乙烯-醋酸乙烯共聚物的流变性能

第23卷第6期高分子材料科学与工程Vol. 23.No.62007年11月POLYMER MATERIALS SCIENCE AND ENGINEERINGNov. 2007乙烯-醋酸乙烯共聚物的流变性能李新法'，黄灵阁'，胡宏伟2,蒋爱云'，孟程程',牛明军'，陈金周'(1.郑州大学材料科学与工程学院，河南郑州450052; 2. 河南金田地农化有限公司,河南郑州40000)摘要;利用XLY-1型毛细菅流变仪测试了己烯-醋酸己烯共聚物(EVA)的表现黏度、粘流活化能、非牛顿摺数等流变参数，讨论了剪切迷卑、剪切应力和温度等对己烯-醋酸乙烯共聚物熔体的表观黏度的影响,研究了粘流活化能与剪切速率的变化规律。实验结果表明,乙烯=醋酸乙烯共聚物熔体的表观黏度随温度的升高而降低;粘流活化能AE随剪切速率的增大而减小。在实验温度苑围内,EVA熔体的表观黏度随剪切迷率和剪切应力的增大而降低,其非牛顿指敷n小于1,说明EVA熔体为假塑性流体。关键词:乙烯-醋酸乙烯共聚物;流变性能;表观黏度中围分类号:0631.2*1文献标识码:A文章编号100555<20006-0124-030由于EVA具有优异的耐屈挠性、耐低温挤出,电子记录仪自动记录挤出速度和温度。性、抗冲击性和耐环境开裂性等特点,因此,被1.4流变数据处理广泛用于模塑制品、热熔胶、增韧改性剂、涂料.1.4.1剪切应力(t_):及织物加工等方面(1.2]。然而有关其基础研究却r. = Op R/2L(1)不多见0.0,至今尚未见到对EVA流变性能的1.4.2表观剪切速率(Y.):研究报道。为此,本文利用XLY- 1型毛细管流y. = 4Q/xR*(2)变仪测试了EVA的表观黏度、粘流活化能和非1.4.3表观黏度(n.):牛顿指数等流变参数,并系统研究了其流变性n.= r./9.(3)能,从而为其成型工艺条件的合理确定,成型机1.4.4非牛顿 指敷(n):由幂律方程τ.= K%,械及模具的设计和提高制品质量提供了重要的两边取对数得理论依据。.lgτ.=lgK +nlg9.(4)以lgτ.对lg%作图,在一定范围内可得一直1实验部分线,由直线斜率可得非牛顿指数n。1.1 主要原料乙烯=醋酸乙烯共聚物(EVA):醋酸乙烯式(1)~(4)中:Op- -作用在毛细管两端的压力降;R- - 毛细管的半径;L-一毛细 管的长含量28%,上海化工研究院生产。度;Q一从毛细管挤 出的容速;K一-流 体的1.2 实验仪器毛细管流变仪:XLY-I型,吉林大学科教稠度系数。仪器厂,毛细管长径比为40,未做人口校正。1.4.5乙烯~醋酸乙烯共聚物 的粘流活化能:乙烯-醋酸乙烯共聚物熔体的流动行为服从Ar-1.3实验方法将一定量的EVA试样放人一定温度下的rhenius方程:7.= A exp(OE/RT)(5)毛细管流变仪的料筒中,压实,恒温7min,然后式(5)中:OE-粘流活 化能;R一-气体常在恒定温度和压力下将EVA熔体从毛细管中中国煤化工收稿H期2006-07-12;铅订日期:2007-05-08若金项目:阿南省自然科学基金资助项目(0311060500DHCNMHG联系人:李新法,主要从事高分子复合材料研究,E-mailslixinfa@zu.edu.cn'第6期.李新法等:乙烯~醋酸乙烯共豪钧的流变性能125数;T-绝对温 度。2.2EVA表观黏度与剪切速率的关系以In,对1/T作图,可得一-直线,由直线斜EVA在120 C~180 C的表观黏度与剪切率可求出EVA的粘流活化能OE。速率的关系见Fig.2.由Fig.2可见,在实验温度范围内,EVA的表观黏度均随表观剪切速率的升高而降低,即出现了剪切变稀现象。这主要是因为当剪切速率增大时，流动时间比松弛时间短,分子链来不及松弛收缩或已取向的分子链只收缩了一部分，从而减小了收缩所产生的流动阻力,故表观黏度降低;此外,表观剪切速率的增大使影响流动的缠结点更容易解缠,这也↓是EVA表观黏度降低的主要原因之一。lgIr.(s')|Flg. 1 Rbeologlcal curves of EVA1:130比12;140Cr3:150C:4,160C;5; 170 c三王5lg|r.IP.1IFlg.3 The relatoaship betwen 7. and T. tar EVA1120 C+2: 130C13, 140C141 150 C15i160C16.170C.7.180ClgIs.1s"ll2.3EVA表观黏度与剪切应力的关系Flg.2 The relhtionshlip belween n andy. for EVAEVA在120 C~180 C表观黏度与剪切应1120 C12; 130 C13t 140C14s 150 C;力的关系如Fig.3所示.由Fig.3可见,随剪切应5, 160 C16.170 C17; 180 C力的增大,EVA熔体的表观黏度降低.这主要是因为剪切应力的增大,使影响熔体流动的缠2结果与讨论结点容易解缠,从而表观黏度降低。