Ultrasonic welding of plasticized PLA films

Poly(lactic acid) (PLA) is a commercially available biobased material that has become an ideal material in packaging applications because of its low toxicity along with its environmentally friendly characteristics. Unfortunately, PLA is rigid and brittle. These characteristics impede its wide application. The flexibility of PLA can be improved by plasticization. In addition, welding polymer films is essential in the packaging production. Therefore, the weldability by means of ultrasonic welding of the neat and with polyethylene glycol plasticized PLA films was analyzed in this study. Moreover, the study examines the influence of the material composition on the processing window, that is, the range of welding parameters which could be used to weld films efficiently, and on the weld quality. This research showed that all examined films can be welded by ultrasonic welding. Furthermore, it was discovered that the addition of a plasticizer has a strong influence on the processing window and on the weld quality. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41351.     

Film extrusion and film weldability of poly(lactic acid) plasticized with triacetine and tributyl citrate

Film extrusion and welding of biodegradable polymer films are important processes that must be considered in the development of compostable packaging materials. Film extrusion of poly(lactic acid) (PLA) has proved to be rather difficult because of its brittleness, but the flexibility of PLA can be improved by incorporation of a plasticizer in the material. PLA was plasticized with triacetine (TAc) and tributyl citrate (TbC). The blended materials and neat PLA were film extruded and the films were welded with constant heat (CH) welding. The films were analyzed by means of gas chromatography (GC), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), contact angle measurements, and tensile testing. Storage of the plasticized films resulted in an increased crystallinity and changes in the film properties, rendering CH welding difficult. The welding process had no influence on thermal properties, such as cold crystallization temperature, melting temperature, crystallization temperature, and degree of crystallinity, of neat PLA but caused significant changes in the crystallinity of the plasticized materials. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3239–3247, 2003     

Properties of linear poly(lactic acid)/polyethylene glycol blends

Poly(lactic acid) (PLA) has great potentials to be processed into films for packaging applications. However, film production is difficult to carry out due to the brittleness and low melt strength of PLA. In this investigation, linear PLA (L‐PLA) was plasticized with poly(ethylene glycol) (PEG) having MW of 1000 g mol^?1 in various PEG concentrations (0, 5, 10, 15, and 20 wt%). In relation to plasticizer content, the impact resistance and crystallinity of L‐PLA was increased, whereas a decrease in glass transition temperature and lower stiffness was observed. Nevertheless, the phase separation has been found in samples which contained PEG greater than 10 wt%. The dynamic and shear rheological studies showed that the plasticized PLA possessed lower viscosity and more pronounced elastic properties than that of pure PLA. Both storage and loss moduli decreased with PEG loading at all frequencies while storage modulus exhibited weak frequency dependence with increasing PEG content. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Preparation and characterization of poly(lactic acid)/poly(ethylene oxide) blend film: effects of poly(ethylene oxide) and poly(ethylene glycol) on the properties

Poly(lactic acid) (PLA) film plasticized with poly(ethylene oxide) (PEO) at various weight percentages (1–5 wt%) was prepared to improve the elongation, thus overcoming the inherent brittleness of the material. After optimization of the amount of PEO (4 wt%) through mechanical analysis, poly(ethylene glycol) (PEG), a well‐established plasticizer of PLA, was added (0.5–1.5 wt%) without hampering the transparency and tensile strength much, and again its amount was optimized (1 wt%). Neat PLA and PLA with the other components were solvent‐cast in the form of films using chloroform as a solvent. Improvement in elongation at break and reduction in tensile strength suggested a plasticizing effect of both PEO and PEG on PLA. Thermal and infrared data revealed that the addition of PEO induced β crystals in PLA. Scanning electron micrographs indicated a porous surface morphology of the blends. PEO alone in PLA exhibited the best optical clarity with higher percentage crystallinity, while PEG incorporation in PLA/PEO resulted in superior barrier properties. Also, the stability of the blends under a wide range of pH means prospective implementation of the films in packaging of food and non‐food‐grade products. © 2018 Society of Chemical Industry     

