Microstructure and Impact Fracture Surface of PCABS Polymer Alloys by Electron Microscopy

KeyWord : microscopic structure and impact fracture surface of the polymer alloy ; . Yang Xuang, State Key Laboratory of Fiber Materials Modification, China Textile University, Shanghai, 251 Effects of microstructure and compatibility on fracture mechanism.

Chinese and French Classification D 9322.3 0 Person 83 The blend system has good mechanical properties 13. Appropriate raw material selection and processing techniques can make these materials obtain high impact resistance. Here, the impact fracture surface morphology is tested in relation to the impact resistance of the material, and the compatibility between the components is detected from the microstructure of the material and is related to the mechanical properties of the material. 3 There are many methods that can be used for this kind of material microstructure and phase. Capacitive studies, such as electron microscopy, dynamic mechanical methods, parallographic calorimetry, and laser small-angle scattering methods, among which electron microscopy plays a decisive role in various methods because of its reliable methods and intuitive results. The relationship between the impact resistance of rubber-toughened plastics and the structure of the alloys was recognized by the successful use of electron microscopy. To obtain high impact resistance of materials, in addition to the appropriate chemical composition, it is critical to have certain microscopic features. 89. The use of suitable compatibilizers is an important means of obtaining this specific microstructure. 1. The rubber particle size and its distribution, the degree of dispersion of the disperse phase, and the compatibility of 0 and 433 are the most closely related to the material properties. These structural factors can all be obtained in the transmission electron image. There is no substitute for other methods.

1 Materials All tested materials were supplied by the chemical plant of Shanghai Gaoqiao Petrochemical Company and divided into two series.

The series has the same, 3 ratio 6040, using a different compatibilizer system. Named 412,34 and 焱5. One of them is not added with a compatibilizer, two kinds of compatilizers are added to 2 and 3 respectively, and 44 is a product with high impact resistance. Series 1 This series of materials is not the same , 7 people 33 ratio, experimental method 5, as observed using the British, 13; 1 scanning electron microscope for low magnification observation of the fracture surface, high magnification observation using Japanese production only 8, the scanning mode, to be observed The impact fracture surface was previously used as a gold spray key in the vacuum chamber to improve its electrical conductivity and strong secondary electron emission capabilities.

The electron microscope accelerating voltage is 15 and 351 respectively for the two electron microscopes.

A river image observation sample was treated with 1 concentration of 0,04 water solution 361 to harden the rubber phase in the material and stained with heavy metals to increase the contrast, and then for ultrathin sectioning, using a Swedish 4800 ultra-thin slicer, slice thickness Below 1, acceleration voltage takes 200 results and discussion 3.1 fracture surface morphology Received date 1999 times the obvious feature is the concentric ring formed by the crack 3, wide cracks on both walls from fibrils up to tens to lOOμm The phase is irregular, the section is uneven, and the height of the protrusion is several hundred microns 3. The small peak in the same direction is the tearing feature. This sample is ductile fracture.

However, it is a typical brittle fracture morphology that is not found in the local area at high magnification.

Bad development from right to left. A ring-shaped crack 3 can be seen with clear fibrils in between. A pit of several hundred microns in depth appears on the right side. The small peak-like fibrils 3 formed on the cross-section after propagation of the small cracks in the inseam, which are characteristic features of the vertical bending stress. The specimen was found to be fracture-ruptured.

Specimen 3 Impact fracture surface morphology 3. It is characterized by a distance of 600 μm from the gap in the center of the specimen that has not been fully broken. (4) A large gap between the two cracks has been broken. During the fracture process of the micron fibrils, a step develops with the discontinuous expansion of the cracks, and the material at the junction of the steps forms microfissures in the fibril-like morphology with a high magnification, and the bridging fibrils have a diameter of 12 and a length of 101 or more.

The microscopic morphology of the fracture reveals a peak structure and micro-pits with a diameter of several microns. The typical ductile fracture characteristics described above clearly demonstrate that the material undergoes destructive fibrillation and fibrillation during the formation and propagation of fractures. This process absorbs a lot of energy and now has a high impact strength.

Specimen 4 has a fracture surface morphology that is quite different from the previous materials. 4. The fracture surface is relatively flat from a macroscopic perspective, and there are no residual cracks and high bulges or depressions in several samples.

The features are appearance, line-type stripes and oval-shaped pits of different sizes. They are all generally parallel and the direction of crack propagation when the material is destroyed. The high-magnification micro-morphological features are high-density and mostly circular. The micro-pits, which are about a few microns in size, are different from the first few samples and the small peaks are not obvious.

The fracture interface morphology of sample man 5 is shown in Fig. 5. In terms of macroscopic view, similar to the sample person 1 person 2 and child 3, they all have a circular band shape 3 formed by residual cracks, and have a higher convexity. Starting or recessed, about a few hundred microns in height. There are also fibril structural units available in the fractures, and microstructures with high magnifications show that their morphology is similar to that of the 4 and is characterized by dense micro-pits, which are accompanied by strong energy.

8 series of samples have different, 0 into 83 ratio, of which 8 1 is pure 85 and 84 is pure, 0.

