Crystallization kinetics of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) blends

The crystallization kinetics of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) (PET/PEN) blends were investigated by DSC as functions of crystallization temperature, blend composition, and PET and PEN source. Isothermal crystallization kinetics were evaluated in terms of the Avrami equation. The Avrami exponent (n) is different for PET, PEN, and the blends, indicating different crystallization mechanisms occurring in blends than those in pure PET and PEN. Activation energies of crystallization were calculated from the rate constants, using an Arrhenius‐type expression. Regime theory was used to elucidate the crystallization course of PET/PEN blends as well as that of unblended PET and PEN. The transition from regime II to regime III was clearly observed for each blend sample as the crystallization temperature was decreased. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 23–37, 2001     

Effects of electron beam irradiation on poly(ethylene 2,6‐naphthalate)/poly(ethylene terephthalate) blends

The effect of electron beam (EB) irradiation on the properties and compatibility of poly(ethylene 2,6‐naphthalate) (PEN)/poly(ethylene terephthalate) (PET) blends was investigated. Upon EB irradiation, PEN/PET blends underwent transesterification reactions, resulting in the formation of more random copolymers from the original binary pair. The degree of transesterification increased with dose rate, and all of the irradiated blends exhibited a single glass transition temperature. This indicated that transesterification reactions promoted by EB irradiation led to the formation of a single phase. Transesterification reactions promoted by EB irradiation led to more random copolymers, and the reduced regularity in the irradiated blends decreased the melting temperature. A higher degree of randomness and lower number‐average sequence lengths for the blend systems indicated that a more random chain structure was formed in the blends. The rheological measurements demonstrated that the irradiated PEN/PET blends were miscible. EB irradiation could promote transesterification reaction, thus enhancing the compatibility of PEN/PET blends.     

Reactive blending of poly(ethylene terephthalate)(pet)/ poly(ethylene 2,6‐naphthalate)(pen). I: Effect of mixing conditions on chain structure

Reactive blending of poly(ethylene terephthalate)/poly(ethylene naphthalene 2,6dicarboxylate) with addition of 2,2'‐bis(1,3‐oxazoline) (BOZ) has been studied under various mixing conditions for the different compositions. The transesterification level, the sequence length of both PET and PEN short blocks, and the degree of randomness were estimated using¹H NMR. The results indicate that both mixing time and temperature are the primary factors controlling the transesterification, while the chain extender BOZ can significantly accelerate the transesterification between PET and PEN at 275°C. The composition also, to some extent, influences the transerification level as the mixing time is increased. As a consequence of transesterification proceeding, the sequence structures of the reactive blends are also markedly changed, which corresponds to a transfer from an initial block structure to a multiblock structure with higher randomness. The change in the microstructure of the reactive blends has also been analyzed by a Bernoullian statistics model. The effect of the BOZ on the intrinsic viscosity of the reactive blends is discussed.     

Influence of the mixing time on the phase structure and glass‐transition behavior of poly(ethylene terephthalate)/poly(ethylene‐2,6‐naphthalate) blends

Blends of poly(ethylene terephthalate) and poly(ethylene‐2,6‐naphthalate) (70 : 30 w/w) were prepared via a melt‐mixing process at 280°C with various mixing times. The melt‐mixed blends were analyzed by magnetic resonance spectroscopy, differential scanning calorimetry, dynamic mechanical measurements, transmission electron microscopy, and tensile tests. The results indicate that the blends mixed for short times had lower extents of transesterification and were miscible to a limited extent. The blends initially show two glass transitions, which approached more closely and merged gradually with increasing mixing time. A mechanical model was used to help understand the glass‐transition behavior. With increasing mixing time, the phase structure of the blends improved, and this led to an increase in the tensile strength. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Transesterification in poly(ethylene terephthalate) and poly(ethylene naphthalate 2,6-dicarboxylate) blends: model compounds study