Thermal and mechanical properties of plasticized poly(L‐lactic acid)

Acetyl tri‐n‐butyl citrate (ATBC) and poly(ethyleneglycol)s (PEGs) with different molecular weights (from 400 to 10000) were used in this study to plasticize poly(L‐lactic acid) (PLA). The thermal and mechanical properties of the plasticized polymer are reported. Both ATBC and PEG are effective in lowering the glass transition (T_g) of PLA up to a given concentration, where the plasticizer reaches its solubility limit in the polymer (50 wt % in the case of ATBC; 15–30 wt %, depending on molecular weight, in the case of PEG). The range of applicability of PEGs as PLA plasticizers is given in terms of PEG molecular weight and concentration. The mechanical properties of plasticized PLA change with increasing plasticizer concentration. In all PLA/plasticizer systems investigated, when the blend T_g approaches room temperature, a stepwise change in the mechanical properties of the system is observed. The elongation at break drastically increases, whereas tensile strength and modulus decrease. This behavior occurs at a plasticizer concentration that depends on the T_g‐depressing efficiency of the plasticizer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1731–1738, 2003     

Reinforcement of graphene nanoplatelets on plasticized poly(lactic acid) nanocomposites: Mechanical,thermal, morphology,and antibacterial properties

Plasticized poly(lactic acid) (PLA)‐based nanocomposites filled with graphene nanoplatelets (xGnP) and containing poly(ethylene glycol) (PEG) and epoxidized palm oil (EPO) with ratio 2 : 1 (2P : 1E) as hybrid plasticizer were prepared by melt blending method. The key objective is to take advantage of plasticization to increase the material ductility while preserving valuable stiffness, strength, and toughness via addition of xGnP. The tensile modulus of PLA/2P : 1E/0.1 wt % xGnP was substantially improved (30%) with strength and elasticity maintained, as compared to plasticized PLA. TGA analysis revealed that the xGnP was capable of acting as barrier to reduce thermal diffusion across the plasticized PLA matrix, and thus enhanced thermal stability of the plasticized PLA. Incorporation of xGnP also enhanced antimicrobial activity of nanocomposites toward Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Listeria monocytogenes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41652.     

Plasticized poly(lactic acid) with low molecular weight poly(ethylene glycol): Mechanical,thermal, and morphology properties

Poly(lactic acid) PLA was plasticized with low molecular weight poly(ethylene glycol) PEG‐200 to improve the ductility of PLA, while maintaining the plasticizer content at maximum 10 wt%. Low molecular weight of PEG enables increased miscibility with PLA and more efficient reduction of glass transition temperature (T_g). This effect is enhanced not only by the low molecular weight but also by its higher content. The tensile properties demonstrated that the addition of PEG‐200 to PLA led to an increase of elongation at break (>7000%), but a decrease of both tensile strength and tensile modulus. The plasticization of the PLA with PEG‐200 effectively lowers T_g as well as cold‐crystallization temperature, increasing with plasticizer content. SEM micrographs reveal plastic deformation and few long threads of a deformed material are discernible on the fracture surface. The use of low molecular weight PEG‐200 reduces the intermolecular force and increases the mobility of the polymeric chains, thereby improving the flexibility and plastic deformation of PLA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4576–4580, 2013     

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     

Mechanical,thermal, and morphology properties of poly(lactic acid) plasticized with poly(ethylene glycol) and epoxidized palm oil hybrid plasticizer

Poly(lactic acid) (PLA) has received great attention recently due to its good physical and mechanical properties such as high tensile strength and modulus, good processability and biodegradability. In this study, low molecular weight poly(ethylene glycol) (PEG) and epoxidized palm oil (EPO) were used as hybrid plasticizers to improve toughness and ductility of PLA. Using the solubility parameter, a tentative evaluation of the hybrid plasticizer that could act as the most effective plasticizer for PLA has been performed and the obtained results have been corroborated with the materials physical properties. Excellent plasticizing effect was obtained by hybrid plasticizer PEG:EPO with ratio 2:1. Addition of PEG:EPO (2:1) hybrid plasticizer to PLA shows a significant improvement of 12,402%, compared to neat PLA. The improvement in flexibility and decrease in rigidity for the plasticized PLA is well evidenced by lower glass transition temperature (T_g) and tensile modulus values. In relation to the thermal stability, a decrease in thermal properties of the hybrid plasticized PLA was observed due to the volatility of the plasticizers. Scanning electron microscopy (SEM) shows that the hybrid plasticizer was turned PLA's smooth surface to fibrous structure and rough fracture surface. POLYM. ENG. SCI., 56:1169–1174, 2016. © 2016 Society of Plastics Engineers     

