Does the long time of plastic gear affect the strength? I made it on 20 15, and now my teeth are broken during use.

AS(SAN) acrylic acid-styrene transparent adhesive

For example, the polymer of acrylonitrile (a) and styrene (s) has moderate weather resistance, is not affected by high humidity environment, is resistant to common grease, detergent and mild alcohol, has poor fatigue resistance, is not easy to crack due to energy stress, has high transparency and is better than ABS.

Applicable plastic products: trays, cups, tableware, toothbrushes, refrigerator compartments, knobs, lighting accessories, ornaments, instrument mirrors, packaging boxes and stationery.

Acrylonitrile-butadiene-styrene polymer

ABS acrylonitrile (chemical resistance, surface hardness) butadiene (toughness) styrene (good processability, good dyeability, poor weather resistance and easy oxidation) has good comprehensive properties, high impact toughness, good mechanical properties, excellent heat and oil resistance and chemical stability, stable size, easy processing, surface electroplating and good electrical properties.

Suitable for plastic products: used for general structures or wear-resistant transmission parts and corrosion-resistant equipment. Gear, pump impeller, bearing, handle, pipeline, motor casing, electronic parts, clock casing, water tank casing, cold storage and refrigerator inner casing, stationery, toys.

GPPS modified polystyrene 204

The transparency is 88-92% and the refractive index is 1.59- 1.60. Suitable for light-transmitting products, it has strong dyeability, no toxicity, no bacteria, high impact strength, good acid and alkali resistance, solvent resistance, excellent electrical properties, easy molding, moisture absorption rate less than 0.02%, and can maintain strength and size under high humidity.

Suitable for plastic products: decorations, lighting signs, lampshades, stationery, transparent toys, daily necessities, instrument lenses, refrigerators (after foaming).

High impact polystyrene

After the composition contains rubber, the impact strength is greatly improved. The product can be designed with buckle position and column position, and the column position can also use self-tapping screws, which can be used for a long time at 85 degrees, and the aging accelerated life is reduced.

Suitable for plastic products: all kinds of household appliance shells, stationery, toys, electronic parts, electronic instrument shells, cold storage and refrigerator inner shells, telephones.

Polypropylene hundred fold adhesive

Similar to white wax, it is more transparent and lighter than polyethylene, with good fluidity during injection molding, water absorption less than 0.02%, resistance to chemical organic solvents, stability in various media except concentrated nitric acid and concentrated sulfuric acid, high impact strength, very high return yield, poor high-frequency electrical properties, easy shrinkage during molding, strong temperature resistance, high brittleness at low temperature and low wear resistance.

Applicable plastic products: general structural parts, corrosion-resistant parts, heating electrical insulation parts. All kinds of household goods, stationery, toys, chemical containers, medical supplies.

PE polyethylene

Applicable plastic products: universal cable sheath, corrosion-resistant parts, surface coating.

HDPE: plastic bags, daily necessities barrels, wires, toys and building materials.

LDPE: plastic bags, plastic flowers, toys, high-frequency wires.

PMMA polymethacrylate secondary strength plexiglass

Applicable plastic products: transparent structural parts with certain strength requirements.

Keywords instrument lens, optical products, electrical, medical equipment, transparent model,

Decorations, sunglasses, billboards.

Soft polyvinyl chloride

Soft and friction-resistant, flexible, good elasticity, low water absorption, easy processing and molding, good cold resistance and electrical properties, strong chemical stability, strong flame retardancy and self-absorption, noise elimination and shock absorption can be made into various bright and transparent products, and rigid PVC has high mechanical strength. But the service temperature is low (-15-+55 degrees).

Suitable plastic products: usually made into tubes, rods, sheets, insulating sheaths and soft sheaths.

Household articles, stationery, packaging materials, sports equipment, water pipes, etc.

PC polycarbonate

It has outstanding impact toughness and creep resistance, high heat resistance and good cold resistance. The brittleness temperature reaches-100 degree, the bending strength is equivalent to that of nylon, and it has high elongation and elastic modulus, but the fatigue strength is less than that of nylon 66. Low water absorption, small shrinkage and good dimensional stability. Molded parts can achieve very precise tolerances and maintain dimensional stability in a wide range of changes. The wear resistance is equivalent to that of nylon, and it has certain corrosion resistance, but the molding conditions are high. It can be used for a long time at high Gao Qian temperature and high load, but it cannot be used at humid temperature.

