Effect of plasticizer on the crystallization behavior of poly(lactic acid)

In this article, the spherulitic morphology and growth rate of the neat and plasticized poly(lactic acid) (PLA) with triphenyl phosphate (TPP) were compared and analyzed by polarizing optical microscopy with hot stage at a temperature range of 100?142°C. The spherulitic morphology of the neat PLA underwent a series of changes such as the typical Maltese Cross at less than 132°C, the disappearance of the Maltese Cross at 133°C, the irregular and distorted spherulites at higher than 134 and 142°C, respectively. For plasticized PLA, the spherulitic morphology exhibited the same changes as neat PLA, but these changes were shifted to lower temperature when compared with neat PLA. In the case of the spherulitic growth, neat PLA had the maximum value of 0.28 μm/s at 132°C, and plasticized PLA had higher values than that of neat PLA. Further analysis based on the Lauritzen–Hoffman theory was presented and results showed that the values of nucleation parameter K_g increased with TPP content. The crystallization behavior of PLA was analyzed by differential scanning calorimetry and wide‐angle X‐ray diffraction. The results showed that the degree of crystallinity of plasticized PLA markedly increased when compared with neat PLA sharply with the incorporation of plasticizer. The crystallization kinetics for the neat and plasticized PLA under isothermal crystallization at 114°C was described by the Avrami equation and the Avrami exponent is close to 2, implying that the crystallization mechanism did not change. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Kinetics and crystal structure of poly(lactic acid) crystallized nonisothermally: Effect of plasticizer and nucleating agent

The kinetics of neat poly(lactic acid) (PLA) and its composites with triphenyl phosphate (TPP) and/or talc crystallized nonisothermally at different cooling rates of 1, 2.5, 5, 7.5, and 10°C/min was analyzed by differential scanning calorimetry and described by Avrami equation and combined Avrami‐Ozawa equation. The results showed that talc acted as PLA nucleating agent accelerated crystallization rate by decreasing the crystallization half‐time t_1/2 or rate parameter F(T), whereas TPP acted as PLA plasticizer decreased crystallization rate. For neat PLA and plasticized PLA, the average values of Avrami exponent n were almost close to each other, but added TPP decreased crystallization rate constant k. As for PLA composites with talc, the crystallization process was relatively complex, and was divided into three regimes. At a given cooling rate, the value of n₂ was almost larger than that that of n₁ or n₃, whereas the value of k₂ was less than that of k₁ or k₃. The effective activation energy ΔE_x calculated from Friedman formula increased with the increase of relative crystallinity and TPP content, whereas decreased with the presence of talc. Wide angle X‐ray diffraction verified that all samples crystallized nonisothermally in cooling rate range of 1–10°C/min form α‐form. POLYM. COMPOS., 31:2057–2068, 2010. © 2010 Society of Plastics Engineers     

Isothermal crystallization kinetics and spherulite morphologies of poly(lactic acid)/ethylene acrylate copolymer blends

Isothermal crystallization kinetics and spherulite morphologies of partially immiscible blends of poly(lactic acid) (PLA) and ethylene acrylate copolymer (EAC) were investigated by differential scanning calorimetry (DSC) and polarized optical microscopy. The DSC data obtained was analyzed using the Avrami equation. Crystallization kinetics of PLA from the melt was strongly influenced by the blend composition and the crystallization temperature. At a given crystallization temperature, the overall crystallization rate value was greater in the blends than in PLA suggesting that the presence of EAC enhanced crystallization of PLA. Polarized optical micrographs showed that the crystallization of PLA initially took place at the PLA/EAC interface. At high EAC content (>1 wt %), EAC domains acted as hindrance to crystallization reducing the overall crystallization rate of PLA in the blends. Based on the DSC analysis, the crystallization rate was maximum when PLA blend with 1 wt % EAC was isothermally crystallized at 103 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45487.     

