New multifunctional poly(lactide acid) composites: Mechanical,antibacterial, and degradation properties

The aim of this work was to study the effect of the innovative combination of microcrystalline cellulose (MCC) and silver nanoparticles (Ag) on the poly (lactide acid) (PLA) composite properties, to modulate the PLA mechanical response and induce an antibacterial effect. The preparation and characterization of PLA‐based composites with MCC and Ag nanoparticles by twin‐screw extrusion followed by injection molding is reported. A film procedure was also performed to obtain PLA and PLA composite films with a thickness ranged between 20 and 60 μm. The analysis of disintegrability in composting conditions by means of visual, morphological, thermal, and chemical investigations was done to gain insights into the post‐use degradation processes. Tensile test demonstrated the MCC reinforcing effect, while a bactericidal activity of silver‐based composites against a Gram‐negative bacteria (Escherichia coli) and a Gram‐positive bacteria (Staphylococcus aureus) was detected at any time points and temperatures analyzed. Moreover, the disintegrability in composting showed that MCC is able to promote the degradation process. The combination of MCC and Ag nanoparticles in PLA polymer matrix offers promising perspectives to realize multifunctional ternary composites with good mechanical response and antibacterial effect, maintaining the optical transparency and the disintegrability, hence suitable for packaging applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of single poly(lactic acid) composites

An approach for making poly(lactic acid) (PLA) single‐polymer composites (SPCs) on the basis of PLA's slowly crystallizing characteristics was investigated. As a slowly crystallizing polymer, PLA can be processed with standard polymer processing techniques into end‐use products with varied crystallinities, from amorphous films to highly crystalline fibers. In this study, amorphous PLA sheets and crystalline PLA fibers/fabrics were laminated and compression‐molded to form an SPC at a processing temperature substantially lower than PLA's melting temperature. The effects of the major process conditions on the performance of the SPC were studied. The processing temperature played a profound role in affecting the fiber–matrix bonding properties. As the processing temperature increased, a drastic improvement in the interfacial bonding occurred at a temperature of around 135°C, which indicated the lower boundary of the process window. The compression‐molded SPC exhibited enhanced mechanical properties; particularly, the tearing strength of the fabric‐reinforced SPC was almost an order higher than that of the nonreinforced PLA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Methanolysis of poly(lactic acid) using acidic functionalized ionic liquids as catalysts

The methanolysis of poly(lactic acid) (PLA) was studied by using acidic ionic liquids (ILs) as catalyst in detail. The results showed that HSO₃‐functionalized ILs exhibited higher catalytic activity than non‐functionalized ILs and traditional acid catalyst such as H₂SO₄. The influences of experimental parameters, such as the amount of catalyst, reaction temperature, methanolysis time, and dosages of methanol on the conversion of PLA, yield of methyl lactate were investigated. Under the optimal conditions, using 1‐methyl‐3‐(3‐sulfopropyl)‐immidazolium hydrogen sulfate ([HSO₃‐pmim][HSO₄]) as catalyst, the IL could be reused up to six times without apparent decrease in the conversion of PLA and yield of methyl lactate. The kinetics of the reaction was also investigated. The results indicated that the methanolysis of PLA in [HSO₃‐pmim][HSO₄] was a first‐order kinetic reaction with activation energy of 47.01 kJ/mol and Arrhenius constant of 2.7 × 10⁷ min^?1. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40817.     