Applicable plastic products: all kinds of gears, turbines, racks, cams, bearings, spindles, pulleys, conveyor chains, nuts, washers, pump impellers, lampshades, containers, casings, cover plates, high-temperature electrical products, fan casings, fire cow casings, motor casings, tool boxes, baby bottles, camera parts, helmets, food trays, medical devices, compact discs, etc.

Others: the shrinkage rate is 0.5-0.7%, the thickness is 2-3.5mm, and the overflow value is 0.06 mm.

Adding glass fiber to PC can improve its shrinkage, mechanical strength and temperature resistance, and the rigidity will increase when it is used for a long time at 100 degrees. Products can be annealed to improve internal stress.

PA nylon

The mechanical properties of PA, such as tensile strength and compressive strength, change with temperature and hygroscopicity, so water is the plasticizer of PA. After adding glass fiber, its tensile and compressive strength can be improved by about 2 times, and its temperature resistance is also improved accordingly. PA itself has very high wear resistance, so it can run without lubrication. If you want to obtain special lubrication effect, you can add sulfide to PA.

Suitable for plastic products: all kinds of gears, turbines, racks, cams, bearings, propellers and transmission belts.

◆PA66 has high fatigue strength and rigidity, good heat resistance, low friction coefficient and good wear resistance, but it has high hygroscopicity and insufficient dimensional stability.

Application: medium load, working temperature

◆ The fatigue strength, rigidity and heat resistance of ◆PA6 are lower than those of nylon 66, but it has good elasticity and good vibration and noise reduction ability. white

Application: light load, moderate temperature (80- 100), no or little lubrication.

◆ The strength, rigidity and heat resistance of ◆PA6 10/0 are lower than those of nylon 66, but the hygroscopicity is low and the wear resistance is good. Khaki

Usage: Like nylon 6, it is suitable for gears with relatively precise requirements and parts with large humidity changes under working conditions.

◆PA 100 1 has lower strength, rigidity and heat resistance than nylon 6 10, lower hygroscopicity, good molding process and good wear resistance.

Application: Parts working under light load, low temperature, great humidity change and no or little lubrication.

◆MCPA is superior to PA6 and PA66 in strength, fatigue resistance, heat resistance and rigidity, with lower hygroscopicity and better wear resistance. Can be directly aggregated in the model, suitable for casting large parts. Application: High load, high working temperature (below 120), no or little lubrication. elephant's tusk

Polyoxymethylene and polyacetal (Saigang)

High tensile strength, impact toughness, rigidity, fatigue strength, creep resistance, good dimensional stability, low water absorption, low friction coefficient, excellent friction and wear performance, high rigidity at high temperature and in water, chemical corrosion resistance, performance equivalent to PA, but low price, repeated torsion resistance and outstanding resilience. Molding is more difficult than nylon, and it is easy to decompose when heated.

Applicable plastic products: it can replace most non-ferrous metals and be used in various gears, turbines, racks, cams, bearings, pump impellers, automobiles, instruments, machine tools, etc.

PSU or polysulfone polysulfone

Its mechanical properties, heat resistance, oxidation resistance, medium resistance and thermal stability are better than PC, but its processability, fracture sensitivity, weather resistance, light and ultraviolet resistance and organic solvent performance are poor, so it can not be used in boiling water for a long time like PC. After being filled with F-4, it can be used as friction parts. The surface can be electroplated.

Applications: Wear-resistant transmission parts, gears, internal parts of microwave ovens, camera housings, medical instruments, automobile parts and projectors that work at high temperature.

Ethylene terephthalate

It has excellent impact resistance, low friction coefficient and wear resistance, the wear is only 1/4 of POM, good dimensional stability, small hygroscopicity, short cooling time, and resistance to general solvents and hydrolysis.

Application: Some parts that require lubrication and corrosion resistance. Gears, bearings, propellers, pump shells, etc.