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     

Crystallization and melting behavior of partially miscible six‐armed poly(l‐lactic acid)/poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) blends

The crystallization kinetics and spherulitic morphology of six‐armed poly(L‐lactic acid) (6a‐PLLA)/poly(3‐hydroxybutyrate‐co?3‐hydroxyvalerate) (PHBV) crystalline/crystalline partially miscible blends were investigated with differential scanning calorimetry and polarized optical microscopy in this study. Avrami analysis was used to describe the isothermal crystallization process of the neat polymers and their blends. The results suggest that blending had a complex influence on the crystallization rate of the two components during the isothermal crystallization process. Also, the crystallization mechanism of these blends was different from that of the neat polymers. The melting behavior of these blends was also studied after crystallization at various crystallization temperatures. The crystallization of PHBV at 125°C was difficult, so no melting peaks were found. However, it was interesting to find a weak melting peak, which arose from the PHBV component for the 20/80 6a‐PLLA/PHBV blend after crystallization at 125°C, and it is discussed in detail. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42548.     

Morphology,mechanical properties,and durability of poly(lactic acid) plasticized with Di(isononyl) cyclohexane‐1,2‐dicarboxylate

Di(isononyl) cyclohexane‐1,2‐dicarboxylate (DINCH) was used as a new plasticizer for poly(lactic acid) (PLA), and the effects of DINCH and tributyl citrate ester (TBC) on the morphology, mechanical and thermal properties, and durability of PLA were compared. DINCH has limited compatibility with PLA, leading to PLA/DINCH blends with phase separation in which DINCH forms spherical dispersed phase. TBC is compatible with PLA and evenly distributed in PLA. Plasticized PLA with 10 and 20 phr DINCH have a constant glass transition temperature (T_g) of 50°C and are stiff materials with high elongation at break and impact strength. TBC could significantly decrease the T_g and increase the crystallinity of PLA, and PLA/TBC (100/20) blend is a soft material with a T_g of 24°C. The durability of plasticized PLA was characterized by weight loss measurement under water immersion, mechanical properties, and thermal analysis. The results reveal that PLA/DINCH blends have better water resistance and aging resistance properties than PLA/TBC blends, which is attributed to the relatively high hydrophobicity of DINCH and high T_g of PLA/DINCH blends. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Thermal properties and non‐isothermal crystallization behavior of poly(trimethylene terephthalate)/poly(lactic acid) blends

Thermal properties and non‐isothermal melt‐crystallization behavior of poly(trimethylene terephthalate) (PTT)/poly(lactic acid) (PLA) blends were investigated using differential scanning calorimetry and thermogravimetric analysis. The blends exhibit single and composition‐dependent glass transition temperature, cold crystallization temperature (T_cc) and melt crystallization peak temperature (T_mc) over the entire composition range, implying miscibility between the PLA and PTT components. The T_cc values of PTT/PLA blends increase, while the T_mc values decrease with increasing PLA content, suggesting that the cold crystallization and melt crystallization of PTT are retarded by the addition of PLA. The modified Avrami model is satisfactory in describing the non‐isothermal melt crystallization of the blends, whereas the Ozawa method is not applicable to the blends. The estimated Avrami exponent of the PTT/PLA blends ranges from 3.25 to 4.11, implying that the non‐isothermal crystallization follows a spherulitic‐like crystal growth combined with a complicated growth form. The PTT/PLA blends generally exhibit inferior crystallization rate and superior activation energy compared to pure PTT at the same cooling rate. The greater the PLA content in the PTT/PLA blends, the lower the crystallization rate and the higher the activation energy. Moreover, the introduction of PTT into PLA leads to an increase in the thermal stability behavior of the resulting PTT/PLA blends. Copyright © 2011 Society of Chemical Industry     