Relationship of welding technology to degree of plasticization in the PVC films

The influence of the degree of plasticization on optimum heat-sealing or high-frequency welding conditions has been studied for plasticized PVC films with different quantities of DOP plasticizer. Two equations were obtained that relate the parameters of the welding process (time and temperature, or time and specific anodic current) with the degree of PVC film plasticization. The equations allow calculation of welding conditions needed to obtain maximum strength of welded joints. One describes the durability of lap joints; the other of T-joints.     

Epoxidized soybean oil‐plasticized poly(lactic acid) films performance as impacted by storage

This study examined the effect of storage time at room temperature on the melt viscosity, thermal, and tensile properties of epoxidized soybean oil plasticized poly(lactic acid) (PLA) films manufactured through a cast extrusion process. Infrared results indicate that plasticizer migration to the surface of the film occurred after only 30 days of storage, which significantly affected the performance of plasticized films. While the melt viscosity, glass transition temperature, degree of crystallinity, tensile strength, and modulus increased, the elongation at break and energy to break decreased with storage time up to 30 days and all properties remained constant thereafter. However, the ability of stored plasticized film to cold crystallize remained unaffected since both the cold crystallization temperature and melting temperature were not affected during storage. Although plasticized film lost some flexibility after only 30 days of storage due to plasticizer migration to the surface of the film, sufficient plasticization performance still remained in plasticized PLA films for flexible packaging application even after a long storage period at ambient conditions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43201.     

Tri‐(butanediol‐monobutyrate) citrate plasticizing poly(lactic acid): Synthesis,crystallization, thermal,and mechanical properties

Tri‐(butanediol‐monobutyrate) citrate (TBBC) as a new plasticizer for poly(lactic acid) (PLA) was synthesized via a two‐step esterification. The chemical structure of TBBC was characterized by ¹H‐nuclear magnetic resonance. The studies on solubility parameters, transparence, and storage stability indicated the good miscibility between PLA and TBBC. The glass transition, crystallization, thermal, and mechanical properties of PLA plasticized by TBBC were evaluated. With an increase in TBBC content, the glass transition temperature (T_g), melting point (T_m), and the cold crystallization temperature (T_cc) of plasticized PLA gradually shifted to a lower temperature. The elongation at break and flexibility were greatly improved by the addition of TBBC. After 30 days of storage, PLA plasticized with up to 20 wt% of TBBC exhibited good storage stability and remained the original transparence and mechanical properties. The flexibility of PLA/TBBC films can be tuned by changing TBBC content. The corresponding crystalline morphology and structure were investigated by Polarizing optical microscope and X‐ray diffraction as well. This study revealed that TBBC was miscible with PLA and may therefore be a promising plasticizer for PLA‐based packaging materials. POLYM. ENG. SCI., 55:205–213, 2015. © 2014 Society of Plastics Engineers     

聚乙二醇对聚乳酸纤维性能的改善

采用在双螺杆中熔融共混,以不同相对分子质量聚乙二醇(PEG)作为增塑剂,对聚乳酸(PLA)进行增塑改性,并把改性后的PLA进行熔融纺丝。用扫描电子显微镜(SEM)、熔体流动速率仪(MFR)、单纤维电子强力仪(EYST)和差示扫描量热仪(DSC)对改性PLA纤维进行表征。讨论了不同相对分子质量的PEG对PLA纤维性能的影响,发现随着PEG含量的增加,改性PLA的流动性增加。当PEG质量分数≤8%时,随着PEG含量的增加,改性PLA纤维强度增加,断裂伸长率增加,玻璃化转变温度(Tg)和熔点(Tm)下降。PLA与PEG组分间表现出较好的相容性。PEG200改性的PLA纤维综合效果最好。     