Fluoropolymer PVF

Is the floorboard of fluoroplastics,

◆ PTFE F-4 plastic king

It has excellent high and low temperature resistance and can work continuously for more than 200 hours in the range of-195-+200 degrees. Chemical corrosion resistance is the best among all plastics. It does not react with strong acid, strong alkali and strong oxidant, and its friction coefficient is very low, only 0.04. It is an excellent self-lubricating material. The disadvantages are poor mechanical properties, poor rigidity, poor cold fluidity, low thermal conductivity, large thermal expansion, low wear resistance (which can be improved by adding fillers), and the method of preloading and sintering is needed, which leads to high molding cost.

Application: Containers or seals that require chemical corrosion resistance.

◆ PTFE filled with polytetrafluoroethylene

PTFE filled with glass fiber powder, molybdenum disulfide, graphite, oxide scale, tungsten sulfide, bronze powder and lead powder improves the bearing capacity and stiffness to a certain extent.

Application: Friction parts working in high temperature or corrosive medium, such as piston rings.

◆ Polytrifluoroethylene

Heat resistance, electrical properties and chemical stability are second only to F-4, while mechanical strength, creep resistance and hardness are stronger than F-4.

Uses: Corrosion-resistant equipment and parts can be used as anti-corrosion coatings for metals.

◆ PFEP FEP F-46

The mechanical properties, electrical properties and chemical stability are basically the same as those of F-4. It has extremely high impact toughness and can work for a long time in the range of -85-+205 degrees.

The application is the same as F-4, which can be injection molded.

◆PPO, Chinese name polyphenylene ether. It has the advantages of high rigidity, high heat resistance, flame retardancy, high strength and excellent electrical performance. In addition, polyphenylene ether also has the advantages of wear resistance, non-toxicity and pollution resistance. The dielectric constant and dielectric loss of PPO is one of the smallest varieties of engineering plastics, which is almost unaffected by temperature and humidity, and can be used in low, medium and high frequency electric fields. The load deformation temperature of PPO can reach above 190℃, and the brittleness temperature is-170℃.

They are widely used in:

Electronic and electrical: it can meet the requirements of excellent electrical insulation under wet, load and high temperature conditions. It is used to prepare TV tuners, coil cores, microwave insulation, shielding sleeves, high-frequency printed circuit boards, various high-voltage electronic components, televisions, computers, fax machines, photocopier housings, etc.

Automobile industry: suitable for dashboard parts, window frames, shock absorbers, pump filters, etc.

Machinery industry: used as gears, bearings, pump impellers, blower impellers, etc.

Chemical field: used to manufacture corrosion-resistant parts such as pipes, valves, filters and submersible pumps.

◆ PPE polyphenylene ether

Polyphenylene ether resin (PPE or PPO for short) belongs to thermoplastic general engineering plastics. Polyphenylene ether alloy is one of the five engineering plastics, and it is also the most widely used variety in engineering plastics alloys.

The application fields of PPE and its alloy products are mainly household appliances, office and communication equipment and automobile industry. In household appliances, it is mainly used for movement bracket, color TV output transformer, air conditioning electric cabinet and so on. In the aspect of office and communication equipment, it is mainly used for the bracket, base, middle frame, bottom frame and flap of copier, the shell and bracket of fax machine, the toner box of copier and the external connector of computer. In the automobile industry, it is mainly used to manufacture some small parts, such as windshield, wiper, vehicle decorative cover, various wire clamps and so on. Household goods (dishwasher, washing machine, etc. ), controller shell, optical fiber coupler and other electrical equipment.

Normethyl modified polyphenylene ether

NORYL is a mixture of PPE and PS. Hard and tough, the strength is higher than PA, POM and PC, and the creep ratio is less than the three. The mechanical strength decreases only slightly with the increase of temperature, and it can work in the environment of -95-+ 1 10 degree, with low water absorption, stable size in boiling water, good insulation performance and chemical corrosion resistance, but it is sensitive to ultraviolet rays.

Applications: High-frequency electronic parts, insulation materials, medical instruments, high-temperature tableware, gears, plastic screws, photocopier housings and parts.

Others: Shrinkage rate 0.5-0.7%

Suitable wall thickness: 2-3.5mm.