Crystallization kinetics of a PEEK/LCP blend

The crystallization kinetics of a polyetheretherketone (PEEK)/liquid crystalline polymer (LCP) blend was studied by using differential scanning calorimetry. Nonisothermal runnings were performed on heating and on cooling at different rates. Isothermal crystallization experiments at 315, 312, 310, and 307°C, from the melt state (380°C) were performed in order to calculate the Avrami parameters n and k and the fold surface free energy, σ_e. Polarized light optical micrographs were also obtained to confirm the Avrami predictions. It was observed that the LCP retarded the PEEK crystallization process and that the PEEK melting temperature decreased with the amount of LCP, but the LCP melting temperature increased with the amount of PEEK. Probably the PEEK improves the perfection of the LCP crystalline domains. A spherulitic morphology in pure PEEK and its blends was predicted by the Avrami analysis; however this morphology was only observed for pure PEEK and for the 80/20 composition. The other compositions presented a droplet and fibrillar-like morphology. The overall crystallization rate was observed to decrease with the crystallization temperature for all compositions. Finally, σ_e was found to decrease with the increase of LCP in the blends, having unrealistic negative values. Thus, calculations were made assuming σ_e constant at all compositions. It was observed that δ, the interfacial lateral free energy, decreased but still remained positive. It was concluded that in these blends neither σ_e nor σ could be considered constant. © 1995 John Wiley & Sons, Inc.     

Nonisothermal crystallization kinetics of biodegradable poly(butylene succinate)/poly(vinyl phenol) blend

Nonisothermal melt crystallization kinetics of biodegradable PBSU/PVPh blend was investigated with differential scanning calorimetry (DSC) from the viewpoint of practical application. PBSU/PVPh blends were cooled from the melt at various cooling rates ranging from 2.5 to 40°C/min. The crystallization peak temperature decreased with increasing the cooling rate for both neat and blended PBSU. Furthermore, the crystallization peak temperature of PBSU in the blend was lower than that of neat PBSU at a given cooling rate. Two methods, namely the Avrami equation and the Tobin method, were used to describe the nonisothermal crystallization of PBSU/PVPh blend. It was found that the Avrami equation was more suitable to predict the nonisothermal crystallization of PBSU/PVPh blend than the Tobin method. The effects of cooling rate and blend composition on the crystallization behavior of PBSU were studied in detail. It was found that the crystallization rate decreased with decreasing the cooling rate for both neat and blended PBSU. However, the crystallization of PBSU blended with PVPh was retarded compared with that of neat PBSU at the same cooling rate. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 972–978, 2007     

Crystallization behavior and isothermal crystallization kinetics of PLLA blended with ionic liquid, 1‐butyl‐3‐methylimidazolium dibutylphosphate

The crystallization behavior and isothermal crystallization kinetics of neat poly(l ‐lactic acid) (PLLA) and PLLA blended with ionic liquid (IL), 1‐butyl‐3‐methylimidazolium dibutylphosphate, were researched by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and wide angle X‐ray diffraction (WXRD). Similar to the non‐isothermal crystallization behavior of neat PLLA, when PLLA melt was cooled from 200 to 20°C at a cooling rate of 10°C min^?1, no crystallization peak was detected yet with the incorporation of IL. However, the glass transition temperature and cold crystallization temperature of PLLA gradually decreased with the increase of IL content. It can be attributed to the significant plasticizing effect of IL, which improved the chain mobility and cold crystallization ability of PLLA. Isothermal crystallization kinetics was also analyzed by DSC and described by Avrami equation. For neat PLLA and IL/PLLA blends, the Avrami exponent n was almost in the range of 2.5–3.0. It is found that t_1/2 reduced largely, and the crystallization rate constant k increased exponentially with the incorporation of IL. These results show that the IL could accelerate the overall crystallization rate of PLLA due to its plasticizing effect. In addition, the dependences of crystallization rate on crystallization temperature and IL content were discussed in detail according to the results obtained by DSC and POM measurements. It was verified by WXRD that the addition of IL could not change the crystal structure of PLLA matrix. All samples isothermally crystallized at 100°C formed the α‐form crystal. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41308.     

