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.     

Miscibility,morphology and thermal properties of poly(para‐dioxanone)/poly(D,L‐lactide) blends

BACKGROUND: Poly(para‐dioxanone) (PPDO) is a biodegradable polyester with excellent biodegradability, bioabsorbability, biocompatibility and mechanical flexibility. However, its high cost and relatively fast degradation rate have hindered the development of commercial applications. Blending with other polymers is a simple and convenient way of modifying the properties of aliphatic polyesters. Poly(D ,L ‐lactide) (PDLLA) is another polyester that has been extensively studied for biomedical applications due to its biocompatibility and suitable degradation rate. However, to our knowledge, blends of PPDO/PDLLA have not been reported in the literature. RESULTS: A series of biodegradable polymers were blended by solution co‐precipitation of PPDO and PDLLA in various blend ratios. The miscibility, morphology and thermal properties of the materials were investigated. DSC curves for all blends revealed two discrete glass transition temperatures which matched the values for pure PPDO and PDLLA. SEM images of fracture surfaces displayed evidence of phase separation consistent with the DSC results. The contact angles increased with the addition of PDLLA. CONCLUSION: PPDO/PDLLA blends exhibit two distinct glass transition temperatures that remain nearly constant and correspond to the glass transition temperatures of the homopolymers for all blend compositions, indicating that blends of PPDO and PDLLA are immiscible. Images of the surface obtained using SEM were also suggestive of a two‐phase material. The crystallinity of the PPDO phase in the blends was affected by the PDLLA content. The mechanical properties of the blends changed dramatically with composition. Adding PDLLA makes the blends less hydrophilic than PPDO. Copyright © 2008 Society of Chemical Industry     

Poly(para‐dioxanone) and poly(L‐lactic acid) blends: thermal,mechanical, and morphological properties

Blends of two semicrystalline polymers, poly(L ‐lactic acid) (PLLA) and poly‐p‐dioxanone (PPD) have been prepared by solvent casting in different compositions. Thermal, morphological, and mechanical properties of the blends were studied using modulated differential scanning calorimetry, wide‐angle X‐ray diffractometry, scanning electron microscopy (SEM), polarizing light microscopy (PLM), and tensile tests. Thermal analysis showed two glass transition temperatures nearly constant and equal to the values of the homopolymers and constant values of melting temperature (T_m) for all blend compositions, suggesting that both polymers are immiscible. The PLM and SEM observations validated these results, and showed the different morphology obtained by changing the composition of the blend. The blends 40/60, 50/50, and 60/40 presented a clearly macroseparated system, while the 20/80 and 80/20 blends presented better homogeneity, probably due to the low amount of one component in the other. It was found by PLM that PPD is able to crystallize according to a spherulitic morphology when its content is above 40%. Under this content, the crystallization of PPD is hardly observed. The blend 20/80 is more flexible, and tough material and neck formation during elongation is also observed, due to PPD, which may act as a plasticizer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 12: 2744–2755, 2003     

Regulating the physical and biological performances of poly(p‐dioxanone) by copolymerization with L‐phenylalanine

The high crystallinity, low solubility in normal solvents, and low hydrophilicity of poly(p‐dioxanone) (PPDO) are unsuitable for the expansion of its biomedical applications. In order to circumvent these problems and induce biological properties, a series of poly(ester amide)s based on p‐(dioxanone) and l ‐phenylalanine were synthesized by copolymerization of p‐dioxanone with l ‐phenylalanine N‐carboxyanhydride monomers. The structures of the copolymers were confirmed by ¹H NMR. The crystallinity of the copolymers was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Increasing contents of phenylalanine resulted in decreased crystallinity owing to the rigid phenyl groups of phenylalanine, which disrupted the regularities of the chains, thus confining their movement. The synthesized copolymers were more soluble in chloroform than PPDO. Moreover, the copolymers were more hydrophilic and hydrolyzed more slowly than PPDO, as indicated by water angle contact measurements and in vitro hydrolysis studies. Especially, the copolymers showed inhibition on cell proliferation of L929 mouse fibroblasts by MTT assay, suggesting that the polymers might be useful in the areas where cell proliferation need to be inhabited such as adhesion prevention. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2311–2319, 2013     

