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毕业设计 (论文 )外文资料翻译 设计题目 : 电磁屏蔽罩注塑模具及其工艺设计 翻译题目: 复合过程中的相变化 粘度随温度变 化的影响 学生姓名: 曹 春 生 学 号: 20064480218 专业班级: 材控 0602 班 指导教师: 吴 海 宏 附 件: 1.外文资料翻译译文; 2.外文原文。 指导教师评语: 签名: 年 月 日 nts 本文出自中国知识网 附件 1:外文资料翻译译文 复合过程中的相变化 粘度随温度变化的影响 拉姆勒德纳吉里, 克里斯 .斯科特 材料科学与工程,麻省理工学院,马萨诸塞州剑桥研究所, 02139 部 摘要 不相容的混合物在形态化合发展过程中,各组成部分的不同的保温的流变反应的影响已被研究。混合物中低粘度的次要成分发生相位转变,在化和过程中从扩散到组分 B 的组分 A 的一种形态转变成扩散到组分 A 的组 分 B 的一种形态。相对转变温度和相对粘度有关联地变化。个别组分的粘度影响温度并且决定相转变反应已经被研究过。 引言 一个具体的目标形态往往是不互溶 混合物复合 的目标。 当混合两个或两个以上不同的流变和保温的性质的组分时,这种形态就会形成。很好地理解混合物在在化合过程中的配制机制对决定工艺条件是很有必要的。在充分被融化的熔融状态下配制 比较好理解 。但是事实证明,在固体颗粒聚合物转变成最后的分散的相的形态过程中,大部分的尺寸减少在熔融的状态下发生。 在熔融和软化条件下的混合方面并不很好理解。据观察,在低熔点次要组分存在 时,一种相的转化现象可能在混合的过程中发生,次要成分形成连续相。这种有趣的现象也被证实低粘度的次要组分在相同的转化温度条件下也会发生。我们的工作重点就是通过粘度比和相对转变温度能够独立变化的混合系统模型解释这两个参数对混合反应的影响。在具有代表性的剪切率和单一温度条件下粘度比不可能充分地描绘混合的特征。因此,流变学的测量方法对固态和熔融态物质都适用,这些方法和已知混合工序方法关联。 试验 材料 组成混合物的个别组分的选择取决于它们的 熔点 /软化点 和在可加工温度条件下,在熔化器中具有代表性的剪切速率时的粘度。 除了已经被报道的 聚碳酸酯 和聚乙烯混合物体系之外,还有一系列出自 Shell 的四聚丁烯、出自 Bayer 的聚碳酸酯nts 和出自 Eastman 化工公司的非晶态共聚多酯都应经被应用。图表 1 中总结了混合物的物理热学特性。根据聚乙烯和聚丁烯分子量的不同可以把混合物的流动性分类二不改变各组成部分的熔点 /软化点温度。 步骤(过程) 每种成分在低于转化温度的空间里干燥 40 小时。混合物的不同组成成分被用来制作不同的粘性和相对转化温度的混合物。聚丁烯和 聚碳酸酯 的混合物,聚碳酸酯和聚乙烯的混合物, 聚对苯二甲酸乙二醇 和聚乙烯混合物都已经被 调查研究过了。这些混合物的肖像成分占总重量的 10 . 一个 Haake Rheomix 型的间歇式搅拌机用来进行混合工作。这些干颗粒经人工在托盘里混合后在送入高效的间歇式搅拌机,这种间歇式搅拌机带有每分 50 转的旋转刀片装置。紧接着,用来驱动恒定转速的聚合化合物的扭转力矩开始起作用。 在混合过程中的选定的时间,停止搅拌机,从中选取样本,并在液态氮中急速冷却这些样本,使它们保持原来的形态。二氯甲烷用来有选择性地溶解一种组成成分,并测定连续相。在上述提到的每一种混合机制中,只有一种混合机制在二氯甲烷可以溶解。 运用 一个来自 Rheometrics 机械光谱仪是流变学的测量方法取得成功。在熔融状态,应用一个平行板装置,可以在动态剪切状态下测定合成的粘度和系数。为了测定固态下的流动性,要用到一个扭转夹具。聚合物中的矩形片状物被压缩成型,并在扭转力的作用下剪切变形,能够获得固态的低应变的动态剪切变形条件下的综合系数。我们的目的是通过整个温度变化范围测量聚合物的流变能力,正像前面所描述,这个温度变化范围是一个小颗粒的一个典型的配合工序所经历的。 结果 聚对苯二甲酸乙二醇 和聚乙烯的混合物 图表 2 显示了这两种混合物的综合粘度的大小随 着时间的变化,作为混合物的重要组成部分的 聚对苯二甲酸乙二醇 是一种非结晶的高粘度的成分。两种不同的聚乙烯(聚乙烯 A 和聚乙烯 D)被用作次要成分。这些关于聚乙烯的 DSC 曲线表明融融峰值接近 100。图表 1 中显示了这些混合物在 180的搅拌机设定温度条件下的扭力矩曲线。在含有低粘度聚乙烯的混合物中,发现了一个显著地低扭矩区域。在这个时候收集的样本表明,聚乙烯是连续相。在混有聚乙烯 A 的混合物中,分别在混合的 30 秒、 70 秒和五分钟是采集样本。第一次采集的样本大致和扭力矩峰值nts 相一致。进入混合的这个时间,发现聚乙烯 A 是连续 相。在以后的时间里, 聚对苯二甲酸乙二醇 是连续相。 聚乙烯和氯化磷的混合物 聚丁烯(聚乙烯 A 接通着聚乙烯 D)的不同分子量和低分子量氯化磷 B 混合。在这个混合体系中,次要成分(氯化磷)的熔点比主要成分的低。一个 180 设定温度的连续式搅拌机用于混杂这些混合物。在这个温度和的剪切速率 100s 1 的条件下,这些混合物的粘度比接近于 1。图表 3 显示了混合过程中的扭力矩曲线。与低粘度次要成分的扭力矩变化曲线不同,这些混合物在混合过程中没有出现低扭力矩区域。在混合开始 45s 是采集的样本与扭力矩峰值的下降一致。对二氯甲烷分解的 研究表明聚乙烯在样本中是连续相。尽管低熔点次要成分的出现,即使是在很短的混合时间内主要成分就已是连续相了。图表 4 显示了 PE-A 和 PCL-B 的混合物及PB-D 和 PCL-B 的混合物的混凝和粘度随时间变化的情况。 聚碳酸酯和聚乙烯的混合物 与前述的混合物恰恰相反,聚碳酸酯和聚乙烯组合成的混合物含有更多的有粘性的主要成分,这种主要成分的软化温度( 150 )远远高于次要成分聚乙烯的熔点温度。要应用到一个设定温度为 180的搅拌机。图表 5 显示的低粘度混合物的扭矩曲线表明低扭力矩区域和聚乙烯为连续相的区域相相符。图表 6 显示了这些混合成分的流变性的数据。 论述 表格 2 给出了一个给不同混合体系分类的简便方法。基于 DSC 测量方法的粘度率和转变温度的有代表性的价值是用于区分混合物。决定连续相的分解的研究结果也包含在内。我们对混合物的相转变机制的理解表明了组成混合物的各种组分的相对转变温度和剪切率的重要性。我们先前已经报道了关于考虑相对粘度率的重要性,相对粘度转化率决定相的转变,即使是在含有较高熔点的次要相的混合物。我们已经试图通过研究混合物的流动性弄懂相转变机制,通过混合物的添加物的整个温度变化范围研究混合物的流动性。 我们的流 变学的测量方法表明与从固态到聚合物熔态变化有关的混合粘度的急剧下降是预料中的预料中。