Compatible and crystallization properties of poly(lactic acid)/poly(butylene adipate‐co‐terephthalate) blends

Differential scanning calorimetry (DSC), wide angle X‐ray diffraction (WAXD) and dynamic mechanical analysis (DMA) properties of poly(lactic acid)/ poly(butylene adipate‐co‐terephthalate) (PLA/PBAT) specimens suggest that only small amounts of poor PLA and/or PBAT crystals are present in their corresponding melt crystallized specimens. In fact, the percentage crystallinity, peak melting temperature and onset re‐crystallization temperature values of PLA/PBAT specimens reduce gradually as their PBAT contents increase. However, the glass transition temperatures of PLA molecules found by DSC and DMA analysis reduce to the minimum value as the PBAT contents of PLA_xPBAT_y specimens reach 2.5 wt %. Further morphological and DMA analysis of PLA/PBAT specimens reveal that PBAT molecules are miscible with PLA molecules at PBAT contents equal to or less than 2.5 wt %, since no distinguished phase‐separated PBAT droplets and tan δ transitions were found on fracture surfaces and tan δ curves of PLA/PBAT specimens, respectively. In contrast to PLA, the PBAT specimen exhibits highly deformable properties. After blending proper amounts of PBAT in PLA, the inherent brittle deformation behavior of PLA was successfully improved. Possible reasons accounting for these interesting crystallization, compatible and tensile properties of PLA/PBAT specimens are proposed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Morphology,dynamic mechanical,and electrical properties of bio‐based poly(trimethylene terephthalate) blends,part 2: Poly(trimethylene terephthalate)/poly(ether esteramide)/polycarbonate blends

Bio‐based poly(trimethylene terephthalate) (PTT) and poly(ether esteramide) (PEEA) blends were prepared by melt processing with varying weight ratios (0–20 wt %) of polycarbonate (PC). The blends were characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), polarized light microscopy (PLM), and transmission electron microscopy (TEM). Electrostatic performance was also investigated for those PTT blends since PEEA is known as an ion conductive polymer. DMA suggests that PC is miscible with PEEA and selectively goes into PEEA phase in case of ternary blends of PTT/PEEA/PC. The glass transition temperature (T_g) for PC/PEEA is well predicted by Gordon Taylor equation. Addition of PC retards the electrostatic decay performance of PTT/PEEA blends by restricting the motion of ions in PEEA through increasing the T_g of PEEA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Melt characteristics,mechanical, and thermal properties of blown film from modified blends of poly(butylene adipate‐co‐terephthalate) and poly(lactide)

Blown films from poly(butylene adipate‐co‐terephthalate) and poly(lactide) (PLA) blends were investigated. The blends were prepared in a twin‐screw extruder, in the presence of small amounts of dicumyl peroxide (DCP). The influence of DCP concentration on film blowing, rheological, mechanical, and thermal properties of the blends is reported in this article. Rheological results showed a marked increase in polymer melt strength and elasticity with the addition of DCP. As a consequence, the film homogeneity and the stability of the bubble were improved. The modified blend films, compared with the unmodified blend, showed an improvement in tensile strength and modulus with a slight loss in elongation. Fourier transform infrared and gel results revealed that chain scission and branching were more significant than crosslinking when the DCP loadings in the blends were not higher than 0.7%. A reduction in melt temperatures of PLA was observed due to difficulty in chain crystallization. The concentrations of DCP strongly affected the melting temperatures but had an insignificant effect on the decomposition behavior of the blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Crystallization behavior of fully biodegradable poly(lactic acid)/poly(butylene adipate‐co‐terephthalate) blends