Modification of zein films by incorporation of poly(ethylene glycol)s

The thermal and mechanical properties of corn (maize) (CZ) films plasticized with poly(ethylene glycol) (PEG) of two different molar masses (400 and 1000 g mol⁻¹) were studied using differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), tensile strength, moisture absorption isotherms and water vapour transmission rate measurements. The glass transition temperature (T_g) of plasticized films is determined primarily by the amount of moisture contained in the film. DMTA data show contraction of films with loss of absorbed water during heating/cooling cycles. The moisture absorption behaviour of films plasticized with PEG400 and PEG1000 is similar at low relative humidities but significantly different at higher relative humidities. Incorporation of up to about 30 wt% PEG substantially enhances the tensile strength and the resistance to water vapour transmission of the protein film, and PEG1000 is more effective than PEG400. © 2000 Society of Chemical Industry     

Poly(lactic acid) plasticized by biodegradable glyceryl lactate

The esterification of glycerol with lactic acid was carried out to synthesize glyceryl lactate, which was used as a as a plasticizer with different contents and blended with poly(lactic acid) (PLA) to get a completely biodegradable material with potential applications because of its biodegradability. The structural, morphological, thermal, and mechanical properties of the plasticized PLA were studied to evaluate the plasticizing effects. The results show that the PLA plasticized with glyceryl lactate had a lower glass‐transition temperature and a better ductility. With increasing plasticizer content, the crystallinity of PLA increased. The elongation at break reached 380%, and the impact strength was 1.7 times that of neat PLA. Simultaneously, the migration rate measurements showed that glyceryl lactate presented relatively low migration toward the surface compared with glycerol and citrate esters. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43460.     

Characterization of the Plasticized GAP/PEG and GAP/PCL Block Copolyurethane Binder Matrices and its Propellants

Though glycidyl azide polymer (GAP) is a well‐known and promising energetic polymer, propellants based on it suffer from poor mechanical and low‐temperature properties. To overcome these problems, plasticized GAP‐based copolymeric binders were prepared and investigated through the incorporation of flexible‐structural polyethylene glycol (PEG) and polycaprolactone (PCL) into a binder recipe under a Desmodur N‐100 polyisocyanate (N‐100)/isophorone diisocyanate (IPDI) (2 : 1, wt. ratio) mixed curative system. The nitrate esters (NEs) or GAP oligomer were used as energetic plasticizers at various ratios to the polymers. The GAP/PCL binders held the plasticizers much more than the GAP/PEG binders did. The glass transition temperatures (T_g) of segmented copolymeric binders were more dependent on the plasticizer level than the PEG or PCL content. The increase in the plasticizer content decreased the mechanical strength and modulus of binders, while the change of strain was modest. Finally, the NE plasticized GAP‐based solid propellants showed enhanced mechanical and thermal properties by the incorporation of PEG or PCL. The properties of GAP/PCL propellants were superior to those of GAP/PEG propellants.     

Films of chitosan and N‐carboxymethylchitosan. Part II: effect of plasticizers on their physiochemical properties

Chitosan (Ch) and N‐carboxymethylchitosan (N‐CMCh) films were prepared by the casting method at concentrations of 1% and 2% of polymer, with or without plasticizer: polyethylene glycol (PEG‐400) and glycerol (G), at 15% (w/w). The influence of composition on mechanical properties, water vapour transmission rate (WVTR), water saturation, and aqueous dissolution of the films was analysed. The thermal stability of the mixture (polymer:plasticizer, 1:1) was evaluated by thermogravimetric analysis (TGA). In general, all the properties were affected by the plasticizers. The plasticized films showed lower strength and a higher percentage of elongation (%E), in the following order: G > PEG‐400 > unplasticized film. The total WVTR increased with Ch concentration, with a different WVTR profile for Ch and N‐CMCh. While the PEG‐400 addition did not significantly modify the WVTR profile of films, the glycerol enhanced the transport of water vapour through both polymers. The plasticizer addition increased the time of water film saturation, in the following order: G > PEG‐400 > unplasticized film; this was more pronounced in the N‐CMCh films, probably due to the formation of hydrogen bonds. The solubility of the films was also affected by their composition. Copyright © 2006 Society of Chemical Industry     

