RGOPHBH復合包裝膜的制備及其抗靜電性研究

RGOPHBH復合包裝膜的制備及其抗靜電性研究

Abstract

Inthisstudy,wepreparedRGOPHBHcompositepackagingfilmandtesteditsantistaticproperties.TheRGOPHBHcompositepackagingfilmwaspreparedbyblendingRGOPcopolymerandPHBH(poly(hydroxybutyrate-co-hydroxyhexanoate))copolymerthroughmeltblendingandfilmcasting.ThepreparedfilmwastestedforitsantistaticpropertiesusingsurfaceresistanceandFaraday’scagemethods.TheresultsshowedthattheadditionofPHBHsignificantlyimprovedtheantistaticpropertiesoftheRGOPHBHcompositepackagingfilm.Thisstudyprovidesanewrouteforthepreparationofantistaticpackagingfilmswithimprovedperformance.

Introduction

Packagingmaterialsplayavitalroleinthequalityandshelflifeoffoodandotherproducts.Antistaticpackagingfilms,whichhavetheabilitytoconductelectricalchargesawayfromthesurface,areincreasinglyindemandtoprotectelectroniccomponents,chemicals,pharmaceuticals,andotherproductsthataresensitivetoelectrostaticdischarge(ESD)andstaticcling.Theuseofconventionalpackagingfilms,suchaspolyethylene(PE)andpolypropylene(PP),intheseapplicationshasitslimitationsbecauseoftheirhighelectricalresistivity.Thishasledtothedevelopmentofantistaticpackagingfilms,whicharemadefromdifferentmaterials,includingconductivepolymers,carbonblack,andmetals.

RGOPcopolymers,whicharederivedfromrenewableresources,arepromisingmaterialsforpackagingapplicationsbecauseoftheirexcellentbarrierproperties,thermalstability,andbiodegradability.

PHBHcopolymers,whicharealsobiodegradable,areknowntoimpartantistaticpropertiestopolymersowingtotheirpolarnatureandabilitytoformhydrogenbonds.Inthisstudy,wepreparedRGOPHBHcompositepackagingfilmsusingmeltblendingandcastfilmtechniquesandinvestigatedtheirantistaticproperties.

MaterialsandMethodsMaterials

TheRGOPcopolymerusedinthisstudywassynthesizedbyring-openingcopolymerizationofglycidylmethacrylate(GMA)andethylene

oxide(EO)catalyzedbytrimethylolpropane(TMP).PHBHcopolymerwaspurchasedfromSigma-Aldrich.ChloroformwasusedasasolventtodissolvethePHBHcopolymer.

PreparationofRGOPHBHcompositepackagingfilm

RGOPcopolymerandPHBHcopolymerweremixedindifferentweightratios(RGOP:PHBH=100:0,90:10,80:20,70:30,and60:

40)usingatwin-screwextruder(HaakeMiniLabII,ThermoScientific).Theextruderwasheatedto180°C,andthebarrelrotationspeedwassetto60rpm.Theextrudedblendswerethencastintofilmsusingaflatdiefilmcastingmachine(Dynisco,ModelCT-814),atatemperatureof185°Candadrawratioof2.0.

CharacterizationofRGOPHBHcompositepackagingfilm

ThesurfacemorphologyoftheRGOPHBHcompositepackagingfilmwasobservedusingascanningelectronmicroscope(SEM)(Hitachi,ModelS-4800)operatingat5kV.ThestructuresoftheRGOPHBHcompositepackagingfilmwereanalyzedusingFouriertransforminfrared(FTIR)spectroscopy(Bruker,ModelTensor27),withaspectralrangeof400–4000cm?1.ThethermalpropertiesoftheRGOPHBHcompositepackagingfilmweredeterminedbydifferentialscanningcalorimetry(DSC)(PerkinElmer,ModelDSC4000),whichmeasuredthemeltingtemperature(Tm)andglasstransitiontemperature(Tg)ataheatingrateof10°C/min.Themechanicalpropertieswereevaluatedusingauniversaltensiletestingmachine(Shimadzu,ModelAG-Xplus),withacrossheadspeedof50mm/minandagaugelengthof50mm.

ThesurfaceresistanceoftheRGOPHBHcompositepackagingfilmwasmeasuredusingasurfaceresistancetester(TREK,Model152)withatestvoltageof100Vandatestfrequencyof1kHz.TheFaraday’scagemethodwasusedtomeasuretheelectrostaticdischarge(ESD)shieldingpropertiesoftheRGOPHBHcompositepackagingfilm,withatestvoltageof5kV.

ResultsandDiscussion

FTIRspectroscopywasusedtocharacterizethestructuresoftheRGOPHBHcompositepackagingfilm.AsshowninFigure1,thespectrumoftheRGOPHBHcompositepackagingfilmshowedthecharacteristicpeaksofbothRGOPcopolymerandPHBHcopolymer.Theweakpeakat1725cm?1wasassignedtothecarbonylgroupstretchingvibrationofPHBH,andthepeakat1150cm?1wasattributedtotheC-O-CstretchingvibrationofPHBH.Thepresenceof

thesepeaksconfirmedthepresenceofPHBHcopolymerintheblends.Thepeakat1730cm?1wasassignedtothecarbonylgroupstretchingvibrationofRGOPcopolymer,andthepeakat3000–3500cm?1wasattributedtothestretchingvibrationofthehydroxylgroupofRGOPcopolymer.ThesepeaksconfirmedthepresenceofRGOPcopolymerintheblends.

SEMimagesoftheRGOPHBHcompositepackagingfilmareshowninFigure2.AsthePHBHcontentincreased,thesurfaceoftheRGOPHBHcompositepackagingfilmbecamerougherandmoreporous.Thiswasduetothehigherpolarityandhigherhydrogen-bondingabilityofthePHBHcopolymer,whichledtophaseseparationandtheformationofmicrodomains.

ThethermalpropertiesoftheRGOPHBHcompositepackagingfilmareshowninTable1.TheTgoftheRGOPcopolymerwasfoundtobearound20°C,whilethatofthePHBHcopolymerwasaround?4°C.TheadditionofPHBHtotheRGOPcopolymerreducedtheTgoftheblends,indicatingtheformationofmiscibleblends.TheTmoftheRGOPcopolymerwasaround229°C,whilethatofthePHBHcopolymerwasaround101°C.AsthePHBHcontentincreased,theTmoftheblendsdecreased,indicatingthatPHBHhadaplasticizingeffectontheRGOPcopolymer.

Figure3showsthetensilepropertiesoftheRGOPHBHcompositepackagingfilm.TheadditionofPHBHcopolymertotheRGOPcopolymerincreasedtheelongationatbreakoftheblends,whilereducingthetensilestrengthandYoung’smodulus.ThiswasattributedtothehighermolecularweightofthePHBHcopolymeranditsflexibility.

ThesurfaceresistanceoftheRGOPHBHcompositepackagingfilmisshowninFigure4.AsthePHBHcontentincreased,thesurfaceresistanceoftheblendsdecreased,indicatingthatPHBHimprovedtheantistaticpropertiesoftheRGOPcopolymer.

TheFaraday’scagetestwasusedtoevaluatetheESDshieldingpropertiesoftheRGOPHBHcompositepackagingfilm.TheresultsareshowninTable2.AsthePHBHcontentincreased,theESDshieldingeffectivenessoftheblendsincreased,indicatingthatPHBHimprovedtheESDshieldingpropertiesoftheRGOPcopolymer.

Conclusion

Inthisstudy,wepreparedRGOP