Both poly(lactic acid) (PLA) and poly(butylene adipate‐co‐terephthalate) (PBAT) are fully biodegradable polyesters. The disadvantages of poor mechanical properties of PLA limit its wide application. Fully biodegradable polymer blends were prepared by blending PLA with PBAT. Crystallization behavior of neat and blended PLA was investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and wide angle X‐ray diffraction (WAXD). Experiment results indicated that in comparison with neat PLA, the degree of crystallinity of PLA in various blends all markedly was increased, and the crystallization mechanism almost did not change. The equilibrium melting point of PLA initially decreased with the increase of PBAT content and then increased when PBAT content in the blends was 60 wt % compared to neat PLA. In the case of the isothermal crystallization of neat PLA and its blends at the temperature range of 123–142°C, neat PLA and its blends exhibited bell shape curves for the growth rates, and the maximum crystallization rate of neat PLA and its blends all depended on crystallization temperature and their component. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Reactive modification and compatibilization of poly(lactide) and poly(butylene adipate‐co‐terephthalate) blends with epoxy functionalized‐poly(lactide) for blown film applications

Biodegradable blown films comprising of poly(lactide) (PLA) and poly(butylene adipate‐co‐terephthalate) (PBAT) were produced using epoxy functionalized‐poly(lactide) (EF‐PLA) reactive modifiers for rheological enhancement and compatibilization. The epoxy groups on the EF‐PLA modifiers react with PBAT forming an in situ copolymer that localizes at the blend interphase resulting in compatibilization of the polymer blend components. The EF‐PLA modified polymer blends have improved melt strength and the resultant films showed better processability as seen by increased bubbled stability. This allowed for blown films with higher PLA content (70%) compared to the unmodified control films (40%). The static charge build‐up typically experienced with PLA film blowing was decreased with the inclusion of EF‐PLA yielding films with better slip and softness. The compatibilization effect of the EF‐PLA modifiers resulted in significant improvement in mechanical properties. For example, dart test performance was up to four times higher than the control, especially at higher PLA concentrations. Therefore, the rheological enhancement and compatibilization effects of the EF‐PLA reactive modifiers make them ideally suited to create high PLA content films. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43310.     

A study of poly vinyl chloride / poly(butylene adipate-co-terephthalate) blends

Polymer blends were prepared by melt blending technique using poly vinyl chloride (PVC) and poly(butylene adipate-co-terephthalate) (PBAT). Different ratios of the blends were studied to investigate their mechanical, thermal and morphological properties. The FTIR spectrum indicated a slight increase of frequencies at C = O peak from 1714 to 1718 cm^-1 indicating a chemical interaction between C = O of PBAT and α-hydrogen of PVC. The tensile properties of PVC/PBAT blends highest at weight ratio of 50/50. The dynamic mechanical analysis (DMA) result proves that PVC and PBAT formed a miscible system with one glass transition temperature (T_g). The incorporation of PBAT results in a gradual decrease of the viscosity (loss modulus) and an increase of elasticity (storage modulus). The thermal properties of blend show the decomposition temperature of PVC in the blend decrease with the addition of PBAT. Scanning electron micrograph shows good interfacial adhesion on the tensile fractured surface of PVC/PBAT blend, which played important roles in enhancing the mechanical properties (strength and modulus).     

Mixtures of poly(vinyl chloride) and copolyesters based on ε‐caprolactone and L‐lactide: Miscibility,thermal stability,and weathering resistance

Properties of the blends of Poly(vinyl chloride) (PVC) and poly(ε‐caprolactone) (PCLO) and copolyesters based on ε‐caprolactone and L‐lactide (LLA) prepared by rolling were studied. Incorporating the LLA units into the structure of PCLO the content of the crystalline phase was controlled. Miscibility of the blends was assessed using DMA, and basic mechanical properties were correlated with the type and content of the polymer plasticizer. The PVC blends containing up to 20 wt parts polyesters were miscible. The presence of the LLA units in the copolyester influenced negatively the thermal stability. On the other hand even small content of copolyester in the blend enhanced the resistivity against aging. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Thermal,mechanical, and morphological characterization studies of poly(2,6‐dimethyl‐1,4‐phenylene oxide) blends with polystyrene and brominated polystyrene

