Maleic Anhydride Groups Research Articles

Effect of sequence of melt mixing on the properties and morphology of blends of polypropylene, styrene–ethylene–butylene–styrene copolymer grafted with maleic anhydride, and organophilic montmorillonite clay

Styrene–ethylene–butylene–styrene (SEBS) copolymer, grafted or not, with maleic anhydride and organophilic montmorillonite clay was melt mixed with polypropylene (PP) using different mixing sequences to understand its effect on properties and morphology. The addition of clay changed the blend morphology from large elongated domains to droplets. The nanocomposites without maleic anhydride presented clay in the intercalated form. In the formulation containing maleic anhydride, clay is exfoliated on the blend, indicating that the maleic anhydride group acted to increase the interaction between the clay lamellae and the polymer chains. The best balance of mechanical properties was achieved in the formulation in which the clay was first melt mixed in SEBS without maleic anhydride and afterward melt mixed with clay and PP. It is reported in the literature that nanocomposites with exfoliated structures have better mechanical properties than nanocomposites with intercalated structure. However, in this study, an opposite trend was found, which may be related to the higher amount of crystalline phase formed in the intercalated structure nanocomposites, since the clay intercalation phenomenon in the polymer chains favored the polymer crystallization process.

Study of matrix-filler interaction of polypropylene/silica composite by combined infrared (IR) spectroscopic imaging and disrelation mapping

We demonstrate a Fourier transform infrared (FTIR) spectroscopic imaging combined with two-dimensional (2D) correlation analysis to elucidate matrix-filler interaction of polymer composites. Composite of maleic anhydride grafted polypropylene (MAPP) and silica sphere (SS) was fabricated. The FTIR image and disrelation map derived from sets of FTIR spectra suggest that the maleic anhydride groups in MAPP surround the SS surface and interact with the silanol on the surfaces of SS via hydrogen bonding. This clear link between MAPP and SS indicates that MAPP can be utilized as a suitable amphiphilic compatibilizer for an SS filler when it is mixed with hydrophobic polymer. FTIR imaging analysis was then further extended to categorize the interfacial states of more complicated polymer composites consisting of polypropylene (PP)/SS containing MAPP as a compatibilizer. Probing the interfacial chemical state using FTIR imaging revealed the interaction between MAPP and SS to contribute to improved elastic modulus of PP/MAPP/SS.

Copolymers containing two types of reactive groups: New compatibilizer for immiscible PLLA/PA11 polymer blends

While reactive compatibilization has been widely used, both the compatibilization efficiency and the varieties still need further enhancements. Herein, we demonstrated a novel “Dual-reactive compatibilization” strategy using a compatibilizer containing bifunctional groups. It was shown that the compatibilizer containing two types of reactive groups shows higher compatibilization efficiency as compared with traditional compatibilizer with only one type of reactive groups. Specifically, a series of poly(styrene-co-(glycidyl methacrylate)-co-(maleic anhydride)) ternary copolymers (SGM) containing both reactive epoxide groups and maleic anhydride groups were synthesized and then incorporated into the immiscible poly(amide 11)/poly(l-lactic acid) (PA11/PLLA) blend. The terminal amino groups of PA11 are ready to react with the maleic anhydride groups of the SGM while the carboxyl groups of PLLA react with the epoxide groups of SGM. Double-grafted copolymers with both PA11 and PLLA chains were in-situ formed and located along the PA11-PLLA interface, in which the grafted PLLA chains were buried in PLLA phase while the grafted PA11 chains were immersed in PA11 phase. Thus the compatibility of PA11/PLLA was significantly improved. In addition, the effect of SGM structure on compatibilization efficiency was investigated. The PA11/PLLA (50/50) blends with 3 wt % specific compatibilizer (P(S93-G5-M2)) show the elongation at break and tensile strength of 411% and 57.9 MPa, respectively, the highest values reported so far for the blends. This work provides a new strategy to compatibilize immiscible polymer blends (especially the blends of engineering plastics containing reactive groups). Moreover, the novel bifunctional reactive compatibilizers are also ready for large-scale industrial applications.

Optimization of Maleinized Linseed Oil Loading as a Biobased Compatibilizer in Poly(Butylene Succinate) Composites with Almond Shell Flour.

