Synthesis and properties of ethylene‐substituted styrene copolymers

The copolymerization of ethylene and substituted styrenes [RSt's; p‐methylstyrene (MSt), p‐tert‐butylstyrene (BSt), 2‐vinylnaphthalene (VN), and p‐(tert‐butyldimethylsilyloxy)styrene (BMSiOSt)] were investigated with dimethylsilylene(tetramethylcyclopentadienyl)(N‐tert‐butyl)titanium dichloride to yield the corresponding ethylene–RSt copolymers. The substituent on the styrene (St) monomers did not affect the monomer reactivity ratio. The effect of the substituent structure of RSt on the thermal and mechanical properties was studied with differential scanning calorimetry, dynamic mechanical thermal spectroscopy, and elongation testing. The glass‐transition temperature (T_g) of the copolymers increased with increasing RSt content, and the order of T_g was as follows: BSt > VN > MSt = St. A copolymer with p‐hydroxystyrene (HOSt) was successively synthesized by means of deprotection of the copolymer with BMSiOSt. The copolymer showed a much higher T_g than the other copolymers because of the hydrogen connection of its OH groups. The mechanical properties of the copolymer in the glass state, at a lower temperature than T_g, were almost independent of the nature of the RSt. The substituent of the St monomers affected the pattern of the stress–strain curve in the elongation testing in the amorphous state. An improvement in the shape memory effect was observed in poly(ethylene‐co‐BSt). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Novel latent initiator for cationic polymerization of epoxides

A novel latent initiator for cationic polymerization of epoxides, a composite catalyst containing aluminum complexes and phenol derivatives protected with tert‐butoxycarbonyl groups (tBOC), is reported. At a certain temperature, protected phenols generate the parent phenols which are coinitiators with aluminum complexes. The deprotection temperature of the tBOC group depends on the structure of the phenol moieties. Bis(p‐t‐butoxycarbonyloxyphenyl)sulfone (Ph1) generates (p‐dihydroxyphenyl)sulfone (PhH1) at around 150°C, the temperature at which the curing of epoxides is conventionally carried out. The thermally generated PhH1 and aluminum complexes initiate the curing of epoxides. Epoxy resin compositions containing these composite catalysts have a long shelf life at room temperature and are cured at around 150°C, showing that the composite catalyst has excellent latent properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 181–187, 2001     

Morphology and photophysical properties of a thermally responsive fluorescent material based on a rod‐coil tri‐block copolymer

A thermally responsive rod‐coil poly[poly (N‐isopropylacrylamide)‐b‐polyfluorene‐b‐poly(N‐isopropylacrylamide)] triblock copolymer has been successfully synthesized by atom transfer radical polymerization from an end‐functionalized macroinitiator. The thermochromic behavior and relevant morphology of this polymer were investigated by UV‐vis spectra, DLS, and AFM, respectively, at various temperatures. A thermally responsive fluorescent material was achieved facilely by combining the optically active polyfluorene with temperature‐responsive poly(N‐isopropylacrylamide). All the measurements demonstrated that in the region of 25–45°C, the polymer underwent a phase transition and the corresponding change in optical properties in its water solution. However, the polymer did not show completely reversible behavior upon heating and cooling. On the basis of the comparison with two other thermally responsive conjugated polymers in literatures, a tentative mechanism has been proposed that π–π interaction induced rigid segments to remain chain conformation and packing styles as in collapsed state. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polymerization of N-(tert-butyldimethylsilyloxy)maleimide and applications of the polymers as resist materials

