正规授权彩票

6e彩票

最新最全的文档下载
当前位置:6e彩票 > Preparation and characterizations of HDPE–EVA alloy

Preparation and characterizations of HDPE–EVA alloy

Preparation and characterizations of HDPE–EVA alloy

Preparation and characterizations of HDPE–EVA alloy

Thermochimica Acta451(2006)

Preparation and characterizations of HDPE–EVA alloy

44–51

正规授权彩票Preparation and characterizations of HDPE–EV A alloy/OMT

nanocomposites/paraffin compounds as a shape stabilized

phase change thermal energy storage material

Yibing Cai a,Yuan Hu a,∗,Lei Song a,Hongdian Lu a,Zuyao Chen b,Weicheng Fan a

a State Key Laboratory of Fire Science,University of Science and Technology of China,Hefei,230027Anhui,People’s Republic of China

b Department of Chemistry,University of Science and Technology of China,Hefei,230026Anhui,People’s Republi

c of China

Received31May2006;received in revised form22July2006;accepted29August2006

Available online2October2006

Abstract

A kind of shape stabilized phase change nanocomposites materials(PCNM)based on high density polyethylene(HDPE)/ethylene-vinyl acetate (EV A)alloy,organophilic montmorillonite(OMT),paraffin and intumescentflame retardant(IFR)are prepared using twin-screw extruder technique. The structures of the HDPE–EV A alloy/OMT nanocomposites are evidenced by the X-ray diffraction(XRD)and transmission electron microscopy (TEM).The results show that an ordered intercalated nanomorphology of the HDPE–EV A alloy/OMT nanocomposites is formed.Then the structures of the shape stabilized PCNM are characterized by scanning electron microscopy(SEM).The HDPE–EV A alloy/OMT nanocomposites act as the supporting material and form the three-dimensional network structure.The paraffin acts as a phase change material and disperses in the three-dimensional network structure.Its latent heat is given by differential scanning calorimeter(DSC)method.The SEM and DSC results show that the additives of IFR have little effect on the network structure and the latent heat of shape stabilized PCNM,respectively.The thermal stability properties are characterized by thermogravimetric analysis(TGA).The TGA analysis results indicate that theflame retardant shape stabilized PCNM produce a larger amount of char residue at800◦C than that of shape stabilized PCNM,although the onset of weight loss of theflame retardant shape stabilized PCNM occur at a lower temperature.The formed multicellular char residue contributes to the improvement of thermal stability performance.The probable combustion mechanisms are also discussed in this paper.

©2006Elsevier B.V.All rights reserved.

Keywords:Phase change nanocomposites materials(PCNM);Organophilic montmorillonite(OMT);Thermal stability;Latent heat;Flame retardant mechanism

1.Introduction

Energy needs for a wide variety of applications are depended on time and some energy resources.Therefore storage of energy is necessary to meet these energy needs.Among the different methods of thermal energy storage,the latent energy storage is one of the most attractive.It is able to store and to release large quantities of energy per weight of material.In addition,the temperature remains nearly constant during the phase change. Much attention has been paid to form-stable phase change mate-rial(PCM),which represent a rational alternative to traditional PCM.The traditional PCMs have several defects,one of which is that to store and to release the latent heat of the PCM,special ∗Corresponding author.Tel.:+865513601664;fax:+865513601664.

E-mail address:yuanhu@http://xzccx.com/doc/03ad712c2af90242a895e5a0.html (Y.Hu).latent storage device or elements such as shell-and-tube PCM heat exchanger or many cans to encapsulate the PCM will have to be involved,it causes the increase not only in heat resistance but also in the associated cost,to develop heat exchanger in which the heat transfer medium can contact PCMs directly,it is important to investigate form-stable PCMs[1–8].Among the various kinds of PCMs of interest,paraffin have been found to exhibit many desirable characteristics,such as high latent heat, negligible supercooling,low vapor pressure in the melt,chemi-cally inert and stable,self-nucleating,etc.Zhang et al.,Xiao et al.and Sari et al.study the latent heat,the thermal storage and thermal conductivity of PCM using paraffin as a phase change material[3,4,6–8].

At the same time,much attention has been paid to polymer nanocomposites,especially polymer-layered silicate nanocom-posites,which represent a rational alternative to conventional filled polymers.Because by employing minimal addition lev-

0040-6031/$–see front matter©2006Elsevier B.V.All rights reserved. doi:10.1016/j.tca.2006.08.015