Effect of particle size and surface modification on mechanical properties of poly(para‐dioxanone)/inorganic particles

Poly(para‐dioxanone) (PPDO)‐based composites have been prepared by blending PPDO with three different types of CaCO₃ particles, CC1 (nano‐CaCO₃), CC2 (CaCO₃ whisker), and CC3 (silane‐coated CaCO₃ whisker). The effects of particles size, interface adhesion, and crystallinity of composites on mechanical properties were discovered through analysis of the morphology of fracture surfaces, thermal characteristics, and crystalline structure. DSC revealed that the CaCO₃ particles acted as a nucleating agent and promoted crystallinity of PPDO. The effect of CaCO₃ particles on crystallization of PPDO was clearly revealed by using the nucleating efficiency. Smaller size particles exhibit greater nucleating efficiency. Adhesion between PPDO and the CaCO₃ particles plays major roles on the mechanical properties of composites. The tensile strength of PPDO was improved over 54%. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Synthesis and characterization of ABA type tri‐block copolymers derived from p‐dioxanone,L‐lactide and poly(ethylene glycol)

A series of triblock co‐polymers, consisting of a poly(ethylene glycol) (PEG) central block joined to two blocks of random p‐dioxanone‐co‐L ‐lactide copolymers were synthesized by ring‐opening polymerization of p‐dioxanone (PDO) and L ‐lactide (LLA) initiated by PEG in the presence of stannous 2‐ethylhexanoate catalyst. The resulting copolymers were characterized by various techniques including ¹H and ¹³C NMR and FTIR spectroscopies, gel permeation chromatography, inherent viscosity, wide‐angle X‐ray diffractometry (WAXD) and differential scanning calorimetry (DSC). The conversion of PDO and L ‐lactide into the polymer was studied various mole ratios and at different polymerization temperature from ¹H NMR spectra. Results of WAXD and DSC showed that the crystallinity of PEG macroinitiator was greatly influenced by the composition of PDO and L ‐lactide in the copolymer. The triblock copolymers with low molecular weight were soluble in water at below room temperature. © 2003 Society of Chemical Industry     

Thermal properties and non‐isothermal crystallization behavior of biodegradable poly(p‐dioxanone)/poly(vinyl alcohol) blends

Blends of two biodegradable semicrystalline polymers, poly(p‐dioxanone) (PPDO) and poly(vinyl alcohol) (PVA) were prepared with different compositions. The thermal stability, phase morphology and thermal behavior of the blends were studied by using thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). From the TGA data, it can be seen that the addition of PVA improves the thermal stability of PPDO. DSC analysis showed that the glass transition temperature (T_g) and the melting temperature (T_m) of PPDO in the blends were nearly constant and equal to the values for neat PPDO, thus suggesting that PPDO and PVA are immiscible. It was found from the SEM images that the blends were phase‐separated, which was consistent with the DSC results. Additionally, non‐isothermal crystallization under controlled cooling rates was explored, and the Ozawa theory was employed to describe the non‐isothermal crystallization kinetics. Copyright © 2006 Society of Chemical Industry     

Effect of calcium carbonate whisker content on the morphology,crystallization, and mechanical properties of poly(para‐dioxanone)/Calcium carbonate whisker composites