Degradation of poly(L‐lactide) by a mesophilic bacterium

A Gram negative, rod‐shaped mesophilic bacterium active for poly(L ‐lactide) (PLA) degradation was isolated through the enrichment culture and clear‐zone method. The isolated strain was identified to be Bordetella petrii PLA‐3 on the basis of 16S rDNA gene sequence analysis. B. petrii PLA‐3 was active not only for the degradation of low‐molecular‐weight PLA but also for the degradation of high‐molecular‐weight PLA. The strain seemed to attack the crystalline part of PLA as well as the amorphous region. The PLA film incubated in compost inoculated with the isolated strain lost its weight more notably and exhibited a lower molecular weight than that incubated in the sterilized compost without living microorganisms. Moreover, the profile of the cumulative amount of CO₂ after 20 days of burial in the sterilized compost and subsequent inoculation of the isolated strain into compost was nearly the same as that of CO₂ evolved from PLA buried in compost with the isolated strain at the very beginning when the time was shifted by 20 days. This indicated that not only the abiotic hydrolysis but also the microbial enzymes of the strain contributed to the initial chain cleavage of PLA molecules and resolved the doubt that PLA molecules should be initially cleaved into very low‐molecular‐weight substances by abiotic hydrolysis to be subsequently absorbed into and biodegraded by microorganisms. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Investigation of the interaction of CO2 with poly (L‐lactide), poly(DL‐lactide) and poly(ε‐caprolactone) using FTIR spectroscopy

Fourier transform infrared (FTIR) spectroscopy was used to reveal intermolecular interactions between carbon dioxide (CO₂) and the carbonyl groups of poly(L ‐lactide) (PLLA), poly(D,L ‐lactide) (PDLLA), and poly(ε‐caprolactone) (PCL). After exposing polymer films to high pressure CO₂, the wave number of the absorption maxima of the polymer carbonyl groups shifted to higher values. Also, due to the interaction between CO₂ and the carbonyl groups of the polymers, a new broad peak in the bending mode region of CO₂ appeared. To distinguish between polymer‐associated and nonassociated CO₂, and to quantify these contributions, the bending mode peaks were deconvoluted. From these contributions, it was found that in the case of PCL more CO₂ is interacting with the polymer carbonyl groups than in the case of PDLLA and PLLA. Under our experimental conditions, 40°C and pressures up to 8 MPa, a significant depression of the PCL melting temperature was observed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal oxidative degradation kinetics and thermal properties of poly(ethylene terephthalate) modified with poly(lactic acid)

The thermal oxidative degradation kinetics of poly(ethylene terephthalate) (PET) copolymers modified with poly(lactic acid) (PLA) were investigated with thermogravimetric analyzer (TGA). The thermal properties of the modified products were also determined by differential scanning calorimeter (DSC) technique. Waste PET (P100) obtained from postconsumer water bottles was modified with a low‐molecular‐weight PLA. The PET/PLA weight ratio was 90/10 (P90) and 50/50 (P50) in the modified samples. The thermal oxidative degradation kinetics of the modified samples was compared with those of PET (P100). The segmented block and/or random copolymer structure of the modified samples formed by a transesterification reaction between the PLA and PET units in solution and the length of the aliphatic and aromatic blocks were found to have a great effect on the degradation behavior. On the basis of the results of the degradation kinetics determined by Kissinger method, the degradation rate of the samples decreased in the order of P50 > P90 > P100, depending on the amount of PLA in the copolymer structure. However, the degradation activation energies (E_A) of the samples decreased in the order of P100 > P90 > P50. It was concluded that the degradation rate and mechanism were affected significantly by the incorporation of PLA into the copolymer structure. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of terephthalamides from poly(ethylene terephthalate) waste

Poly(ethylene terephthalate) (PET) waste flakes (blow‐molded‐grade industrial waste) were degraded with aqueous methylamine and ammonia at room temperature in the presence and absence of quaternary ammonium salt as a catalyst for various times. The catalyst reduced the time required for the degradation of the PET waste. The degraded products were analyzed with IR, nuclear magnetic resonance, mass spectrometry, and differential thermal analysis and were characterized as N,N′‐dimethylterephthalamide and terephthalamide in the case of methylamine and ammonia, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1515–1528, 2005     

Reactive‐extrusion route for the closed‐loop recycling of poly(ethylene terephthalate)

