超微细改性Al(OH)3填充LDPE/EVA的研究

Al(OH）3是LDPE／EVA主要的阻燃，消烟填充剂。研究了不同粒度，表面处理及填充量的Al(OH）3对LDPE／EVA的氧指数（OI），烟密度等级（SDR）和物理机械性能的影响。     

无卤阻燃EVA复合材料阻燃性和力学性能的研究

本文用热分析方法研究了氢氧化铝／ＺＤ（一种有机硅）复合添加剂对ＥＶＡ阻燃性的影响，并对其力学性能进行了探讨。研究结果表明：掺混工艺对ＥＶＡ复合材料的力学性能有极大的影响；在本实验的ＥＶＡ体系中只需加入６５～１００份氢氧化铝／ＺＤ复合添加剂，即可起到显著的效果，使该体系表现出不滴落、低烟，ＯＩ＞３２％，σＢ＞１０ＭＰａ，εＢ＞４００％。     

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。     

炭黑填充EVA/LDPE体系发泡复合材料导电性能的研究

文章以乙烯-乙酸乙烯酯(EVA)和低密度聚乙烯(LDPE)为主基体,特导炭黑(HG-1P)和乙炔炭黑(ACET)为导电填料,偶氮二甲酰胺(AC)为发泡剂,过氧化二异丙苯(DCP)为交联剂,制备了EVA/LDPE/炭黑(CB)导电泡沫复合材料.研究了此复合材料的泡孔结构、阻温特性,并分析了炭黑质量含量、不同配比EVA/LDPE、发泡剂、交联剂对复合材料电性能的影响.结果发现特导HG-1P的导电性高于ACET,由其填充的聚合物导电性优于乙炔炭黑;随着LDPE在共混物中的含量增加,复合材料的NTC强度减弱.制备的导电泡沫具有比较理想的泡孔结构,经过升温电阻测试,EVA/LDPE/CB导电发泡复合材料具有良好的开关特性,呈现明显的NTC特性.确定了发泡剂及交联剂的合适用量,从而获得既具有良好的泡沫性能,又有良好NTC特性的导电泡沫材料.     

LDPE/EVA鞋底发泡材料的研究

讨论了发泡剂偶氮二甲酰胺(AC)、橡胶(EPDM、NBR)、填料超细碳酸钙(CaCO3)用量对LDPE／EVA发泡材料性能的影响,研制出发泡材料密度及力学性能满足运动鞋中底要求的配方。结果表明：AC用量为6份时,发泡材料密度达到0．078g／cm^3;EPDM有效改善了发泡材料的强度,当EPDM加入15份时,发泡材料密度和力学性能优异;超细CaCO3可以提高LDPE／EVA／NBR发泡材料的强度,当超细CaCO3用量为30份时,发泡材料性能较好。     

纳米氢氧化镁的阻燃LDPE性能的研究

以纳米级氢氧化镁为主阻燃剂，研究了其形态及对LDPE的阻燃性能。氢氧化镁复合阻燃体系可使LDPE达到难燃水平。     

特种LDPE和EVA制造新工艺

利安德巴赛尔公司于2008年8月26日宣布，开发出制造特种LDPE和EVA的新技术，该技术采用高压釜工艺，称之为Lupotech A工艺。     

氢氧化铝含量对聚酯/玻璃纤维复合材料阻燃性能和力学性能的影响

通过熔融混炼和模压成型工艺,制备含氢氧化铝(ATH)的干式不饱和聚酯/玻璃纤维(UP/GF)共混复合材料。采用氧指数法(LOI)和垂直燃烧法(UL94)表征UP/GF复合材料的阻燃性能,采用DMA研究UP/GF复合材料的动态力学性能,采用静态力学方法研究UP/GF复合材料的冲击和弯曲性能。结果表明:UP复合材料中,ATH的含量在25%时,既能够满足V—0级阻燃级别,氧指数值为28.7%,且材料的冲击和弯曲强度分别为5.66kJ/m2和58.72MPa,同时也有较好的动态力学性能。     

氢氧化铝对PE-HD／木粉复合材料阻燃性能和力学性能的影响

对Al(OH)3阻燃的高密度聚乙烯／木粉复合材料研究结果表明：随木粉和Al(OH)3添加量的增加，Al(OH)3对复合材料的阻燃效率增加，高木粉添加量的复合材料氧指数达27．1％，Al(OH)3的阻燃效率达0．203。增加木粉含量，复合材料的拉伸强度和弯曲强度明显提高；但Al(OH)3对拉伸强度的影响不大，而明显提高弯曲强度。增加木粉和Al(OH)3的含量，均能明显降低复合材料的冲击强度，破坏复合材料的韧性。     

HDPE/EVA/LDPE共混物拉伸性能和流变性能研究

用ＥＶＡ、ＬＤＰＥ、ＣａＣＯ３改性,填充ＨＤＰＥ,研究了它们的用量,品种对共混珠拉伸性能和流变性能的影响。结果表明,共混物熔体为假塑性流体。ＥＶＡ、ＬＤＰＥ用量增加,共混物拉伸强度下降,但断裂伸长率和熔体流动性提高。     

