Tailoring Mechanical Properties of Polymers Through Localisation of Polymeric Phases

在新应用程序中使用聚合物涉及将材料属性与应用程序要求匹配。在大多数情况下，聚合物将经过设计以适合该应用。这涉及选择单体并设计制造工艺，以量身定制诸如韧性，硬度，弹性和电性能等机械性能。

When more than one type of polymer is used to leverage the properties of the two (or more) chemical types, synergism can be achieved in the combination. The physical properties of the finished materials will depend on the chemical composition as well as the polymer’s morphology. Two methods are used to combine the chemical phases. Polymerising all monomers simultaneously will make random co-polymers. Blending, an alternative method for engineering products that combines the properties of polymer types is a physical mixing. This is not just economic and simple but also enables re-cycling used material.

The first section of this article is concerned with the dispersion of the two components in a polyethylene-polybutylene terephthalate blend. The second part deals with the depth analysis of laminated films made of different polymer layers.

Experiments – PBT Blend

Figure 1 shows a 0.5µm thick sample of the PE/PBT film illuminated in transmission that indicates heterogeneities. The image shows contrast, however it was only when the Raman spectra were recorded, one could say that the more transparent material contained PBT while the more opaque material contained higher concentrations of PE.

Figure 1.Phase identification

Using the microprobing capability of theLabRAM, the two phases can be fingerprinted within seconds. The upper spectrum was recorded from the clear phase, and the lower spectrum was recorded from the darker material. The clear material was identified as PBT. The dark material spectrum had some residual bands from PBT, but most of the intensity was attributed to PE.

如图2所示，PBT在1615和1735厘米处具有频段^-1that are diagnostic of the aromatic ring and carbonyl groups; it also has CH bands above 3100 cm^-1indicating non-saturated organics.

Figure 2.聚乙烯聚丁烯第烯酸酯（PBT）混合物

诊断光谱特征可以总结如下：

• 指纹带1060、1130和1300厘米^-1和2800至3000厘米之间的CH带^-1are typical for PE.
• The difficulty in obtaining a pure spectrum of PE could be interpreted to indicate a certain degree of miscibility of PBT in PE.
• These spectra were recorded in a matter of seconds on theLabRAM，使这些聚合物的表征足够容易地进行常规测量。

Chemical Mapping of Phases

拉曼图用于进一步确认电视图像中具有不透明和透明材料的两个相的化学身份。通过独特的专利共透明扫描，可以在Labram上获得共聚焦地图。

With this system, the line-illumination on the sample is multiplexed by focusing a spectrum from each point on that line on to a track on the CCD. The full spectrum from each sample point is stored. After the spectral acquisition, one can examine the full file, and select the analytical band in the spectrum from which an image can be reconstructed.

By selecting these Raman bands with cursors, the LabSpec software creates a map showing the PBT in red and the PE in blue as shown in Figure 3.

Figure 3.地图以红色和蓝色为pe显示PBT

By comparing the TV image and the Raman map these is a less than perfect correspondence between the two images. The Raman map created by theLabRAM在这种混合物中，与使用电视图像和不具有映射功能的拉曼微探针可以实现的聚合物物种的化学分布更全面。人们认为具有最纯PBT（红色）的田地大于纯PE（蓝色）的区域。此外，最大的域显示了混合光谱，但是有许多突然的边界。

Raman Chemical Depth Profiling With Automated Z Focus

A confocal Raman microscope can be used to depth profile a multi-layered structure. In this experiment several layers of pressure sensitive adhesive tape were stacked on a microscope slide that produced a multilayer structure for test purposes. The spectra of the polymer film and the adhesive layer are shown Figure 4.

Figure 4.聚合物膜和粘合剂层的光谱

By comparing the spectrum of the film to reference polymer spectra, the film is identified as isotactic polypropylene of medium crystallinity. Similar comparisons indicate that the glue layer consists of low-crystallinity, atactic polypropylene with some short polyethylene sequences (1305cm^-1）和酯羰基（1727cm^-1）。

因此，胶水层最有可能由部分酯化的乙烯 - 丙烯共聚物组成。2836厘米的CH频带的大部分强度^-1is attributed to the polymer film. Figure 5 shows the analytical regions of the spectra showing more detail.

Figure 5.光谱的分析区域

The multilayer sample structure is represented in Figure 6.

Figure 6.Multilayer sample structure

In theLabRAM spatial filteringis achieved by closing a computer controlled, variable aperture, confocal pinhole. Depth profiles are automatically acquired with the piezo focus objective.

Two profiles are displayed for demonstration purposes, one with the pinhole open to 1000µm diameter and one with the pinhole set to 100mm diameter (for good spatial filtering).When spectra are acquired with the 100x microscope objective, the depth resolution has been shown to be 2-3µm.

图7a中所示的轮廓代表了各个组件的拉曼分析带的综合强度，图7b中显示了拉曼带区域的比率。

Figure 7.a. Polymer film-top, adhesive bottom, b. Adhesive/Polymer

深度轮廓，共聚焦孔设置为100µm

这些深度轮廓是用共聚焦孔设置为100µm的，以更好地定义层。粘合信号曲线的FWHM（最大宽度最大宽度）除以聚合物信号非常重要。

Its value is improved from about 9µm in the first layer when the confocal is open, to about 6 µm in the first layer when the confocal hole is set to 100µm.

层流样品的横截面

以下结果涉及对由2聚乙烯层制成的75µm层膜膜夹在中部尼龙层中的分析。XZ平面映射是通过沿X方向上的一条线成像记录光谱来完成光谱的，并在不同的深度下重复该光谱。图8所示的结果说明了需要高深度空间分辨率时的共聚焦方法。聚合物层压层的深度曲线和横截面都证明LabRAM’s Raman microprobe。

图8。Confocal approach

This information has been sourced, reviewed and adapted from materials provided by HORIBA Scientific.

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