◆ Pet features:

The scientific name of PET is polyethylene terephthalate, commonly known as polyester. It has a highly symmetrical aromatic ring structure, the functional groups on the linear molecular chain are arranged regularly, and there is no branch chain, so it has high strength and good fiberization and formability. Its density is1.37 ~1.41g/cm2, its melting point is 248oC, its viscosity is low, its adhesion to metal is high, it is easy to hydrolyze, and its intrinsic viscosity is (1.v.) dl/g0.8/kloc-0. The bottles made of PET have the characteristics of high strength, good transparency, non-toxicity, anti-permeability, light weight and high production efficiency.

◆PS plastic

Chemical name: polystyrene

English name: polystyrene

Specific gravity:1.05g/cm3

Molding shrinkage: 0.6-0.8%

Molding temperature: 170-250℃

Features: Excellent electrical insulation (especially high-frequency insulation), colorless and transparent, light transmittance second only to plexiglass, colored water resistance, good chemical stability, average strength, but fragile, prone to stress embrittlement, and not resistant to organic solvents such as benzene and gasoline.

Uses: Suitable for making insulating transparent parts, decorative parts, chemical instruments, optical instruments and other parts.

Molding characteristics:

1. Amorphous material, with small hygroscopicity, does not need to be fully dried, and is not easy to decompose, but it has a large thermal expansion coefficient and is easy to generate internal stress. It has good fluidity and can be molded by screw or plunger injection molding machine.

2. It is advisable to adopt high material temperature, high mold temperature and low injection pressure, and prolonging injection time is beneficial to reduce internal stress and prevent shrinkage and deformation.

3. Various gates can be used, and the gates are connected with the plastic parts in an arc shape to avoid damaging the plastic parts when the gates are removed. The demoulding slope is large and the ejection is uniform. The wall thickness of plastic parts is uniform, and it is best not to have inserts. If there are inserts, preheat them.

◆ PPS plastic (polyphenylene sulfide)

English name: phenyl sulfide

Specific gravity:1.36g/cm3

Molding shrinkage: 0.7%

Molding temperature: 300-330℃

Drying conditions:-

materials performance

1, excellent electrical insulation (especially high-frequency insulation), hard and brittle white, metallic noise when landing, good coloring, water resistance and chemical stability. It has excellent flame retardancy and is a non-combustible plastic.

2, general strength, good rigidity, but fragile, prone to stress embrittlement, not resistant to benzene, gasoline and other organic solvents. Long-term use temperature can reach 260 degrees, 400 degrees in air or nitrogen to maintain stability. By adding glass fiber or other reinforcing materials, the impact strength can be greatly improved, and the heat resistance and other mechanical properties can also be improved. The density is increased to 1.6- 1.9, and the molding shrinkage is as low as 0. 15-0.25%, which is suitable for making heat-resistant parts, insulating parts and chemical and optical instruments.

◆LCP (liquid crystal polymer), English name: Liquid Crystal polyester.

Liquid-crystalline aromatic polyester has an unusually regular fiber structure and special properties because of its liquid-crystalline macromolecular chain orientation, and its products have as high strength as metals and ceramics. The tensile strength and bending modulus of various thermoplastic engineering plastics can exceed 10 years. High strength, good rigidity, good dimensional stability, good optical performance, good electrical insulation, good chemical resistance, good flame retardancy, good processability, high temperature resistance (thermal deformation temperature can reach 335℃) and very small thermal expansion coefficient. Can be injection molded, and is suitable for injection molding of various thin-walled electronic and electrical components.

The formation process of liquid crystal polymer;

The forming temperature of LCP is high, and the melting temperature is between 300 ~ 425℃ due to different varieties. LCP melt has low viscosity and good fluidity, which is similar to olefin plastics. LCP has very small linear expansion coefficient and good dimensional stability. The reference of molding process conditions is: molding temperature is 300 ~ 390℃; Mold temperature100 ~ 260℃; The molding pressure is 7 ~ 100 MPa, the compression ratio is 2.5 ~ 4, and that of molding shrinkage is 0. 1 ~ 0.6.

Characteristics and applications of liquid crystal polymers

I. Characteristics

Liquid crystal polymer resin is generally beige, and there are also white opaque solid powders. The density is 1.4 ~ 1.7g/cm3. Liquid crystal polymers have high strength and high modulus mechanical properties, and are reinforced because of their structural characteristics, so unreinforced liquid crystal plastics can reach or even exceed the level of mechanical strength and modulus of ordinary engineering plastics reinforced with dozens of glass fibers; If reinforced with glass fiber and carbon fiber, it will far exceed other engineering plastics.