A new silicon-containing maleimide monomer, N-(tert-butyldimethylsilyloxy)-maleimide (SiOMI) has been synthesized. SiOMI was radically copolymerized with styrene derivatives (XSt) to obtain alternating copolymers, P(SiOMI/XSt), in high conversions. The copolymers have high glass transition temperatures above 190°C, and the tert-butyldimethylsilyloxy groups are thermally stable up to 300°C. The SiOMI units in the copolymers were converted into N-hydroxymaleimide (HOMI) units by acidolytic deprotection of the tert-butyldimethylsilyloxy protecting groups. The facile deprotection of the side-chain tert-butyldimethylsilyloxy groups from the protected copolymers provided a significant change in solubility of the polymers due to the large polarity change. Submicron positive-tone images were obtained from the copolymers containing an onium salt as a photoacid generator by irradiation with electron beam and development with alkaline solutions. The polymer films also showed very high oxygen plasma etch resistance compared with novolac resins. The silicon-containing maleimide polymers were found to have required properties, such as good alkaline solubility after deprotection, superior adhesion, low optical density, high thermal stability with high T_g, and high plasma etch resistance for applications as deep ultraviolet and electron beam resist materials. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2507–2516, 1997     

Synthesis of a photo‐patternable cross‐linked epoxy system containing photodegradable carbonate units for deep UV lithography

Bis(2‐(oxiran‐2‐ylmethyl)‐1,3‐dioxoisoindolin‐5‐yl) carbonate and polymers containing 9‐anthracenylmethylmethacrylate (AMMA), p‐tert‐butoxy styrene (PTBS), and methacrylic acid (MAA) monomeric units were synthesized with the aim of developing a novel photo‐patternable cross‐linked epoxy system. The oxirane groups in bis(2‐(oxiran‐2‐ylmethyl)‐1,3‐dioxoisoindolin‐5‐yl) carbonate were reacted with the carboxylic acid in the polymer to generate a cross‐linked epoxy film, and the photo degradation of the cross‐linked film was achieved through decomposition of the carbonate groups in the cross‐linked film by deep UV irradiation. Because the copolymer containing anthracene groups has relatively high reflective index and absorption at 248 nm, this cross‐linked system can be applied to patternable bottom antireflective coating materials for deep UV lithography applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Temperature‐responsive alginate‐g‐poly(N,N‐diethylacrylamide) copolymer: Synthesis,characterization, and swelling behavior

Temperature‐responsive polymers have recently gained importance due to their applications in drug delivery. Herein, temperature‐responsive graft copolymer (Alg‐g‐PDEAAm) of alginate and N,N‐diethylacrylamide was synthesized by microwave‐assisted copolymerization using potassium persulfate/N,N,N′,N′‐tetramethylethylenediamine initiator system. The reaction conditions for the best grafting (331%) have been optimized by changing microwave irradiation time, temperature, N,N‐diethylacrylamide, and alginate concentrations. The spectroscopic characteristic, thermal properties, and surface morphology of the copolymers were investigated by FTIR, ¹H‐NMR, DSC/TGA, XRD, gel permeation chromatography, and SEM. Furthermore, low critical solution temperatures of Alg‐g‐PDEAAm copolymers were detected by UV spectroscopy. Swelling ratio of graft microspheres was carried out at 25, 32, and 37 °C, and microspheres were found exhibiting temperature‐responsive property. Cytotoxicity test indicated the Alg‐g‐PDEAAm copolymer and its microsphere were biocompatible. Therefore, based on the results the synthesized temperature‐responsive copolymer could be considered as a promising biomaterial. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46688.     

Synthesis and reactivity of functionalized alkoxyamine initiators for nitroxide‐mediated radical polymerization of styrene

The synthesis and examination of different functionalized (2,2,6,6‐tetramethyl‐1‐piperidinyloxy free radical) TEMPO‐containing alkoxyamine initiators for nitroxide‐mediated radical polymerization of styrene are reported. Initiators with ester and carbonate functional groups were synthesized by a low‐temperature radical‐abstraction reaction of the functionalized ethylbenzene in the presence of TEMPO to introduce the functional groups onto the initiating chain‐end of polystyrene. An initiator with two alkoxyamine groups symmetrically located at each end of a carbonate bond was also synthesized and used for nitroxide‐mediated styrene polymerization. Styrene polymerization using these initiators followed first‐order kinetics up to approximately 60 min at 140 °C or 30% monomer conversion. Alkoxyamines bearing an acetoxy or tert‐butylcarbonate group at the p‐position of 1‐(2,2,6,6‐tetramethyl‐1‐piperidinyloxy)ethylbenzene behave in a similar way to the unfunctionalized initiator. With an initiator containing two alkoxyamine groups, the resulting polymer molecular weight was twice that of the polymer obtained from initiators with only one alkoxyamine group, as expected from propagation from both chain‐ends. Upon hydrolysis of the carbonate bond, it was revealed that equivalent polymer chain growth occurred from each alkoxyamine site in the difunctional initiator. Copyright © 2003 Society of Chemical Industry     