The effectiveness of the reactive extrusion technique was investigated for poly(ethylene terephthalate) to promote the concept of closed‐loop recycling, that is, the reuse of waste material in the initial application. More specifically, a chain‐extender system, consisting of pyromellitic dianhydride, polyol, and a catalyst, was employed, and its efficiency regarding the improvement of the recyclate quality was evaluated. Accordingly, rheological and thermal characterizations were performed and used as criteria of the modification induced in the polymer molecular structure during processing due to the counteracting degradation and chain‐extension reactions. In particular, the molecular weight, related to intrinsic viscosity and melt flow rate measurements, of modified poly(ethylene terephthalate) samples was found to increase with the additive content. Simultaneously, a decrease in the crystallinity was observed, attributed to the branching effect of the chain extender, which restricted the ability of the macromolecules to organize in the crystal structure. Beyond a critical concentration of the additive system, the molecular weight of the treated samples started to decrease again, and this was accompanied by a small increase in the crystallinity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1671–1678, 2007     

Degradability and biocompatibility of bioglass/poly(amino acid) composites with different surface bioactivity as bone repair materials

Bioglass (BG) possesses excellent bioactivity and has been widely used in the manufacture of biomaterials. In this study, a composite with different surface bioactivity was fabricated via in situ melting polymerization by incorporating BG and poly(amino acid) (PAA) at a suitable ratio. The structure of the composite was characterized by Fourier transform infrared spectroscopy and XRD. The compressive strength of the BG/PAA composites was 139 MPa (BG:PAA = 30:70). The BG/PAA composites were degradable, and higher BG in composite showed higher weight loss after 4 weeks of incubation in simulated body fluid. In addition, the BG/PAA composite maintained adequate residual compressive strength during the degradation period. The SEM results showed the differences in surface bioactivities of the composites directly, and 30BG/PAA composite showed thicker apatite layer and higher Ca/p than 15BG/PAA. in vitro MG-63 cell culture experiments showed that the composite was noncytotoxic and thus allows cells to adhere, proliferate, and differentiate. This indicates that the composite has good biocompatibility. The implantations in the bone defects of rabbits for 4 and 12 weeks were studied. The composites had good biocompatibility and were capable of guiding new bone formation without causing any inflammation. The composite may be successfully used in the development of bone implants.     

Poly(L‐lactide). X. Enhanced surface hydrophilicity and chain‐scission mechanisms of poly(L‐lactide) film in enzymatic,alkaline, and phosphate‐buffered solutions

Attempts were carried out to enhance the surface hydrophilicity of poly(L ‐lactide), that is, poly(L ‐lactic acid) (PLLA) film, utilizing enzymatic, alkaline, and autocatalytic hydrolyses in a proteinase K/Tris–HCL buffered solution system (37°C), in a 0.01N NaOH solution (37°C), and in a phosphate‐buffered solution (100°C), respectively. Moreover, its chain‐scission mechanisms in these different media were studied. The advancing contact‐angle (θ_a) value of the amorphous‐made PLLA film decreased monotonically with the hydrolysis time from 100° to 75° and 80° without a significant molecular weight decrease, when enzymatic and alkaline hydrolyses were continued for 60 min and 8 h, respectively. In contrast, a negligible change in the θ_a value was observed for the PLLA films even after the autocatalytic hydrolysis was continured for 16 h, when their bulk M_n decreased from 1.2 × 10⁵ to 2.2 × 10⁴ g mol^?1 or the number of hydrophilic terminal groups per unit weight increased from 1.7 × 10^?5 to 9.1 × 10^?5 mol g^?1. These findings, together with the result of gravimetry, revealed that the enzymatic and alkaline hydrolyses are powerful enough to enhance the practical surface hydrophilicity of the PLLA films because of their surface‐erosion mechanisms and that its practical surface hydrophilicity is controllable by varying the hydrolysis time. Moreover, autocatalytic hydrolysis is inappropriate to enhance the surface hydrophilicity, because of its bulk‐erosion mechanism. Alkaline hydrolysis is the best to enhance the hydrophilicity of the PLLA films without hydrolysis of the film cores, while the enzymatic hydrolysis is appropriate and inappropriate to enhance the surface hydrophilicity of bulky and thin PLLA materials, respectively, because a significant weight loss occurs before saturation of θ_a value. The changes in the weight loss and θ_a values during hydrolysis showed that exo chain scission as well as endo chain scission occurs in the presence of proteinase K, while in the alkaline and phosphate‐buffered solutions, hydrolysis proceeds via endo chain scission. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1628–1633, 2003     