Crystallization Study of Glassy PET/PEN Blends by Means of Real Time X-ray Scattering

Abstract

The crystallization of several blends of poly(ethylene terephthalate) (PET) and poly(ethylene 2,6 naphthalene dicarboxylate) (PEN) has been investigated by wide angle- (WAXS) and small angle X-ray scattering (SAXS) using synchrotron radiation. The role of transesterification reactions, giving rise to a fully amorphous non-crystal-lizable material (copolyester) is brought up. For the blends rich in PET, crystallization temperatures (T_c ) of 105 and 117°C were used. For blends rich in PEN, crystaffization was performed at T_c =150 and 165°C, respectively. The time variation of the degree of crystallinity was fitted into an Avrami equation considering the induction time prior to the beginning of crystallization. The Avrami parameters, the half times of crystallization, as well as the nanostructure development (SAXS invariant and long period) for the blends, are discussed in relation to blend composition and are compared to the parameters observed for the homopolymers PET and PEN.     

Preparation and properties of foamed cellulose acetate/polylactic acid blends

In order to improve the foaming performance of pure cellulose acetate (CA), blends were prepared by mixing polylactic acid (PLA) in CA and foamed by supercritical CO₂ (ScCO₂) in this study. The effect of PLA content (percentage by mass of blend) on structure, thermal properties, rheological properties, foaming properties and mechanical properties of the blends was investigated. The results showed that the addition of PLA destroyed the original hydrogen bonds of CA, while the blends had good crystallization properties. At the same time, compared with pure CA, the glass transition temperature (T_g) of the blends decreased, and the initial decomposition temperature (T₀) was reduced from 349.41°C (pure CA) to 334.68°C (CA/20%PLA). In addition, the rheological properties of the blends were improved, and the viscosity was reduced, which was obviously beneficial to foaming process. The pore size and density of the foamed blends both reached the maximum value at 20%PLA. The presence of PLA could degrade the mechanical properties of the blends. However, the overall drop (1.01 KJ/m²) of impact strength of the blends after foaming is much smaller than that before foaming (12.11 KJ/m²), indicating that the improvement of foaming performance was beneficial to improve its impact strength.     

Crystallization behavior of α‐cellulose short‐fiber reinforced poly(lactic acid) composites

The isothermal crystallization behavior of α‐cellulose short‐fiber reinforced poly(lactic acid) composites (PLA/α‐cellulose) was examined using a differential scanning calorimeter and a petrographic microscope. Incorporating a natural micro‐sized cellulose filler increased the spherulite growth rate of the PLA from 3.35 μm/min for neat PLA at 105°C to a maximum of 5.52 μm/min for the 4 wt % PLA/α‐cellulose composite at 105°C. In addition, the inclusion of α‐cellulose significantly increased the crystallinities of the PLA/α‐cellulose composites. The crystallinities for the PLA/α‐cellulose composites that crystallized at 125°C were 48–58%, higher than that of the neat PLA for ～13.5–37.2%. The Avrami exponent n values for the neat and PLA/α‐cellulose composites ranged from 2.50 to 2.81 and from 2.45 to 3.44, respectively, and the crystallization rates K of the PLA/α‐cellulose composites were higher than those of the neat PLA. The activation energies of crystallization for the PLA/α‐cellulose composites were higher than that of the neat PLA. The inclusion of α‐cellulose imparted more nucleating sites to the PLA polymer. Therefore, it was necessary to release additional energy and initiate molecular deposition. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Crystallization kinetics of poly(trimethylene terephthalate)/poly(ether imide) blends

The crystallization kinetics of a melt‐miscible blend, consisting of poly(trimethylene terephthalate) (PTT) and poly(ether imide) (PEI) prepared by solution precipitation, has been investigated by means of optical polarized microscopy and differential scanning calorimeter. It was found that both the PTT spherulitic growth rate (G) and overall crystallization rate constant (k_n) were depressed, with increasing PEI composition or crystallization temperature (T_c). The kinetic retardation was attributed to the decrease in PTT molecular mobility, and the dilution of PTT concentration due to the addition of PEI, which has a higher glass transition temperature (T_g). According to the Lauritzen–Hoffman theory of secondary nucleation, the crystallization of PTT in blends was similar to that of neat PTT as regime III, n = 4 and regime II, n = 2 growth processes, while the transition point of regime III to II has been shifted from 194°C for neat PTT to 190°C for blends. POLYM. ENG. SCI. 46:89–96, 2006. © 2005 Society of Plastics Engineers     