Preparation of doubly responsive polymer functionalized silica hybrid nanoparticles via a one‐pot thiol‐isocyanate click reaction at room temperature

Well‐defined poly(N‐isopropylacrylamide) and poly(2‐(diethylamino) ethyl methacrylate) were synthesized first by a reversible addition‐fragmentation chain transfer process. These polymers were then reduced to generate an end thiol group to react with isocyanate groups on the surface of silica nanoparticles, which were pretreated with toluene‐2,4‐diisocyanate, by a one‐pot “click” reaction to prepare temperature and pH responsive polymer functionalized hybrid silica nanoparticles. The polymer functionalized silica hybrid nanoparticles were characterized by a range of techniques such as Fourier transform infrared spectroscopy and dynamic light scattering. The doubly responsive polymer functionalized silica hybrid nanoparticles show both temperature and pH responsive behavior and their solution properties were dependent on the ratio of the two polymers on the surface of silica. Covalent functionalization of the silica nanoparticle with well‐defined temperature and pH responsive polymers was accomplished via a one‐pot thiol‐isocyanate click reaction. This reaction was found to be extremely efficient in producing doubly responsive polymer functionalized silica hybrid nanoparticle, even at relatively low reaction temperature and short reaction time. Thermogravimetric analysis indicated that the same ratio of poly(N‐isopropylacrylamide) and poly(2‐(diethylamino)ethyl methacrylate) functionalized silica hybrid nanoparticle consisted of 42.46 wt% polymer. POLYM. COMPOS., 38:1454–1461, 2017. © 2015 Society of Plastics Engineers     

Preparations and properties of thermosensitive terpolymers of N‐isopropylacrylamide,sodium 2‐acrylamido‐2‐methyl‐propanesuphonate,and N‐tert‐butylacrylamide

Terpolymers based on N‐isopropylacrylamide, sodium 2‐acrylamido‐2‐methyl‐propanesulfonate, and N‐tert‐butylacrylamide were synthesized by free‐radical copolymerization with 2,2′‐azobisisobutyronitrile as an initiator. The lower critical solution temperatures (LCSTs) of the linear polymer aqueous solutions were determined by the measurement of the transmittance on UV at different temperatures. The influence of the polymer concentration, polymer composition, and ionic strength on the LCSTs of the linear polymers was investigated. The LCST decreased with increases in the hydrophobic monomer N‐tert‐butylacrylamide, polymer concentration, and ionic strength. The phase transition became sharp when the polymer concentration and ionic strength increased. Meanwhile, the crosslinked hydrogels were prepared with the same recipe used for the linear terpolymers, but a crosslinker was added to the reaction system. The swelling ratios of the hydrogels at various temperatures and salt solutions were determined. The hydrogels possessed both high swelling ratios and thermosensitivity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Functionalization of high‐density polyethylene in the molten state by glycidyl methacrylate grafting

:This study concerns the melt‐free radical grafting of glycidyl methacrylate (GMA) onto high‐density polyethylene (HDPE). We studied the effect of two initiators (tert‐butyl cumyl peroxide and di‐tert‐butyl peroxide) onto HDPE. Crosslinking of polymer was observed in the presence of 0.3 wt % tert‐butyl cumyl peroxide but not with 0.3 wt % di‐tert‐butyl peroxide. The grafting was carried out in a Brabender batch mixer at 190 °C. The grafting yield of GMA onto HDPE (determined by infrared spectrometry) is weak (<1 wt % for an initial concentration in monomer of 6 wt %). Moreover, it was noted that the degree of grafting did not vary with the concentration and the nature of peroxide used. To increase the grafting yield of GMA, we added to the HDPE/peroxide/GMA system an electron‐donating monomer, such as styrene. Adding this comonomer multiplied the rate of grafted GMA 3‐ or 4‐fold, resulting in a ratio [styrene]_i/[GMA]_i = 1 mol/mol with [GMA]_i = 6 wt %. So, the copolymerization is favored compared with the homopolymerization. This kind of copolymer presenting reactive functions is very attractive in the field of compatibilizing immiscible polymers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 581–590, 2001     

