Preparing and Analyzing PET with Additives

将带有几种添加剂和普通树脂的宠物样品混合在一起。在混合时，在集成的缝隙毛细管中测量了组成/分解。然后将混合物转移到微型注塑机上，以制备盘状测试样品。使用这些椎间盘，聚合物熔体的流变测试后来在旋转流变仪上进行。目的是证明，只有7 g样品的微型化合物中的测试可用于快速筛选宠物和添加剂，并为聚合物的化学回收提供指示。

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Methods

样品制备

这Thermo Scientific™Haake™Minilab微型复合器with co-rotating screws (Figure 1) was used to prepare the mixtures of PET with additives at 270 °C with a screw speed of 50 rpm. For 15 minutes, the sample was mixed by re-circulating. During the mixing process the pressure drop was monitored in the slit capillary of the backflow channel (Figure 2).

图1。HAAKE MiniLab Micro Compounder.

图2。HAAKE MiniLab Micro Compounder backflow channel built as slit capillary with two pressure sensors.

Injection Molding of the Test Specimens

混合过程完成后，将聚合物直接挤出到Thermo Scientific™Haake™Minijet Pro系统的加热圆柱体中（图3），以进行测试样品（20 mmØ和1.5 mm厚度）的注射成型，以进行其他流变测试。加热的气缸的温度为270°C，并将霉菌加热至80°C。样品已注入500 bar五秒钟，后压力为300 bar，持续五秒钟。

图3。HAAKE MiniJet System and molds.

流变测试

使用20毫米平行板和在氮气气氛下270°C的电加热烤箱的Thermo Scientific™Haake™MARS™莱茵河上使用20毫米平行板和1.4毫米的缝隙进行流变测试。所有样品都主要在振幅扫描中测试，以确定线性粘弹性范围。新的测试样品用于从0.1到46 Hz的频率扫描。所有测试的变形均为0.5％，因此在所有样品的线性粘弹性范围的安全状态下。

图4。Thermo Scientific™Haake™MARS™颗粒计算机

结果

在再循环模式下，可以通过在回流通道内置的两个压力传感器的压力差（见图2）在一段时间内监视压力曲线（见图2）。在测试开始时，材料被填充到微型化合物中。这会导致压力峰。填充所有材料并平衡温度后，随着时间的推移压力曲线可以指聚合物的反应。随着时间的推移，压力的降低显示出材料的改变。例如，对于普通宠物而言，这可以是聚合物（水分）的反应，其中聚合物会降解。压力的降低与PET的粘度较低一致。当压力随着时间的推移增加时，这是链长或分支中PET增加的缩合反应的迹象，从而导致更高的粘度。用在Haake Minilab微观复合物中循环15分钟的材料制备了用于流变学测试的样品。最终压力值可以与复杂的粘度|η*|相关。 of a dynamic oscillatory test done with a rheometer. For the plain PET illustrated in Figure 5 after the loading peak, the pressure drop shows a decomposition of the PET. After 15 minutes, pressure is nearly constant with a value of approximately 18 bar. In Figure 6, the frequency sweep for the same sample indicates that the loss modulus G" is significantly higher than the storage modulus G'. The slight bumpy curve of G" is because of the fact that the phase shift δ is nearly 90° and the smallest changes have big influences on G". The complex zero shear viscosity |η*| is 200 Pas.

Figure 5.没有添加剂的宠物的压力依赖性。

图6。没有添加剂的宠物频率扫描。

Figure 7 shows the PET with 1% 1,2,4-Benzenetricarboxylic anhydride after the loading peak, a pressure increase which correlates with the condensation reaction of the PET. After 15 minutes, the pressure continues to increase with a value of approximately 15 bar. Compared to the plain PET it is marginally less of an indication of a lower viscosity.

Figure 7.PET具有1％1％1,2,4-苯甲酸羧酸酐的压力依赖性。

查看图8中同一样本中的频率扫描表明，G'和g“越来越近。这是在低频下的较低δ的较低δ频率约为85°。宠物获得了更多的弹性。|η*|。在低频率下为150个PA。与普通PET相比，添加剂对较低的压力负责，一方面是较低的|η*|，但另一方面，添加剂带来了PET的反应。

图8。用1％1,2,4-苯甲酸羧酸酐进行PET的频率扫描。

图9中PET具有1％1％1％1％1％1％1％的苯甲酸羧酸酐和1％Meta-Dioxazolinebenzene的压力依赖性说明了压力降低，然后在加载峰后增加了压力。与普通PET相比，55 bar的末端压力高得多，并且具有1％1％1,2,4-苯甲酸羧酸酐作为添加剂的化合物。测试结束时的压力波动是由于橡胶形态。图10中的频率扫描说明了粘弹性材料的G'和g”的共同趋势。与普通PET和具有PET的化合物相比，|η*|近2800 pa的趋势高于10倍以上，1％1，2,4-Benzenetricarboxylic anhydride as an additive. An observation of the change of δ from 88° at low to 52° at high frequencies shows a higher elastic behavior coming near the crossover. The mixture of both additives reveals first a decomposition of the PET followed by a reaction to build up a new structure. It is very likely that the molecular weight is considerably higher. The rise in pressure and |η*| correlates well in comparison to the tests of plain PET and the compound with 1% 1,2,4-Benzenetricarboxylic anhydride.

图9。PET具有1％1％1,2,4-苯甲酸羧酸酐和1％Meta-Dioxazolinebenene的压力依赖性。

Figure 10.PET的频率扫描为1％1,2,4-苯甲酸羧酸酐和1％Meta-Dioxazolinebenzene。

结论

这HAAKE MiniLab Micro Compounder is a suitable instrument to screen the effects of various additives. Only a small quantity of sample (7 g) is needed. Just viewing the pressure dependence provides a first revelation of the functionality of the additives. The time required for one test is reasonable. If additional rheological or other physical tests have to be done, the transfer of the polymer melt into theHAAKE MiniJet Pro System可能。可以迅速制备不同的测试样品，并且可再现。与GPC数据相比，通过全面的流变学测试（例如，时间温度叠加）可以真正建立假设。

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