Kinetics of transesterification reaction in poly(ethylene terephthalate)-poly(ethylene naphthalate 2,6-dicarboxylate), PET-PEN, blends resulting from melt processing was simulated using model compounds of ethylene dibenzoate (BEB) and ethylene dinaphthoate (NEN). The exchange reaction between BEB and NEN was followed by ¹H NMR spectroscopy using signals from the aliphatic protons of ethylene glycol moieties at 4.66 and 4.78 ppm, respectively. The first-order kinetics was established under pseudo-first-order conditions for both reactants. Thus, the overall transesterification reaction was second order reversible. The reversibility was confirmed experimentally by heating a mixed sequence of 1-benzoate 2-naphthoate ethylene (BEN) under similar conditions. Both forward reaction of the equimolar amounts of the reagents and reverse reaction came to equilibrium at the same molar ratio of the reactants and reaction products of roughly 0.25:0.50:0.25 for BEB, BEN, and NEN, respectively. The rate equation for the transesterification reaction in the model system was modified using half-concentration of BEN, which is the only effective in the intermolecular exchange. Direct ester-ester exchange was deduced as a prevailing mechanism for the transesterification reaction under the conditions studied, and the values of equilibrium and rate constants, as well as other basic thermodynamic and kinetic parameters were determined. The use of Zn(OAc)₂ as a catalyst resulted in a significant decrease in the activation enthalpy of transesterification, which might be due to the partial switch of the reaction mechanism from primarily pseudo-homolytic to more heterolytic where Zn^II acts as a Lewis base which binds to the ester carbonyl oxygen.     

Transesterification reactions in triphenyl phosphite additivated‐poly(ethylene terephthalate)/poly(ethylene naphthalate) blends

The occurrence of transesterification reactions in poly(ethylene terephthalate) (PET)/poly(ethylene naphthalate) (PEN) blends prepared in presence of triphenyl phosphite (TPP) was investigated. When PEN was processed with TPP, which is a known chain extender for PET, chain extension reactions also took place. Torqueprocessing time curves obtained during preparation of 75/25 PET/PEN blends containing TPP, showed a build‐up profile followed by a fast decrease that was interpreted as chain extension between blend components and degradation due to phosphite residues formation, respectively. Although transesterification inhibition was expected, this type of reaction was not suppressed by TPP.     

Miscibility and transesterification in ternary blends of poly(ethylene naphthalate)/poly(pentamethylene terephthalate)/poly(ether imide)

Miscibility and morphology of poly(ethylene 2,6‐naphthalate)/poly(pentamethylene terephthalate)/poly(ether imide) (PEN/PPT/PEI) blends were studied by differential scanning calorimetry (DSC), optical microscopy (OM), proton nuclear magnetic resonance imaging (¹H‐NMR), and wide‐angle X‐ray diffraction (WAXD). OM and DSC results from ternary blends revealed the immiscibility of PEN/PPT/PEI blends, but ternary blends of all compositions were phase‐homogeneous following heat treatment at 300°C for over 60 min. Annealing samples at 300°C yielded an amorphous blend with a clear and single T_g at the final state. Experimental data from ¹H‐NMR revealed that PEN/PPT copolymers (ENPT) were formed by the so‐called transesterification. The effect of transesterification on glass transition and crystallization was discussed in detail. The sequence structures of the copolyester were identified by triad analysis, which showed that the mean sequence lengths became shorter and the randomness increased with heating time. The results reveal that a random copolymer improved the miscibility of the ternary blends, in which, the length of the homo segments in the polymer chain decreased and the crystal formation was disturbed because of the irregularity of the structure, as the exchange reaction proceeded. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3840–3849, 2006     

Transesterifications of poly(bisphenol A carbonate) with aromatic and aliphatic segments in ethylene terephthalate–caprolactone copolyester