Preparation and characterization of poly(silyl ester)s containing 2,2‐bis(p‐dimethylsiloxy‐phenyl)propane units in the polymer backbones

The two poly(silyl ester)s containing 2,2‐bis(p‐dimethylsiloxy‐phenyl)propane units in the polymer backbones have been prepared via polycondensation reaction of di‐tert‐butyl adipate and di‐tert‐butyl fumarate with 2,2‐bis(p‐chloro dimethylsiloxy‐phenyl)propane to give tert‐butyl chloride as the condensate. The polymerizations were performed under nitrogen at 110°C for 24 h without addition of solvents and catalysts to obtain the poly(silyl ester)s with weight average molecular weights typically ranging from 5000 to 10,000 g/mol. Characterization of the poly(silyl ester)s included ¹H NMR and ¹³C NMR spectroscopies, infrared spectroscopy, ultraviolet spectroscopy, differential scanning calorimetry, thermogravimetric analysis (TGA), gel permeation chromatography, and Ubbelohde viscometer. The glass transition temperatures (T_g) of the obtained polymers were above zero because of the introducing 2,2‐bis(p‐dimethylsiloxy‐phenyl)propane units in the polymer backbones. The TGA/DTG results showed that the obtained poly(silyl ester)s were stable up to 180°C and the residual weight percent at 800°C were 18 and 9%, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1937–1942, 2006     

Thermomechanical and electroactive behavior of a thermosetting styrene‐based carbon black shape‐memory composite

A thermosetting styrene‐based shape memory polymer (SMP) filled with nanoscale (30 nm) carbon black are prepared to reinforce the thermomechanical performances and realize the high‐efficient electronic actuation at macro scale due to the carbon–carbon network morphology at nano/micro scale. The elastic modulus of this thermosetting SMP composite is significant strengthened and can maintain at 1–2.5 GPa at around the room temperature, which is suitable for used as a structural material. The electronic resistivity decreases sharply at a quite low percolation threshold range (2–5%), and maintains at a relatively low and stable level of electronic resistivity. Furthermore, the electronic resistivity also exhibits relative stability in terms of the resistivity–temperature–time relationship and the evolution of resistivity upon heating–cooling cycles. This shape memory styrene‐based composite is suitable to be used as an electroactive functional material in realistic engineering. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45978.     

Preparation of heat‐resistant branched poly(styrene‐alt‐NPMI) by ATRP with divinylbenzene as the branching agent

Heat‐resistant branched poly(styrene‐alt‐NPMI) has been prepared via atom transfer radical polymerization (ATRP) of styrene (St) and N‐phenyl maleimide (NPMI) with divinylbenzene (DVB) as the branching agent in anisole at 80°C. Gas chromatography (GC) was used to determine the conversion of the reactants. Triple detection gel permeation chromatography (TD‐GPC) was used to analyze the copolymers. The results show that the polymerization yields primary chains predominately in the early stages and the formation of branched molecules occurs mainly when conversion is higher than 50%. As expected, higher dosage of DVB in our investigation range favors the formation of polymers with higher degree of branching. All the resulting branched poly(styrene‐alt‐NPMI)s have glass transition temperature (T_g) above 175°C, extrapolated initial weight loss temperature (T_i) above 410°C and statistic heat‐resistant index above 200°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation,photoisomerization, and microfabrication with two‐photon polymerization of crosslinked azo‐polymers