Hydrolytic degradation of poly(L-lactic acid): Combined effects of UV treatment and crystallization

Amorphous and crystallized poly(L -lactic acid) (PLLA) films were prepared and the hydrolytic degradation of the ultraviolet (UV)-treated and UV-nontreated films was investigated. This study reveals that the combination of UV and thermal treatments can produce the PLLA materials having different hydrolytic degradation profiles and that the UV-irradiation in the environment will affect the design of recycling process for PLLA articles. In an early stage, the degrees of hydrolytic degradation monitored by weight loss (W_loss), number-average molecular weight (M _n), and melting temperature (T _m) were higher for the UV-treated films than for the UV-nontreated films. In a late stage, the trend traced by W_loss was reversed, and the difference in the degrees of hydrolytic degradation between the UV-treated and UV-nontreated films monitored by M _n and T _m became smaller, with the exception of the degrees of hydrolytic degradation of the amorphous films traced by T _m. Also, in the early stage, the degrees of hydrolytic degradation monitored by W_loss and M _n were higher for the crystallized films than for the amorphous films. In the late stage, this trend was reversed, with the exception of the degrees of hydrolytic degradation of the UV-treated films monitored by M _n. The main factors that determined the W_loss and T _m were the molecular weight and initial crystallinty but not the molecular structures such as terminal CC double bonds and crosslinks. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Influence of processing parameters on the degradation of poly(L‐lactide) during extrusion

The influence of processing conditions during melt extrusion on the degradation of poly(L ‐lactide) (PLLA) has been investigated. PLLA polymer was processed by melt extrusion in a double screw extruder at 210 and 240°C. For each extrusion temperature, two screw rotation speeds, 20 and 120 rpm, were used. To investigate the influence of moisture on the thermal degradation during processing, the PLLA granules were dried at 100°C for 5 h and then either extruded directly or conditioned at 65% RH, 20°C for 24 h prior to extrusion. The results show that a decrease in molecular weight measured as number‐average (M_n) molecular weight occurs for all combinations of process parameters used. At processing temperature of 210°C, the change in molecular weight for the dry granules was shown to be dependent on the residence time (i.e., screw rotation speed) in the melt. By changing the screw rotation speed from 120 to 20 rpm at 210°C, M_n decreased from 33,600 to 30,200 g/mol. When the processing temperature was increased to 240°C, the dry granules showed an M_n of 25,600 and 13,600 g/mol when extruded at 120 and 20 rpm, respectively. M_n for the conditioned specimens extruded at 210°C was 18,400 g/mol when processed at 120 rpm and 12,300 g/mol at 20 rpm. When processed at 240°C, 20 rpm, M_n is independent of whether the granules were dry or moist prior to extrusion. It is probably due to the fact that the degradation at 240°C is so extensive that the presence of moisture in the polymer does not contribute further to the degradation process. The stress and strain at break decreased due to degradation and were dependent on the molecular weight of the samples. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2128–2135, 2001     

Pulverization of rubber using modified solid state shear extrusion process (SSSE)

