高分子材料与应用(英文版)Chapter4Thermsets课件

1、高分子材料与应用(英文版)Chapter4Thermsets课件高分子材料与应用(英文版)Chapter4ThermsetsThermosetsResin Phenolics Epoxies Melamines Silicones Polyesters CompositesThermoset vs. thermoplasticThermosetsResinGeneral Properties of ThermosetsStrengthFlexibilityThermalCreepAbility to reinforceAbility to cure at room temperatureGen

2、eral Properties of ThermoseFormaldehyde ResinsPhenolicsUrea formaldehydeMelamine formaldehydeFormaldehyde ResinsPhenolicsCrosslinking of PhenolicsReactive GroupsPhenolics PhenolFormaldehydePlusCrosslinking of PhenolicsReactCompression MoldingCompression molding was specifically developed for replace

3、ment of metal components with composite parts. The molding process can be carried out with either thermosets or thermoplastics. However, most applications today use thermoset polymers. In fact,compression molding is the most common method of processing thermosets.Compression MoldingCompressionResin

4、Transfer MoldingIn the RTM process, dry (i.e.,unimpregnated ) reinforcement is pre-shaped and oriented into skeleton of the actual part known as the preform which is inserted into a matched die mold.The heated mold is closed and the liquid resin is injectedThe part is cured in mold.The mold is opene

5、d and part is removed from mold.Resin Transfer MoldingIn the RInjection MoldingGlass Reinforced CompositesPlastic pellets with glass fibers are melted in screw, injected into a cold mold, and then ejected.Glass filled resin pelletsInjection MoldingGlass ReinfoApplication of PhenolicsWiring devicesSw

6、itch gearCircuit breakersInsulatorsGearsWear guidesPulleysRollersApplication of PhenolicsWiringAmino Resins (UF and MF) Formaldehyde + -NH2(amine group) (1) Urea-formaldehyde (2) Melamine-formaldehydeAmino Resins (UF and MF) FormaCrosslinkingReactive GroupsAmino plasticsAminePlusFormaldehydeCrosslin

7、kingReactive GroupsAmUrea formaldehydeUrea formaldehydeMelamineCrosslinking as Polymers are FormedThree active sitesFormaldehydePlusMelamineCrosslinking as PolymeCrosslinking as Polymers are FormedMelamine FormaldehydeWaterCrosslinking as Polymers are FCrosslinking as Polymers are FormedMelamine For

8、maldehydeWaterCrosslinking as Polymers are FAmine plastics clear adhesiveChipboard Applications: wood particleboard, plywood, boat hulls flooring furniture assemblies Cellulose-filled urea compound: Electrical wall plates, receptacles, knobs, handle Cellulose-filled melamine compound: dinnerware, bu

9、ttons, control buttons, knobAmine plastics clear adhesivApplication of melamine plasticsMelamine PlasticsApplication of melamine plastiPolyester Thermosets (TS) or Unsaturated Polyesters (UP)Largest group of thermosetsMost like to be reinforced with fiberglassPolyester Thermosets (TS) or UInitiator(

10、usually peroxide)Carbon-carbonDouble bondCrosslinkingReactive GroupsUnsaturated polyestersPlusInitiatorCarbon-carbonCrosslinViscosity and Thermal Control during CrosslinkingViscosity and Thermal Control Thermoset TypesUnsaturated PolyestersThermoset TypesUnsaturated PolCrosslinking Mechanism for The

11、rmoset PolyestersPolyesterPeroxideStyrene(large quantities)Crosslinking Mechanism for TheCrosslinking HeatPeroxidebreaks apartCrosslinking HeatPeroxideCrosslinking Approach of styreneCrosslinking Approach of styCrosslinking bond to styreneHalf of peroxide bonds with other end of broken styrene molec

12、uleWhen styrenes double bond breaks, one end forms a free radicalCrosslinking bond to styreneCrosslinking approach to polymerStyrene free radical causes the polymers double bond to break and allows it to accept a new pi bondCrosslinking approach to polCrosslinking bonding to polymerProblems: Polymer

13、s not lined up, steric interferenceSolution: StyreneNew bondNew free radicalCrosslinking bonding to polymCrosslinking approach of styreneCrosslinking approach of styrCrosslinking activation of styreneStyrenes double bond opens, allowing two new free radical sitesCrosslinking activation of stCrosslin

14、king bonding of styreneProblems: Polymers still not lined up, steric interferenceSolution: Still more styreneNew bondDouble bond opens but cant create a bond with any other open bond because of steric effectsCrosslinking bonding of styrCrosslinking bonding of 2nd styreneNew bondFree radicalCrosslink

15、ing bonding of 2nd Crosslinking bonding with 2nd polymerUp to 8 styrenes might be needed in the bridgeNew bondCrosslinking bonding with 2ndCrosslinking bonding with 2nd polymerEtc.Crosslinking bonding with 2ndCrosslinking more styreneCrosslinking more styreneCrosslinking more styreneCrosslinking mor

16、e styreneCrosslinkingbonding to 3rd polymerCrosslinkingbonding to 3rd poLaminating ResinsLaminating ResinsAdditives to Thermoset PolyestersFillers like Calcium CarbonateTougheners like rubbersAntioxidants and UV stabilizersReinforcementsAdditives to Thermoset PolyestGlass fiber reinforced plastics (

17、GFRP)Glass fiber reinforced plasticSheet Molding Compound (SMC)Sheet Molding Compound (SMC)Sheet Molding Compound (SMC)Sheet Molding Compound (SMC)Hardener(amine shown)Epoxy RingsEpoxiesReactive GroupsEpoxies PlusHardenerEpoxy RingsEpoxiesReacReaction schemes for the synthesis of DGEBA-type epoxy re

18、sinbisphenol A (DGEBA)Reaction schemes for the synthThermoset TypesEpoxiesThermoset TypesEpoxiesCrosslinking of PolyurethanesReactive GroupsPolyurethanes PlusPolyolsDiisocyanatesCrosslinking of PolyurethanesRChemical structures of common isocyanates used for PU synthesis异佛尔酮二异氰酸酯Chemical structures of common Sy