Ethylene-vinyl acetate thermal properties

Blends of ethylene-vinyl acetate (EVA) copolymer with metallocene-catalysed elastomeric ethylene-alpha-olefin copolymer were investigated and were found to be immiscible in the melt and solid state but mechanically compatible. The morphology (SEM), thermal (DSC), rheological (viscosity), mechanical (including tensile, shear thinning and elastic behaviour) and optical properties of EVA-rich and ethylene-alpha-olefin copolymer-rich blends were studied and the results are discussed in terms of processibility in film applications. 24 refs. 

The most widely used thermoplastic polymer is the ethylene—vinyl acetate copolymer, which is obtainable in a wide range of molecular weights as well as in a variety of compositions. Often flexibilizers or plasticizers are added in order to improve both the mechanical shock resistance and the thermal properties of the adhesive. Polybutenes, phthalates, and tricresyl phosphate have been used as plasticizers. Tackifying agents can also be added. Because hot-melt adhesives are frequendy ethylene-based, they are subject to oxidation if, as in a typical situation, the adhesive sits in an applicator for long periods before use. Thus, antioxidants such as hindered phenols are often used, as are fillers. Fillers are added to opacify or to modify the adhesive s flow characteristics, as well as to reduce cost. Wax is also a very important component. Wax alters surface characteristics by decreasing both the liquid adhesive s surface tension and its viscosity in the melt. Upon solidification, however, the wax acts to increase the strength of the adhesive. Both paraffin and microcrystalline wax are used (see Waxes). 

Wang, B., Wang, X., Shi, Y. et al. 2012. Effect of vinyl acetate content and electron beam irradiation on the flame retardancy, mechanical and thermal properties of intumescent flame retardant ethylene-vinyl acetate copolymer. Radiation Physics and Chemistry 81 308-315. 

K.A. Tawab, S.M. Ibrahim, M.M. Magida, The effect of gamma irradiation on mechanical, and thermal properties of recycling polyethylene terephthalate and low density polyethylene (R-PET/LDPE) blend compatibilized by ethylene vinyl acetate (EVA). J. Radioanal. Nucl. Chem. 295, 1313-1319 (2013)... 

Poomalai, P, Ramaraj, B., and Siddaramaiah. 2007. Thermal and mechanical properties of poly (methyl methacrylate) and ethylene-vinyl acetate co-polymer blends. Journal of Applied Polymer Science 106 (1) 684-691. 

T. Kuila, P. Khanra, A.K. Mishra, N.H. Kim, and J.H. Lee, Functionalized-graphene/ethylene vinyl acetate co-polymer composites for improved mechanical and thermal properties. Polymer Testing, 31 (2), 282-289,2012. 

Kuila, T., Acharya, H., Srivastava, S. K., and Bhowmick, A. K. 2008. Effect of vinyl acetate content on the mechanical and thermal properties of ethylene vinyl acetate/Mg-Al layered double hydroxide nanocomposites. Journal of Applied Polymer Science 108 1329-1335. 

The addition of nanoparticles to synthetic mbber resulting in enhancement in thermal, stiffness and resistance to fracture is one of the most important phenomena in material science technology. Thermal and mechanical properties of clays mul-tiwalled carbon nanotubes reinforced ethylene vinyl acetate (EVA) prepared through melt blending showed synergistic effect in properties [86]. Malas et al. reported (SBR/BR)/expanded graphite (EG) and black carbon (CB) nanocomposites by melt blending, this study demonstrated that the presence of EG improvement thermo-mechanical properties and the presence of CB are a factor important to... 

Wang, B.B., Song, L., Hong, N.N., Tai, Q.L., Lu, H.D., Hu, Y. Effect of election beam irradiation on the mechanical and thermal properties of intumiscent flame retarded ethylene-vinyl acetate copolymer/orcanically modified montmorillonite compositions. Radiat. Phys. Chem. 80, 1275-1281 (2011)... 

T. H. Chuang, W. Guo, K. C. Cheng, S. W. Chen, H. T. Wang, and Y. Y. Yen, Thermal properties and flammability of ethylene-vinyl acetate copolymer/montmorillonite/ polyethylene nanocomposites with flame retardants. Journal of Materials Research, 11 (2004), 169-74. 

B. Ramaraj and K.-R. Yoon, Thermal and physicomechanical properties of ethylene-vinyl acetate copolymer and layered double hydroxide composites. Journal of Applied Polymer Science, 108 (2008), 4090-95. 

Until 2003, Chen s [28], Qu s [29-31], and Hu s [32] groups independently reported nanocomposites with polymeric matrices for the first time the. In Hsueh and Chen s work, exfoUated polyimide/LDH was prepared by in situ polymerization of a mixture of aminobenzoate-modified Mg-Al LDH and polyamic acid (polyimide precursor) in N,N-dimethylactamide [28]. In other work, Chen and Qu successfully synthesized exfoliated polyethylene-g-maleic anhydride (PE-g-MA)/LDH nanocomposites by refluxing in a nonpolar xylene solution of PE-g-MA [29,30]. Then, Li et al. prepared polyfmethyl methacrylate) (PMMA)/MgAl LDH by exfoliation/adsorption with acetone as cosolvent [32]. Since then, polymer/LDH nanocomposites have attracted extensive interest. The wide variety of polymers used for nanocomposite preparation include polyethylene (PE) [29, 30, 33 9], polystyrene (PS) [48, 50-58], poly(propylene carbonate) [59], poly(3-hydroxybutyrate) [60-62], poly(vinyl chloride) [63], syndiotactic polystyrene [64], polyurethane [65], poly[(3-hydroxybutyrate)-co-(3-hydroxyvalerate)] [66], polypropylene (PP) [48, 67-70], nylon 6 [9,71,72], ethylene vinyl acetate copolymer (EVA) [73-77], poly(L-lactide) [78], poly(ethylene terephthalate) [79, 80], poly(caprolactone) [81], poly(p-dioxanone) [82], poly(vinyl alcohol) [83], PMMA [32,47, 48, 57, 84-93], poly(2-hydroxyethyl methacrylate) [94], poly(styrene-co-methyl methacrylate) [95], polyimide [28], and epoxy [96-98]. These nanocomposites often exhibit enhanced mechanical, thermal, optical, and electrical properties and flame retardancy. Among them, the thermal properties and flame retardancy are the most interesting and will be discussed in the following sections. 

C. Nyambo and C. A. Wilkie, Layered double hydroxides intercalated with borate anions Fire and thermal properties in ethylene vinyl acetate copolymer. Polymer Degradation and Stability, 94 (2009), 506-12. 

Since butyl acrylate is higher in molecular weight than vinyl acetate, higher weight fractions are needed to aehieve the same final level of erystallinity in the ethylene eopolymer. Typically packaging grades eontain 33% butyl aerylate. Thermal stability is far better than EVA, with butene rather than aeetic aeid produeed upon decomposition. Acetic acid can catalyze further polymer deeomposition and eorrosion of the applieation equipment. Low temperature properties are also... 

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