We report the preparation, photoisomerization properties, and three‐dimensional (3D) microstructure fabrication with two‐photon polymerization of crosslinked azo‐polymers. A series of bi‐acrylate‐substituted azobenzene derivatives were designed and synthesized as the monomers and/or crosslinkers of the crosslinked azo‐polymers. The doping concentration of the derivatives in pre‐polymer resins was significantly increased due to the introduction of bulky tert‐butyl and flexible alkyl chains. The double‐exponential dynamics of trans‐to‐cis photoisomerization of the azo‐polymers indicated the coexistence of different processes for the azobenzene moieties in the polymeric crosslinked networks. The crosslinked azo‐polymers exhibited ideal “on–off” switching performance in the highly reversible trans–cis–trans isomerization cycles. Furthermore, we prepared a photoresist containing the azobenzene derivative for 3D microstructure fabrication based on two‐photon polymerization. A woodpile photonic crystal with a photonic bandgap at telecommunication wavelength region was successfully fabricated with the azobenzene‐containing photoresist, which would open the way for the design and manufacturing of miniature optical communication devices. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2947–2956, 2013     

Synthesis and tunable thermoresponsive solution morphologies of 2,2‐bis‐methylolpropionic acid dendron–azobenzene–poly(N‐isopropyl acrylamide) copolymers

Amphiphilic temperature‐ and photoresponsive linear–dendritic block copolymers comprising second‐generation acetonide‐2,2‐bis‐methylolpropionic acid‐based polyester dendron and linear poly(N‐isopropyl acrylamide) (PNIPAM) linked by an azobenzene unit were synthesized using atom transfer radical polymerization (ATRP) followed by click chemistry. Linear PNIPAM precursor was prepared from an azide‐functionalized azobenzene containing ATRP initiator. Two polymers obtained by varying the chain length of the PNIPAM block showed different morphologies and lower critical solution temperature (LCST) values in aqueous solution. Complete change in morphology of the two polymers into large spherical aggregates and nanotubes, respectively, was observed upon heating the micellar solution above LCST. The azobenzene unit was found to undergo trans–cis photoisomerization in the assemblies and caused a change in the microenvironment of an encapsulated hydrophobic dye without any release. Acetonide groups on the dendron were deprotected to afford hydroxylated polymer that showed well‐defined morphologies above the LCST and after heating–cooling cycle while significant dye encapsulation was seen only above the LCST. © 2017 Society of Chemical Industry     

Novel fully conjugated 2H‐ and metal‐phthalocyanine network polymers: Synthesis,characterization, and dielectric spectra analysis

2,7‐di‐tert‐butylpyrene was oxidized to 2,7‐di‐tert‐butylpyrene‐4,5,9,10‐tetraone. The latter through condensation reactions with vicinal diamine such as 4,5‐diaminophthalonitrile produced heterocyclic monomer, 2,7‐di‐tert‐butyl pyrene[4,5][9,10]bisquinoxaline‐6,7‐dinitrile, which was cyclo‐tetramerized to the corresponding tetra[2,3‐(1,4‐diaza‐6,6‐di‐tert‐butylphenanthreno)[4,5]phthalocyanine]‐based network polymer (2H‐Pc), and tetra [2,3‐(1,4‐diaza‐6,6‐di‐tert‐butylphenanthreno)[4,5]phthalo‐cyaninato metal II‐based network polymers (M‐Pc, M= Co, Ni, Zn, or Cu). Elemental analytical results, IR and NMR spectral data of the new prepared molecules are consistent with their assigned formulations. Molecular masses and metal contents of the synthesized polymers proved to be of high molecular masses which confirm the efficiency of tetramerization polymerization and complexation reactions. The dielectric constant (ε′) and dielectric loss tangent (tan δ) were studied as a function of temperature and frequency. The detailed analysis of the results showed that the dielectric dispersion consists of both dipolar and interfacial polarization. Measurements of ac conductivity as a function of frequency at different temperatures revealed that the nonoverlapping small polaron tunneling is the most suitable mechanism for ac conduction behavior. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Blending of styrene‐block‐butadiene‐block‐styrene copolymer with sulfonated vinyl aromatic polymers