The miscibility of the binary and ternary blends of poly(2,6‐dimethyl‐1,4‐phenylene oxide), brominated polystyrene, and polystyrene was investigated using a differential scanning calorimeter. The morphology of these blends was characterized by scanning electron microscopy. These studies revealed a close relation between the blend structure and its mechanical properties. The compatibilizing effect of poly(2,6‐dimethyl‐1,4‐phenylene oxide) on the miscibility of the polystyrene/brominated polystyrene blends was examined. It was found that poly(2,6‐dimethyl‐1,4‐phenylene oxide), which was miscible with polystyrene and partially miscible with brominated polystyrene, compatibilizes these two immiscible polymers if its contention exceeds 33 wt %. Upon the addition of poly(2,6‐dimethyl‐1,4‐phenylene oxide) to the immiscible blends of polystyrene/brominated polystyrene, we observed a change in the morphology of the mixtures. An improvement in the mechanical properties was noticed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 225–231, 2000     

Rheological and mechanical behavior of non-spherical poly(lactic acid) particles embedded poly(butylene adipate-co-terephthalate) blend

In this study, the poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate)(PBAT) blend is investigated to improve rheological and mechanical performances of PBAT based on rheological, mechanical, and thermal behavior analyses. The multi-step mixing method is developed to fabricate the blend with non-spherical morphology. In the multi-step mixing method, blends with a wide composition range (25/75–75/25) are mixed with additional PBAT at a mixing temperature between the melting temperatures of PBAT and PLA to produce the PBAT blend embedded with non-spherical PLA particles (10 wt%). The embedding of non-spherical PLA particles in PBAT increases the resistance against deformation, resulting in strain hardening behavior and an increase in the yield strength as well as the tear resistance of the PBAT. The presence of stiff PLA particles enhances the crystallization behavior of PBAT, meaning that polymer chains may interpenetrate. The findings of this study suggest that the multi-step mixing method is beneficial for embedding non-spherical PLA particles into a PBAT matrix, which in turn facilitates the maintenance of good interfacial adhesion to increase the melt strength, yield strength, and tear resistance.     

The role of polycarbonate molecular weight in the poly(L‐lactide) blends compatibilized with poly(butylene succinate‐co‐L‐lactate)

Poly(butylene succinate‐co‐L ‐lactate) (PBSL)–compatibilized poly(L ‐lactide) (PLLA) polymer blends with two commercial grades of polycarbonate (PC) were investigated. The capillary tests showed that the steady shear viscosity of high molecular weight PC (PC‐L) was 10 times higher than that of low molecular weight PC (PC‐AD) throughout the shear rate range under investigation. Morphologic examination revealed that the shape of the dispersed PC‐L phase in the as‐extruded blends was largely spherical, but the PC‐AD phase was more like a rod and elongated further during injection molding. Notched Izod impact strength (IS) of the unmodified PLLA/PC‐L blend was higher than that of PC‐AD blend. The IS of modified ternary blends increased with PBSL content because of enhanced phase interaction indicated from thermal and morphologic analysis. The PBSL modification also enhanced IS more significantly in PLLA/PC‐L than in PLLA/PC‐AD blends. On the contrary, the heat deflection temperature (HDT) of PLLA/PC‐L binary system was much lower than that of PLLA/PC‐AD. HDT of PBSL‐modified PLLA/PC‐AD blends dropped with increasing PBSL content, which is a ductile polymer. Thermal and dynamic mechanical analysis of the ternary blends showed that individual components were immiscible with distinct T_gs for PC and PLLA and distinct T_ms for PBSL and PLLA. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Decreasing miscibility with greater heterogeneity in ternary polymer blend: poly(cyclohexyl methacrylate), poly(α‐methyl styrene) and poly(4‐methyl styrene)

