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首页> 外文学位 >Processing characteristics of blends of Poly(ethylene terephthalate) (PET) and Poly(ethylene naphthalate) (PEN).
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Processing characteristics of blends of Poly(ethylene terephthalate) (PET) and Poly(ethylene naphthalate) (PEN).

机译：聚对苯二甲酸乙二醇酯（PET）和聚萘二甲酸乙二醇酯（PEN）的混合物的加工特性。

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Blends of Poly(ethylene terephthalate) (PET) and Poly(ethylene naphthalate) (PEN) have exhibited properties that are of commercial interest to the packaging industry. Melt processing of PET with PEN results in transesterification reactions. The kinetics of these reactions as well as their effect on blend properties like glass transition temperature, crystallization and haze has been widely studied. These studies show that the blend properties become independent of the reaction once a certain critical level of transesterification has been achieved. However, there is little data available on the injection molding and stretch blow molding characteristics of these blends. In this dissertation, it was proposed to study the processing characteristics (primarily stretch blow molding) of the PET/PEN blends after the blends attain the critical transesterification level. Modifications to the chemical kinetic equations have been made to predict a theoretical processing temperature for different compositions of the blends to achieve critical transesterification. These values were found to be in close agreement with the experimentally observed values when blends were processed in a twin screw extruder. The processes of extrusion and injection molding involve the melting of the polymer at high temperature. Subsequently, an understanding of the melt rheology and the different degradation processes that occur is important. An instron capillary rheometer was used to study the melt viscosity as a function of temperature and shear rate. The flow behavior of blends containing 10, 20 and 40% PEN by weight was very similar to that of PET. A model equation has been developed to describe the dependence of the melt viscosity on shear rate and temperature. Melt viscosity measurements using a cone and plate viscometer showed that addition of low amounts of PEN to PET causes a depression in the melt viscosity. A critical composition of 10% PEN by weight is required before we observe an increase in blend viscosity.; Degradation kinetics (thermal and thermal-oxidative) was studied as a function of material composition. Melt viscosity loss was measured as a function of time and temperature. Activation energies for degradation were calculated from experimental data. Results show that blends containing a minimum of 10% PEN by weight are as stable as pure PEN. Optically clear performs were injection molded from the PET/PEN blends. The optical clarity is primarily dependent on the processing temperature, the level of transesterification in the blends and the crystallizability of the polymers.; Free blow experiments were conducted to study the strain hardening property of the blends. The blow up ratio for the blends was modeled as a function of the PEN composition, molecular weight, the difference between the stretching temperature and the glass transition temperature and the degree of randomness in the blends. Results show that for a given IV, the blow up ratio increases with increasing PEN composition in the blends. In order for us to maintain the same blow up ratio as that of PET of a given molecular weight, the blends must have higher molecular weights greater than PET. Finally, the preforms were stretch blow molded into containers using a conventional PET mold and the physical properties of the containers made from different materials were studied to optimize the resin properties.
机译：聚对苯二甲酸乙二醇酯（PET）和聚萘二甲酸乙二醇酯（PEN）的共混物显示出的特性对包装工业具有商业意义。用PEN对PET进行熔融加工会导致酯交换反应。这些反应的动力学及其对共混物性能（如玻璃化转变温度，结晶度和雾度）的影响已得到广泛研究。这些研究表明，一旦达到一定临界水平的酯交换反应，共混物的性质就变得与反应无关。然而，关于这些共混物的注射成型和拉伸吹塑特性的数据很少。本文提出了研究PET / PEN共混物达到临界酯交换水平后的加工特性（主要是拉伸吹塑）。已经对化学动力学方程式进行了修改以预测共混物的不同组成以实现临界酯交换反应的理论加工温度。当在双螺杆挤出机中加工共混物时，发现这些值与实验观察到的值非常一致。挤出和注射成型的过程涉及聚合物在高温下的熔融。因此，了解熔体流变学和发生的不同降解过程很重要。用Instron毛细管流变仪研究熔体粘度随温度和剪切速率的变化。含有10％，20％和40％（重量）PEN的共混物的流动行为与PET非常相似。已经开发出模型方程来描述熔体粘度对剪切速率和温度的依赖性。使用锥板粘度计进行的熔体粘度测量表明，向PET中添加少量PEN会导致熔体粘度降低。在我们观察到共混物粘度增加之前，需要关键的组成是PEN重量为10％。研究了降解动力学（热和热氧化）与材料组成的关系。测量熔体粘度损失随时间和温度的变化。从实验数据计算出降解的活化能。结果表明，按重量计算，PEN含量最低为10％的混合物与纯PEN一样稳定。由PET / PEN共混物注塑成型光学透明的瓶胚。光学透明度主要取决于加工温度，共混物中的酯交换水平和聚合物的结晶性。进行自由吹气实验以研究共混物的应变硬化性能。将共混物的吹胀比建模为PEN组成，分子量，拉伸温度和玻璃化转变温度之间的差以及共混物中无规度的函数。结果表明，对于给定的IV，掺混物中PEN组成的增加，吹胀比增加。为了使我们保持与给定分子量的PET相同的吹胀比，共混物的分子量必须大于PET。最后，使用常规的PET模具将预成型件拉伸吹塑成容器，并研究了由不同材料制成的容器的物理性能，以优化树脂性能。

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