2.1 EVA 的流变曲线由Fig.3还可看到,随剪切应力的增大,其EVA在130 C、140 C、150 C、160 C表观黏度变化较小,剪切应力增大近两个数量和170C的流变曲线如Fig.1所示。由Fig.1可级,表观黏度降低不到一个数量级,这说明求出不同温度下EVA的非牛顿指数,结果见EVA熔体的表观黏度对剪切应力的敏感性较Tab. 1.由Fig.1和Tab.1可见,EVA熔体在120 C小。这主要是由于其分子量较小或熔体流动速~180 C温度范围内,其非牛顿指数n均小率较大所致。于1.说明EVA熔体为假塑性流体;而且随着温2.4表观黏度与温度的关系由Fig.2、Fig. 3、Fig. 4和Fig. 5可见,EVA度的升高,其非牛顿指数x增大,说明EVA熔熔体的表观黏度随温度的升高而降低.这是因体的非牛顿性随温度升高而减弱。为温度升高,分子链的热运动能增大,分子链间Tab.1 Non- Newtonian index(n) of EVA的距离中国煤化工于分子链的1(() 12030 140 150 160 170 180相对滑YHCNMHG黏度降低，0.680.70 0.71 0.72 0.74 0.75 0.76流动性提高,对成型加工比较有利。126高分子材料科学与工程2007年3所示。Tab.3 The relationship between OE andT. for EVA力2τ.(MPa) 6.130 12.28 36.75 73.50 196.0oE (kJ/mol) 94.20 93.50 93.00 91.50 91. 40由Fig. 4和Fig. 5可见,随温度升高,EVA熔体的表观黏度降低,服从Arrhenius定律。由+x 10Yk*)Tab.2和Tab.3可见,随着剪切速率和剪切应力的增大,EVA的粘流活化能减小,但剪切速率Fig4 The relatlosbilp betweea n and 1/T forEVA ,比剪切应力对粘流活化能的影响明显.1 100o-15 2; 316.2s-'; 3; 1000s-1;4 1778s-1;51 3162 s-13结论(1)EVA在实验条件下为假塑性流体,其表观黏度随着剪切应力和剪切速率的增大而降低,非牛顿指数n小于1,且随温度的升高而增大.(2)EVA熔体的表观黏度随温度升高而降低,在实验条件下,其恒剪切速率下的粘流活化能为21.06 kJ/mol~ 38.29 kJ/mol,恒剪切应力下粘流活化能为91.40kJ/mol~94.20kJ/2.224 23mol.一x 10'K)FIg.5 The reatioasblp betwee n and 1/T tor参考文献;EVA[1] 夏成林(XIA Cheng-lin), 贺均林(HE Jun-lin),黄诗1。6. 130X10Pas 2; 1. 228X10Pa; 3, .(HUANG Tao),等.高分于材料科学与工程(PolymerMaterials Science & Enginering), 1988. 4(2); 33~3. 675X10*Pa1 4 7.350X 10*Pas 5;381. 960X10'Pa[2]胡继文 (HU Ji-wen),孙友德(SUN You-de).高分子Tab.2 The relationship between oE and材料科学与工程(Polymer Materisls Science & Eagi-y. tor EVAneering), 1993, 9(1); 42~46.六(s-1)00316.2 10007783162[3] 李新怯(LI Xin-fa), 牛明军(NIU Mingijun),陈金周(CHEN Jin-zhou),等.离分子材料科学与工程(Poly-OE (kJ/mol) 38. 2929.67 27.18 22.97 21. 06ner Materials Science & Engineering). 2003, 31(4);103~ 105.2.5 EVA 的粘流活化能[4] 李新法(LI Xin-fa), 牛明军(NIU Mingijun),陈金周EVA的表观黏度与温度的关系如Fig.4和(CHEN Jin-zhou),等.高分子材料科学与工程(Poly-mer Materials Seience & Engineering). 2002, 30(2); 20Fig.5所示。由Fig.4可求出EVA的恒剪切速率~21.下的粘流活化能OE,如Tab.2所示;由Fig.5可(下转第131页,t0 be cninued on P. 131)求出恒剪切应力下的粘流活化能,结果如Tab.