Liquid crystal polymers also have excellent thermal stability, heat resistance and chemical resistance. The creep defects of most plastics can be ignored, and the wear resistance and wear reduction are excellent.

LCP has good weather resistance, radiation resistance and excellent flame retardancy, and can extinguish the flame without continuing to burn. Its combustion grade reaches UL94V-0. LCP is one of the special plastics with the best fire resistance.

LCP has excellent electrical insulation performance. Its dielectric strength is higher than that of general engineering plastics, and its arc resistance is good. As an electrical product, its electrical performance will not be affected if it is used continuously at 200 ~ 300℃. The intermittent use temperature can reach about 365438 06℃.

LCP has excellent corrosion resistance. LCP products will not be corroded in 90% acid and 50% alkali. For industrial solvents, fuel oil, detergents and hot water, they will not dissolve after contact and will not cause stress cracking.

Second, the application

LCP has been used in microwave oven containers, which can withstand high and low temperatures. LCP can also be used as printed circuit boards, satellite electronic parts and jet engine parts: parts or components of electronic and electrical and automobile machinery; It can also be used for medical treatment.

LCP can add high filler as the packaging material of integrated circuit, instead of epoxy resin as the packaging material of coil skeleton and epoxy resin as the packaging material of coil skeleton. As a protective sleeve and high strength component of optical cable joint; Used as packing in chemical separation tower instead of ceramics.

LCP can also be mixed with polysulfone, PBT, polyamide and other plastics to make alloys. After molding, the mechanical strength of the product is high. It can be used to replace glass fiber reinforced polysulfone and other plastics, which can not only improve the mechanical strength, but also improve the use strength and chemical stability. At present, LCP for spacecraft exterior panels and automobile braking systems is being studied.

◆EVA (ethylene vinyl acetate, rubber rubber)

Thermoplastic resin prepared by polymerization of ethylene and vinyl acetate. The content of vinyl acetate (VA) in industrial products is 5% ~ 95%, and the properties of different varieties are quite different. Generally, with the increase of vinyl acetate content, the crystallinity, hardness, rigidity and thermal deformation temperature gradually decrease, while the gloss, transparency, impact resistance, flexibility, stress cracking resistance, solubility in solvents, thermal shrinkage and thermal weldability are improved to varying degrees.

Uses of ethylene-vinyl acetate copolymer:

(1) Foamed shoe material

The VA content of ethylene-vinyl acetate copolymer used for foamed products is 15% ~ 30%. This material has the properties of softness, good elasticity, shock absorption, chemical resistance, etc., and is widely used in the soles of middle and high-grade travel shoes, hiking shoes, slippers and sandals, as well as sound insulation boards, gymnastics mats, sealed profiles, toys, etc.

(2) Movies

The content of ethylene-vinyl acetate copolymer VA used in the film is less than 20%. EVA film has the advantages of high transparency, good impact toughness, good thermal stability, physiological harmlessness, good air permeability and low shrinkage at low temperature. As an agricultural functional greenhouse film, it has high light transmittance, good thermal insulation performance, aging resistance and fog drop prevention, and is an ideal agricultural film substrate. In addition, EVA can also be used as packaging film, medical film, composite film and casting film.

(3) Wires and cables

Ethylene-vinyl acetate copolymer with VA content of 12% ~ 24% is used for wires and cables. The advantages of EVA used in insulating materials such as wires and cables are that it can accommodate a large number of fillers without brittle cracking, comprehensive mechanical properties are not lost, and it is easy to cross-link. Typical applications in this field include heat shrinkable insulators, semiconductor shielding materials and flame retardant insulating materials.

(4) Hot melt adhesive

The hot melt adhesive adopts ethylene-vinyl acetate copolymer, and the VA content is 25% ~ 40%. Because EVA hot melt adhesive contains no solvent, has no danger of environmental pollution and flammability, and is suitable for high-speed automatic production line operation, it is widely used in wireless binding of books, packaging, edge sealing of furniture, assembly of automobiles and household appliances, shoemaking, carpet coating and anticorrosion coating of metal products. The adhesive has short curing time, no need of drying, and is easy to store and transport.