Different polymers containing sulfonic groups attached to the phenyl rings were prepared by sulfonation of polystyrene (PS) and styrene‐block‐(ethylene‐co‐1‐butene)‐block‐styrene (SEBS). The sulfonation degree (SD) was varied between 1 and 20 mol% of the styrene units. Polyphase materials containing sulfonated units were prepared by blending styrene‐block‐butadiene‐block‐styrene (SBS), with both sulfonated PS and sulfonated SEBS in a Brabender mixer. Such a procedure was performed as an alternative route to direct sulfonation of SBS which is actually not selective towards benzene rings because of the great reactivity of the double bonds in polybutadiene (PB) blocks to sulfonation agents. Thermal and dynamic‐mechanic analysis, together with morphology characterization of the blends, is consistent with obtaining partially compatible blends characterized by higher T_g of the polystyrene domains and improved thermal stability. © 2001 Society of Chemical Industry     

The use of acrylated fatty acid methyl esters as styrene replacements in triglyceride‐based thermosetting polymers

Resins containing plant oil‐based cross‐linkers were studied with two reactive diluents: a styrene and an acrylated fatty acid methyl ester‐based (AFAME) monomer. Acrylated epoxidized soybean oil and maleinated castor oil monoglyceride were bio‐based cross‐linkers used. The viscosity and mechanical properties of the resulting polymers were measured and analyzed. Both bio‐based cross‐linkers prepared using the modified AFAME as diluent had a fairly high viscosity, so blends of AFAME and styrene were needed to meet the viscosity requirements established by the composite industry (<1000 cP at room temperature). In addition, the glass transition temperature (T_g) and stiffness of bio‐based cross‐linker/AFAME polymers were significantly lower than the resin/styrene polymers. Ternary blends of maleinated castor oil monoglyceride with AFAME and styrene improved the mechanical properties to acceptable comparable values (storage modulus at 30°C ～ 1200 MPa and T_g ～ 100°C). The addition of 5 wt% of chemically modified lignin led to an improvement in the mechanical properties of the polymeric matrix but caused an increase in the viscosity. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Visible‐light‐induced controlled/living radical polymerization of styrene with a phenyl seleno group at one terminal chain end: 1‐(Phenylseleno)ethyl benzene as a photoiniferter

The photopolymerization of styrene with a well‐defined molecular architecture and a low polydispersity index and with methyl and phenylseleno (? SePh) groups at α‐ and ω‐chain ends, respectively, was performed via a controlled/living radical polymerization with a new initiating system, 1‐(phenylseleno)ethyl benzene/tert‐butyl diphenyl (phenylseleno) silane, through the absorption of visible light at room temperature. A novel initiating living radical polymerization was examined. The yield and number‐average molecular weight (M_n) of the resulting polymer increased with the reaction time. Furthermore, a linear relationship was found in a plot of M_n versus the polymer yield. These results indicated that this polymerization proceeded through a living radical mechanism. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 348–355, 2004     

Thermodynamic hydrogen bonding inpoly(styrene‐co‐acrylic acid)/poly(styrene‐co‐4‐N,N‐dimethylacrylamide) blends

FTIR study of the hydrogen bonding interactions within blends of different ratios of poly(styrene‐co‐acrylic acid) containing 18, 27, and 32 mol% of acrylic acid (SAA) and poly(styrene‐co‐N,N‐dimethylacrylamide) containing 17 mol% of N,N‐dimethylacrylamide (SAD‐17) was carried out qualitatively and quantitatively in the temperature range varying from room temperature to 210°C. Two new bands characterizing these interactions appeared in the 1800–1550 cm^–1 region at 1730 cm^–1 and 1616 cm^–1 and are attributed to “liberated” carbonyl group of the acidic copolymer and the “associated amide” carbonyl group, respectively. Equilibrium constants describing both the self‐association K₂ and inter‐association K_A and the enthalpy of hydrogen bonding formation in the different blends were experimentally determined using a curve fitting analysis of the infra‐red spectra as a function of temperature using the appropriate equations derived from the Painter‐Coleman association model. The obtained results confirm the miscibility of these blends in the considered temperature range from the negative values of the total free energy of mixing ΔG_M. Optimization of the extent of intermolecular interactions between the two polymers in these blends is investigated. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers