【作者】 于妍；

【导师】 张长春；

【作者基本信息】 吉林大学 ， 材料学， 2004， 硕士

【摘要】 本文利用自制的超声波混炼装置，研究了UHMWPE及共混物UHMWPE/HDPE/EVA的流变行为、力学性能、热力学行为及结晶行为。超声波混炼装置为本实验组成员自行设计研制，它由超声波装置（超声波频率为20KHz,功率400W-1000W连续可调）和聚合物混炼装置两部分构成，并且通过固定装置将这两部分巧妙结合起来，达到了在聚合物混炼过程中成功加入超声波场致作用的目的，并且取得了良好的实验效果。此超声波混炼装置适用于聚合物的物理共混，根据物料的物理及化学性能指标调节混炼温度及时间等工艺参数，使混炼达到最佳状态。并且在混炼的同时根据实验需要自动调节施加超声场致作用的时间与功率。本实验组自制的此套超声波混炼设备，由于设计时间比较短还存在一些不足之处，有待于进一步改进。本论文利用自行研制的超声波混炼装置对UHMWPE进行超声混炼，实验过程中我们将超声功率调至400W、500 W、 600 W、 700 W，将施加超声场致作用的时间分别设定为5min、10min、15min, 研究在不同的超声条件下UHMWPE的流变性能、力学性能等其他方面的性能变化。实验结果表明混炼加工过程中引入超声波场致作用对UHMWPE的性能产生了显著影响。一方面，超声波的振动空化作用使缠结在一起的大分子链受到有规律的搅动而解缠，致使缠结点大大减少、分子链段运动阻力减少，宏观上表现为粘度降低、流变性能改善。实验结果表明超声作用时间为10 min时流动性最好。并且我们看到logηa与logγw的关系曲线基本呈线性，说明在超声作用下UHMWPE熔体的剪切流动仍服从幂律公式；另一方面，实验结果表明超声混炼后的UHMWPE材料的宏观力学性能如屈服强度、断裂伸长率等得到明显提高。从DSC分析结果中看出，超声波场致作用使得UHMWPE的熔点升高,峰高增大，熔融热焓显著提高。并且结晶峰变窄变陡变高，（Tonset-Tc）值变小，表明超声波场致作用的空穴效应对UHMWPE<WP=58>的颗粒产生了明显的破碎作用，使得体系中的晶体尺寸变小，并且加速了结晶速率，结晶度变大。超声波场致作用对UHMWPE/HDPE/EVA共混物性能同样有着显著的影响。由于HUMWPE相对分子质量很高，主链很长且相互缠结，熔体粘度极高，流动性很差，其熔体只能就字面上的意义来理解。在熔融温度以上处于凝胶状态，熔体流动速率一般不易测定，因此要用加工普通PE的设备加工UHMWPE ,需要对其进行流动改性。目前对UHMWPE改性最有效可行的方法就是物理共混改性，但共混时由于不同物料之间的相容性很难达到最佳状态，这就使得共混效果不理想，相与相之间熔和的不好，分散相分布不均匀。当超声波在聚合物熔体中传播时，会在熔体中产生超声空化现象，这种空化效应能够搅拌、破碎聚合物颗粒从而使得聚合物共混更均匀。通过SEM图片可以明显看到，与未经过超声波场致作用的试样相比，引入超声波场致作用后,EVA颗粒的粒径有了很大程度的减小。当超声波功率为500W时，不仅EVA颗粒尺寸明显减小，颗粒分散性也有所改善，在基体中分布均匀性提高，亦即与基体相容性增大。所以将超声波场致作用应用于聚合物共混中可以使相与相之间熔合得更好，有效的促进低分子填料在聚合物中分散，改善填充体系的混合特性。聚合物加工过程中引入超声波场致作用是一项很有发展前景的新型成型、改性技术。超声波场致作用在控制聚合物的结晶，改善聚合物的相容性，解决纳米粉体在聚合物中的团聚现象、提高纳米聚合物中纳米粉体的分散性方面有其独特作用。随着超声技术的不断发展以及人们对超声作用认识的逐渐深入, 超声波场致作用在聚合物加工、改性及改善现有成型、改性设备，提高制件性能方面发挥越来越大的作用。本论文主要致力于超声波场致作用对UHMWPE、及UHMWPE/HDPE/EVA共混体系的性能研究，它对于开辟新的UHMWPE 改性方法，创新加工成型设备都极富实际意义。更多还原