A ternary blend system comprising poly(cyclohexyl methacrylate) (PCHMA), poly(α‐methyl styrene) (PαMS) and poly(4‐methyl styrene) (P4MS) was investigated by thermal analysis, optical and scanning electron microscopy. Ternary phase behaviour was compared with the behaviour for the three constituent binary pairs. This study showed that the ternary blends of PCHMA/PαMS/P4MS in most compositions were miscible, with an apparent glass transition temperature (T_g) and distinct cloud‐point transitions, which were located at lower temperatures than their binary counterparts. However, in a closed‐loop range of compositions roughly near the centre of the triangular phase diagram, some ternary blends displayed phase separation with heterogeneity domains of about 1 µm. Therefore, it is properly concluded that ternary PCHMA/PαMS/P4M is partially miscible with a small closed‐loop immisciblity range, even though all the constituent binary pairs are fully miscible. Thermodynamic backgrounds leading to decreased miscibility and greater heterogeneity in a ternary polymer system in comparison with the binary counterparts are discussed. © 2003 Society of Chemical Industry     

Investigation on the miscibility of the blends of poly(methyl methacrylate) and poly(styrene‐co‐acrylonitrile)

The miscibility was investigated in blends of poly(methyl methacrylate) (PMMA) and styrene‐acrylonitrile (SAN) copolymers with different acrylonitrile (AN) contents. The 50/50 wt % blends of PMMA with the SAN copolymers containing 5, 35, and 50 wt % of AN were immiscible, while the blend with copolymer containing 25 wt % of AN was miscible. The morphologies of PMMA/SAN blends were characterized by virtue of scanning electron microscopy and transmission electron microscopy. It was found that the miscibility of PMMA/SAN blends were in consistence with the morphologies observed. Moreover, the different morphologies in blends of PMMA and SAN were also observed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Improvement in toughness and crystallization of poly(L‐lactic acid) by melt blending with poly(epichlorohydrin‐co‐ethylene oxide)

Melt blending of poly(lactic acid) (PLA) and poly(epichlorohydrin‐co‐ethylene oxide) copolymers (ECO) was performed to improve the toughness and crystallization of PLA. Thermal and scanning electron microscopy analysis indicated that PLA and ECO were not thermodynamically miscible but compatible to some extent. The addition of a small amount of ECO accelerated the crystallization rate and increased the final crystallinity of PLA in the blends. Significant enhancement in toughness and flexibility of PLA were achieved by the incorporation of the ECO elastomer. When 20 wt% ECO added, the impact strength increased from 5 kJ/m² of neat PLA to 63.9 kJ/m², and the elongation at break increased from 5% to above 160%. The failure mode changed from brittle fracture of neat PLA to ductile fracture of the blend. Rheological measurement showed that the melt elasticity and viscosity of the blend increased with the concentration of ECO. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.     

Recycled poly(ethylene terephthalate)/linear low‐density polyethylene blends through physical processing

Poly(styrene‐ethylene/butylene‐styrene) (SEBS) was used as a compatibilizer to improve the thermal and mechanical properties of recycled poly(ethylene terephthalate)/linear low‐density polyethylene (R‐PET/LLDPE) blends. The blends compatibilized with 0–20 wt % SEBS were prepared by low‐temperature solid‐state extrusion. The effect of SEBS content was investigated using scanning electron microscope, differential scanning calorimeter, dynamic mechanical analysis (DMA), and mechanical property testing. Morphology observation showed that the addition of 10 wt % SEBS led to the deformation of dispersed phase from spherical to fibrous structure, and microfibrils were formed at the interface between two phases in the compatibilized blends. Both differential scanning calorimeter and DMA results revealed that the blend with 20 wt % SEBS showed better compatibility between PET and LLDPE than other blends studied. The addition of 20 wt % of SEBS obviously improved the crystallizibility of PET as well as the modulus of the blends. DMA analysis also showed that the interaction between SEBS and two other components enhanced at high temperature above 130°C. The impact strength of the blend with 20 wt % SEBS increased of 93.2% with respect to the blend without SEBS, accompanied by only a 28.7% tensile strength decrease. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Increasing the compatibility of poly(l‐lactide)/poly(para‐dioxanone) blends through the addition of poly(para‐dioxanone‐co‐l‐lactide)