In addition, ethylene-vinyl acetate copolymer is also widely used in ink, luggage, bottle cushion cover, various extrusion hoses/pipes and other fields.

Thermoplastic elastomers

Generally speaking, the common thermoplastic elastomers in the market are styrene thermoplastic elastomer (SBC), polyolefin thermoplastic elastomer (TPO), thermoplastic polyurethane (TPU), polyester thermoplastic elastomer (TPEE) and polyamide thermoplastic elastomer (TPAE). Among these elastomers, each elastomer has different properties. Styrene thermoplastic elastomers include SBS and SEBS. SEBS is a hydrogenated styrene elastomer with high polymer chain saturation. Therefore, SEBS is much better than SBS elastomer in temperature resistance, weather resistance and ultraviolet resistance, and it is one of the most widely used thermoplastic elastomers.

◆SBS

SBS is a styrene/butadiene/styrene ternary block copolymer, which belongs to styrene-butadiene thermoplastic elastomer. It has the high elasticity of rubber and the formability of plastic. High strength, soft texture, non-toxic, wear-resistant, cold-resistant, good resilience and low temperature resistance. It can be processed by injection molding, extrusion, blow molding and thermoforming. Because of its good compatibility with other plastics, it can be directly used as modifier and toughening agent to modify HIPS, PS, ABS, PC, PP and other resins, greatly improving their impact strength and low temperature impact strength. Widely used in shoes, pipes, toys, wires, handles, sealants, daily necessities, medical devices and other products; And can be mixed with thermoplastics, thermosetting resins and asphalt; It is also used in adhesive, coating and other fields.

◆TPE (thermoplastic elastomer)

Thermoplastic elastomer (TPE) or thermoplastic rubber (TPR) is a kind of polymer material with the characteristics of rubber and thermoplastic, which shows high elasticity of rubber at room temperature and can be plasticized at high temperature. It is also the so-called third generation rubber after natural rubber and synthetic rubber. The structural characteristics of thermoplastic elastomer polymer chains are composed of resin segments (hard segments) and rubber segments (soft segments) with different chemical compositions.

Thermoplastic elastomers TPR and TPE are rubber with high elasticity, high resilience and high strength, and also have the characteristics of injection molding. It has the advantages of environmental protection, non-toxicity, safety, light weight (specific gravity as low as 0. 15), water resistance, cold resistance, high temperature resistance, wide hardness range, good coloring, soft hand feeling, weather resistance, fatigue resistance, excellent processability, no need for vulcanization, recycling and cost reduction. It can not only be used for secondary injection molding, but also be combined with matrix materials such as PP, PE, PC, PS and ABS.

But the heat resistance of TPE is not as good as that of rubber. At the same time, the compression deformation, elastic recovery and durability are worse than those of the same rubber, and the price is often higher than that of similar rubber.

TPR/TPE produced by a company has the characteristics of softness, sanitation, transparency (completely transparent and translucent), acid and alkali resistance, good sealing performance, simple processing, injection extrusion and overflow recovery, which can replace PVC. Cushion pad that can be used to clamp the sole insole pen cover.

There are many kinds of TPE particles, and their typical classification is as follows:

TPE-s (based on SEBS)

TPE-o(TPO) is based on the mixture of thermoplastic olefin POE, plastic PP and EPDM. * * * Polymers include reactor type and polyolefin rubber)

TPE-v(TPV, thermoplastic vulcanized rubber based on plastic and crosslinked rubber)

TPE-p(TPE, based on advanced vinyl technology)

TPE-m(TPEs, modified TPE-s, TPE-o, TPE-r, TPE-u, etc. )

TPE-u(TPU, polymerized from ethane hard selenium and polyether or polyester rubber)

TPE-e(COPE, polyester TPE, polymerized from hard polyester, soft polyester and rubber)

TPE-a(COPA, polyamide TPE, polymerized from hard polyesteramine and soft polyester)

◆ Polyolefin

Polyolefin (PO) is a polymer derived from propylene and ethylene. As polymers, they can form high-strength and flexible plastic products with various uses, and can also be used to produce hard materials in refrigerators, computers and automobile parts and flexible fibers in baby diapers. Some polyolefin products have high heat resistance and can be used to make microwave food containers. Some of them are fusible and can be used to produce heat-sealed food packaging.