Structural characterization of LDPE/EVA blends containing nanoclay‐flame retardant combinations

The combination of different types of organo‐modified montmorillonite (MMT) with aluminum hydroxide (aluminum trihydrate—ATH), as a flame retardant system for polyethylene‐ethylene vinyl acetate (LDPE/EVA), blends were studied. Five different types of organically modified montmorillonite clays, each with different modifier, were used. The structural characterization was carried out by X‐ray diffraction (XRD) and scanning electron microscopy in transmission mode (STEM). The mechanical and rheological properties were also evaluated. The XRD analysis showed a clear displacement of the d₀₀₁ signal, which indicates a good degree of intercalation, especially for the MMT‐I28 and MMT‐20, from Nanocor and Southern Clay Products, respectively. The presence of ATH and the compatibilizer did not have any effect on the exfoliation of the studied samples. The thermal stability and flame retardant properties were evaluated by thermogravimetric analysis (TGA), limiting oxygen index (LOI—ASTM D2863), and flammability tests (Underwriters Laboratory—UL‐94). The effect of different compatibilizers on the clay dispersion and exfoliation was studied. The results indicated that the addition of montmorillonite makes it possible to substitute part of the ATH filler content while maintaining the flame retardant requirements. The thermal stability of MMT/ATH‐filled LDPE/EVA blends presented a slight increase over the reference ATH‐filled LDPE/EVA blend. Compositions with higher clay content (10 wt %) showed better physicochemical properties. The increased stability of the higher clay content compositions results from the greater inorganic residual formation; this material has been reported to impart better performance in flammability tests. The mechanical properties and flame retardancy remained similar to those of the reference compound. The reduced ATH content resulted in lower viscosities and densities, facilitating the processing of the polymer/ATH/clay compounds. Extrusion of these compounds produced a lower pressure in the extrusion head and required reduced electrical power consumption. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

LDPE／EVA发泡材料的研制

研究了低密度聚乙烯／乙烯醋酸乙烯酯共聚物（ＬＤＰＥ／ＥＶＡ）共混发泡材料的生产工艺条件及其组成对泡体性能的影响,结果表明：在１７０℃、模压时间为１５ｍｉｎ的条件下,质量比为１００／３０的ＬＬＤＰＥ／ＥＶＡ发泡材料冲击回弹性达到３９．０８％,同时有较低的永久变形（２５％）,凝胶铉为７５．５３％,泡孔大小均匀,性能良好。     

m(APP)/m(PER)对LDPE阻燃性能和力学性能的影响

研究了不同配比的聚磷酸铵(APP)／季戊四醇(PER)组成的膨胀型阻燃剂及不同阻燃剂含量对低密度聚乙烯(LDPE)阻燃性能和力学性能的影响。m(APP)／m(PER)最佳为3:2,膨胀型阻燃剂质量分数最佳为30％。与纯LDPE相比,含有最佳配比和质量分数的阻燃剂体系的复合材料的极限氧指数从17．8％提高至24．5％,550℃的残重率从30．6％提高至87．0％;力学性能有所下降,拉伸强度从10．3 MPa降为7．39 MPa,断裂伸长率从115％下降到57％。阻燃LDPE的放热量比未阻燃的LDPE减少,说明形成的膨胀炭层对内部基材起着保护作用。550℃阻燃试样的残余物中成炭较致密,在炭层中除了含C外,还含有较大量的P和少量的N。     

无卤阻燃剂在LDPE/EVA共混物中的应用

以氢氧化铝为主阻燃剂,磷及氮化合物、硼酸盐和有机硅化合物作为阻燃增效剂,研究了LDPE/EVA共混物的阻燃性能和力学性能,并对各种阻燃剂的阻燃机理及阻燃效果作了研究.试验结果表明：氢氧化铝与阻燃增效剂有良好的协同效应,加入有机硅能够提高LDPE/EVA共混物的阻燃性能和加工性能.     

Investigations of environmental stress cracking resistance of LDPE/UHMWPE and LDPE/EVA blends

Abstract

Low density polyethylene (LDPE)/ultrahigh molecular weight polyethylene (UHMWPE) and LDPE/poly(ethylene-co-vinylacetate) (EVA) blends were tested and compared with respect to their environmental stress cracking resistance (ESCR) using the Bell telephone test. The time to failure in the ESCR test improved with increasing UHMWPE and EVA content, and considerable improvements were produced when an UHMWPE weight fraction of 0.4 and EVA weight fraction of 0.03 were used. Thermal and morphological studies were conducted, and a relationship between morphological features and composition was established. Furthermore, the failed specimens were further characterised by scanning electron microscopy and fractographic methodology to investigate the failure mechanism for ESCR samples.