Fiberglass is a commonly used filler for engineering plastics, mainly composed of silica and other derived metal oxides. Currently, the international mainstream production process is the pool kiln drawing method; According to the alkali content in glass, it can be divided into alkali free glass fiber, medium alkali glass fiber, and high alkali glass fiber; The commonly used glass fibers in engineering plastics are alkali free short cut glass fibers and untwisted long glass fibers. After adding glass fibers, the engineering plastics will undergo the following changes.

Advantages:

1. Enhancing rigidity and hardness, the increase of fiberglass can enhance the strength and rigidity of plastics;

2. Improving heat resistance and hot deformation temperature, taking nylon as an example, by adding fiberglass nylon, the hot deformation temperature can be increased by at least 30 ℃, and the temperature resistance of general fiberglass reinforced nylon can reach 220 ℃ or above;

3. Improve dimensional stability and reduce shrinkage rate;

4. Reduce warping deformation;

5. Reduce creep;

6. Reduce moisture absorption.

Disadvantages:

As the modulus of the product increases, its toughness will decrease; It has a negative impact on flame retardant performance, as the candle core effect can interfere with the flame retardant system and affect the flame retardant effect; Exposed fiberglass can reduce the surface gloss of plastic products.

The length of fiberglass directly affects the brittleness of the material; If fiberglass is not handled properly, short fibers will reduce the impact strength; Proper treatment of long fibers will increase impact strength. To prevent a significant decrease in material brittleness, it is necessary to choose a certain length of fiberglass.

The fiber content of a product is also a key issue. The industry generally adopts integer contents such as 15%, 25%, 30%, and 50%, and the specific content of fiberglass needs to be determined based on the product's purpose.

To achieve good mechanical properties and surface effects, it is crucial to choose the diameter and length of the glass fiber, as well as the surface treatment and glass fiber content during subsequent modification!

calcium carbonate

Calcium carbonate products are divided into heavy calcium carbonate and light calcium carbonate. Heavy calcium carbonate, abbreviated as heavy calcium or GCC in English, is produced by directly crushing natural calcite, limestone, white marble, shells, etc. using mechanical methods. Due to the smaller sedimentation volume of heavy calcium carbonate compared to light calcium carbonate, it is called heavy calcium carbonate. At present, there are two main processes for industrial production of heavy calcium carbonate: dry process and wet process. Compared with wet processes, dry processes can produce products with lower costs and wider applications.

Light calcium carbonate, also known as precipitated calcium carbonate or PCC, is produced by calcining limestone and other raw materials to produce lime. The main components of lime are calcium oxide and carbon dioxide, which are then digested with water to form lime milk. The main component is calcium hydroxide, which is then introduced with carbon dioxide to form calcium carbonate precipitate. Finally, the lime milk is dehydrated, dried, and crushed to obtain it. Alternatively, sodium carbonate and calcium chloride can be first subjected to a double decomposition reaction to generate calcium carbonate precipitate, which can then be obtained by dehydration, drying, and crushing.

Calcium carbonate is one of the earliest inorganic fillers used to fill, enhance and toughen PP, and the application of micrometer scale calcium carbonate has always been dominant. Research has shown that the addition of calcium carbonate can increase the impact strength of PP, but reduce the tensile strength. The addition of lightweight calcium carbonate can simultaneously improve the impact strength and yield strength, and PCC treated with stearic acid has a better effect. Calcium carbonate treated with titanate coupling agent can significantly improve the impact strength of PP.

With the emergence of nanoscale calcium carbonate, it has been found that using nanoscale calcium carbonate can simultaneously enhance toughness, and the toughening effect is better than that of micrometer scale calcium carbonate. Research has shown that the mechanical properties of composite materials vary greatly depending on the morphology of nano calcium carbonate. Cubic nano calcium carbonate is beneficial for improving the impact performance of composite materials, while fibrous nano calcium carbonate can significantly improve the tensile properties of materials. Nano calcium carbonate can significantly refine PP spherulites and promote β Formation of crystal forms.

Glass microbeads

Glass microbeads are a new type of silicate material, including solid and hollow materials. Glass beads with a particle size of 0.5-5mm are usually referred to as fine beads, while those with a particle size below 0.4mm are referred to as microbeads; There are various types of microbeads available from different sources. Fly ash glass microbeads are a lightweight, micro spherical substance extracted from fly ash, mainly composed of silica and containing various metal oxides. Fly ash glass microbeads have advantages such as high temperature resistance and low thermal conductivity. When used to fill plastics, they can not only increase the material's wear resistance, compression resistance, flame retardancy, and other properties, but their special spherical surface can also improve the material's processing flowability, In addition, its surface glossiness is good, which can increase the surface gloss of the product and reduce the adsorption of dirt on the surface.

Glass microspheres are widely used for strengthening and toughening PP. Research has shown that with the increase of glass bead dosage, the tensile modulus, flexural strength, and modulus of PP/glass bead composites extruded by single and double screw extrusion show a linear increasing trend, while the yield strength slightly decreases; The fracture strain increases at low content and then rapidly decreases. The impact strength of both single and double screw extruded materials is improved, and within a certain range, it increases with the increase of glass bead dosage. The impact strength of single screw extruded materials is slightly higher than that of double screw extruded materials, and the particle size of glass beads has a significant impact on the toughness of PP/glass bead composite materials.

Silicate minerals

At present, the most widely used and researched silicate minerals include talc powder, montmorillonite, wollastonite, etc. Among them, attapulgite and zeolite have also received more attention.

Talc powder and montmorillonite (MMT) are both layered silicate minerals. Talc powder is a magnesium silicate mineral with a sheet-like structure. Generally, the finer the particle size, the better the dispersion effect, which can improve the thermal deformation temperature and surface smoothness of the material; The interlayer spacing of MMT is relatively large, and PP composite materials are often prepared by intercalation method. MMT can form a good intercalation structure in the PP matrix, thereby improving the impact resistance and dimensional stability of PP.

Attapulgite (ATP) is a chain layered silicate. ATP is a natural one-dimensional nanomaterial silicate mineral, with a basic structural unit of needle like or short fiber like single crystals. ATP can composite with polypropylene at both micro filling and nano reinforcement levels to improve the mechanical properties of the material. This new type of clay short fiber overcomes the disadvantages of poor flowability, rough appearance, and severe wear on processing equipment of general glass fiber reinforced resins, and therefore has high development value.

Wollastonite is a single chain silicate mineral, usually in the form of sheet-like, radial, or fibrous aggregates. Research has shown that wollastonite filled plastics can not only improve their mechanical properties, but also replace glass fibers to reduce costs. However, as the filling amount increases, the hardness of the composite material increases, leading to more severe wear on processing equipment.

Zeolite is a framework silicate mineral. It has a rich pore structure and can prepare highly functional polypropylene composite materials by adsorbing or loading functional particles, thereby increasing the added value of the product. Therefore, the development of PP/zeolite functional composite materials has great potential and has become a hot research and attention topic at present.

Titanium dioxide

The chemical composition of titanium dioxide is titanium dioxide. According to the different crystal forms, there are rutile type and rutile type. Rutile type is the most stable crystal form, with a dense structure, better hardness, weather resistance, and powder resistance than rutile type. It is stable to various chemical substances in the atmosphere, insoluble in water, and has good heat resistance. After adding titanium dioxide, it can not only improve the whiteness of the product, but also reduce the destructive effect of ultraviolet rays, improve the photoaging performance of polypropylene, and also improve the rigidity, hardness, and wear resistance of the product. However, its compatibility with crystalline materials such as PP and PA is poor, so it is necessary to carry out compatibilization modification on it.