Green composites of poly(butylene succinate) (PBS) were manufactured with almond shell flour (ASF) by reactive compatibilization with maleinized linseed oil *MLO) by extrusion and subsequent injection molding. ASF was kept constant at 30 wt %, while the effect of different MLO loading on mechanical, thermal, thermomechanical, and morphology properties was studied. Uncompatibilized PBS/ASF composites show a remarkable decrease in mechanical properties due to the nonexistent polymer‒filler interaction, as evidenced by field emission scanning electron microscopy (FESEM). MLO provides a plasticization effect on PBS/ASF composites but, in addition, acts as a compatibilizer agent since the maleic anhydride groups contained in MLO are likely to react with hydroxyl groups in both PBS end chains and ASF particles. This compatibilizing effect is observed by FESEM with a reduction of the gap between the filler particles and the surrounding PBS matrix. In addition, the Tg of PBS increases from −28 °C to −12 °C with an MLO content of 10 wt %, thus indicating compatibilization. MLO has been validated as an environmentally friendly additive to PBS/ASF composites to give materials with high environmental efficiency.

In-vitro degradation behavior and biological properties of a novel maleated poly (D, L-lactide-co-glycolide) for biomedical applications

Synthesized biodegradable polymers with controlled degradability and good biological safety would be useful in biomedical applications. In this work a novel maleated poly(D,L-lactide-co-glycolide) (MPLGA) was melt copolymerized from maleic anhydride, D,L-lactide and glycolide monomers. The degradation behavior in phosphate-buffered solution (PBS) was investigated and the biological properties were studied by using fibroblastic cells cultured in an extract of MPLGA and by an in-vitro cell cytotoxicity test. The results indicated that the MPLGA was successfully obtained using the melt-copolymerization method. The maleic anhydride groups in the MPLGA led to a faster degradation in PBS than PLGA. Fibroblastic cells showed normal morphologies in MPLGA extracts, and the MPLGA materials showed no cell cytotoxicity. The in-vitro biological properties indicated that the obtained MPLGA had good biocompatibility and would be useful for medical applications.

Selectively localized nanosilica particles at the phase interface of PS/PA6/nanosilica composites with co-continuous structure via reactive extrusion

Selectively dispersed functional nanoparticles within one phase or at the phase interface in polymer composites with co-continuous morphology is the most effective way to reduce the percolation threshold of the nanoparticles. In this study, amino-modified nanosilica particles (mSiO2) have been selectively localized at the interface of the PS/PA6/mSiO2 composites with co-continuous morphology via reactive extrusion. Styrene maleic anhydride (SMA) with different maleic anhydride (MAH) contents is used as compatibilizers. Nanosilica particles can be induced to the interface of PS and PA6 phases by SMA macromolecules through the chemical reaction between the amino groups on nanosilica particle surfaces and MAH groups in SMA macromolecules. The MAH content of SMA macromolecules has large effect on the distribution of nanosilica particles. When nanosilica particles are premixed with SMA2, whose MAH content is 23 wt% and more compatible to PA6 phase, only ∼26% of the nanosilica particles can be induced to the interface; However, when nanosilica particles are premixed with SMA3, which contains only 8 wt% of MAH and is more compatible to PS phase, nearly 95% of the nanosilica particles can be located at the interface. This work creates a new facile approach to prepare polymer composites where nanoparticles are selectively distributed at the phase interface.

High-Performance Adhesives Based on Maleic Anhydride-g-EPDM Rubbers and Polybutene for Laminating Cast Polypropylene Film and Aluminum Foil

The adhesion between aluminum (Al) foil and cast polypropylene (CPP) film laminated with mixtures of amorphous- and crystalline-maleic anhydride-grafted ethylene-propylene-diene monomer (MAH-g-EPDM) rubbers and highly reactive polybutene (HRPB) as the adhesives was investigated. Specifically, the HRPB was used as an adhesion promoter of the MAH-g-EPDM rubbers and CPP as well as a compatibilizer of two kinds of MAH-g-EPDM rubbers having limited miscibility. To introduce strong chemical bonds between the MAH-g-EPDM rubbers and Al foil, the surface of Al foil was treated with 3-aminopropyl triethoxysilane (APTES). The weak adhesion between Al foil and MAH-g-EPDM rubbers was improved by imidization between the amine groups (–NH2) of APTES and the maleic anhydride groups (MAH) of MAH-g-EPDM rubbers. The effects of the composition of adhesives, tempering time and adhesive thickness were also studied to optimize the adhesion of the CPP/Al foil laminates. We concluded that MAH-g-EPDM rubber based adhesives containing HRPB can be applied for the lamination of Al foil and CPP films to satisfy the requirements of high-performance packaging materials for various purposes.

