the LDPE/EVA/organoclay systems were significantly lower than that of the LDPE/organoclay sample. The LDPE/EVA/organoclay films had better mechanical properties than their counterparts lacking the EVA, a result which could be attributed to the improvement of the organoclay reinforcement efficiency in the presence of EVA. Differential scanning calorimetry and thermogravimetric analysis experiments were performed to follow the effects of the EVA and/or organoclay on the thermal properties of LDPE. Finally, the films produced from the two‐step‐procedure compound showed enhanced oxygen barrier properties and mechanical behavior as compared to the properties of the films produced via the one‐step procedure. J. VINYL ADDIT. TECHNOL., 19:132–139, 2013. © 2013 Society of Plastics Engineers     

Low density polyethylene and grafted lignin polyblends using epoxy‐functionalized compatibilizer: mechanical and thermal properties

Lignin was graft copolymerized with methyl methacrylate using manganic pyrophosphate as initiator. This modified lignin was then blended (up to 50 wt%) with low density polyethylene (LDPE) using a small quantity of poly[ethylene‐co‐(glycidyl methacrylate)] (PEGMA) compatibilizer. The mechanical properties of the blend were substantially improved by using modified lignin in contrast to untreated lignin. Differential scanning calorimetry studies showed loss of crystallinity of the LDPE phase owing to the interaction between the blend components. Thermogravimetric analysis showed higher thermal stability of modified lignin in the domain of blend processing. This suggested that there is scope for useful utilization of lignin, which could also lead to the development of eco‐friendly products. Copyright © 2005 Society of Chemical Industry     

Multtphase Materials with Lignin. III. Polyblends with Ethylene-Vinyl Acetate Copolymers

Abstract

Organosolv lignin (OSL) from red oak, and its corresponding hydroxypropyl lignin (HPL) derivative, were blended in the melt with polyethylene and with ethylene-vinyl acetate (EVA) copolymer, and injection molded. Lignin (derivative) content and vinyl acetate (VA) content both served as process variables. All mixtures produced immiscible blends, both by scanning electron microscopy and dynamic mechanical analysis. However, the compatibility of the two polymers increased with VA content. Both lignin products proved to be effective modulus builders, but. HPI, was more effective than OSL at VA contents above 20%. Modulus increased roughly in accordance with the rule of mixing. Inferior tensile strength properties were observed with the EVA copolymer if VA content was below 10%, and superior characteristics were noted in materials containing more than 25% VA and between 5 and 20% HPL.     

纳米氢氧化铝填充LDPE/EVA的力学和阻燃性能

对纳米氢氧化铝（CG-ATH）在低密度聚乙烯/乙烯-醋酸乙烯酯共聚物体系中(low density polyethylene /ethylene vinyl acetate copolymer,简称LDPE/EVA),填充量对力学性质和阻燃性质的影响进行了研究.通过力学性能测试和SEM分析表明,随着CG-ATH填充量的增加,树脂体系的断裂伸长率急剧下降,而其拉伸强度则呈先下降后上升的趋势,当CG-ATH的填充量为60%时,其拉伸强度达12.5 MPa.通过燃烧性能测试、TG和DSC分析表明,CG-ATH的添加能够提高树脂体系的分解温度,增加结炭率,显著提高极限氧指数.通过综合分析,得到填充量为60%时,能够达到树脂体系力学性能与燃烧性能的最佳状态.     

Mechanical properties of recycled LDPE/EVA/ground tyre rubber blends: Effects of EVA content and postirradiation

Thermoplastic elastomers were prepared from recycled low density polyethylene [rLDPE] and virgin low density polyethylene (LDPE), respectively, ground tyre rubber (GTR), and ethylene vinyl acetate (EVA) copolymer. The amounts of the rLDPE and GTR were fixed at 40 and 30 wt %, respectively, in the formulations, whereas the LDPE and EVA contents varied each between 0 and 30 wt %. The fresh LDPE served for reduction of the melt viscosity and EVA was used for improving the elastomeric properties. Blends of different compositions (by varying the LDPE/EVA ratio) were produced by twin-screw extrusion and pelletized. Specimens were produced by injection molding and subjected to tensile and instrumented falling weight impact (IFWI) tests. To improve the mechanical performance of the blends, the injection molded specimens were electron beam irradiated at 150 kGy absorbed dose. Static tensile and hysteresis, IFWI and dynamic mechanical thermal analysis tests were performed on the specimens and the fracture surface was inspected with a scanning electron microscope. The results indicated that better rubber-like properties were achieved with increasing EVA content. Moreover, postirradiation proved to be very beneficial, especially for blends containing relative high amounts of EVA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Rheological and mechanical characteristics of low density polyethylene/ethylene‐vinyl acetate/organoclay nanocomposites