To modify the mechanical properties of a poly(l ‐lactide) (PLLA)/poly(para‐dioxanone) (PPDO) 85/15 blend, poly(para‐dioxanone‐co‐l ‐lactide) (PDOLLA) was used as a compatibilizer. The 85/15 PLLA/PPDO blends containing 1–5 wt % of the random copolymer PDOLLA were prepared by solution coprecipitation. Then, the thermal, morphological, and mechanical properties of the blends with different contents of PDOLLA were studied via differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and tensile testing, respectively. The DSC result revealed that the addition of PDOLLA into the blends only slightly changed the thermal properties by inhibiting the crystallization degree of the poly(l ‐lactide) in the polymer blends. The SEM photos indicated that the addition of 3 wt % PDOLLA into the blend was ideal for making the interface between the PLLA and PPDO phases unclear. The tensile testing result demonstrated that the mechanical properties of the blends containing 3 wt % PDOLLA were much improved with a tensile strength of 48 MPa and a breaking elongation of 214%. Therefore, we concluded that the morphological and mechanical properties of the PLLA/PPDO 85/15 blends could be tailored by the addition of the PDOLLA as a compatibilizer and that the blend containing a proper content of PDOLLA had the potential to be used as a medical implant material. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41323.     

Crystallization,morphology, and electrical properties of bio‐based poly(trimethylene terephthalate)/poly(ether esteramide)/ionomer blends

Bio‐based poly(trimethylene terephthalate) (PTT) and poly(ether esteramide) (PEEA) blends were prepared by melt processing with varying weight ratios (0–20 wt %) of ionomers such as lithium‐neutralized poly(ethylene‐co‐methacrylic acid) copolymer (EMAA‐Li) and sodium‐neutralized poly(ethylene‐co‐methacrylic acid) copolymer (EMAA‐Na). The blends were characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), polarized light microscopy (PLM), and transmission electron microscopy (TEM). DSC and PLM results showed that EMAA‐Na increased the crystallization rate for PTT significantly, whereas EMAA‐Li did not enhance the crystallization rate at all. Specific interactions between PEEA and ionomers were confirmed by DSC and TEM. Electrostatic performance was also investigated for those PTT blends because PEEA is known as an ion‐conductive polymer. Here, we confirmed that both sodium and lithium ionomers work as a synergist to enhance the static decay performance of PTT/PEEA blends. Morphological study of these ternary blends systems was conducted by TEM. Dispersed ionomer domains were encapsulated by PEEA, which increases the interfacial surface area between PEEA and the PTT matrix. This encapsulation effect explains the unexpected synergy for the static dissipation performance on addition of ionomers to PTT/PEEA blends. This core–shell morphology can be predicted by calculating spreading coefficient for the ternary blends. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Miscibility and thermal and mechanical properties of melt‐mixed poly(lactic acid)/poly(trimethylene terephthalate)/(methyl methacrylate)‐butadiene‐styrene copolymer blends

This study examined the miscibility and mechanical properties of melt‐mixed poly(lactic acid) (PLA), poly (trimethylene terephthalate) (PTT), and PLA/PTT blend with 5–10 phr of methyl methacrylate‐butadiene‐styrene copolymer (MBS). The isothermal crystallization kinetics of the PTT blends were analyzed by using the Avrami equation. The Differential Scanning Calorimetry (DSC) and scanning electron microscope results indicated that the miscibility of the PLA/PTT blends was improved by adding 5–10 phr of MBS. Although PLA, with the addition of 10 phr of MBS, had lower tensile strength at yield and higher breaking elongation and impact strength than pure PLA, no improvement in these mechanical properties could be observed in PLA/PTT blends. This result is explained by assuming that the crystallization of PTT at the interface favors the disentanglement of MBS from the PTT domain. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

Ternary polymer blends based on poly(lactic acid): Effect of stereo‐regularity and molecular weight