The challenge of reusing scrap rubber material is mainly due to its crosslinked/vulcanized structure, which prevents the material from melting and from being melt processed into new items. The most feasible recycling approach is believed to be a process in which the vulcanized rubber is first pulverized into a fine powder and then incorporated into new products. Solid state shear extrusion (SSSE), developed at Illinois Institute of Technology, is a process for continuous pulverization of rubber materials into a fine powder (Aratoopour, H. U.S. Pat. 5,704,555 15 ; Arastoopour, H.; Schocke, D. A.; Bernstein, B.; Bilgili, E. U.S. Pat. 5,904,885 11 ; Ivanov, G. Polym Eng Sci 18 ). In this work, the design of the SSSE apparatus was modified to overcome heat generation due to pulverization and the limitation from the torque/feeding rate relation and, thus, to increase the efficiency of the process in the production of finer particles at higher throughput. The modification was achieved by separating the original process into the extrusion section and the pulverization section. The extrusion section is dedicated to convey material to the pulverization section, which consists of a cylindrical housing and a rotatable cylindrical element that rotates independent of the extruder's screw. The rotatable cylindrical element can be treaded or flightless. Both sections are connected with an adapter. This new approach to the design allowed us to apply a more efficient cooling system, capable of removing the heat of pulverization and, in turn, results in the production of finer rubber particles. Furthermore, separation of the conveying process from the pulverization process resulted in a reduction in extruder's torque and a significant increase in the throughput. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 119–127, 2006     

Effect of the melting temperature on the crystallization behavior of a poly(l‐lactide)/poly(d‐lactide) equimolar mixture

The effect of the final melting temperature (T_f) on the crystallization of poly(l ‐lactide) (PLLA)/poly(d ‐lactide) (PDLA) was studied via a combination of differential scanning calorimetry, wide‐angle X‐ray scattering, polarized optical microscopy, and Fourier transform infrared (FTIR) spectroscopy. We observed that a residual stereocomplex (SC) crystal induced the formation of SC crystals during cooling from a T_f (230°C) just above the melting peak of the SC crystals. On cooling from a T_f (240°C) just above the endset temperature of SC crystal melting [T_m(S)(E)], the possible order structure and the strong interchain interaction promoted the preferential crystallization of SC crystals; this enhanced the formation of α crystals. During cooling from a T_f (≥250°C) far above T_m(S)(E), the crystallization peaks of α and SC crystals converged. The FTIR results indicated that the residual SC crystals, possible ordered structure, and interchain interactions in the melt might have been the key factors for the different crystallization of PLLA/PDLA. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43015.     

Enhanced toughness and strength of poly (d‐lactide) by stereocomplexation with 5‐arm poly (l‐lactide)

The enhancement of mechanical properties were achieved by solution blending of poly(d ‐lactide) (PDLA) and 5‐arm poly(l ‐lactide) (5‐arm PLLA). Differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD) results indicated almost complete stereocomplex could be obtained when 5‐arm PLLA exceeded 30wt %. Tensile test results showed that the addition of 5‐arm PLLA in linear PDLA gave dramatically improvement both on tensile strength and elongation at break, which generally could not be increased simultaneously. Furthermore, this work transformed PDLA from brittle polymer into tough and flexible materials. The mechanism was proposed based on the TEM results: the stereocomplex crystallites formed during solvent evaporation on the blends were small enough (100–200 nm), which played the role of physical crosslinking points and increased the interaction strength between PDLA and 5‐arm PLLA molecules, giving the blends high tensile strength and elongation at break. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42857.     

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.     

Chitosan from Muga silkworms (Antheraea assamensis) and its influence on thermal degradation behavior of poly(lactic acid) based biocomposite films