In this work, poly(para‐dioxanone) (PPDO) was mixed with 0, 1, 5, 10, 20, and 30 weight percent (wt%) calcium carbonate (CaCO₃) whiskers by solution coprecipitation. Samples were compression molded into bars using a platen vulcanizing press. It has assessed the influence of the CaCO₃ whisker content on the morphology, thermal, mechanical, and crystalline properties of the PPDO/CaCO₃ whisker composites, using differential scanning calorimetry (DSC), polarized optical microscopy, scanning electron microscopy, and X‐ray diffraction. DSC showed that the glass transition temperature (T_g) and crystallization temperature (T_c) of the composites increased with increasing CaCO₃ whisker content. At low CaCO₃ whisker content (1 wt%), the degree of crystallinity (Dc) of PPDO increased sharply. The addition of higher content of CaCO₃ whisker would cause more agglomeration in PPDO matrix, so that the mechanical properties of PPDO/CaCO₃ whisker composites would gradually decrease. The mechanical properties of PPDO were changed by the presence of CaCO₃ whiskers; the optimal amount of CaCO₃ whisker was 1 wt%, which sharply improved the tensile strength of PPDO by 54%. POLYM. COMPOS., 37:3442–3448, 2016. © 2015 Society of Plastics Engineers     

Part 7. Effects of poly(L‐lactide‐co‐ϵ‐caprolactone) on morphology,structure, crystallization,and physical properties of blends of poly(L‐lactide) and poly(ϵ‐caprolactone)

Blended films of poly(L ‐lactide) [ie poly(L ‐lactic acid)] (PLLA) and poly(?‐caprolactone) (PCL) without or mixed with 10 wt% poly(L ‐lactide‐co‐?‐caprolactone) (PLLA‐CL) were prepared by solution‐casting. The effects of PLLA‐CL on the morphology, phase structure, crystallization, and mechanical properties of films have been investigated using polarization optical microscopy, scanning electron microscopy, differential scanning calorimetry and tensile testing. Addition of PLLA‐CL decreased number densities of spherulites in PLLA and PCL films, and improved the observability of spherulites and the smoothness of cross‐section of the PLLA/PCL blend film. The melting temperatures (T_m) of PLLA and PCL in the films remained unchanged upon addition of PLLA‐CL, while the crystallinities of PLLA and PCL increased at PLLA contents [X_PLLA = weight of PLLA/(weight of PLLA and PCL)] of 0.4–0.7 and at most of the X_PLLA values, respectively. The addition of PLLA‐CL improved the tensile strength and the Young modulus of the films at X_PLLA of 0.5–0.8 and of 0–0.1 and 0.5–0.8, respectively, and the elongation at break of the films at all the X_PLLA values. These findings strongly suggest that PLLA‐CL was miscible with PLLA and PCL, and that the dissolved PLLA‐CL in PLLA‐rich and PCL‐rich phases increased the compatibility between these two phases. © 2003 Society of Chemical Industry     

Compatibility of poly(butadiene‐co‐acrylonitrile) with poly(L‐lactide) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)

Poly(L ‐lactide) (PLLA) and poly(3‐hydrobutyrate‐co‐3‐hydroxyvalerate) (PHBV) were blended with poly(butadiene‐co‐acrylonitrile) (NBR). Both PLLA/NBR and PHBV/NBR blends exhibited higher tensile properties as the content of acrylonitrile unit (AN) of NBR increased from 22 to 50 wt %. However, two separate glass transition temperatures (T_g) appeared in PLLA/NBR blends irrespective of the content of NBR, revealing that PLLA was incompatible with NBR. In contrast, a single T_g, which shifted along with the blend composition, was observed for PHBV/NBR50 blends. Moreover NBR50 suppressed the crystallization of PHBV, indicating that PHBV was compatible with NBR50. Decrease of both elongation modulus and stress at maximum load was less significant and increase of elongation at break was more pronounced in PHBV/NBR50 blends than in PLLA/NBR50 blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3508–3513, 2004     

Compatibilizing effect of starch‐grafted‐poly(L‐lactide) on the poly(ε‐caprolactone)/starch composites

