Poly(propylene carbonate phthalate)(PPC-P)is a chemically modified poly(propylene carbonate)(PPC)biodegradable thermoplastic by introducing phthalic anhydride(PA)as the third monomer into the copolymerization of propy...Poly(propylene carbonate phthalate)(PPC-P)is a chemically modified poly(propylene carbonate)(PPC)biodegradable thermoplastic by introducing phthalic anhydride(PA)as the third monomer into the copolymerization of propylene oxide(PO)and CO_(2).To enhance the thermal and mechanical properties of PPC-P,a branching agent pyromellitic anhydride(PMDA)was introduced into the terpolymerization of PO,PA and CO_(2).The resulting copolymers with branched structure,named branched PPC-P,can be obtained using metal-free Lewis pair consisting of triethyl borane(TEB)and bis(triphenylphosphine)iminium chloride(PPNCl)as catalyst.The products obtained were analyzed by NMR spectroscopy and their thermal,mechanical properties and melt processability were evaluated by DSC,TGA,tensile test and melt flow index(MFI)measurement.The obtained branched PPC-P has a high molecular weight up to 156.0 kg·mol^(-1).It shows an increased glass transition temperature(Tg)higher than 50℃and an enhanced tensile strength as high as 38.9 MPa.Noteworthily,the MFI value decreases obviously,indicative of an improved melt strength arising from the branched structure and high molecular weight.What is more,the branched PPC-P exhibits reasonable biodegradability,which demonstrates the great potential as a new green thermoplastic for the family of biodegradable plastics.展开更多
The Mo-promoted Cu-Fe bimetal catalysts were prepared and used for the formation of dimethyl carbonate （DMC） from CO2 and methanol. The catalysts were characterized by X-ray diffraction （XRD）, temperature programm...The Mo-promoted Cu-Fe bimetal catalysts were prepared and used for the formation of dimethyl carbonate （DMC） from CO2 and methanol. The catalysts were characterized by X-ray diffraction （XRD）, temperature programmed reduction （TPR）, laser Raman spectra （LRS）, energy dispersive spectroscopy （EDS） and temperature programmed desorption （TPD） techniques. The experimental results demonstrated that the Mo promoters can decrease the reducibility and increase the dispersion of Cu-Fe clusters, The concentration balance of base-acid sites can be readily adjusted by changing the Mo content. The moderate concentration balance of acid and base sites was in favor of the DMC formation, Under optimal experimental conditions, the highest methanol conversion of 6,99% with a DMC selectivity of 87.7% can be obtained when 2.5 wt% of Mo was loaded.展开更多
A series of semi-aromatic polyesters named as Poly(PO-CHO-PA) were facilely synthesized via ring-opening terpolymerization of biobased cyclohexane oxide(CHO)/propylene oxide(PO)/phthalic anhydride(PA) using economical...A series of semi-aromatic polyesters named as Poly(PO-CHO-PA) were facilely synthesized via ring-opening terpolymerization of biobased cyclohexane oxide(CHO)/propylene oxide(PO)/phthalic anhydride(PA) using economical U1/PPNCl as dual catalyst. The proportion of CHO-PA and PO-PA segments in polymer can be readily altered by changing the feed ratio of CHO/PO because the reactivity ratios of CHO and PO with PA calculated by Fineman-Ross method are comparable. All synthesized amorphous polyesters with various compositions show one Tg ranging from 62 ℃ to 133 ℃. Significantly, the mechanical, thermal and barrier properties of these amorphous semi-aromatic polyesters are also adjustable and investigated for the first time. The results indicate the semi-polyesters exhibit superior thermostability(T5% ranging from 306 ℃ to323 ℃) and high tensile strength(40.21-55.7 MPa) that is comparable with polystyrene(PS). Furthermore, Poly(PO-CHO-PA) films possess a promising prospect as packaging materials because of its colorless and highly transparent nature, along with low oxygen and water vapor transmission rate. All above performances may guarantee its potential alternative to commercial PS.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51673131)the Fundamental Research Funds for the Central Universities(No.171gjc37)。
