For plastic products,I believe that everyone is no stranger,but for a small classification in plastic products,we may know less about it.Today,Xiaobian mainly shares some knowledge points about PP plastic products.

　　Features:Polypropylene homopolymer PP,food acceptability,homopolymer,medium flow,suitable for burly,tape applications.

　　Chemical and physical properties of PP plastic materials

　　Both the homopolymer type and the copolymer type PP plastic material have excellent moisture absorption resistance,acid and alkali corrosion resistance,and solubility resistance.However,it is not resistant to aromatic hydrocarbons such as benzene solvents,chlorinated hydrocarbons(carbon tetrachloride)solvents,and the like.PP plastic products are not as resistant to oxidation at high temperatures as PE.

　　PP plastic products have a flow rate MFR ranging from 1 to 40.Low MFR PP materials have better impact resistance but lower elongation.For materials of the same MFR,the strength of the copolymer type is higher than that of the homopolymer type.Due to crystallization,the shrinkage of PP plastic products is quite high,generally 1.8 to 2.5%.And the direction uniformity of shrinkage is much better than materials such as PE-HD.The addition of 30%glass additive can reduce the shrinkage to 0.7%.

　　The strength of PP plastic products increases with increasing ethylene content.PP plastic products have a Vicat softening temperature of 150C.Due to the high degree of crystallinity,this material has excellent surface stiffness and scratch resistance.PP plastic products do not have environmental stress cracking problems.Typically,PP plastic articles are modified by the addition of glass fibers,metal additives or thermoplastic rubber.

　　PP plastic products are a semi-crystalline material.It is harder and has a higher melting point than PE.Since PP plastic products of homopolymer type are very brittle when the temperature is higher than 0C,many commercial PP plastic materials are random copolymers with 1~4%ethylene or clamp copolymers with higher ethylene content..The copolymer type PP plastic material has a low heat distortion temperature(100C),low transparency,low gloss,low rigidity,but has stronger impact strength.

　　Moplen HP550J large plastic products PP product performance:

　　First,electrical performance

　　Electrical properties:PP plastic products are non-polar polymers,have good electrical insulation,and have very low water absorption,and electrical insulation is not affected by humidity.The dielectric constant and dielectric loss factor of PP plastic products are very small,and are not affected by frequency and temperature.PP plastic products have a high dielectric strength and increase with temperature.These are beneficial to electrical insulation materials in wet and hot environments.On the other hand,its surface resistance is very high,and in some cases,it must be subjected to antistatic treatment.

　　Second,aging performance

　　Aging performance:There are tertiary carbon atoms in the PP plastic products,which are easily broken and degraded under the action of light and heat.PP plastic products without stabilizers are heated at 150°C for more than half an hour,or exposed to sunlight for 12 days will become significantly brittle.The PP plastic powder without stabilizer will be seriously degraded after being stored in the room for 4 months,and it will emit obvious acidity.Adding 0.2%or more of antioxidant before granulation can effectively prevent degradation and aging of PP during processing and use.Antioxidants are divided into two categories:free radical chain reaction terminator(also known as primary antioxidant)and peroxide decomposing agent(also called auxiliary antioxidant).The reasonable combination of primary and secondary antioxidants will be Will play a good synergy effect.The currently recommended B215 antioxidant is a combination of primary antioxidant 1010(phenolic)and secondary antioxidant 168(phosphite)in a ratio of 1:2.In order to prevent photoaging,it is necessary to add an ultraviolet absorber to the PP,which converts the ultraviolet absorption of the wavelength of 290 to 400 nm into a non-destructive longer wavelength light.For PP plastic products buried in the soil or used indoors in the dark,only the main and auxiliary antioxidants can be added,and no ultraviolet absorber is added.

　　Third,resistance to stress cracking

　　Stress crack resistance:Stress is left in the molded product,or the product works under continuous stress for a long time,which may cause stress cracking.Organic solvents and surfactants can significantly promote stress cracking.Therefore,the stress cracking test is carried out in the presence of a surfactant.A commonly used auxiliary is an alkyl aryl polyethylene glycol.Tests have shown that PP plastic products have good resistance to stress cracking when immersed in surfactants,and have good resistance in air,and the smaller the melt flow rate of PP plastic products(the higher the molecular weight),the more resistant to stress cracking.Strong.

　　Fourth,chemical stability

　　Chemical stability:PP plastic products have excellent chemical stability and are inert to most acids,bases,salts and oxidants.For example,it is stable in concentrated phosphoric acid,hydrochloric acid,40%sulfuric acid and their salt solutions at 100°C,and only a few strong oxidants such as fuming sulfuric acid may change it.It is a non-polar compound that is very stable to polar solvents such as alcohols,phenols,aldehydes,ketones and most carboxylic acids,but does not swell or partially swell in some non-polar organic solvents.

　　V.Air tightness(gas barrier)

　　Air tightness(gas barrier):PP plastic products have a certain permeability to oxygen,carbon dioxide and water vapor,which is significantly different from nylon(PA)and polyester(PET).For high barrier plastics,Such as PVDC,EVOH,etc.,the difference is even more.However,its air tightness is quite good compared to other non-plastic materials.The airtightness can be greatly improved by adding a barrier material or by coating a barrier plastic on the surface.