The poly(ε‐caprolactone) (PCL)/starch blends were prepared with a coextruder by using the starch grafted PLLA copolymer (St‐g‐PLLA) as compatibilizers. The thermal, mechanical, thermo‐mechanical, and morphological characterizations were performed to show the better performance of these blends compared with the virgin PCL/starch blend without the compatibilizer. Interfacial adhesion between PCL matrix and starch dispersion phases dominated by the compatibilizing effects of the St‐g‐PLLA copolymers was significantly improved. Mechanical and other physical properties were correlated with the compatibilizing effect of the St‐g‐PLLA copolymer. With the addition of starch acted as rigid filler, the Young's modulus of the PCL/starch blends with or without compatibilizer all increased, and the strength and elongation were decreased compared with pure PCL. Whereas when St‐g‐PLLA added into the blend, starch and PCL, the properties of the blends were improved markedly. The 50/50 composite of PCL/starch compatibilized by 10% St‐g‐PLLA gave a tensile strength of 16.6 MPa and Young's modulus of 996 MPa, respectively, vs. 8.0 MPa and 597 MPa, respectively, for the simple 50/50 blend of PCL/starch. At the same time, the storage modulus of compatibilized blends improved to 2940 MPa. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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     

Miscibility and phase structure of binary blends of poly(L‐lactide) and poly(vinyl alcohol)

Blend films of poly(L ‐lactide) (PLLA) and poly(vinyl alcohol) (PVA) were obtained by evaporation of hexafluoroisopropanol solutions of both components. The component interaction, crystallization behavior, and miscibility of these blends were studied by solid‐state NMR and other conventional methods, such as Fourier transform infrared (FTIR) spectra, differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WAXD). The existence of two series of isolated and constant glass‐transition temperatures (T_g's) independent of the blend composition indicates that PLLA and PVA are immiscible in the amorphous region. However, the DSC data still demonstrates that some degree of compatibility related to blend composition exists in both PLLA/atactic‐PVA (a‐PVA) and PLLA/syndiotactic‐PVA (s‐PVA) blend systems. Furthermore, the formation of interpolymer hydrogen bonding in the amorphous region, which is regarded as the driving force leading to some degree of component compatibility in these immiscible systems, is confirmed by FTIR and further analyzed by ¹³C solid‐state NMR analyses, especially for the blends with low PLLA contents. Although the crystallization kinetics of one component (especially PVA) were affected by another component, WAXD measurement shows that these blends still possess two isolated crystalline PLLA and PVA phases other than the so‐called cocrystalline phase. ¹³C solid‐state NMR analysis excludes the interpolymer hydrogen bonding in the crystalline region. The mechanical properties (tensile strength and elongation at break) of blend films are consistent with the immiscible but somewhat compatible nature of these blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 762–772, 2001     

Direct synthesis of poly(D,L‐lactic acid) by melt polycondensation and its application in drug delivery

Starting from D,L ‐acid and SnCl₂ as catalyst, poly(D,L ‐lactic acid) (PDLLA) was directly synthesized by melt polycondensation. Under the appropriate conditions such as 0.5 wt % SnCl₂, 170–180°C, 70 Pa, and 10 h, the viscosity‐average molecular weight (M_η) of PDLLA was 4100 Da. PDLLA produced by the most practical method was used as the drug‐delivery material for erythromycin and ciprofloxacin. The optimal conditions for the preparation of erythromycin–poly(D,L ‐lactic acid)–microsphere (ERY–PDLLA–MS) for lung targeting was investigated, and further confirmed by good reappearance tests. DSC and SEM demonstrated that ERY–PDLLA–MS had good spherical shape. The release in vitro of ERY–PDLLA–MS was effective and the half‐time (T_1/2) was 51.0 h. After 175 h, the accumulated release percentage was 80.0%. The test in vivo showed that ERY–PDLLA–MS was more easily distributed in rabbit lung tissue. When PDLLA was applied in an antibacterial ciprofloxacin drug‐delivery microsphere (CIP–PDLLA–MS), CIP–PDLLA–MS was also characterized with DSC and SEM, and the release T_1/2 in vitro was 24.9 h. After 53.2 h, the accumulated release percentage reached 84.0%, which indicated that CIP–PDLLA–MS was advantageous to long‐term release. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2143–2150, 2004     

Properties and morphology of bioceramics/poly(D,L‐lactide) composites modified by in situ compatibilizing extrusion