文摘Poly(propylene carbonate phthalate)(PPC-P)is a chemically modified poly(propylene carbonate)(PPC)biodegradable thermoplastic by introducing phthalic anhydride(PA)as the third monomer into the copolymerization of propylene oxide(PO)and CO_(2).To enhance the thermal and mechanical properties of PPC-P,a branching agent pyromellitic anhydride(PMDA)was introduced into the terpolymerization of PO,PA and CO_(2).The resulting copolymers with branched structure,named branched PPC-P,can be obtained using metal-free Lewis pair consisting of triethyl borane(TEB)and bis(triphenylphosphine)iminium chloride(PPNCl)as catalyst.The products obtained were analyzed by NMR spectroscopy and their thermal,mechanical properties and melt processability were evaluated by DSC,TGA,tensile test and melt flow index(MFI)measurement.The obtained branched PPC-P has a high molecular weight up to 156.0 kg·mol^(-1).It shows an increased glass transition temperature(Tg)higher than 50℃and an enhanced tensile strength as high as 38.9 MPa.Noteworthily,the MFI value decreases obviously,indicative of an improved melt strength arising from the branched structure and high molecular weight.What is more,the branched PPC-P exhibits reasonable biodegradability,which demonstrates the great potential as a new green thermoplastic for the family of biodegradable plastics.
基金the China High-Tech Development 863 Program(N0.2009AA03Z2340)Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2010)+2 种基金Guangdong Province Sci & Tech Bureau(Key Strategic Project Nos. 2008A080800024 and 10151027501000096)Chinese Universities Basic Research Founding for financial support of the work.National University of Singapore for financial support
文摘The Mo-promoted Cu-Fe bimetal catalysts were prepared and used for the formation of dimethyl carbonate （DMC） from CO2 and methanol. The catalysts were characterized by X-ray diffraction （XRD）, temperature programmed reduction （TPR）, laser Raman spectra （LRS）, energy dispersive spectroscopy （EDS） and temperature programmed desorption （TPD） techniques. The experimental results demonstrated that the Mo promoters can decrease the reducibility and increase the dispersion of Cu-Fe clusters, The concentration balance of base-acid sites can be readily adjusted by changing the Mo content. The moderate concentration balance of acid and base sites was in favor of the DMC formation, Under optimal experimental conditions, the highest methanol conversion of 6,99% with a DMC selectivity of 87.7% can be obtained when 2.5 wt% of Mo was loaded.
基金financially supported by the National Natural Science Foundation of China (No. 51673131)the Fundamental Research Funds for the Central Universities (No.171gjc37)。
文摘A series of semi-aromatic polyesters named as Poly(PO-CHO-PA) were facilely synthesized via ring-opening terpolymerization of biobased cyclohexane oxide(CHO)/propylene oxide(PO)/phthalic anhydride(PA) using economical U1/PPNCl as dual catalyst. The proportion of CHO-PA and PO-PA segments in polymer can be readily altered by changing the feed ratio of CHO/PO because the reactivity ratios of CHO and PO with PA calculated by Fineman-Ross method are comparable. All synthesized amorphous polyesters with various compositions show one Tg ranging from 62 ℃ to 133 ℃. Significantly, the mechanical, thermal and barrier properties of these amorphous semi-aromatic polyesters are also adjustable and investigated for the first time. The results indicate the semi-polyesters exhibit superior thermostability(T5% ranging from 306 ℃ to323 ℃) and high tensile strength(40.21-55.7 MPa) that is comparable with polystyrene(PS). Furthermore, Poly(PO-CHO-PA) films possess a promising prospect as packaging materials because of its colorless and highly transparent nature, along with low oxygen and water vapor transmission rate. All above performances may guarantee its potential alternative to commercial PS.