In this article, transesterification of poly(bisphenol A carbonate) (PC) with a ethylene terephthalate–caprolactone copolyester at a weight ratio 50/50 (TCL50) was investigated by infrared spectroscopy (IR), proton nuclear magnetic resonance spectroscopy (¹H‐NMR), and a model compound. The IR and ¹H‐NMR results showed that transesterification occurred between PC and ethylene terephthalate (ET) segments in TCL50 and resulted in the formation of bisphenol A–terephthalate ester units as in the annealed blend of PC with the PET homopolyester. By comparison with a model compound, the new signal at 2.55 ppm in the ¹H‐NMR spectrum confirmed the appearance of bisphenol A–caprolactone ester units resulting from the exchange reaction of PC with caprolactone (CL) segments. The ¹H‐NMR analysis of the transesterification rates revealed that the reactions of PC with aromatic and aliphatic segments in TCL50 proceeded in a random or free manner. In addition, we separately examined the interchange reaction between a PC and poly(ε‐caprolactone) (PCL) homopolyester in an annealed blend. It was found that in the presence of a Ti compound catalyst the predominant reaction was a transesterification rather than a thermooxidative branching reaction. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1558–1565, 2001     

Role of 2‐hydroxyethyl end group on the thermal degradation of poly(ethylene terephthalate) and reactive melt mixing of poly(ethylene terephthalate)/poly(ethylene naphthalate) blends

In an attempt to minimize the acetaldehyde formation at the processing temperatures (280–300°C) and the outer–inner transesterification reactions in the poly (ethylene terephthalate) (PET)–poly(ethylene naphthalate) (PEN) melt‐mixed blends, the hydroxyl chain ends of PET were capped using benzoyl chloride. The thermal characterization of the melt‐mixed PET–PEN blends at 300°C, as well as that of the corresponding homopolymers, was performed. Degradations were carried out under dynamic heating and isothermal conditions in both flowing nitrogen and static air atmosphere. The initial decomposition temperatures (T_i) were determined to draw useful information about the overall thermal stability of the studied compounds. Also, the glass transition temperature (T_g) was determined by finding data, indicating that the end‐capped copolymers showed a higher degradation stability compared to the unmodified PET and, when blended with PEN, seemed to be efficient in slowing the kinetic of transesterification leading to, for a finite time, the formation of block copolymers, as determined by ¹H‐NMR analysis. This is strong and direct evidence that the end‐capping of the ? OH chain ends influences the mechanism and the kinetic of transesterification. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Effects of molecular weight on phase structure of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) blends

The phase structure of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) (PET/PEN) blends was studied in relation to the molecular weight. The samples were prepared by both solution blends, which showed two glass‐transition temperatures (T_g), and melt blends (MQ), which showed a single T_g, depending on the composition of the blends. The T_g of the MQ series was independent of the molecular weight of the homopolymer, although the degree of transesterification in the blends was affected by the molecular weight. The MQ series showed two exotherms during the heating process of a differential scanning calorimetry scan. The peak temperature and the heat flow of the exotherms were affected by the molecular weight of the homopolymers. The strain‐induced crystallization of the MQ series suggested the independent crystallization of PET and PEN. Based on the results, a microdomain structure of each homopolymer was suggested. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2428–2438, 2005     

Properties of poly(ethylene terephthalate)–poly(ethylene naphthalene 2,6‐dicarboxylate) blends with montmorillonite clay

The production and properties of blends of poly(ethylene terephthalate) (PET) and poly(ethylene naphthalene 2,6‐dicarboxylate) (PEN) with three modified clays are reported. Octadecylammonium chloride and maleic anhydride (MAH) are used to modify the surface of the montmorillonite–Na⁺ clay particles (clay–Na⁺) to produce clay–C18 and clay–MAH, respectively, before they are mixed with the PET/PEN system. The transesterification degree, hydrophobicity and the effect of the clays on the mechanical, rheological and thermal properties are analysed. The PET–PEN/clay–C18 system does not show any improvements in the mechanical properties, which is attributed to poor exfoliation. On the other hand, in the PET–PEN/clay–MAH blends, the modified clay restricts crystallization of the matrix, as evidenced in the low value of the crystallization enthalpy. The process‐induced PET–PEN transesterification reaction is affected by the clay particles. Clay–C18 induces the largest proportion of naphthalate–ethylene–terephthalate (NET) blocks, as opposed to clay–Na⁺ which renders the lowest proportion. The clay readily incorporates in the bulk polymer, but receding contact‐angle measurements reveal a small influence of the particles on the surface properties of the sample. The clay–Na⁺ blend shows a predominant solid‐like behaviour, as evidenced by the magnitude of the storage modulus in the low‐frequency range, which reflects a high entanglement density and a substantial degree of polymer–particle interactions. Copyright © 2005 Society of Chemical Industry     