The research work is focused on extraction of chitin from Muga silkworms (MS) and its conversion into chitosan by chemical treatment process. The extracted amount of chitin and chitosan from MS were obtained ～8 wt % and ～7 wt %, respectively. Potentiometric titrations, conductometric titrations, elemental analysis, ¹H‐NMR and FTIR analyses were employed to calculate the degree of deacetylation of chitosan (extracted at 80 ºC after 10 h) and found as 77% ± 2, 81% ± 1.8, 82% ± 2.4, 97.77% ± 0.3, and 82% ± 1.8, respectively. The deacetylation process of chitin showed pseudo‐first order reaction kinetics and activation energy was estimated as ～15.5 kJ/mole. The extracted chitosan (at 80 ºC after 10 h) showed higher crystallinity and improved thermal stability with respect to chitosan extracted from other marine sources. Subsequently, poly(lactic acid) (PLA) and extracted chitosan dispersed biocomposite films were prepared by solution casting method. Significant dispersion of chitosan (extracted at 80 ºC after 10 h) micro‐particles were observed in biocomposite films using FESEM analysis. Due to chitosan interaction with PLA, significant reduction in thermal degradation and activation energy was observed during nonisothermal degradation scan of such films using Flynn‐Wall‐Ozawa and Kissinger‐Akahira‐Sunose models. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43710.     

In vitro degradation of poly(L-lactic acid) fibers produced by melt spinning

In vitro degradation of poly(L -lactic acid) fibers was investigated for a period of 16 weeks in Ringer solution at 37°C. Two sets of fibers, with similar initial mechanical properties, molar mass, and crystallinity content, but markedly different in diameter (72 and 120 μm) were studied. Viscometric molar mass decreased during the immersion time at a faster rate for the thinner fibers compared to the thicker ones. As a consequence, the fiber mechanical properties changed; the elastic modulus was only slightly affected by the molar mass decrease whereas ultimate mechanical properties (stress and strain at break) showed a strong decrease. A quantitative correlation between tensile strength and viscometric-average molar mass was attempted. A possible explanation of the faster degradation rate of the thinner fibers was proposed on the basis of the higher surface/volume ratio and water uptake. Dynamic mechanical properties were also measured as a function of immersion time. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 213–223, 1997     

Fabrication and surface characterization of electrosprayed poly(L‐lactide) microspheres

Electrospraying is a one‐step technique for fabricating polymeric microspheres/nanospheres, and the surface characterization of polymeric microspheres fabricated under high voltage is different from an emulsion method. In this study, biodegradable poly(l ‐lactide) (PLLA) microspheres were successfully fabricated by electrospraying, and electrospraying parameters were used to investigate the size and ζ potential of the electrosprayed PLLA microspheres. The results demonstrate that electrospraying was a one‐step method for fabricating monodispersed PLLA microspheres with a size of 1.92 ± 0.35 μm and that the enrichment of methyl groups on the surface of the microspheres contributed to the strong hydrophobicity of electrosprayed PLLA microspheres. Of all the electrospraying parameters investigated, the size and ζ potential of the PLLA microspheres increased with increasing solution concentration and flow rate and decreased with increasing injection voltage and collecting distance. The results provide a theoretical basis for preparing electrosprayed polymeric microspheres as drug carriers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Hydrolysis reaction of poly(ethylene terephthalate) using ionic liquids as solvent and catalyst

The hydrolysis of poly(ethylene terephthalate) (PET) was studied using ionic liquid 1‐n‐butyl‐3‐methylimidazolium chloride ([Bmim][Cl]) as solvent and acid‐functionalized ionic liquid 1‐methyl‐3‐(3‐sulfopropyl)‐imidazolium hydrogen sulfate ([HSOpmim][HSO₄]) as catalyst. The effects of temperature, time, and dosages of solvent and catalyst on hydrolysis results were examined. Under the optimum conditions of m(PET) : m(H₂O) : m([Bmim][Cl]) : m([HSOpmim][HSO₄]) = 3 : 4 : 6 : 0.6, reaction temperature 170°C and time 4.5 h, the conversion of PET and the yield of terephthalic acid (TPA) were almost 100% and ≥88%, respectively. After easily separated from the product, the ionic liquids could be reused eight times without obvious decrease in the conversion of PET and yield of TPA. Hence, an environmental friendly strategy for chemical recycling of PET was developed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009