Foam plastic is a kind of plastic with countless tiny pores inside, which has the properties of softness, heat insulation, sound absorption, and cushioning.

Product Introduction

Foam Plastic

Classification: According to the degree of hardness and softness, it can be divided into three types of soft, semi-rigid and rigid foam plastics; according to the bubble structure, it can be divided into open-cell foam plastics and closed-cell foam plastics. Open-cell foam plastics refer to foams that are interconnected and ventilated; its characteristics are good sound absorption and cushioning performance; closed-cell plastics refer to foams that are not interconnected and irrelevant; its characteristics are low thermal conductivity, low water absorption, and floating.

Use: Foam plastics are widely used in sound insulation, heat insulation, thermal insulation, insulation, shockproof, filtration, packaging and other materials. Low-foaming foam plastics such as polyurethane, polystyrene, and polyvinyl chloride can be used as substitutes for wood; polyethylene, polystyrene, and polyvinyl chloride foam paper can be printed on special documents, maps, or made into cardboard, which is used for packaging and ceilings and other building materials. In addition, composite materials of foam plastics and fibers, such as foamed artificial leather and synthetic leather, feel soft and full, and can replace leather to make shoes, hats, boxes, bags, gloves, etc.

Artificial leather

Artificial leather is a composite material made of fiber and plastic. Currently, the most common artificial leather is polyvinyl chloride artificial leather.

Artificial leather has the characteristics of soft texture, elasticity, high mechanical strength, acid and alkali resistance, non-flammability, easy washing, bright color, and various patterns, so it is widely used. It is often used to make covering materials for clothing, hats, gloves, shoes, sofas, chairs, etc.

Synthetic leather

The surface of synthetic leather is polyurethane resin. It is a composite material formed by coating polyurethane microporous elastomer on composite fiber knitted fabric or non-woven fabric.

Synthetic leather has the characteristics of anti-oxidation, wear resistance, and oil resistance. Its mechanical strength, wear resistance, and elasticity are better than artificial leather; its air permeability and moisture vapor permeability are close to natural leather; its surface hardness is high, it is not easy to be eaten by insects, mildew, and has good water and oil resistance; the product size is stable, not easy to deform, and the texture is also soft at low temperatures; the product appearance is bright, beautiful, easy to maintain, and durable. Therefore, it has a wide range of uses. It can replace natural leather to make a variety of leather products such as boxes, bags, clothes, and hats, and is widely used as a raw material for shoemaking.

Identification method

Plastics can be identified by scientific methods such as infrared spectrometers, paramagnetic resonance instruments, and X-rays, but they can also be identified by simpler methods. The following briefly introduces the simple identification method

1. Sensory identification (organize students to participate in the identification of plastics)

(I) Look

First look at the color and transparency of the product.

Transparent products include: polystyrene and plexiglass.

Translucent products include: low-density polyethylene, cellulose plastics, polyvinyl chloride, polypropylene, epoxy resin, unsaturated resin.

Opaque products include: high-density polyethylene, polyurethane and various colored plastics.

(ii) Listening

When knocked with a hard object, the sound is different. Polystyrene sounds like metal, while organic glass sounds rough and muffled.

(iii) Touching

If the product feels waxy when touched, it must be a polyolefin material. Secondly, the degree of hardness can be simply expressed as follows:

Hard¡úSoft

Polystyrene¡úPolypropylene¡úPolyamide¡úOrganic glass¡úHigh-density polyethylene¡úHard polyvinyl chloride¡úLow-density polyethylene¡úSoft polyvinyl chloride

Then test the surface hardness and scratch the surface with pencils of different hardness to make a difference:

Polyethylene plastic can be scratched with an HB pencil;

Polypropylene plastic can be scratched with a ZH pencil.

Due to differences in people's physiological conditions, the sensory identification results are not the same, so this method is for reference only.

II. Identification basis for several easily mixed plastics

(I) Identification basis for polyethylene and polypropylene plastics

Both polyethylene and polypropylene plastics are milky white and translucent, light and can float on the water surface, and their combustion phenomena are basically the same. However, there are also obvious differences between the two: polyethylene feels like paraffin wax, soft and bendable, while polypropylene feels smooth and delicate, but has no waxy greasy feeling, and has a hard and tough texture; polyethylene plastic softens significantly in boiling water, while polypropylene plastic does not soften significantly in boiling water; polyethylene plastic has a "thin neck" when stretched in strips, while polypropylene does not.

(II) Identification basis of polyvinyl chloride and polyethylene plastic films

The processing methods of polyvinyl chloride and polyethylene are different: polyvinyl chloride is pressed into a single film by calendering, and polyethylene is made into a cylindrical double-layer bag by blow molding; in terms of color and transparency: polyethylene is milky white and translucent, with a brighter surface and a waxy and greasy feel to the touch. Multiple layers stacked together are still milky white and translucent, while polyvinyl chloride is more transparent than polyethylene and has a slightly yellowish color. Multiple layers stacked together are yellowish, smooth to the touch, but sticky, and fine mold lines can be found upon careful observation; the combustion phenomena are different: polyethylene is flammable, melts and drips, and has a paraffin smell, while polyvinyl chloride is difficult to burn, the root of the flame is green, and the pungent smell of hydrochloric acid is released; polyethylene has a small specific gravity and can float on the water surface, while polyvinyl chloride sinks in water.

(III) Identification basis of phenolic and urea-formaldehyde plastics

Both are thermosetting plastics, which are hard and opaque. There are mainly the following differences: phenolic plastics are generally dark brown, while urea-formaldehyde plastics are mostly light-colored and bright in color; the cross-sectional structure of phenolic plastics is loose, while the cross-sectional structure of urea-formaldehyde plastics is tight; when burning, phenolic plastics emit a phenolic odor, and the part in contact with the flame shows carbonization and cracking, while urea-formaldehyde emits a urea odor, and the part in contact with the flame shows whitish cracking.

(IV) Identification basis of polystyrene, polyvinyl chloride, and polyethylene plastics

The identification basis of these three types of plastics is based on the following five aspects.

1. Color and transparency

Polystyrene plastics are brightly colored and as transparent as glass; the color and transparency of polyvinyl chloride plastics are worse than those of polystyrene; polyethylene plastics are translucent, look like wax products, and the dyes are easy to seep out.

2. Feel

Polystyrene feels smooth and has a hard surface, so it is afraid of bumps and squeezes; polyvinyl chloride also feels smooth, and its film products feel sticky; there are soft and hard products; polyethylene feels waxy and greasy, and its products are soft and resistant to bending.

3. Relative density

The relative density of polystyrene is 1.05~0.06, and it sinks slowly in water; the relative density of polyvinyl chloride soft plastic is 1.24~1.45, and the relative density of hard plastic is 1.35~1.45, so it sinks quickly in water; the relative density of high-density polyethylene is 0.94~0.97, and the relative density of low-density polyethylene is 0.91~0.93, so it floats in water.

4. Sound

When a hard object is knocked, polystyrene has a crisp metallic sound, polyvinyl chloride is loud but not brittle, and polyethylene is dull but not brittle.

5. Combustibility

Polystyrene is flammable, with an orange flame, black flocculent smoke, and a pungent smell of styrene monomer; polyvinyl chloride cannot spontaneously ignite, and will go out away from the fire. The flame is yellow, the root is green, and there is a smell of hydrochloric acid; polyethylene is flammable, with a yellow flame, a blue root, and a small amount of black smoke. It softens when burning, drips wax tears like a candle, and emits a paraffin smell.

Plastic Industry Video