Glass‐transition and melting behavior of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) blends

The glass‐transition temperatures and melting behaviors of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) (PET/PEN) blends were studied. Two blend systems were used for this work, with PET and PEN of different grades. It was found that T_g increases almost linearly with blend composition. Both the Gibbs–DiMarzio equation and the Fox equation fit experimental data very well, indicating copolymer‐like behavior of the blend systems. Multiple melting peaks were observed for all blend samples as well as for PET and PEN. The equilibrium melting point was obtained using the Hoffman–Weeks method. The melting points of PET and PEN were depressed as a result of the formation of miscible blends and copolymers. The Flory–Huggins theory was used to study the melting‐point depression for the blend system, and the Nishi–Wang equation was used to calculate the interaction parameter (χ₁₂). The calculated χ₁₂ is a small negative number, indicating the formation of thermodynamically stable, miscible blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 11–22, 2001     

Phase separation,physical properties and melt rheology of a range of variously transesterified amorphous poly(ethylene terephthalate)–poly(ethylene naphthalate) blends

Amorphous, partially transesterified poly(ethylene terephthalate)/poly(ethylene naphthalate) (PET/PEN) blends of different levels of transesterification and blend composition were investigated in terms of resultant phase behavior, thermal transitions, and melt rheological properties. Intrinsic viscosities of the lowest transesterified material were found to be significantly below those of a physical blend of an identical composition, but at higher levels of transesterification, there was little difference. This was similarly found in melt rheometry measurements, where the zero‐shear rate viscosity of the low and highly transesterified mixtures were similar. Both solution and melt rheometry indicated that the molecular weight decreased by thermal degradation from processing. This is believed to play an important role in determining the final molecular architecture and properties. For similar levels of ester interchange, there was a minimum observed in zero shear melt viscosity at around 40 wt % PEN. This is likely due to competition between the slightly transesterified copolymer chains having poorer packing in the melt and reduced entanglement. Differential scanning calorimetry and dynamic mechanical thermal analysis were used to investigate the phase behavior of partially and fully transesterified blends. Results for the glass transition of the highly transesterified blends were compared with the theoretical values calculated from the Fox equation and were found to be close, although slightly lower. A correlation between the melting temperature of the blend and the degree of transesterification was shown to exist. This correlation can be used to estimate the degree of ester exchange reaction from these melting transitions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1556–1567, 2002     

Synthesis and characterization of a poly(ether–ester) copolymer from poly(2,6 dimethyl‐1,4‐phenylene oxide) and poly(ethylene terephthalate)

A series of poly(ether–ester) copolymers were synthesized from poly(2,6 dimethyl‐1,4‐phenylene oxide) (PPO) and poly(ethylene terephthalate) (PET). The synthesis was carried out by two‐step solution polymerization process. PET oligomers were synthesized via glycolysis and subsequently used in the copolymerization reaction. FTIR spectroscopy analysis shows the coexistence of spectral contributions of PPO and PET on the spectra of their ether–ester copolymers. The composition of the poly(ether–ester)s was calculated via ¹H NMR spectroscopy. A single glass transition temperature was detected for all synthesized poly(ether–ester)s. T_g behavior as a function of poly(ether–ester) composition is well represented by the Gordon‐Taylor equation. The molar masses of the copolymers synthesized were calculated by viscosimetry. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Modification of bismaleimide resin by poly(ethylene phthalate‐co‐ethylene terephthalate), poly(ethylene phthalate‐co‐ethylene 4,4′‐biphenyl dicarboxylate), and poly(ethylene phthalate‐co‐ethylene 2,6‐naphthalene dicarboxylate)