【Abstract】 Developed a sonicated mixer by ourselves, and did the research on the rhe-ology behavior,mechanical performance,thermodynamic performance and crys-tallization behavior of UHMWPE and UHMWPE/HDPE/EVA by it.This sonicated mixer was developed by ourselves, and it is composed of ultrasonic equipment (20KHz,400W-1000W) and polymer mixer. The two parts were united successfully by a fixer, so the ultrasonic field could be introduced during blending, and we got favourable experiment results .This equipment is f-it for the physical blending of polymer. In order to get favourable blending stat-e we can adjust the temperature and time ect. according to the physical and che-mical properties of the polymer, and the vibration time and power of the ultras-onic field can also be adjusted during blending according to the requirement. B-ecause of the time of design was so short that there are still many disadvantag-es, and it should be improved later. During the blending of UHMWPE , we set the power value of ultrasonic field as 400W,500W,600W,700W, and the time v-alue as 5min,10min,15min. Studied on the rheology behavior,mechanical perfo-rmance etc.of UHMWPE under different ultrasonic field conditions.The results showed the effect of ultrasonic field did great influence on the properties of the UHMWPE. One side, the long chain of the polymer was dista-ngled by the vibration cavitating effect of the ultrasonic field ,so the tangle poi-nts decreased greatly, and the resistance of movement decreased too, finally the viscosity reduced, and the rheology was improved. The results showed, the rhe-ology was best when the ultrasonic vibration time was 10min. Furthermore, the curve of logηa Vs logγw is linear, and it showed that the shear flow of UHM-WPE obeyed exponential law under the ultrasonic field;on the other hand, the results showed, the yield strength, elongation at break increased evidently. From the results of DSC analysis we could see the Tm , the Peak Height and the ΔHm <WP=60>of UHMWPE increased by the effect of ultrasonic field. Furthermore, the cryst-allization peak became narrower and higher, and the value of （Tonset-Tc）became smaller, so it showed the cavitating effect of ultrasonic field broke the UHMWPE particle smaller, and accelerated the velocity of crystallization, and increased the degree of crystall-ization. The effect of ultrasonic field have great influence on the blending of UHMWPE/H-DPE/EVA too. Because the molecular weight of UHMWPE is so high that its viscosity is very high and the rheology is bad. Beyond the melting temperature, the polymer is gelatinous, and it is very difficult to measure the flow rate, so if we want to process the UHMWPE with the common equipment for PE we sho-uld improve the rheology. At present, the feasible way is physical blending, but because it is so difficult for the compatibility of the different material to get the best state that the effect of the blending is not perfect, and it is not compatible well between the different phase, and the disperse phase is not homogeneous. It occurs cavitating effect when the ultrasound wave is spreading inside the poly-mer melting, and this effect will blend and break the particle of polymer meltin-g so the blending will be homogeneous.From the SEM photograph we saw that the particle of EVA became sma-ller evidently after inducing ultrasonic field . It was not only the size of EVA particle was decreased a lot , but also the dispersing was improved, and the dis-perse phase was more homogeneous, viz. the compatibility is better. So ultraso-nic field can effectively improve not only the compatibility of polymer blends, but also the dispersibility of the additive in polymer.It is a perspective novel technology to apply high power ultrasonic field to the polymer melts during processing. Ultrasonic field is a quite effective means in controlling crystallization of the polymer, improving the compatibility of polymer blends, preventing the reuniting of the nano-powder, and enhancing the dispersibi更多还原