Improvement of the flame retardancy of plasticized poly(lactic acid) by means of phosphorus‐based flame retardant fillers

The aim of this study is to improve the flame resistance and toughness of poly(lactic acid) (PLA) with the addition of low amount of flame retardant fillers and plasticizer simultaneously. Poly(ethylene glycol) (PEG) was used as plasticizer for PLA. Ammonium polyphosphate, boron phosphate, and tri‐phenyl phosphate (TPP) were used as flame retardant additives. Among these flame retardant additives, boron phosphate was synthesized from its raw materials by using microwave heating technique. Characterization of PLA/PEG‐based flame retardant composites was performed by conducting tensile, impact, differential scanning calorimeter, thermal gravimetric analysis, scanning electron microscope, limiting oxygen index, and UL‐94 vertical burning tests. Mechanical tests showed that the highest tensile strength, impact strength, and elongation at break values were obtained with the addition of ammonium polyphosphate and TPP into PLA/PEG matrix, respectively. Scanning electron microscopy analysis of the composites exhibited that the more homogeneous filler distribution in the matrix was observed for TPP containing composite. The best flame retardancy performance was also provided by TPP when compared with the other flame retardant additives in the plasticized PLA‐based composites.     

Ageing of poly(lactic acid) films plasticized with commercial polyadipates

BACKGROUND: Amorphous poly(lactic acid) (PLA) was plasticized with two polyadipates with different molar masses. Some physical properties were studied over time to evaluate the stability of these blends. The aim of this study was to improve PLA ductility and consider the feasibility of its use in flexible films for food packaging. RESULTS: The addition of polyadipates caused a decrease of the glass transition temperature (T_g) and an increase of PLA chain mobility. Samples with T_g values above the storage temperature suffered physical ageing with a reduction in free volume. All the unaged blends were mainly amorphous, but samples with T_g below the storage temperature developed crystallinity during ageing leading to phase separation. Ductile properties of films improved with plasticizer content immediately after blending, but there was a deterioration in such properties upon ageing due to matrix densification and crystallization of PLA chains. CONCLUSION: PLA can be efficiently plasticized by polyadipates and the results have shown that some of the prepared films remain flexible with no phase separation after 150 days. Copyright © 2009 Society of Chemical Industry     

Thermal and mechanical properties of plasticized poly(L‐lactide) nanocomposites with organo‐modified montmorillonites

Nanocomposites of poly(lactide) (PLA) and the PLA plasticized with diglycerine tetraacetate (PL‐710) and ethylene glycol oligomer containing organo‐modified montmorillonites (ODA‐M and PGS‐M) by the protonated ammonium cations of octadecylamine and poly(ethylene glycol) stearylamine were prepared by melt intercalation method. In the X‐ray diffraction analysis, the PLA/ODA‐M and plasticized PLA/ODA‐M composites showed a clear enlargement of the difference of interlayer spacing between the composite and clay itself, indicating the formation of intercalated nanocomposite. However, a little enlargement of the interlayer spacing was observed for the PLA/PGS‐M and plasticized PLA/PGS‐M composites. From morphological studies using transmission electron microscopy, a finer dispersion of clay was observed for PLA/ODA‐M composite than PLA/PGS‐M composite and all the composites using the plasticized PLA. The PLA and PLA/PL‐710 composites containing ODA‐M showed a higher tensile strength and modulus than the corresponding composites with PGS‐M. The PLA/PL‐710 (10 wt %) composite containing ODA‐M showed considerably higher elongation at break than the pristine plasticized PLA, and had a comparable tensile modulus to pure PLA. The glass transition temperature (T_g) of the composites decreased with increasing plasticizer. The addition of the clays did not cause a significant increase of T_g. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006