| Summary: | 碩士 === 國立中興大學 === 化學工程學系所 === 100 === In this study, polycarbonate/poly(ethylene terephthlate)/halogen-free flame retardant/impact modified composites were prepared via melt blending. Two flame retardants were utilized in this system. They can be classified into two types: aluminum phosphinate (OP1230) and aluminum phosphonate (EXY). The purpose of this study is to develop PC/PET blends to produce halogen-free flame retardant material. These blends can be applied to manufacture high value-added products like electronic appliances, automobiles and construction materials.
PC and PET encounters the transesterification reaction in melt-processing. A band of 1070 cm-1 (aromatic ester vibration) is observed for PC/PET blends in IR spectrograph, and this indicates that transesterification reaction occurring. DSC results comfirms the transesterification reaction that increases the Tg in PET-phase and decreases the Tg in PC-phase, and is consistent with DMA results.
OP1230 is added to PC, it results Tg of PC decreased from PC thermal degradation caused by aluminum ion from itself. On the other hand, OP1230 did not effect Tg, Tm of PET, but we can observed cooling peak of OP1230 from DSC first cooling, indicates that OP1230 separate out PET matrix as cooling process, and the OP1230 makes PET ingredient became brittle. Impact modifier, ethylene glycidyl methacrylate butylacrylate terpolymer (PTW), is used to PET/PTW/OP1230 ternary blends aid OP1230 dispersion in PET matrix to achieve flame retardant and toughening performance, but OP1230 result PTW degradation that PET/PTW/OP1230 composties became brittle.
PC/PET/OP1230 blends is a foaming product; in IR spectrograph, a shoulder of aromatic ester vibration of 1070 cm-1 is observed, which illustated transesterification reaction occurring when melt blending. As the sample is heated by annealed 300℃, N2 for 5 min, the IR results showe 1773 cm-1 C=O stretching of PC was gone. This indicates that aluminum ion from OP1230 makes PC thermal degradation, and this causes PC/PET over transesterification. Therefore, DSC first heating PC/PET/OP1230 just had a single Tg 106.4℃ and no melting peak of PET. In order to inhibit the degradation reaction caused by aluminum ion from OP1230 on PC, polymer with acid group, such as Engage-g-MA and ionomer Surlyn are utilized; otherwise, compound with unpaired electron, amine modified styrene ethylene butylene styrene copolymer MP-10 are also used; or using triphenyl phosphite (TPPi) and (Tris(2,4-di-tert.-butylphenyl)phosphit), Irgafos 168 to blend with PC/PET/OP1230, hoping chelated aluminum ion of OP1230. However, while above compounds are blended with PC/PET/OP1230, the DSC first heating result shows a single Tg 90.4℃ and the melting peak of PET is almost invisible, indicates that these formulations can’t chelate aluminum ion of OP1230 completely. This result in PC/PET blends over
transesterification, and forms a foamed product.
While the EXY is added to PC, the Tg of PC decreases; while 10 wt% EXY is added that Tg is reduced from 149.5℃ to 143.3℃. But the blending of EXY with PET didn''t effect Tg and Tm of PET. PC/PET/EXY blends is slightly foaming, indicates that blending with EXY have lower transesterification level than blending with OP1230, so first heating of DSC is still observed two Tgs and a melting peak of PET.
PC/PET/MBS-g-GMA/EXY composites were scaled up by twin-screw extruder. PC/PET blends can’t molding because die swelling phenomenon, adding impact modifier methyl methacrylate- butadiene-styrene (MBS) and MBS graft glycidyl methacrylate product (MBS-g-GMA) improves on die swelling. PC/PET/MBS or (MBS-g-GMA) blends, DSC second heating shows that MBS-g-GMA blends are still observed two Tgs and melting peak of PET compared to MBS blends, indicating that using MBS-g-GMA has lower transesterification level. When both impact modifying contents reach 10 wt%, the impact strength is about 70 kg-cm/cm. Since MBS-g-GMA had better thermal stability and mechanical properties than MBS, it can be used to prepared PC/PET/halogen-free flame retardant composites while EXY is added. DSC first heating and second heating results show that the Tg and Tm of PC/PET/MBS-g-GMA/EXY are similar to the PC/PET/MBS-g-GMA blends. Adding 10 phr. EXY, the flammability test of composites reaches UL 94 V-0 (1/8’’), but the impact strength and strain rate reduced dramatically, which indicates that phosphorous salt system is not effective in raising the mechanical properties of PC/PET blending.
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