在含有两不同转变问的种成分的混合物中,两种成分的粘度的相对下降趋势严格地决定了复合性能。 nts 正如图表 3 中的两种聚乙烯的粘度曲线所示,在 DSC 中测量的熔点温度不能准确地代表包括有消耗性的混合熔融的加工操作的相对转变温度。较低分子量的聚乙烯在较低的温度开始软化。在混有聚乙烯 D 的混合物中发现了由于相转变的原因引起的扭力矩的增加【图表 1】。在含有较黏的聚乙烯 A 混合物中没有发现扭力矩的上升。 在聚乙烯和氯化磷 B 的混合物中,尽管有低熔点次 要成分的出现 。氯化磷和聚乙烯的粘度相当,它们遮掩了关于已被发现加工性能的氯化磷的低熔点的影响。我们对不同混合时刻的分解的研究表明,聚乙烯是连续相。但是这并不表明氯化磷永远不会形成连续相。因此这个结果在图表 2 中记作不确定的。 在聚碳酸酯和聚乙烯的混合物中,聚乙烯的低粘度和低熔点证实了相转化,这正是通过分解研究所发现的。另外,在较低粘度比的聚碳酸酯和聚乙烯 D 的混合物中发现了与相转变有关的扭力矩的显著增加。 结论 从上述的这些工作中可以得到如下结论: 1)相转化很可能在有低粘度的成分出现时发生,既是它有较高的熔点 。在含有低粘度低熔点的组分的混合体系中,它是最有利的。 2)在混合过程中,单独的扭利矩曲线不是相转化发生的可靠指示。这一点被PETG 和聚乙烯 A 及聚碳酸酯和聚乙烯 A 的混合物的曲线证明。 3)与半晶状态聚合物的熔化和非结晶状态聚合物的软化有关的粘性的急剧下降是决定混合过程中的形态演变的重要因素。聚乙烯 D 的低融化粘度和低软化点的组合改变已被发现的加工性能已经被证实。 4)相对转化温度和相对粘度提供了一个化合反应可以被研究的框架。这是确定决定熔化 /软化环境下的混合机制参数的第一步。 鸣谢 这项研究受到 麻省理 工学院材料科学与工程 系和 Eastman 化工公司的支持 参考文献 1. J. M. Rallison, J. Fluid Mech., , 625, (1980). 2. C. E. Scott, PhD Thesis, Univ. of Minnesota, (1990). 3. C. K. Shih, D. G. Tynan, D. A. Denelsbeck, Polym. Eng. Sci., 31, 1670 (1991). nts 4. U. Sundararaj, PhD Thesis, Univ. of Minnesota,(1994) 5. C. E. Scott, S. K. Joung, Polym. Engr. Sci., 36 , 1666(1996). 6. R. Ratnagiri, C. E. Scott, SPE ANTEC Tech. Papers,(1995). (关键词 : 相转变 , 不相容的混合物 ,粘度比 ,混合 ) 表格 1:混合物各成分的物理热学性质 表格 2: 混合系统模型加工性质摘要 图表 1: 在 180混合 聚对苯二甲酸乙二醇 和 聚乙烯的 搅拌机的扭力矩曲线 nts 图表 2: 聚对苯二甲酸乙二醇 和聚乙烯的混合物的在间却率为 100s 1 的综合粘度 图表 3: 聚乙烯和聚碳酸酯 B 的混合物在设定温度 180的搅拌机中的扭矩曲线 nts 图表 4: 聚乙烯和聚碳酸酯混合物在剪切率为 100s-1 的条件下的综合粘度 图表 5:聚碳酸酯和聚乙烯混合物在设定温度为 180搅拌机中的的扭矩曲线 nts 图表 6:聚碳酸酯和聚乙烯混合物在剪切率为时的综合粘度 nts 附件 2:外文原文 PHASE INVERSION DURING COMPOUNDING - THE EFFECT OF VISCOSITY VARIATION WITH TEMPERATURE Ram Ratnagiri, Chris E. Scott, Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139. Abstract The effect of different rheological and thermal behavior of the components in an immiscible blend, on the evolution of its morphology during compounding was investigated.Phase inversion, where there is a transformation from a morphology of component A dispersed in component B to that of component B dispersed in component A during compounding was shown to occur in blends with a low viscosity minor component. Relative transition temperatures and relative viscosities were systematically varied. The temperature dependence of viscosity of the individual components and its effect on determining phase inversion behavior was explored. Introduction A specific target morphology is often the goal in the compounding of immiscible blends. This morphology has to be achieved while blending two or more components of different rheological and thermal properties. A good understanding of the mechanisms of mixing during compounding in such blends is essential to determine the process conditions. Mixing in the fully molten melt state is relatively well understood 1. But it has been shown that most of the reduction in size in going from solid pellets of the polymer to the final dispersed phase morphology occurs in the melting