There is only a small difference in height between the flatter fracture surface and the 1st step. There are many stripes that are substantially parallel to each other through the step direction. These stripes often intersect to form parabolic shapes of different sizes, with the tops facing the notches. These tops can be regarded as the origin of secondary fractures, forming a new fracture surface, and the shape is now the emergence of steps. The morphology under high magnification is obvious, and a small number of dimples can be seen, but no fibril and peak-like structure.

82 is the material six details 1.

837 and 82, ie, Human 1, have very similar fracture patterns. In contrast to humans, there is a large height difference in the fracture surface. 3 Apart from the presence of fibril-like structural units in the residual cracks, there is a thin film-like structure 0, which also needs to absorb energy during the formation process. It is evident that a large number of dimples can be obtained at high magnifications, and the sample has a fracture performance.

3, the formation of significant height differences and residual cracks. In another sample of the same material, there may be a height difference of several millimeters to the fracture surface. The radiation stripe is not smooth, sawtooth and has small branches. The formation of the fibrillation of the river pattern is also very obvious. These structural units consume a large amount of damage energy during the process of crack propagation. 8, is a photo at high magnification, without dimples and small peak-like structures.

3.2 Internal Microstructures Impact resistance is usually measured as the energy absorbed by cracks passing through the entire width and thickness of the sample during material failure. Rubber particles can play a role in blocking the development of cracks and absorbing energy, and have a direct impact on impact materials. The size of the rubber particles, and the degree of rubber and matrix inclusions here, including 34 and, have a very important role in notch impact performance. The study found that when the volume ratio of rubber and the rubber matrix do not change, there is a critical size of rubber particles, and the material undergoes a sharp ductile brittle transition. This critical value increases as the rubber composition increases. Obviously, the increase of rubber concentration does not mean that the impact resistance is improved, and the size and distribution of rubber particles play an important role. The TEM image most intuitively reflects the size and distribution of the rubber particles most reliably. It is also recognizable. The 6 and 83 materials are multiphase structures. In addition to the typical 5-man phase and rubber particle phase in the 83, there are still The lower density, phase 3 and 15. It can be said that human 1 sample, and human milk showed a phase separation structure.

In some areas, 0 and 83 have a clear interface, while other areas have a more obscure interface. It can be estimated that the area occupied is larger than the area occupied by human milk, which probably reflects the ratio of the two components of the material. Sixty-three phases are generally connected and the same applies. In the material, the 83 phase and the 0 phase exist in the continuous phase. Under high magnification, like the rubber particles in the 85 phase as the dispersed phase, there is a more complex structure. The rubber phase contains the particles. The human elbow image of this sample 2 is different between 1 and 9; It is difficult to find the exact boundary between phase and phase 83. However, the rubber particle remains as it is, with its inner containment structure dispersed in the matrix, and its size range is similar to that of sample 1. This form seems to be clear PC phase and ABS The SAN has a considerable degree of mutual compatibility.

That is, the so-called inner structure. The rubber particle size is in the range of 150,400 1 .

At the same time, its structural characteristics are that the rubber particles are evenly dispersed in the matrix of the density. The matrix has been completely indistinguishable, with 8 phases.

This seems to be clear that in the size range observed, the phase and the three humans have been mutually compatible. The size of the rubber particles is similar to that of the first two samples, most of which are toughening polymers for rubber. When the size of the rubber particles is smaller than several tens of nanometers, the main mechanism for the increase of the product is the shear flow, and when the size reaches several At 100 nanometers, the material under tension stress is often more of a factor that mainly affects the toughening mechanism, but is caused by the above-mentioned several samples.

The microstructure 12 of the sampler 4 is very different from the first three samples. The rubber particles are not homogeneously dispersed in the matrix, but bundled into clusters to form a collection of sizes on the order of a few microns. These collectives are equivalent to people 85, they are dispersed in the matrix. , and capacitive. The size distribution of the rubber particles is obviously dispersed, ranging from several tens of nanometers to 50, and thus coexist with the silver stripes. The shear flow may also become the material's mechanism, which is consistent with the SEM observation of the fracture surface.

Particles with a size of a few microns are dispersed in 0. , 0 out of 83 have very clear boundaries. The rubber particles are spherical and are pure additives that have any effect so that the rubber particles no longer have a circular cross-sectional morphology.

Conclusion The human specimens generally have a tough impact fracture morphology, and high step fibrillation small peaks and dimples are the main morphological features. However, each sample has different emphasis. Among them, sample 3 shows all the ductile fracture characteristics, while sample 4 shows the main feature of micro-pit. This reflects their difference in the toughening mechanism.

In the 8 series of samples, 8 exhibited brittle fracture characteristics, while the remaining samples had different degrees of ductile fracture morphology.

The microscopic structure of the human series sample shows that the PC and the SAN have clear boundaries in the sample 31. In the sample A2, the PC and the SAN are partially dissolved, while the sample 3 is completely dissolved. The sample enters 4 and 5 Similar to the microstructure, the human 83 is embedded in, and has a clear boundary with, the human 83. This is not the same as the first three kinds of samples, and their rubber particles are almost uniformly distributed in the matrix.

4 He Manjun, Chen Weixiao, Dong Xixia. Polymer Physics, Shanghai Fudan University Press, 10 Yang Yi, Yang Jiegang. Reactive processing of new polymer blends. Polymer Materials Li Qiang, Zheng Wenge, Qi Zongneng, et al. Study on the damage of brittle-ductile transition of blends.

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