Evidence of Acid-Base Interfacial Adducts in Various Polymer/Metal Systems by IRAS: Improvement of Adhesion

The physical interactions of polymers with inorganic substrates are determined by two major contributions: Van der Waals forces and acid-base interactions, taken in the most general “Lewis” electron acceptor-donor sense. The present work shows that the work of adhesion can be very appreciably increased by the creation of interfacial acid-base interactions. Practically, polymers such as poly(ethylene-co-vinyl acetate) (EVA), terpene-phenol resins (TPR), and their blends, were solution cast on basic and acidic substrates. The nature of the interfacial bonds and the enthalpy of adduct formation through electron exchange are evidenced by Fourier transform infrared reflection-absorption spectroscopy (IRAS). Moreover, it is shown that, on the one hand, modification of the electron donor ability of the polymer functionalities reveals the amphoteric character of the substrate and, on the other hand, modification of the electron donor ability of the substrate changes the nature of the species involved in interfacial adduct formation. Then, practical adhesion tests were carried out in order to correlate the nature and strength of interfacial acid-base bonds with simultaneous increases in adhesive strengths. Thermodynamic considerations allowed us to propose estimated values of the acid-base work of adhesion, W^ab, and of the density of acid-base sites, n^ab.     

SAN／EVA接枝共聚物的接枝率分析

用体积比为３０／７０的环已烷／丙酮混合溶剂进行了苯乙烯－丙烯腈共聚物／乙烯－醋酸乙烯酯共聚物共混物的选择性溶解分离试验，结果表明，共混物的形态对分离效果有很大影响，当ＳＡＮ含量较低并构成分散相时，ＳＡＮ的溶解非常因素，若用环已烷含量较高的混合溶剂先使共混物全部溶解，再滴入丙酮使ＥＶＡ沉淀，则可得到满意的分离。采用这种分离方法，并用红外光谱法定量分子ＳＡＮ／ＥＶＡ接枝共聚试样的接枝率。     

几种改性沥青试验研究及结果讨论

用两种改性剂对两种沥青进行了改性。从物理性能指标、混合料试验结果对改性效果进行了评价分析，并对其中的问题进行了讨论。     

Evaluation of physical,rheological, and structural properties of vulcanized EVA/SBS modified bitumen

In this study, the performance and modification mechanism of EVA (ethylene‐vinyl‐acetate) modified (EM), EVA/SBS (Styrene‐Butadiene‐Styrene) modified (ESM), and EVA/SBS/sulfur modified (ESSM) bitumens were evaluated. The physical, rheological, morphological, and structural properties were determined before and after aging, and compared with those of base bitumen. These properties were evaluation using conventional physical methods, Fourier transform infrared spectrometer, optical microscopy, dynamic shear rheometer, and bending beam rheometer, respectively. The results showed that sulfur was useful in bitumen, EVA, and SBS modification by forming a vulcanized crosslinking polymer network. The vulcanization improved most of the physical properties of ESM bitumen, especially high‐ and low‐temperature performance, and toughness and tenacity (previously not evaluated in the literature). Meanwhile, vulcanization improved the compatibility between polymers and bitumen and increased the aging resistance of ESM bitumen. Vulcanization reactions took place without new functional groups being presented in the infrared spectrum. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44850.     

干燥剂填料对EVA热熔胶性能的影响

填料的加入在降低成本的同时也引起了一系列实际应用的问题。就二氧化硅，氧化钙，活性炭三种具有吸水性的填料加入EVA热熔胶从而导致热熔胶具有吸水性，以及吸水后的EVA热熔胶的剥离强度的变化做了系统的探讨。还分析讨论了各种填料的加入对热熔胶流动性的影响，结果发现适量填料的加入可以提高热熔胶的剥离强度和流动性。     

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％。     

EVA的技术进展及开发应用

叙述了国内外ＥＶＡ生产的状况及其应用发展，介绍了国内外主要生产厂家的ＥＶＡ产品及其应用、ＥＶＡ生产技术的改进，建议国内增加开发ＥＶＡ树脂及其产品。     

Effect of particle size on flame retardancy of Mg(OH)2‐filled ethylene vinyl acetate copolymer composites

Four kinds of magnesium hydroxide (Mg(OH)₂) with different particle sizes are chosen and mixed with ethylene vinyl acetate copolymer (EVA) to investigate the effect of particle size on the flame retardancy of composites, which is evaluated by limiting oxygen index (LOI) testing, horizontal fire testing, and cone calorimeter. When Mg(OH)₂ filling level changes from 35 to 70 wt %, the composites filled with nano‐Mg(OH)₂ do not always possess the best flame retardancy, and among the composites filled with micro‐Mg(OH)₂, the composites filled with 800 mesh Mg(OH)₂ show the best flame retardancy; however, the composites filled with 1250 mesh presents the worst one. So the effect of particle size on the flame retardancy of micro‐Mg(OH)₂‐filled EVA is not linear as expected. All the differences are thought to result from both particle size effect and distributive dispersion level of Mg(OH)₂. To prepare the composites with better mechanical properties and flame retardancy, authors suggested that Mg(OH)₂ of smaller size should be chosen as flame retardant, and good dispersion of Mg(OH)₂ particles also should be assured. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4461–4469, 2006     

Nano-TiO2/HIPS母料流变性能的研究

采用Rosand Rheometer流变仪研究了nano-TiO2/HIPS母料及EVA蜡改性母料的流变性能。结果表明,nano-TiO2对母料的表观粘度影响较小。在nano-TiO2质量分数低于20％时，表观粘度仅略高于纯HIPS。在低剪切速率下。nano-TiO2可加速熔体偏离牛顿流体的速度。体系的粘弹性增强；而在较高剪切速率下则相反。EVA蜡可在较大范围内调整母料体系的流变性能。在低剪切速率下，EVA蜡质量分数超过5％就可明显改善体系的流动性，且体系流动行为接近牛顿流体，粘弹性很弱；在高剪切速率下，EVA蜡对体系的流动性影响不大，流变行为及牯弹行为与纯HIPS相当。原子力显微镜测试表明。采用EVA蜡改性的nano-TiO2/HIPS母料。可得到表观及分散性良好的制品。     

Effects of different kinds of clay and different vinyl acetate content on the morphology and properties of EVA/clay nanocomposites

A series of EVA/clay nanocomposites and microcomposites have been prepared via melt-blending. Using four kinds of EVA with different vinyl acetate (VA) contents: 28, 40, 50 and 80 wt%, and four kinds of clay: three are organophilic clay (OMMT) and one unfunctionalized clay (Na-MMT), the effects of different VA content of EVA and the kinds of the clay on the morphology and properties of EVA/clay nanocomposites were systematically investigated. In previous studies, there are only two distinct nanostructures to distinguish polymer/clay nanocomposites: the intercalated and the exfoliated. But in this paper, we proposed a new nanostructure—‘the wedged’ to describe the dispersion degree of clay in nanocomposites, it means the sheets of clay were partly wedged by the chains of polymer. The wedged, the intercalated and the partially exfoliated structures of EVA/clay nanocomposites were characterized by X-ray diffraction (XRD) and by high-resolution transmission electron microscopy (HRTEM). The enhanced storage modulus of EVA/clay nanocomposites was characterized by dynamic mechanical thermal analysis (DMTA). The enhanced degree in the storage modulus of the OMMT on EVA/clay nanocomposites with the partially exfoliated and intercalated structure is much higher than that with wedged structure, and that with the higher VA content is higher than that with the lower. The thermal stabilities of EVA/clay nanocomposites were also studied by thermal gravimetric analysis (TGA).