Dual sites fluorescence probe for hydrogen sulfide: AIEE activity and supramolecular assembly with β-cyclodextrin

One aggregation-induced emission enhancement (AIEE) active compound based on α–cyanostilbenes and maleic anhydride group were synthesized. The “Turn-On” fluorescence recognition for H2S was evaluated both in aqueous solution and cells. It was found that cyanostilbenes group acts as the first reactive site and maleimide group acts as the second site to H2S. Supramolecular assembly with β-cyclodextrin successfully revealed the reaction mechanism of 3-state model.

Influence of mixing protocol on the morphology and mechanical properties of PP/SEBS/MMT and PP/SEBS/PPgMA/MMT blends

PP/SEBS blends containing MMT and MMT/PPgMA were obtained by extrusion using different mixing protocols. Specimens were subjected to mechanical testing (tensile, flexural and impact tests) and blend morphologies were characterized by SEM, TEM and XRD. MMT and PPgMA incorporation and the mixing protocol were shown to affect morphology (droplet size), whereas MMT location resulted in variations in nanocomposite mechanical properties. The presence of PPgMA attracted the organoclay towards the matrix phase due to the interaction between the functional groups at the MMT surface layers and the maleic anhydride groups. Nanocomposites with or without PPgMA obtained in one step presented higher stiffness, while nanocomposites obtained in two steps presented higher impact strength.

Maleic anhydride‐modified polyolefins as compatibilizer for lignin‐reinforced polypropylene composites

Lignin is an attractive renewable reinforcing agent for polyolefins, which is also an excellent free‐radical scavenger and promising low‐cost antioxidant for polymers, however, exhibiting poor compatibility with non‐polar polymers. In this work, modified polyolefins containing maleic anhydride group like polybond (PB) were used as compatibilizer and incorporated into polypropylene (PP) with lignin to improve the blending ability of the polar filler in the non‐polar matrix. The composite containing individual lignin possesses a much smaller elongation at break than neat PP, whereas owing to the significantly improved dispersion by compatibilizer, the incorporation of compatibilizer into PP/lignin blends gives rise to remarkably increased elongation at break. Besides, lignin greatly slows down the UV‐induced degradation of PP and dramatically enhances anti‐oxidant effect of PP composites in the existence of compatibilizer, in which the elongation at break of PP/PB/2%lignin retains 77% of its original value when it reduces by 92% for neat PP after 240 h of UV irradiation. POLYM. COMPOS., 40:2594–2601, 2019. © 2018 Society of Plastics Engineers

Molecular interactions arising in polyethylene‐bentonite nanocomposites

ABSTRACTHigh density polyethylene (HDPE), linear low density polyethylene (LLDPE) and low density polyethylene (LDPE) are blended, and compared against a similar mixture but functionalized LDPE with maleic anhydride (MAh), HDPE‐LLDPE‐LDPE‐g‐MAh. In order to obtain nanocomposites from these polymer blends, a modified bentonite was added by incorporating l‐lysine into the bentonite galleries by melt extrusion. The resulting nanocomposites presented improved mechanical properties linked to strong polymer‐bentonite interactions and exfoliated structures as verified by transmission electron microscopy and rheometry. A detailed analysis of the feasible polymer‐bentonite interactions was conducted, of particular concern between the polar MAh groups and the intercalated l‐lysine. To gain further insights into the type of molecular interactions (i.e. polymer‐bentonite), a model nanocomposite was synthesized in solution to carry out further assessments through NMR, infrared spectroscopy and rheology analysis. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46920.

Predicting the adhesion strength of thermoplastic/glass interfaces from wetting measurements

To evaluate compatibility between a substrate and a thermoplastic polymer, the established methodology is to estimate their surface composition in terms of surface energy components, utilizing the results of contact angle measurements of probe liquids onto substrate and polymer surfaces at room temperature. Using this methodology, polymer surfaces are studied in solid state, however, during spreading of polymers on a substrate, polymers are in molten state and at high temperature, having different surface energies and more complex polymer/substrate interactions due to polymer chain mobility.This paper presents a model study with practical relevance to predict polymer/substrate compatibility including contact angle measurements at high temperature directly performed between molten thermoplastics; polypropylene (PP), polyvinylidene fluoride (PVDF) and maleic anhydride-grafted polypropylene (MAPP), on smooth glass fibres and plates. The values of total surface energy of thermoplastics at high temperature (260 °C) are down to 57% of that measured at room temperature, which has a strong influence on the wetting prediction. Surface energies of both the polymer and the substrate were found not to be the only factor controlling the wetting behaviour of molten polymers and the level of adhesion with the substrate, but also some intrinsic characteristics of the polymer melt play a role. We also observed that the wetting behaviour of molten MAPP is affected by the maleic anhydride (MA) content, demonstrating dramatically different results to room temperature measurements, which is suspected to be due to the formation of covalent bonds of MA groups with the glass surface enhancing the interface strength beyond the shear strength of MAPP.

