Plastic mesh teaches you to easily distinguish between various recycled plastics

Physical method

Physical methods are identified based on the physical properties of the plastic, including appearance, density, melting, strength properties, solubility properties, and the like. The following are the identification methods that have been summarized by technicians who have worked for many years:

The easiest way is to look at the plastic film against the sun to see if there is a star point. Usually there is regeneration, and basically nothing is new. (Because the color of the recycled material is not the same, the hand feel is different, and there are many impurities, the color is not good, the original color is less.)

From the appearance, the recycled plastic has poor gloss, the surface of the particles is dull, the size is not uniform, and the impurities are generally colored or grayish; the new material has good gloss, the surface of the particles is smooth, the size is uniform, and no impurities, most of them It is colorless or milky white. The color of the new material is bright and the color of the old material is dim. In addition, if we want to carefully identify, we can distinguish from the following aspects:

Color: Anything that is more transparent than the one that is not transparent, no matter what color.

Gloss: Gloss is better than no gloss, which is the color of the surface. From the point of view of physical and mechanical properties, the recycled materials have been aged and degraded, some of the polymers are oxidized, and the physical and mechanical properties have decreased. The more the number of regenerations, the more the performance is degraded.

Drawing: (CaCO3's drawing is definitely not good, and the reinforcement can't pull the wire.) After blowing the fire, use the iron object to quickly contact the melt, then quickly pull it open to see if the wire is formed evenly and evenly. It is a good material. After several times of pulling, the silk is overlapped and pulled apart again to see if it has elasticity. Can it be pulled again and continuously, and it is good to break after breaking or opening a distance.

Smell (various plastic flavors, including flame retardants, etc.);

If you can't confirm the above, please use the fire again. In the process of burning, you can quickly smoke black smoke or melt quickly. It is not good.

Floating water: As long as there is submerged water, if the above is not sure, or can not make up your mind, then only test machine.

chemical method

The chemical method is based on the chemical properties of the plastic, including combustion experiments, thermal cracking experiments, color reaction reactions, and the like. The following are the combustion identification methods for various plastics for reference:

1, propylene PP is easy to melt and drip, less yellow smoke on the yellow and continue to burn oil

2, polyethylene PE is easy to melt and drip, yellow and blue continue to burn paraffin burning smell

3, PVC PVC is difficult to soften on the yellow under the green smoke from the fire to extinguish the irritating sour taste

4, POM POM is easy to melt and drip on yellow and blue, smokeless continues to burn strongly stimulates formaldehyde

5, polystyrene PS easy to soften foaming orange yellow, thick black smoke, charcoal end burning surface oily bright special vinyl smell

6. Nylon PA slowly melts and drops, foaming slowly extinguishes special wool, nail odor

7. Polymethyl methacrylate PMMA is easy to melt and foam, light blue, white, smokeless and continue to burn, strong fruity odor, rotten vegetable flavor

8, polycarbonate PC is easy, softening foaming, a small amount of black smoke, extinguished from fire, no special taste

9. Polytetrafluoroethylene PTFE does not burn; it decomposes pungent hydrogen fluoride smell in the fire.

10, polyethylene terephthalate PET is easy to soften the foaming orange, a small amount of black smoke from the fire slowly extinguish the sour taste

11. Acrylonitrile-butadiene-styrene copolymer ABS slowly softens and burns without dripping yellow, and black smoke continues to burn special odor.

Instrumental analysis

Instrumental analysis refers to the analysis and detection of plastics by various materials analysis and testing instruments, including infrared spectroscopy, ultraviolet spectroscopy, plasma emission spectroscopy, differential scanning calorimetry (DSC), mechanical thermal analysis (TMA), and thermal weight loss ( TGA), scanning electron microscopy (SEM), and energy spectrum analysis (EDS) have the advantages of quick aging and high accuracy, but the cost of identification is high.

Case:

A lighting factory found that the lamp holder after 2 months of use was yellowed at the customer application end, and the cause of yellowing was detected. A SEM observation of the lamp beads by scanning electron microscopy revealed that there were a large number of pores inside the PPA stent, which was characteristic of a typical nozzle material. This is because many voids or other defects are generated during the recycling of the PPA plastic, and the number of pores increases as the number of regenerations increases. The testing organization pointed out that the PPA bracket with a large amount of voids inside must be the nozzle material, but the PPA bracket of the nozzle material does not necessarily have a gap. In case of such a situation, it is further determined by combining other material detection methods.

hint

1. Surface finish is an important indicator to measure the quality grade of various recycled materials. The surface of high-quality recycled materials is smooth and lubricated.

2. Transparency is an important indicator for measuring the quality grade of medium and high-grade recycled materials. The recycled materials with transparency are of good quality.

3. Uniformity and consistency of color are important indicators for measuring the quality grade of colored recycled materials, mainly white, milky white, yellow, blue, black and other colors.

4. Particle compactness is an important aspect of testing the level of regeneration technology. The low level of technology is mainly due to poor plasticization and loose particles.

5. See if the regenerated particles are floating in water and can be used to check the content of fillers for PP and PE particles.