论文标题:高密度聚乙烯/增韧母料增韧体系研究—制备、结构与性能
The Preparation and Characterization of HDPE/E-TMB
论文作者 白娟
论文导师 王经武,论文学位 硕士,论文专业 材料学
论文单位 郑州大学,点击次数 4,论文页数 86页File Size9919k
2005-05-22论文免费下载 http://paper.dic123.com/lunwen_966493652/ 高密度聚乙烯;增韧母料;增韧;结构;性能
High Density Polyethylene; Toughening Master Batch; Toughening; Structure; Properties
使高密度聚乙烯(HDPE)这一大品种通用塑料能够作为工程塑料使用,是国内外研制开发新型工程塑料的一个努力方向。针对均聚HDPE韧性比较低的缺陷,国内外开展了大量的增韧改性HDPE的研究工作。相比较,用弹性体增韧的增韧效果最好。可是,一般的弹性体增韧HDPE,使HDPE韧性大幅度提高的同时,刚性(拉伸屈服应力,TYS;弯曲弹性模量,FM)却显著降低了。如何使弹性体增韧HDPE韧性大幅度提高的同时刚性不显著降低,一直是弹性体增韧HDPE急待解决的科学技术难题。 本工作首先分析了一般的弹性体增韧HDPE韧性大幅度提高的同时刚性显著降低的原因,认为主要在于增韧HDPE的结构:其一,HDPE是一类非极性、通常情况下易形成结晶的聚合物,与弹性体的相容性差,相界面结合力小,易发生界面脱粘,不能有效地在两相之间传递和分配应力与应变;其二,弹性体作为分散相,未适度交联,外力作用下易发生分子间滑脱而产生“空化”;其三,欲呈现高的冲击强度,必须加大弹性体的质量分数,使增韧HDPE中刚性低的成分太多。从复合法则来看必将导致刚性的显著下降。加入相容剂共混,HDPE与增韧剂之间结合力不同程度提高了,有利于提高增韧效果,但是,要获得高韧性,弹性体的质量含量还必须相当大。依据弹性体增韧塑料的增韧理论和影响因素对增韧效果的影响规律,本工作设计出了能呈现出优良刚性的弹性体增韧HDPE应具有的结构特征:HDPE为连续相,弹性体为分散相;弹性体适度交联。和基体树脂间有化学键连接,尺寸细小均匀,其中包容有一定量的基体树脂,即呈胞状(香肠状)结构;HDPE结晶细化。 为了实现上述设计思想,并获得较佳的技术经济比,本工作首先以HDPE为基体树脂,乙丙弹性体(记为M)和/或丁苯弹性体(记为N)为增韧剂、采用多种特殊的技术,通过化学反应制备出了E型增韧母料(E-TMB),将E-TMB与HDPE热机械共混,制备出了具有优良刚性的增韧HDPE(HDPE/E-TMB)。采用分级提取、TEM、DSC、PLM、电子万能试验机、熔体流动速率仪、毛细管
High Density Polyethylene (HDPE) have been widely used as general plastics. It is a new approach for developing new engineering plastics to make HDPE vise in engineering fields. But toughness of HDPE could not be satisfied. In order to meet the demands of engineering fields , it is necessary to toughen HDPE.In the recent years many researches have made a lot of study on the toughening HDPE. In contrast with other methods, toughening effects are the best when using elastomer as toughening agents. But toughnees often evidently improves with rigidity (Tensile Yield Stress, TYS; Flexural Modulus, FM) decreasing sharply. It is a difficult problem to make rigidity do not decreases to a large degree with toughnees improving remarkably.The reasons for decreasing of rigidity could be summarized as follows: (l)The compatibility between HDPE and elastomer is badly because HDPE tend to crystalline. (2)Elastomer as the dispersed phase are not crosslinked in moderation. The molecule chains are easy to surge under the action of outside force. (3)In order to improving toughness to a large degree, the mass content of elastmer must be increased. So the component of low rigidity is too much.Based on the theory of elastomer toughened plastics and the law of the influence which factors act on toughening effects, We design a kind of structure: the HDPE is as the continuous phase and the crosslinked elastomer as the dispersed phase. Two phases are connected with through the polymer bridge. The dispersed phase have a typical cellular structure(salami structure).We choose elastomers as toughening agents. A series of high desity polyethylene engineering plastics having higher rigidity and highly improved toughness were prepared through thermal mechanical blending HDPE with E toughening master batch (E-TMB) synthesized from HDPE as matrix resin. ethylene-propylene elastomer(M) and(or) butadiene-styrene elastomer(N) as toughening agents. The chemical structure and morphology of E-TMBs, and themechanical and rheological properties, morphology and crystallization behavior of the HDPE/E-TMBs were characterized by using fraction extraction, TEM, DSC, TG. PLM techniques as well as an electronic universal testing machine and a rheometer etc.From the experiment data, it was found that:(1) The structure of E-TMBs and HDPE/E-TMB is uniform with that we designed in advance. HDPE/E-TMB show much better NIIS, maintained much higher TYS and FM compared with simply blended samples (HDPE/elastomer).(2) The MFR of E-TMB is lower than that of simply blended samples, but it is still in the range of MFR fitting for preparing HDPE/E-TMB.(3) when using E-TMB with H:T=56:44,M/N=80/20, anti-crosslinking agent and bridge agent is 1.9% and 12%, and when elastomer content of HDPE/E-TMB is 8%, the 2200JHDPE/E-TMB shows excellent balanced mechanical properties: Notched Izod impact strength is 8.5 times of that of HDPE, TYS and FM is 87% and 70% of that of HDPE. when using E-TMB with H:T=64:36,M/N=0/100, anti-crosslinking agent and bridge agent is 1.9% and 12%, and when elastomer content of HDPE/E-TMB is 8%, the 5000SHDPE/E-TMB shows excellent balanced mechanical properties: Notched Izod impact strength is 76.6 KJ/m2, TYS and FM is 98% and 82% of that of HDPE.(4) When elastomer content in 2911 HDPE/E-TMB is 10%, a brittle-ductile transition occurred in toughened HDPE. This transition occurred in 2200JHDPE/E-TMB when elastomer content in toughened HDPE is 5%. However. This transition don"t occurred in toughened 5000SHDPE .(5) The MFR of HDPE/E-TMB was lower than that of HDPE/elastomer, but it was still in the range of MFR fitting for injection and extrusion molding. Under ordinary sheer flow conditions, the HDPE/E-TMB melt showed a pseudo-plastic feature. The linear relationship between η a and T of the HDPE/ E-TMB melts was similar to In η a and 1/T. The HDPE/ E-TMB melt could be expressed by η a = A + KT, by which the physical nature of the temperature coefficient of apparent viscosity would be more specific.(6) The elastomer have a dou
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