Morphology,biodegradability, mechanical,and thermal properties of nanocomposite films based on PLA and plasticized PLA

In this study, melt intercalation method is applied to prepare poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG)‐plasticized PLA nanocomposite films including 0, 3, and 5% organoclay (Cloisite 30B) using a laboratory scale compounder, which is connected to a microcast film device. To evaluate the nanomorphology and the dispersion state of the clays, X‐ray diffraction (XRD) and transmission electron microscopy (TEM) are conducted. Tensile tests are performed to characterize the mechanical behavior of the films. Biodegradation rate is determined by degradation tests in composting medium. Differential scanning calorimeter (DSC) is applied to observe the thermal behavior of the films. XRD and TEM show that the exfoliation predominantly occurrs in plasticized PLA nanocomposites, whereas unexfoliated agglomerates together with exfoliated clays are observed in the nonplasticized PLA. Tensile tests indicate that the addition of 3% clay to the neat‐PLA does not affect the strength; however, it enhances the modulus of the nanocomposites in comparison to neat‐PLA. Incorporation of 3% clay to the plasticized PLA improves the modulus with respect to PLA/PEG; on the other hand, the strain at break value is lowered ～ 40%. The increase in the rate of biodegradation in composting medium is found as in the order of PLA > PLA/PEG > 3% Clay/PLA/PEG > 5% Clay/PLA/PEG > 3% Clay/PLA. DSC analysis shows that the addition of 3% clay to the neat PLA results in an increase in T_g. The addition of 20% PEG as a plasticizer to the neat‐PLA decreases T_g about 30°C, however incorporation of clays increases T_g by 4°C for the plasticized PLA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Crystallization behavior and morphology of polylactic acid (PLA) with aromatic sulfonate derivative

This article provides a detailed investigation of crystallization behavior and morphology of polylactic acid (PLA) in the presence of a nucleating agent: potassium salt of 5‐dimethyl sulfoisothalate, an aromatic sulfonate derivative (Lak‐301). Isothermal crystallization kinetics of PLA melt mixed with Lak at concentrations of 0.25–1 wt % was investigated at a range of crystallization temperature, 140–150 °C. To gain further insight on the effect of Lak, nonisothermal differential scanning calorimetry (DSC), wide angle X‐ray diffraction (WAXD), polarized optical microscope (POM), heat deflection temperature (HDT), and rheology were also performed. At 0.25 wt % Lak, crystallinity of PLA increased from 10% to 45%, and in 1 wt % Lak, maximum crystallinity of 50% was achieved. With 1 wt % Lak, crystallization half time reduced to 1.8 min from 61 min for neat PLA at 140 °C. The isothermal crystallization kinetics was analyzed using Avrami model. Values of the Avrami exponent for PLA with Lak were mainly in the range of 3 indicating a three dimensional crystal growth is favored. Crystallization rate was found to increase with increase in Lak content. Observation from POM confirmed that the presence of Lak in the PLA matrix significantly increased the nucleation density. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43673.     

Thermal and biodegradation properties of poly(lactic acid)/fertilizer/oil palm fibers blends biocomposites

Poly(lactic acid) (PLA) and NPK fertilizer with empty fruit bunch (EFB) fibers were blends to produced bioplastic fertlizer (BpF) composites for slow release fertilizer. Thermal properties of BpF composites were investigated by thermogavimteric analysis (TGA), differential scanning calorimetry (DSC), and morphological and degradation properties were anlayzed by scanning electron microscopy (SEM), soil burial test, respectively. TGA themogram display that neat PLA, PLA/NPK, and BpF composites degradate at different temperatures. DSC curves of PLA and other composites exhibited same glass transition temperature (T_g) value indicating that both major blend components are miscible. The T_g, crystallization temperature (T_c), melting temperature (T_m) values also decreased with increased amount of fertilizer and fibers. The T_m of BpF composites did not change with an increase in fertilizer content because thermal stability of PLA and PLA/NPK composites was not affected. Soil burial and fungal degradation test of PLA, PLA/NPK, and BpF composites were also carried out. Soil burial studies indicated that BpF composites display better biodegradation as compared with neat NPK. Fungal degradation study indicated that fungi exposure times of BpF composites show higher value of degradation as compared with PLA/NPK. We attribute that developed BpF composites will help oil palm plantation industry to use it as slow release fertilizer. POLYM. COMPOS. 36:576–583, 2015. © 2014 Society of Plastics Engineers     

