|Thesis Advisor||张亚刚 ; 吾满江·艾力|
|Place of Conferral||北京|
|Keyword||玻璃纤维 表面接枝 聚丙烯 复合材料 界面粘附|
玻璃纤维具有拉伸强度大和模量高的特点，用玻璃纤维对热塑性塑料进行增强后，可明显提高其拉伸、弯曲和冲击等性能。然而玻璃纤维与树脂基体间表面性质差异大，致使两者的相容性差，因此难以形成良好的界面粘结强度。在玻璃纤维表面接枝聚合物分子链，是一种改善纤维与树脂间界面强度的方法。为此，本论文设计了一种玻璃纤维表面的多步改性方法，利用二异氰酸酯的活泼性，将玻璃纤维先后用(3-氨丙基)三乙氧基硅烷（γ-APS）、二异氰酸酯和胺类/聚乙二醇（PEG）对纤维进行浸渍处理。为了验证接枝是否成功，用接触角测量、ATR-FTIR、XPS和AFM等方法对改性的玻璃纤维进行了表面表征。将各种不同方法处理的玻璃纤维进行单丝拉伸性能测试，并将结果用双参数Weibull模型进行分析，以研究接枝处理对玻璃纤维拉伸性能的影响。为了研究接枝处理对GF/PP复合材料拉伸性能和界面粘结强度的影响，制取了单向玻璃纤维增强PP复合材料（UD GF/PP）拉伸样条，并进行横向及纵向拉伸性能测试。以下是本论文的主要研究成果：（1）表面表征表明胺类被成功地接枝到玻璃纤维表面上。接触角测试表明胺类改性以后的玻璃纤维疏水较好，从而更容易被树脂润湿。力学性能测试发现，用硅烷γ-APS处理后，UD GF/PP的纵向拉伸强度显著提高。苄胺或十八胺进一步处理后，玻纤表面接枝的有机分子链进一步变长，复合材料的拉伸性能进一步提高。（2）表面表征表明聚乙二醇分子链被成功地接枝到玻璃纤维表面上。AFM分析表明随着PEG平均分子量的增加，接枝在玻纤表面的分子链逐渐变长，表面的粗糙度逐渐变大。力学测试结果表明用PEG对玻璃纤维进行接枝可以明显提高UD GF/PP的横向和纵向拉伸强度，以及界面粘结强度。采用本方法在玻璃纤维表面接枝PEG链，是一种提高GF/PP复合材料拉伸性能的有效手段。（3）利用不同的分子量的PEG的接枝，研究了接枝在玻璃纤维表面的聚合物的分子链长度对GF/PP界面粘结强度的影响。结果表明，随着PEG的平均分子量的增大，接枝的分子链的长度将随之增长，进而越有利于接枝分子链与基体树脂进行纠缠、锁合和共结晶，从而具有更高的界面粘结强度，以及更高复合材料的拉伸强度。并且，当接枝的分子链与基体树脂的分子链长度相近时界面粘结强度最佳。
Glass fibers (GFs) have high tensile strength and modulus. The blending of GF with thermoplastics can significantly improve the tensile, flexural and impact properties of materials. However, the surface properties between glass fiber and polymer matrix are quite different, resulting in bad compatibility between those two. For this reason, glass fiber reinforced thermoplastics often possess poor interfacial adhesion which significantly limits their practical application. Grafting polymer chains on GF surface hold great promise and could be an effective method to increase the interfacial adhesion of composites based on the mechanism of interlocking and entanglement with matrix polymer. In the work reported here, a facile three-stage modification method was developed to graft amines or poly (ethylene glycol) (PEG) onto GF surface. With this novel method, glass fibers were treated by 3-Aminopropyltriethoxysilane (γ-APS), 1,6-Diisocyanatohexane (HDI) and amines or poly (ethylene glycol) (PEG) stepwise. ATR-FTIR, XPS and AFM were used to characterize modified surface and to evaluate whether the grafting was successful. The fiber strength was measured by single fiber tensile strength test and the data were analyzed by using two-parameter Weibull model. The treated GFs were blended with PP to make unidirectional GF reinforced PP composites (UD GF/PP). The UD GF/PP specimens were tested from 90° and 0° off-axis to measure the tensile strength. The influence of grafting on the interfacial adhesion was studied by the analysis of the transverse tensile strength of composites and the theoretical interfacial shear strength was calculated by equations. The main conclusions were summarized as follows. (1) Results from surface analysis showed that amines were successfully grafted onto the GF surface. Contact angle measurements demonstrated that glass fibers became more hydrophobic after grafting by amine, which indicated that GFs could be better wetted by resin. After treated by γ-APS, the longitudinal tensile strength of UD GF/PP significantly increased. The grafting of Benzylamine or octadecylamine further improved the tensile properties of the composite, as the grafted chain becomes long. (2) Surface analysis demonstrated that PEG chains having different molar mass were successfully grafted onto glass fiber surface under mild reaction and processing conditions. AFM analysis revealed that as the M ?_w increased, the surface roughness increased, indicating the grafted PEG chains lengthened. The tensile test showed that the grafting of PEG chains could significantly improve the transverse and longitudinal tensile strength and the interfacial adhesion of UD GF / PP. In summary, treating glass fiber with this three-step method to graft PEG chains onto GF surface is an effective means to improve the tensile properties of GF / PP composites. (3) The interfacial adhesion of composites was studied as a function of the M ?_w of PEG chain grafted on the glass surface to study the influence of grafted chain length on interfacial adhesion. Results showed that as the M ?_w of PEG increased the interfacial adhesion of composites improved, because the longer grafted chains promoted the entanglement, interlocking and co-crystallization between grafted chains and matrix polymer. And the best interfacial adhesion was obtained when the grafted chain length was matched well with the polymer chain length of matrix.
|刘泽宇. 玻璃纤维表面接枝改性及其对GF/PP复合材料性能的影响[D]. 北京. 中国科学院大学,2015.|
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