Biodegradable Poly(butylene adipate-co-terephthalate)/Poly(glycolic acid) Films: Effect of Poly(glycolic acid) Crystal on Mechanical and Barrier Properties

Binary biodegradable polymers films, poly(butylene adipate-co-terephthalate)(PBAT) and poly(glycolic acid)(PGA), were prepared through batch melt mixing to obtain Film Ⅰ and Film Ⅱ under two different processing conditions. PGA crystals played a major role in enhancing the mechanical and barrier properties of the films. For Film Ⅰ, there were initial PGA crystals before the film blowing process, the PGA molecular chain further crystallized, forming the oriented crystallization of PGA. Moreover, the Xcand crystalline size in Film Ⅰ were higher than those in Film Ⅱ. Compared with the different processing methods, Film Ⅰ has excellent mechanical and oxygen barrier properties due to the crystallization and orientation. The tensile strength reached 45.0 MPa, and tear strength exceeded 138.2 kN/m, while the elongation at break was as high as 750% for PBAT/PGA 85/15 in Film Ⅰ. The WVTR, WVP coefficients, and OP coefficients of PBAT/PGA films were decreased obviously with increasing the PGA content both in Film Ⅰ and Film Ⅱ. Moreover, the barrier properties of oxygen in Film Ⅰ were better than that in Film Ⅱ. This work reveals a feasible processing technique by introducing of initial crystallization of PGA to blow PBAT/PGA films with excellent mechanical and barrier properties.

Superior Toughened Biodegradable Poly(L-lactic acid)-based Blends with Enhanced Melt Strength and Excellent Low-temperature Toughness via In situ Reaction Compatibilization

The toughened poly(L-lactic acid)/poly(butylene succinate-butylene terephthalate)(PLLA/PBST) blend with enhanced melt strength and excellent low temperature toughness and strength was prepared by melt compounding through in situ compatibilization reaction in presence of multifunctional epoxy compound(ADR).The PLLA/PBST blend was an immiscible system,and the compatibility of the PLLA/PBST blend was improved after adding ADR.FTIR and GPC curves confirmed the formation of the PLLA-g-PBST copolymer,which improved the interfacial bonding of the blend and therefore the PLLA/PBST/ADR blend showed excellent melt strength and mechanical properties.For the PLLA/PBST/ADR blend with 70/30 PLLA/PBST content,the complex viscosity increased significantly with increasing ADR content.Moreover,the tensile strength,elongation at break and impact strength all increased obviously with increasing the ADR content.The elongation at break of the blend reached the maximum value of 392.7%,which was 93.2 times that of neat PLLA.And the impact strength of the blend reached the maximum value of 74.7 k J/m~2,which was 21.3 times that of neat PLLA.Interestingly,the PLLA/PBST/ADR blend exhibited excellent lowtemperature toughness and strength.At –20 ℃,the elongation at break of the PLLA/PBST/ADR blend was as high as 93.2%,and the impact strength reached 18.8 k J/m~2.Meanwhile,the tensile strength of the blend at low temperature was also high(64.7 MPa),which was beneficial to the application of PLA in the low temperature field.In addition,the PLLA/PBST/ADR blend maintaind good biodegradability,which was of great significance to the wide application of PLLA.

Biodegradable Foaming Material of Poly(butylene adipate-co-terephthalate)(PBAT)/Poly(propylene carbonate)(PPC)

A biodegradable blend foaming material of poly(butylene adipate-co-terephthalate)(PBAT)/poly(propylene carbonate)(PPC)was successfully prepared by chemical foaming agent and screw extrusion method.First,PBAT was modified by bis(tert-butyl dioxy isopropyl)benzene(BIBP)for chain extension,and then the extended PBAT(E-PBAT)was foamed with PPC using a twin(single)screw extruder.By analyzing the properties of the blends,we found that Young’s modulus increased from 58.8 MPa of E-PBAT to 244.7 MPa of E-PBAT/PPC 50/50.The viscosity of the polymer has a critical influence on the formation of cells.Compared with neat PBAT(N-PBAT),the viscosity of E-PBAT increased by 3396 Pa·s and E-PBAT/PPC 50/50 increased by 8836 Pa·s.Meanwhile,the dynamic mechanical analysis(DMA)results showed that the storage modulus(E’)at room temperature increased from 538 MPa to 1650 MPa.The various phase morphologies(“sea-island”,“quasi-co-continuous”and“cocontinuous”)and crystallinity of the blends affected the spread velocity of gas and further affected the foaming morphology in E-PBAT/PPC foam.Therefore,through the analysis of phase morphology and foaming mechanism,we concluded that the E-PBAT/PPC 70/30 component has both excellent strength and the best foaming performance.

Mechanical Properties, Crystallization and Biodegradation Behavior of the Polylactide/Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/ Poly(butylene adipate-co-terephthalate) Blown Films

Polactide(PLA),poly(3-hydroxybutyrate-co-4-hydroxybutyrate)(P(3HB-CO-4HB)),and poly(butylene adipate co-terephthalate)(PBAT)ternary blends were prepared by extrusion blending.The biodegradable PLA/P(3HB-co 4HB)/PBAT films were successfully obtained by using blown films technique.Excellnt siffness-toughness balance was achieved for 55/10/35 PLA/P(3HB-co 4HB)/PBAT film.The tensile strength reached 33.0 MPa(MD)and 23.5 MPa(TD).the elongation at break exceeded 1309%,and tear strength exceeded 110 kN/m.The Young's modulus as low as about 1800 MPa also met packaging applications.SEM observations revealed rough and long ligaments,indicating that the tear specimens were broken yieldingly.The addition of PBAT elastomers was the main reason for the improved toughness of the film.From DMA and SEM analysis,it was demonstrated that PLA P(3HB co 4HB),and PBAT were prilly compatible.With increasing P(3HB CO-4HB)content,the melt and cold crstallization of PLA was promoted.The enzymatic degradation experiments indicated that the films had good biodegradability.These findings gave important implications for designing and manufacturing biodegradation package of high biological carbon content.

Thermal,Rheological and Mechanical Properties of Biodegradable Poly(propylene carbonate)/Epoxidized Soybean Oil Blends

Biodegradable poly(propylene carbonate)(PPC)/epoxidized soybean oil(ESO)blends with different component ratios were prepared by melt blending to improve the performance of PPC.The phase morphology,thermal properties,rheological properties and mechanical properties of the blends were in vestigated in detail.SEM exami nation revealed good in terfacial adhesi on betwee n PPC matrix and ESO.According to DSC and DMA,as the content of ESO increased,the glass transition temperature of the PPC component increased,indicating that there was a strong in terfacial in teracti on between the PPC matrix and ESO.The in terfacial in teraction may be caused by rin g-opening reaction between the hydroxyl end groups of PPC and the epoxy groups of ESO,which restricted the chain movement of PPC matrix.The disappearanee of the epoxy groups in FTIR indicated that the in terfacial in teracti on betwee n the two phases was due to the rin g-openi ng reactio n betwee n PPC and ESO.With the addition of ESO,the thermal stabilities were enhanced.With the increasing ESO content,the modulus gradually decreased.However,the stre ngth at yield,the strength at break and the elon gation at break were in creased for the PPC/ESO blends,suggest!ng that the enhancement of the strength and toughness of PPC was achieved by the incorporation of ESO.The rheological measurement revealed that the complex viscosity,storage modulus and loss modulus of PPC were in creased with the increasi ng ESO content at low freque ncy,which indicated that the addition of ESO enhanced the melt strength of PPC in stead of plasticizi ng PPC.