Attempts were made to trace the effect of organoclay (OC) on the rheological and mechanical behaviors of the low density polyethylene (LDPE)/ethylene‐vinyl acetate (EVA) blends. To do this effectively, in addition to LDPE/EVA/OC system, pure LDPE and LDPE/EVA blends were also examined as model systems. The rheological behavior was determined by the capillary rheometer. Morphological characterization was also carried out using X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and theoretical approach based on interfacial energies. Shear viscosity, tensile strength and elastic modulus of LDPE/EVA were found to decrease by increasing the EVA content, while for LDPE/EVA/OC ternary nanocomposites, such properties showed an increase by increasing the content of EVA. Such behavior was explained by the morphological characteristic of the system in which OC was mainly intercalated/exfoliated in the EVA phase. This morphological characteristic was corroborated by the XRD, TEM and interfacial energies data. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

A comparative evaluation of a novel flame retardant, 3-(tetrabromopentadecyl)-2,4,6-tribromophenol (TBPTP) with decabromodiphenyloxide (DBDPO) for applications in LDPE- and EVA-based cable materials

Flame retardation of polymeric materials for cables is becoming a statutory requirement due to governmental regulations to protect life and property from damages caused by fire. This and other factors such as the ever-increasing cost of existing flame retardants (FRs) have given rise to the search for better FRs. In this article, the suitability of an FR, 3-(pentadecyltetrabromo)-2,4,6-tribromophenol (TBPTP) developed from cardanol was evaluated for use in cable insulating and jacketing materials based on low-density polyethylene (LDPE) and ethylene vinyl acetate (EVA). The processability, mechanical properties, compatibility and miscibility, thermal behavior, flammability behavior, smoke generation, acid emission, aging characteristics etc., of the blends of the FR with LDPE and EVA were studied in comparison to those of decabromodiphenyl oxide (DBDPO), which is a standard FR used by the cable industry. Although TBPTP is found to be less thermally stable than is DBDPO, it exhibited better flame retardancy and has comparable thermal stability when blended with LDPE and EVA. Both LDPE—TBPTP and EVA—TBPTP blends produced less smoke than did the corresponding blends of DBDPO. In the case of the EVA—TBPTP blend, the percentage emission of smoke was almost negligible, placing EVA—TBPTP under the low smoke grade. Formulations containing a synergistic agent, promoter, and filler with the corresponding FR and polymer polymer along with an antioxidant were extruded out into wire and tested for cable properties. At 20% loading, the LOI values of the blends were 34.6 and 32.5, respectively, for the TBPTP—EVA and DBDPO—EVA blends. Vertical burning tests carried out with EVA—TBPTP cable showed that it is self-extinguishable. The processability of the compositions containing TBPTP were better than those of DBDPO. The improved processability was found to be due to the plasticising effect of TBPTP. SEM pictures of the blend showed excellent distribution of TBPTP in the polymer, indicating good compatibility and miscibility. Comparatively, DBDPO did not exhibit uniform distribution. The mechanical properties of the blends were within specifications of standard cable materials except that the % elongation of the DBDPO—LDPE blend was far too low. Aging studies also gave better properties for the TBPTP system than for those of the DBDPO system. The overall results show that the properties of EVA—TBPTP cable fall within specifications for the FARLS grade, whereas the EVA—DBDPO cable did not. In the case of LDPE, both TBPTP and DBDPO did not satisfy specifications for the FRLS grade, but the data indicate that they can be used as FRs. The superiority in properties of the TBPTP system over DBDPO is explained in terms of the structure of TBPTP characterized by the distribution of the flame-retardant element, bromine, almost evenly between the aliphatic and aromatic moieties of the molecule, which can, in contrast to the fully aromatic DBDPO, provide halogen over a wide range of temperatures to the combustion zone of the decomposing polymer. Moreover, the presence of the aliphatic segment assures improved processability and compatibility. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 3057–3073, 1997