Kinetics of isothermal and non‐isothermal crystallization of poly(butylene terephthalate)/ liquid crystalline polymer blends

The melting behavior and isothermal and non‐isothermal crystallization kinetics of poly(butylene terephthalate) (PBT)/thermotropic liquid crystalline polymer (LCP), Vectra A950 (VA) blends were studied by using differential scanning calorimetry. Isothermal crystallization experiments were performed at crystallization temperatures (T_c), of 190, 195, 200 and 205°C from the melt (300°C) and analyzed based on the Avrami equation. The values of the Avrami exponent indicate that the PBT crystallization process in PBT/VA blends is governed by three‐dimensional morphology growth preceded by heterogeneous nucleation. The overall crystallization rate of PBT in the melt blends is enhanced by the presence of VA. However, the degree of PBT crystallinily remains almost the same. The analysis of the melting behavior of these blends indicates that the stability and the reorganization process of PBT crystals in blends are dependent on the blend compositions and the thermal history. The fold surface interfacial energy of PBT in blends is more modified than in pure PBT. Analysis of the crystallization data shows that crystallization occurs in Regime II across the temperature range 190°C‐205°C. A kinetic treatment based on the combination of Avrami and Ozawa equations, known as Liu's approach, describes the non‐isothermal crystallization. It is observed that at a given cooling rate the VA blending increases the overall crystallization rate of PBT.     

Characterization and Properties of Reactive Poly(lactic acid)/Polyamide 610 Biomass Blends

A low molecular weight bisphenol‐A type epoxy resin was used as a reactive compatibilizer for poly(lactic acid) (PLA)/polyamide 610 (PA 610) biomass blends. To the best of our knowledge, this blend is the first biomass PA 610 blend in the literature. The epoxy functional groups could react with the terminal groups of both PLA and PA 610. An ester–amide interchange reaction led to a polyester–polyamide copolymer formation, and improved the compatibility of PLA and PA 610. The blends with epoxy resin showed an enhancement in the phase dispersion and interfacial adhesion compared with the blend without epoxy resin. The differential scanning calorimetry (DSC) analysis showed that the crystallization peak temperatures decreased with increasing epoxy content. The melting temperature of PA 610 decreased with the addition of PLA, but remained unchanged with increased compatibilizer dosages. The dynamic mechanical analysis (DMA) showed that the glass transition temperature (T_g) of the blend, with the addition of 0.5 phr epoxy resin, slightly increased compared with that of neat PLA. However, the T_g of the blends remained unchanged with increasing epoxy resin content, and the higher content of epoxy resin in the blends resulted in improved mechanical properties and higher melt viscosity. The unnotched impact test showed that PA 610 could toughen PLA with the addition of epoxy resin. Moreover, the no‐break unnotched impact behavior was observed with the medium content of the compatibilizer, improving the notch sensitivity of PLA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2563–2571, 2013     

Properties and weldability of plasticized polylactic acid films

The objectives of the presented work were to investigate films based on polylactic acid (PLA) and polyethylene glycol (PEG) in order to improve ductility and weldability of PLA films. The effect of plasticizer amount on the thermal, rheological, and mechanical properties of PLA plasticized films was investigated. The PEG content does affect the glass transition and the cold crystallization temperature of PLA in blends, while the melting temperature was not affected by the addition of PEG. The complex viscosity of the neat PLA granules and of plasticized films showed strong temperature and angular velocity dependence. The Young's modulus and tensile strength of plasticized films were improved with increasing plasticizer concentration, while the elongation at break stays rather constant. Plasticized PLA films were furthermore heat welded. These investigations showed that plasticized PLA films can be welded by heat welding. The obtained weld strength is strongly depending on the PEG amount as well as on selected welding parameters. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40394.