Composites of poly(D ,L ‐lactide) (PDLLA) with hydroxylapatite (HA) and PDLLA with tertiary calcium phosphate (TCP) were prepared by in situ modification with methylenediphenyl diisocyanate (MDI) and molded by piston extrusion at temperature between T_g and T_m of PDLLA. Mechanical properties of the composites increased obviously when compared with the unmodified bioactive ceramic particles/PDLLA composites. The effect of MDI contents on mechanical properties of the composites was studied. At the optimum conditions of 1.0/1.0molar ratios of ? NCO groups in MDI to ? OH groups in PDLLA, bending strength 68.4 MPa and bending modulus 2281.5 MPa, were achieved in composite HA/PDLLA/MDI with 15 wt % HA. Both increased by nearly 30% when compared with that of solution cast HA/PDLLA composites. Interfacial adhesion and compatibility between PDLLA and bioactive ceramic particles (HA and TCP) were investigated. Scanning electron microscopy (SEM) indicated that the interface between HA particles and PDLLA was blurred and HA particles were closely surrounded by PDLLA matrix in HA/PDLLA/MDI composites. Oriented fibrils along with longitudinal direction of extrusion die were also observed on the surfaces of HA/PDLLA/MDI composite. It is confirmed that MDI has improved interfacial adhesion and compatibility between HA particles and PDLLA phase. Fibril structures formed in the extrusion, and it contributed a great deal in enhancing the mechanical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4085–4091, 2006     

The effect of citrate ester plasticizers on the thermal and mechanical properties of poly(DL‐lactide)

Citrate esters triethyl citrate, tributyl citrate, and acetyl tributyl citrate were used as plasticizers for amorphous poly(D,L ‐lactide) (PDLLA). The resultant compositions were analyzed by means of differential scanning calorimetry (DSC), dynamic mechanical thermal analysis, and tensile testing to investigate the properties of the blends. Glass transition temperatures (T_gs) obtained by DSC were also compared to theoretically calculated T_gs. Increasing plasticizer content decreased the resultant T_g of the blend with plasticizer efficiency enhanced as the molecular weight of the citrate ester increased. However, in blends with high plasticizer content, a lack of miscibility also occurred with increased molecular weight. Theoretical results were comparable with those obtained experimentally at compositions, which were miscible. Increasing plasticizer content increased the ductility and decreased the strength of the polymer. The addition of 10 wt % plasticizer to PDLLA decreased tensile strength by over 50% with the deterioration larger at higher concentrations of plasticizer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Enhanced hydrolytic stability of poly(p‐dioxanone) with polycarbodiimide

The effect of polycarbodiimide (PCD) on hydrolytic stability of poly(p‐dioxanone) (PPDO) was investigated by hydrolytic degradation of PPDO and PPDO added with PCD (PPDOCD) in phosphate buffer solution (pH = 7.4) at 37°C. The variation of weight, water absorption, pH, molecular weight, tensile properties, surface morphologies, and thermal properties with degradation time were evaluated. After 11 weeks, the weight loss and water absorption of PPDO was 24 and 30%, respectively, but the corresponding values were only 3 and 5% for PPDOCD5, where 5 represents the weight percentage of PCD added; the molecular weight of PPDO decreased much faster than that of PPDOCD. The pH of the solution was monitored for 15 weeks and a final pH value of the solution involving PPDOCD5 was 6.81 whereas that of PPDO solution was 3.77, indicating that more acid fragments from PPDO samples migrate into the buffer solution. Surface morphological changes showed a better physical integrity for PPDOCD samples and they also kept their mechanical properties for a longer time than PPDO samples. These results revealed that PCD can retard the hydrolysis degradation of PPDO and enhance its hydrolytic stability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Plasticization of Poly‐L‐lactide with L‐lactide,D‐lactide,and D,L‐lactide monomers

