【作者】 刘晓霞；

【导师】 张普玉；

【作者基本信息】 河南大学 ， 高分子化学与物理， 2007， 硕士

【摘要】 聚丙烯(PP)以其机械性能好、无毒、相对密度低、耐化学品以及价廉、易加工成型的优良特性,成为合成树脂中增长速度最快、新产品开发最为活跃的品种之一。然而,由于聚丙烯本身的一些缺陷,如冲击性能不好,材料的拉伸强度、耐热性等抵抗外力作用的能力差,在很大程度上限制了聚丙烯材料的应用。近年来,改性聚丙烯成为聚丙烯发展的主要方向,通过添加成核剂调控聚丙烯的结晶行为和结晶形态,从而达到改善聚丙烯性能的目的,创造高性能化的聚丙烯产品,是非常有效切实可行的调控手段。β晶型聚丙烯具有较高的冲击强度,拓宽了聚丙烯增韧改性的应用空间。添加β成核剂是目前公认的得到高含量β晶型聚丙烯的最有效方法。本文设计合成了一系列酰胺型β成核剂,筛选出高效、稳定和实用的酰胺型β成核剂,大幅度地改善了聚丙烯的冲击实验性能;凭借WAXD研究了成核剂的成核效果,并研究了成核剂晶体结构对成核效果的影响;凭借DSC、POM研究了酰胺型β成核剂作用下等规聚丙烯的结晶行为及微观形态,发现酰胺型β成核剂诱导iPP的结晶过程符合附生结晶的机理。研究发现NA-1、NA-2、NA-3和NA-4对聚丙烯韧性均有不同程度的改善,其中NA-1和NA-2的改善效果更为明显。松香类成核剂对聚丙烯的机械性能和光学性能均有不同程度的提高:1.考察了NA-1β成核剂对聚丙烯结晶性能的影响。改性后的聚丙烯力学性能测试表明,该成核剂具有使聚丙烯增韧的优异性能。用差示扫描量热法(DSC)和X射线粉末衍射仪(XRD)对其结晶形态进行了表征。DSC研究表明,该成核剂的加入可以诱导聚丙烯中α晶向β晶转变;X射线衍射研究发现,当成核剂加入量为0.3%时,β晶型的含量可达到87%,与DSC的研究结果一致。考察了冷却速率对结晶温度和结晶峰温度的影响,实验表明该成核剂的加入使结晶向高温方向偏移,结晶速度加快。2.考察了NA-2作为β成核剂对聚丙烯力学性能及结晶性能的影响。力学研究结果表明,该成核剂具有使聚丙烯增韧的优异性能,当添加量为0.3%时,抗冲击强度由原来的36.06J/m2提高到65.79 J/m2,提高了近一倍。DSC研究表明,添加β成核剂可以诱导PP中β晶生成。考察了冷却速率对结晶温度的影响,当冷却速率为10℃/min时,结晶温度从118.38℃提高到124.53℃提高了6.15℃,成核剂的加入使结晶向高温方向偏移,而且结晶速度加快。3.成核剂可以显著提高聚丙烯的透明性和透光率。当添加量为0.3%时,聚丙烯的雾度降低了58%。4.考察了酰胺类成核剂与松香盐类成核剂复配对聚丙烯力学及结晶性能的影响。结果表明,复配后的成核剂可以小幅度地提高聚丙烯的冲击强度和透明性。更多还原

【Abstract】 Polypropylene(PP) has excellent integrated properties, such as nontoxic, relatively low density, able to endure erode, ease to process and excellent mechanical properties etc. And so, PP has become one of the most active varieties of synthetic resin. However, there are some limitations on PP itself, for instance, low tensile strength, bad heat resistance and low transparaency etc, which have limited the range of application of the PP material to a great extent. In recent years, study and development on modified PP becomes the main direction of PP industry. Modifying crystallization behacior and morphology of PP by adding nucleating agents can improve the performance of PP, which is a practical and reliable method and also is a research hotspot of PP development recently. Good impact properties ofβcrystalline PP widens the application of PP. At present, the introduction ofβ-nucleating agent is a recognized reliable method for preparation of PP rich inβ-modification.A series of amide compounds were designed and synthesized. Some highly active, stable and inexpensive nucleating agents have been prepared and can remarkably increase the impact propriety of PP. The nucleating effect of nucleating agents was investigated by wide angle X-ray diffraction(WAXD), and their influences on crystallization behavior, morphology and mechanical properties of PP were studied by differential scanning calorimeter(DSC), polarized light microscopy(POM). Nucleating mechanism of amideβ-nucleating agent accords with epitaxial crystallization. Major achievements of this dissertation are described as follows.The results show that adding NA-1、NA-2、NA-3 and NA-4 can improve greatly the toughness of the iPP.Especially, the effect is more obvious when NA-1 and NA-2 are added. And the dehydroabietic acid salts can improve the optical properties of iPP.1. The influence of NA-1 nucleating agent on the crystallization characteristics of polypropylene was studied. Polypropylene modified byβ-nucleating agent was characterized by differential scanning calorimetry and X-ray diffraction spectrum.The results showed that the addition of a small aβ-nucleating agent to PP induced a rather high proportion ofβmodification. The relative content ofβphase estimated by XRD was up to 87% in PP containing 0.3%.The results by DSC was consistent with the ones by XRD. The effect of cooling at various rates on crystallization onset temperature and peak temperature was also studied. Compared with pure PP, nucleated PP showed a higher crystallization temperature and a faster crystallization rate. Besides, theβ-nucleating agent has outstanding results increasing the toughness respect of PP.2. The influence ofβ-nucleating agent NA-2 on the mechanical and crystallization characteristics of polypropylene was studied. The results showed that theβ-nucleating agent has outstanding results in increasing the toughness respect of PP .The impact strength rises to 65.79 J/m2 from 36.09 J/m2 original by adding 0.3%β-nucleating agent and it improves nearly one time than pure PP. The results of DSC showed that the addition of a small aβ-nucleating agent to PP induced a rather high proportion ofβmodification. The effect of cooling at various rates on crystallization peak temperature and crystallinity was also studied.When the rate of cooling was 10K/min, the peak temperature increased from 118.38℃to 124.53℃and improved 6.15℃.It was indicated that nucleated PP showed a higher crystallization temperature and a faster crystallization rate.3. The transparency、the transmittance, tensile strength and flexural strength and the like can notably be changed when the dehydroabietic acid salts are added to PP at 0.3 wt %.4. The influence of compounded nucleating agent on the mechanical and crystallization characteristics of polypropylene was studied. The results showed that the compounded nucleating agent can improve the toughness and the transparency.更多还原