regime 2. This aspect of mixing during the melting/softening regime is not very well understood. It has been observed that in the presence of a low melting point minor component, a phase inversion phenomenon, where the minor component forms the continuous phase, may occur during compounding3,4. This interesting behavior has also been shown to occur in systems of similar transition temperatures, with a low viscosity minor component 5. Our work focuses on elucidating the effects of these two parameters on the compounding behavior; by using model blend systems where the viscosity ratios and relative transition temperatures can be independently varied. The viscosity ratio at a representative shear rate and a single temperature is unlikely to adequately characterize the blend. Hence, rheological measurements have been made in both the solid state and the melt, and these have been correlated with the observed processing behavior of the blends. Experiments Materials The choice of the individual components making up the blend was based on their melting/softening points and their viscosity at the processing temperature and at a representative shear rate in the mixer. In addition to the polycapralactone/polyethylene system already reported 6; a series of four polybutylenes from Shell, a polycarbonate from Bayer, and an amorphous copolyester from Eastman Chemical Company were used. The relevant thermophysical properties of the blend components are summarized in Table 1. Different molecular weights of the polybutylenes (PB) and polyethylenes (PE) were used so that the rheology of the blend could be nts varied without changing the melting/softening temperatures of the components. Procedure Each of the components was dried under vacuum at a temperature below the transition temperature for 40hrs. Different combinations of the components were used to prepare blends of different viscosity ratios and relative transition temperatures. Polybutylene/Polycapralactone, Polycarbonate/Polyethylene, PETG/Polyethylene blends were investigated. In all these blends the minor phase was kept at 10 wt.%. A Haake Rheomix 600 batch mixer was used for all the compounding runs. The dried pellets were hand mixed in a tray before being fed into an intensive batch mixer with rotor blades set to rotate at 50 r.p.m. The torque required to drive the polymer mixture at a constant rotor speed was followed as a function of time. At selected times into compounding, the mixer was stopped and samples were collected. These samples were quenched in liquid nitrogen to preserve the morphology at that time. Methylene chloride was used to selectively dissolve away one of the components and determine the continuous phase. In each of the blend systems mentioned above, only one of the two components was soluble inmethylene chloride. Rheological measurements were made using an ARES mechanical