Aromatic polyesters were prepared and used to improve the brittleness of bismaleimide resin, composed of 4,4′‐bismaleimidodiphenyl methane and o,o′‐diallyl bisphenol A (Matrimid 5292 A/B resin). The aromatic polyesters included PEPT [poly(ethylene phthalate‐co‐ethylene terephthalate)], with 50 mol % of terephthalate, PEPB [poly(ethylene phthalate‐co‐ethylene 4,4′‐biphenyl dicarboxylate)], with 50 mol % of 4,4′‐biphenyl dicarboxylate, and PEPN [poly(ethylene phthalate‐co‐ethylene 2,6‐naphthalene dicarboxylate)], with 50 mol % 2,6‐naphthalene dicarboxylate unit. The polyesters were effective modifiers for improving the brittleness of the bismaleimide resin. For example, inclusion of 15 wt % PEPT (MW = 9300) led to a 75% increase in fracture toughness, with retention in flexural properties and a slight loss of the glass‐transition temperature, compared with the mechanical and thermal properties of the unmodified cured bismaleimide resin. Microstructures of the modified resins were examined by scanning electron microscopy and dynamic viscoelastic analysis. The toughening mechanism was assessed as it related to the morphological and dynamic viscoelastic behaviors of the modified bismaleimide resin system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2352–2367, 2001     

Primary structure and physical properties of poly(ethylene terephthalate)/poly(ethylene naphthalate) resin blends

The morphology and properties of blends of poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET) that were injection molded under various conditions were studied. Under injection molding conditions that make it possible to secure transparency, blends did not show clear crystallinity at blending ratios of more than 20 mol% in spite of the fact that crystallinity can be observed in the range of PEN content up to 30 mol%. Because both transparency and crystallinity could be secured with a PEN 12 mol% blend, this material was used in injection molding experiments with various injection molding cycles. Whitening occurred with a cycle of 20 sec, and transparency was obtained at 30 sec or more. This was attributed to the fact that transesterification between PET and PEN exceeded 5 mol% and phase solubility (compatibility) between the PET and PEN increased when the injection molding time was 30 sec or longer. However, when the transesterification content exceeded 8 mol%, molecularly oriented crystallization did not occur, even under stretching, and consequently, it was not possible to increase the strength of the material by stretching. PET/PEN blend resins are more easily crystallized by stretch heat‐setting than are PET/PEN copolymer resins. It was understood that this is because residual PET, which has not undergone transesterification, contributes to crystallization. However, because transesterification reduces crystallinity, the heat‐set density of blends did not increase as significantly as that of pure PET, even in high temperature heat‐setting. Gas permeability showed the same tendency as density. Namely, pure PET showed a substantial decrease in oxygen transmission after high temperature heat‐setting, but the decrease in gas permeability in the blend material was small at heat‐set temperatures of 140°C and higher.     

Preparation and biodegradation of copolyesters based on poly(ethylene terephthalate) and poly(ethylene glycol)/oligo(lactic acid) by transesterification

The poly(ethylene terephthalate‐co‐ethyleneoxide‐co‐DL ‐lactide) copolymers were successfully prepared by the melt reaction between poly(ethylene terephthalate), poly(ethylene glycol), and DL ‐oligo(lactic acid) without any catalysts. The transesterification between ethylene terephthalate, ethyleneoxide, and lactide segments during the reaction was confirmed by the ¹H NMR analysis. The effect of reaction temperatures and the starting feed ratios on the molecular microstructures, molecular weights, solubility, thermal properties, and degradability of the copolyesters was extensively studied. The values of crystallization temperature, melting temperature, crystallization, and melting enthalpy of the copolyesters were found to be influenced by the reaction temperatures, starting feed ratios, etc. The copolyesters showed good tensile properties and were found to degrade in the soil burial experiments during the period of 3 months. The morphology of the copolyester films were also investigated by scanning electron microscopy during soil burial degradation. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Microstructure and crystallization of melt‐mixed poly(ethylene terephthalate)/poly(ethylene isophthalate) blends