Polyolefin composite (PO) is a kind of modified composite with ethylene, propylene, butene and other polymers as the main components. It overcomes the shortcomings of single component, has good toughness and low temperature resistance of polyethylene, high softening temperature of polypropylene and excellent thermal stability and light stability of polybutylene, and is one of the most ideal anti-corrosion materials at present.

Polyolefin has the advantages of good mechanical properties, non-toxicity, heat resistance, chemical resistance and easy processing and molding, and its application field is increasingly extensive. However, due to the structural characteristics of polyolefin, its application in some fields is limited. In order to expand the application range of polyolefin, it can be solved by adding nucleating agent. Polyolefin nucleating agent is a new functional additive. By changing the crystallization behavior of resin, it can accelerate the crystallization speed, improve the crystallization density and refine the grain size, thus shortening the molding cycle and improving the physical and mechanical properties of products, such as transparency, surface gloss, tensile strength, rigidity, thermal deformation temperature, impact resistance and creep resistance. The addition of polyolefin nucleating agent improves the rigidity, dimensional stability, transparency and surface gloss of the product. For example, after adding nucleating agent to polypropylene (PP), the transparency and gloss of the material are improved, so that the product can be used in medical syringes, food containers, stationery and packaging, films, plates and so on. In addition, the nucleating agent can also increase the thermal deformation temperature of the material, so that PP can be used to make transparent hot drink cups, microwave ovens, baby bottles and so on. Adding nucleating agent to polyethylene can obviously reduce the haze of high-pressure polyethylene and linear low-density polyethylene (LLDPE) mesh films, improve the transparency and improve the processability of polyethylene.

◆ MF thermosetting plastics (melamine, melamine)

A polymer obtained by the reaction of melamine with formaldehyde. Also known as melamine formaldehyde resin, melamine resin. English abbreviation MF. Cross-linking reaction occurs during processing and molding, and the product is insoluble thermosetting resin. Traditionally, it is often called amino resin together with urea-formaldehyde resin. The cured melamine formaldehyde resin is colorless and transparent, stable in boiling water, and can even be used at 150℃, with self-extinguishing, arc resistance and good mechanical properties. It has the characteristics of non-toxic, flame retardant, high temperature resistance, arc resistance, good water resistance and high hardness.

Melamine resin does not cure at room temperature, but generally cures at 130 ~ 150℃. Adding a small amount of acid catalysis can improve the curing speed.

Melamine resin with inorganic filler is made into colorful molded products, which are mostly used in decorative boards, tableware, daily necessities and so on. Tableware looks like porcelain or ivory, which is not fragile and suitable for mechanical washing. Melamine resin mixed with urea-formaldehyde resin can be made into adhesive, which is used to make laminated materials. Butanol modified melamine resin can be used as coating and thermosetting paint. Foamed melamine resin can be used to make sound-absorbing materials.

◆ UF thermosetting plastics (urea-formaldehyde resin, urea-formaldehyde resin)

A polymer obtained by the reaction of urea and formaldehyde. Also known as urea-formaldehyde resin. English abbreviation UF. Crosslinking occurs during processing and molding, and the product is insoluble thermosetting resin. The cured urea-formaldehyde resin is lighter in color than phenolic resin, translucent, resistant to weak acid and alkali, good in insulation, excellent in wear resistance and low in price, but easy to decompose when it meets strong acid and alkali, and poor in weather resistance. Trade name Beetle linear urea-formaldehyde resin, with ammonium chloride as curing agent, can be cured at room temperature. Molding powder is cured by heating at 130 ~ 160℃, and accelerators such as zinc sulfate can accelerate the curing process. Non-toxic, hard, scratch-resistant, cheap, but poor heat and water resistance.

Urea-formaldehyde resin is mainly used to make molded plastics, daily necessities and electrical parts, and can also be used as board adhesive, paper and fabric slurry, veneer, building decorative board and so on. Because of its light color and easy coloring, products are often rich in color and magnificent.

Does the long time of plastic gear affect the strength? I made it on 20 15, and now my teeth are broken during use.

Please describe the problem in detail.