spectrometer from Rheometrics. In the melt state, a parallel plate fixture was used and the complex viscosity and modulus were measured in a dynamic shear mode. For measuring the rheology in the solid state, a torsional fixture was used. Rectangular coupons of the polymer were compression molded and were sheared under torsion to obtain the complex moduli in the solid state under dynamic shear deformation at low strains. Our aim was to measure the rhelogy of the polymers across the entire temperature range that a pellet would experience in a typical compounding operation as described above. Results PETG/PE Blends The magnitude of the complex viscosity as a function of temperature of these components is shown in Fig. 2. The PETG used as a major component in these blends was an amorphous high viscosity component with a T of 80 C. Two different Polyethylenes (PE-A and PE-D) were used as the minor component. The DSC traces on these polyethylenes showed a melting peak close to 100 C. The torque traces of these blends at a mixer set temperature of 180 C are shown in Fig. 1. In the blend with the low viscosity PE, a pronounced region of low torque is observed. Samples collected at this time showed that the PE was the continuous phase. In the blend with PE-A; samples were collected at 30s, 70s and 5min into mixing. The first of these corresponds roughly to the peak torque value. At this time into mixing, PE-A was found to be the continuous phase. At later times, PETG was the continuous phase. PB/PCL Blends Different molecular weights of polybutylene (PB-A through PB-D) were blended with the lower molecular weight Polycapralactone PCL-B. In this blend system, the minor component (PCL) has a much lower melting point than the major component. A constant mixer set temperature of 180 C was used to compound these blends. At this temperature and a representative shear rate of 100s-1, the viscosity ratios in these blends is close to one. The torque traces for these blending runs are shown in Fig. 3. Unlike the behavior of the torque with a low viscosity minor component, there is no low torque region during mixing. Samples were taken at about 45 seconds into mixing corresponding to the drop from feed torque peak. Dissolution studies with methylene chloride indicated that PB was the continuous phase in these samples. Despite the presence of a low nts melting minor component, the major component was the continuous phase even at short mixing times. The temperature dependent complex viscosity of PB-A/PCL-B and PB-D/PCL-B blend components is shown in Fig. 4. PC/PE Blends In contrast with the above blends, this system has a more viscous major component whose softening temperature (150 C) is far above the melting point of the minor PE component. A mixer set temperature of 180 C was used. The torque traces (Fig. 5) of the low viscosity blend indicate a low