Physical blends of poly(ethylene terephthalate) (PET) and poly(ethylene isophthalate) (PEI), abbreviated PET/PEI (80/20) blends, and of PET and a random poly(ethylene terephthalate‐co‐isophthalate) copolymer containing 40% ethylene isophthalate (PET₆₀I₄₀), abbreviated PET/PET₆₀I₄₀ (50/50) blends, were melt‐mixed at 270°C for different reactive blending times to give a series of copolymers containing 20 mol % of ethylene isophthalic units with different degrees of randomness. ¹³C‐NMR spectroscopy precisely determined the microstructure of the blends. The thermal and mechanical properties of the blends were evaluated by DSC and tensile assays, and the obtained results were compared with those obtained for PET and a statistically random PETI copolymer with the same composition. The microstructure of the blends gradually changed from a physical blend into a block copolymer, and finally into a random copolymer with the advance of transreaction time. The melting temperature and enthalpy of the blends decreased with the progress of melt‐mixing. Isothermal crystallization studies carried out on molten samples revealed the same trend for the crystallization rate. The effect of reaction time on crystallizability was more pronounced in the case of the PET/PET₆₀I₄₀ (50/50) blends. The Young's modulus of the melt‐mixed blends was comparable to that of PET, whereas the maximum tensile stress decreased with respect to that of PET. All blend samples showed a noticeable brittleness. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3076–3086, 2003     

Mechanism and kinetics of transesterification in poly(ethylene terephthalate) and poly(ethylene 2,6-naphthalene dicarboxylate) polymer blends

In a previous work [L. Alexandrova, A. Cabrera, M.A. Hernández, M.J. Cruz, M.J.M. Abadie, O. Manero, D. Likhatchev, Polymer 43 (2002) 5397. [1]], a model compounds study on the kinetics of a transesterification reaction in poly(ethylene terphthalate)-poly(ethylene naphthalene 2,6-dicarboxylate), PET-PEN blends, resulting from melt processing, was simulated using model compounds of ethylene dibenzoate (BEB) and ethylene dinaphthoate (NEN). A first-order kinetics was established under pseudo first-order conditions for both reactants, and thus the overall transesterification reaction was second-order reversible. Direct ester-ester exchange was deduced as a prevailing mechanism for the transesterification reaction under the conditions studied.In this work, the actual PET-PEN system was melt processed by mixing the polymers below the critical reaction temperature in a twin-screw extruder. Thereafter, the reaction was induced by temperature in open glass ampoules. A second order reversible kinetics was measured, in agreement with the kinetics established in the previous model compounds study. The equilibrium constant value corresponds to a forward rate constant which is four times larger than the reverse rate constant. The activation thermodynamic parameters confirmed the direct ester-ester exchange mechanism for the reaction.     

On the interrelationship of transreaction with viscoelastic properties of poly(ethylene terephthalate)/poly(ethylene naphthalate) blends in the presence of nanoclay

An attempt was made to explore the effects of the interchange reactions on the viscoelastic behavior of binary blends based on poly(ethylene terephthalate) (PET)/poly(ethylene naphthalate) (PEN) and their nanocomposites. It was seen that with an increase in the number of extrusion runs and mixing temperature, the extent of reaction (X) and degree of randomness (RD) both increased, whereas the average sequence block lengths values were decreased. On the contrary, the blend composition did not play a significant role on X and RD values. Addition of nanoclay inhibited the transreactions in PET/PEN blends. The absence of crystallization peaks implied that the crystalline structure was destroyed as a result of blending and an amorphous system was created possibly due to the transreactions simultaneously with the formation of random copolymers inhibiting the crystallization process. The rheological investigations showed that the addition of PEN into the PEN/PET blends enhanced the storage modulus, loss modulus, and complex viscosity. The viscosity upswing observed at low‐frequency region in the case of nanocomposite systems evidently confirmed the occurrence of transreactions. Nonetheless, a significant increment in the viscoelastic properties was perceived in the presence of nanoclay corroborating the proper nanoclay distribution throughout the PET/PEN blend system. POLYM. ENG. SCI., 53:2556–2567, 2013. © 2013 Society of Plastics Engineers