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The Classification and Introduction of Functional Filler

2016/02/19 Plastic Additives

Filler’s classification:

Fillers are usually powder material and inert to polymer. Adding filler in plastic preparation is to improve the molding processability and some product performances, which gives the plastic new performance and reduces the cost.

Fillers can be classified as following according to its characteristics:

The characteristics of functional fillers	Names
Electrical conductivity	Metal powder, metal foil, metal fiber, carbon black, carbon fiber, conductive oxide (tin oxide, Zinc Oxide, molybdenum oxide), non-electrolytic plating
Magnetism	Al Ti Ni Co magnetic alloy, rare earth ferrite, barium ferrite, strontium ferrite
Piezoelectricity	Lead titanate, barium titanate
Vibration damping	Mica, graphite, ferrite, potassium titanate, xonotlite, graphite fiber
Slipping	Graphite, molybdenum disulfide, boron nitride (hex crystal), graphite fluoride, PTFE powder, talcum powder
X-ray protection	Pb, barium sulfate

Conductive filler:

The polymer base material in conductive polymer is to firmly bond conductive particles together and bring stable conductivity to conductive polymer. At the same time, it also gives material processability. Polymeric material properties have great influence on the mechanical strength, heat resistance and aging resistance of conductive polymer.

Conductive filler acts as carrier in composite conductive polymer, so its shape, property and dosage directly determines material conductivity.

Damping filler

Polymer viscoelasticity, viscidity especially, plays an important role in damping materials. Damping effect can be further improved by adding some inorganic compounds such as mica and graphite in damping material. This kind of inorganic substance is called damping filler and classified as follows:

Category	Name
Layered compounds	Mica, graphite, molybdenum disulfide, boron nitride, etc.
Acicular compounds	Xonotlite, potassium titanate, asbestos, carbon fiber, etc.
Granular or platy compounds	Ferrite, talcum powder, vermiculite, argil, etc.

The mechanism of vibration reduction is as follows:

1 Vibrational micro crystal and crystallizing layer rub against each other and reduce vibration.

2 Vibration reduction is caused by the shrink and shear deformation movement of matrix molecules near interface.

3 The friction between crystal and matrix interface reduces vibration.

4 Increase elastic modulus and density to obtain damping effect.

5 Damping effect is achieved by the combined actions of all the above.

Thermal conductive filler

For electronic components requiring high electrical insulation and high thermal conductivity, we can add inorganic compounds with non-electric conductivity and high thermal conductivity in the polymer. This kind of inorganic compounds mainly are BeO (beryllia), AlN (aluminium nitride), BN (boron nitride), Al2O3 (aluminum oxide), etc. Among them BeO is highly toxic, so we can use AlN or Al2O3.

Slide filler

Sliding materials require lubrication as well as certain wear resistance and mechanical strength. Sometimes heat resistance is also needed according to different situations. Therefore, when we design sliding materials, we should add reinforcing filler in addition to adding solid lubricant. The combination and proportion of solid lubricant and reinforcing agent are important factors in determining the performance of sliding material.

Other functional filler

X-ray protective agent: Generally use heavy materials such as plumbum. Also use barium sulfate and other materials except for lead powder.

Optical functional filler: Mainly use glass beads which can diffuse lights and recently adopt newly developed glass beads with high refractive index. Rubber or plastic added optical functional filler are mainly used for landway and waterway traffic signs, night traffic and other related aspects.