Poly‐L ‐lactide (PLLA) is being widely considered for repair of damaged tissues, for controlled antibiotic release, and also as scaffolds for cultured cells. PLLA was blended with the lactide monomer in its two enantiomeric forms: D ‐lactide (D ‐la) and L ‐lactide (L ‐la) and with the cyclic dimmer D ,L ‐la, in order to enhance its flexibility and thereby overcome its inherent problem of brittleness. In this work, the crystallization, phase structure, and tensile properties of PLLA and PLLA plasticized with 5, 10, 15, and 20 wt% of D ‐la, L ‐la, and D ,L ‐la are explored. The three plasticizers used were effective in lowering the glass transition temperature (T_g) and the melting temperature (T_m) of PLLA, around 20°C for a plasticizer content of 20 wt%. The tensile strength and modulus of the blends decreased following the increasing content of plasticizers from approximately 58 MPa to values below 20 MPa, and from 1667 to 200 MPa, respectively. Aging the blends at storage ambient temperature revealed that the enhanced flexibility as well as the morphological stability was lost over time due to the migration of the plasticizer to the surface, this being less marked in the case of D ‐la as a result of interactions between the polymer and its enantiomeric monomer of complementary configuration. POLYM. ENG. SCI., 53:2073–2080, 2013. © 2013 Society of Plastics Engineers     

Characterization of the mechanical and thermal properties and morphological behavior of biodegradable poly(L‐lactide)/poly(ε‐caprolactone) and poly(L‐lactide)/poly(butylene succinate‐co‐L‐lactate) polymeric blends

Two series of biodegradable polymer blends were prepared from combinations of poly(L ‐lactide) (PLLA) with poly(?‐caprolactone) (PCL) and poly(butylene succinate‐co‐L ‐lactate) (PBSL) in proportions of 100/0, 90/10, 80/20, and 70/30 (based on the weight percentage). Their mechanical properties were investigated and related to their morphologies. The thermal properties, Fourier transform infrared spectroscopy, and melt flow index analysis of the binary blends and virgin polymers were then evaluated. The addition of PCL and PBSL to PLLA reduced the tensile strength and Young's modulus, whereas the elongation at break and melt flow index increased. The stress–strain curve showed that the blending of PLLA with ductile PCL and PBSL improved the toughness and increased the thermal stability of the blended polymers. A morphological analysis of the PLLA and the PLLA blends revealed that all the PLLA/PCL and PLLA/PBSL blends were immiscible with the PCL and PBSL phases finely dispersed in the PLLA‐rich phase. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fully bio‐based poly(ɛ‐capolactone)/poly(lactide) alternating multiblock supramolecular polymers: Synthesis,crystallization behavior,and properties

Supramolecular poly(?‐capolactone)/poly(lactide) alternating multiblock copolymers were prepared by UPy‐functionalized poly(lactide)‐b‐ poly(?‐capolactone)‐b‐ poly(lactide) copolymers. The prepared supramolecular polymers (SMPs) exhibit the characteristic properties of thermoplastic elastomers. The stereo multiblock SMPs (sc‐SMPs) were formed by blending UPy‐functionalized poly(l ‐lactide)‐b‐ PCL‐b‐ poly(l ‐lactide) (l ‐SMPs) and UPy‐functionalized poly(d ‐lactide)‐b‐ PCL‐b‐ poly(d ‐lactide) (d ‐SMPs) due to stereocomplexation of the PLLA and PDLA blocks. Sc‐SMPs with low content of d ‐SMPs (≤20%) are transparent, elastic solids, while those having high d ‐SMPs content are opaque, brittle solids. The effects of l ‐SMPs/d ‐SMPs mixing ratios on thermal, crystallization behaviors, crystal structure, mechanical and hydrophilic properties of sc‐SMPs were deeply investigated. The incorporation of UPy groups depresses the crystallization of polymer, and the stereocomplex formation accelerates the crystallization rate. The used initiator functionalized polyhedral oligomeric silsesquioxanes causes a different effect on the crystallization of PLA and PCL blocks. The tensile strength and elongation at break of l _d /d _d ‐SMPs (d represents the initiator diethylene glycol) are significantly larger than that of l _p /d _p ‐SMPs (p represents the initiator polyhedral oligomeric silsesquioxanes), and their heat resistance and hydrophilicity can be also modulated by the l ‐SMPs/d ‐SMPs mixing ratios and the different initiators. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45575.