中国煤化工MYHCNMHG第6期胡小洋等;葭乙二醇及其衍生物改性生物医用材料表面的血液相容性131[31] Lasseter T L, Clare BH, AbbottL N,e al. J. Am.Chem. Soe. , 2004, 126(33); 10220.Blood Compatibility of Biomaterial SurfacesModified with PEG and Its DerivativesHU Xiao-yang' , CHEN Hong'"', ZHANG Yan-xia'WANG Yi-feng', WU Zhong -kui'(1. School of Materials Science and En gineering, Wuhan University ofTechnology, Wuhan 430070, China; 2. Biomnedical Materials andEngineering Center, Wuhan University, Wuhan 430070, China)ABSTRACT :Poly(ethylcne glycol)(PEG) and its derivatives are accepted as a kind of ideal poly-mers to improve surface blood compatibility of biomaterials. Due to their excellent hydrophilici-ty, mobility, biological inertness , resistance properties of protein adsorption and cell adhesion,PEG and its derivatives are widely used in surface modification of biomaterials. In this article,the applications of PEG and its derivatives in surface modification to improve blood compatibilityof biomaterials were reviewed. Some techniques, ATR-FT-IR, Water Contact Angle, X-ray pho-toelectron spectrometer, Surface Plasmon Resonance , Ellipsometry, Western blot, protein La-beling technology, which are used to characterize PEG -modified biomaterial surfaces, were alsointroduced in this paper.Keywords: biomaterials; poly(ethylene glycol); surface modification; blood compatibility(上接第126页.continued from p. 126)Studies on Rheological Properties of EthyleneVinyI-Acetate CopolymerLI Xin-{a', HUANG Ling ge' , HU Hong wei', JIANG Ai-yun'MEN Cheng cheng' , NIU Ming-jun' , CHEN Jin-zhou'(1. School of Materials Science and En gineering, ZhengzhouUniversity, Zhengzhou 450052, China; 2 Henan JintiandiAgricultural Chemistry Co. L.DT , Zhengzhou 450000, China)ABSTRACT: The rhcological properties o[ ethylene vinyl-acetate copolymer (EVA) have beenstudied by means of XLY- 1 Rheometer. The effect of shear rate ,shear stress and temperatureon the apparent viscosity of the ethylene vinyl-acetate copolymer was discussed. Non Newtonianviscosity decreases with the increase of thc temperaturc. With increasing shear rate and shearstress, shear thining of the ethylene vinyl-acetate copolymer was observed clearly. Non-Newtoni-in index is less 1, and increases with the incrcase of the temperature, indicating a pseudoplasticnature of the mclt EVA.Keywords :ethylene vinyl-acetate copolymer; rheologica中国煤化工sityfYHCNMHG