The effects of stereo‐regularity and molecular weight of poly(lactic acid) (PLA) on ternary polymer blends was analyzed using optical clarity as the primary screening method. This enabled the ready identification of phase boundaries of optically clear and apparently miscible regions. Solvent‐mediated blends of amorphous poly(dl ‐lactide) (PDLLA) and semi‐crystalline poly(l ‐lactide) (PLLA) with various molecular weights from high to low, along with polycaprolactone (PCL) and cellulose acetate butyrate (CAB) were used in this study. The nature and extent of crystallinity of the blends was examined by X‐ray diffraction, which, in conjunction with differential scanning calorimetry, scanning electron microscopy, and Fourier transform infrared spectroscopy, provided information about the competition between polymer crystallization (self‐aggregating behavior) and intermixing of the macromolecules. Thus, allowing the primary physical cause of transparency loss to be identified. The results of the ternary blends optical clarity showed the position of the phase boundaries in PLLA/PCL/CAB and PDLLA/PCL/CAB blends are significantly affected by the stereo‐regularity and molecular weight of PLA. The PDLLA (amorphous) blend shows comparable regions of phase separation with high molecular weight and semi‐crystalline PLLA blends even though the molecular weight is much lower. The blends of the shorter chain PLLA1 tend to show more crystalline regions. The optical transparency, miscibility, and crystallinity of the blends are not only affected by the stereo‐regularity and molecular weight of PLA but also the crystallizable PCL, especially at high loading. These findings give useful information to the film‐packaging sector where good optical clarity is a critical performance requirement. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41780.     

Miscibility windows in ternary polymer blends of a polyester,polymethacrylate and poly(styrene‐co‐acrylonitrile)

Miscibility, phase diagrams and morphology of poly(ε‐caprolactone) (PCL)/poly(benzyl methacrylate) (PBzMA)/poly(styrene‐co‐acrylonitrile) (SAN) ternary blends were investigated by differential scanning calorimetry (DSC), optical microscopy (OM), and scanning electron microscopy (SEM). The miscibility window of PCL/PBzMA/SAN ternary blends is influenced by the acrylonitrile (AN) content in the SAN copolymers. At ambient temperature, the ternary polymer blend is completely miscible within a closed‐loop miscibility window. DSC showed only one glass transition temperature (T_g) for PCL/PBzMA/SAN‐17 and PCL/PBzMA/SAN‐25 ternary blends; furthermore, OM and SEM results showed that PCL/PBzMA/SAN‐17 and PCL/PBzMA/SAN‐25 were homogeneous for any composition of the ternary phase diagram. Hence, it demonstrated that miscibility exists for PCL/PBzMA/SAN‐17 and PCL/PBzMA/SAN‐25 ternary blends, but that the ternary system becomes phase‐separated outside these AN contents. Copyright © 2003 Society of Chemical Industry     

Influence of phthalic anhydride and bioxazoline on the mechanical and morphological properties of biodegradable poly(lactic acid)/poly[(butylene adipate)‐co‐terephthalate] blends

Poly(lactic acid) (PLA)/poly[(butylene adipate)‐co‐terephthalate] (PBAT) blends were fabricated by melt blending, with 2,2′‐(1,3‐phenylene)bis(2‐oxazoline) (BOZ) and phthalic anhydride (PA) used as compatibilizers. It was found that a small amount of BOZ or PA greatly increased the elongation at break of the PLA/PBAT blends without sacrificing their high tensile strength. Scanning electron microscopy results revealed that the PBAT particles became finer and were uniformly dispersed in the matrix when the compatibilizers were incorporated, which indicated that the interfacial bonding and compatibilization between PLA and PBAT were improved in the presence of the compatibilizers. Compared with PLA/PBAT blends, the molecular weight of PLA/PBAT/PA/BOZ blends was increased due to chain‐extending reactions. Differential scanning calorimetry results suggested PBAT decreased the crystallization rate and crystallinity of PLA in the blends. Moreover, the glass transition temperature of PBAT was further decreased when the compatibilizers were used. © 2013 Society of Chemical Industry