torque region coinciding with the PE being the continuous phase. The rheological measurements of these blend components are shown in Fig. 6. Discussion A convenient way to group these different blend systems is shown in Table 2. A representative value of the viscosity ratio and the transition temperatures based on DSC measurements were used to differentiate the blends. The results of the dissolution studies to determine the continuous phase are included. Our understanding of the phase inversion mechanism in compounding has clearly shown the importance of both the relative transition temperature and the viscosity ratio of the components making up the blend. We have previously reported on the importance of considering the relative viscosity ratios in determining phase inversion even in blends with a higher melting point minor phase 6. We have tried to understand the mechanism of phase inversion by studying the rheology of the components across the entire temperature range of interest in compounding. Our rheological measurements show the expected sharp drop in the complex viscosity associated with going from a solid to a polymer melt. In a blend of two components of different transition temperatures, the compounding behavior is critically determined by the relative positions of this drop in viscosity of the two components. As shown by the viscosity curves for the two PEs Fig. 2, the melting point as measured in a DSC may not be an accurate representation of the relevant transition temperature for processing operations which involve dissipative mix-melting. The lower molecular weight PE, begins to soften at a lower temperature. This coupled with a very low viscosity in the melt state enables the formation of a continuous phase by the PE. An increase in torque due to phase inversion is observed in the blends with PE-D Fig. 1. This is torque rise is not seen in the blend with the more viscous PE-A. In the PB/PCL-B blends, despite the presence of a low melting point minor component, a single feed torque peak is observed Fig. 3. The comparable melt viscosities of the PCL and PBs Fig. 4 seems to overshadow the effect of the low melting point of PCL on the observed processing behavior. Our dissolution studies at different mixing times indicated that PB was the continuous phase. But this does not imply that PCL never formed the continuous phase. Hence these results have been labeled inconclusive in Table 2. In the PC/PE blends, the low viscosity and the lower melting point of the PEs, favor phase inversion, as was indeed observed by the dissolution studies. In addition, a distinct rise in torque associated with phase inversion is observed in the lower viscosity ratio PC/PE-D blend. Conclusions From the work presented here, the following conclusions can be drawn: 1) Phase inversion is likely to
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