Effect of Compatibilization on Biobased Rubber-Toughened Poly(trimethylene terephthalate): Miscibility, Morphology, and Mechanical Properties.

Fabrication of partially biobased poly(trimethylene terephthalate) (PTT) elastomeric blends was done via melt processing. Both natural rubber (NR) and epoxidized NR (ENR) were investigated as impact modifiers at 40 wt % loading to avoid lowering the overall biobased content of the blend system below that of the PTT alone (35% renewable content), along with maleated polybutadiene rubber (MR) and dicumyl peroxide (DCP) as reactive compatibilizers. The compatibility of the blend components was investigated using contact angle, rheometry, and scanning electron microscopy (SEM). The interfacial tensions and work of adhesions indicated that ENR was more miscible than NR in the PTT blend system, which was corroborated by the higher shear viscosity of the ENR blends and strong shear thinning behavior. Additionally, the predictive modeling of viscosity ratios on the elastomer–thermoplastic morphology was found to match the SEM micrographs with the dispersed elastomeric phase within the PTT matrix. The SEM images of the blends also establish that both the compatibilizers reduced the rubber inclusions size, though DCP hampered the impact performance as compared to the MR. In the presence of the MR, there was an increased cross-linking and observed variation in the Fourier transform infrared peaks demonstrating chemical interactions between the maleic anhydride groups with the PTT that allowed for the impact strength to reach 137 J·m–1 or 4.5 times that of the neat PTT, with the modulus of toughness increased by 82% and an elongation at yield of 50% because of the flexibility and amorphous nature of the rubber constituent.

Polymer coating on a micropillar chip for robust attachment of PuraMatrix peptide hydrogel for 3D hepatic cell culture

For better mimicking tissues in vivo and developing predictive cell models for high-throughput screening (HTS) of potential drug candidates, three-dimensional (3D) cell cultures have been performed in various hydrogels. In this study, we have investigated several polymer coating materials to robustly attach PuraMatrix peptide hydrogel on a micropillar chip for 3D culture of Hep3B human hepatic cells, which can be used as a tool for high-throughput assessment of compound hepatotoxicity. Among several amphiphilic polymers with maleic anhydride groups tested, 0.01% (w/v) poly(maleic anhydride-alt-1-octadecene) (PMA-OD) provided superior coating properties with no PuraMatrix spot detachment from the micropillar chip and no air bubble entrapment in a complementary microwell chip. To maintain Hep3B cell viability in PuraMatrix gel on the chip, gelation conditions were optimized in the presence of additional salts, at different seeding densities, and for growth medium washes. As a result, salts in growth media were sufficient for gelation, and relatively high cell seeding at 6 million cells/mL and two media washes for pH neutralization were required. With optimized 3D cell culture conditions, controlled gene expression and compound toxicity assessment were successfully demonstrated by using recombinant adenoviruses carrying genes for green and red fluorescent proteins as well as six model compounds. Overall, PuraMatrix hydrogel on the chip was suitable for 3D cell encapsulation, gene expression, and rapid toxicity assessment.

An insight into the interaction between functionalized thermoplastic elastomer and layered double hydroxides through rheological investigations

Abstract Nanocomposites based on maleated poly(styrene-(ethylene-co-butylene)-styrene) copolymer (SEBSgMA) and organo-modified layered double hydroxide (OLDH) have been formulated with the aim to investigate the effects of interfacial interactions between the grafted maleic anhydride groups of the copolymer and the OLDH nanolayers on the rheological properties of nanocomposites. The spectroscopic analysis indicates the establishment of specific polymer/nanofiller interactions, whose extent has been highlighted through morphological and rheological investigations. Specifically, oscillatory melt rheology and shear relaxation tests have been considered in order to deeply investigate the interfacial bridging interactions. Obtained results highlight that SEBSgMA-based nanocomposites containing a high amount of OLDH show solid-like rheological behavior, quite similar to that of crosslinked polymers, attributable to the formation of a gel-like structure.

Reactive toughening of injection-molded polylactide pieces using maleinized hemp seed oil

The present study describes the effect of maleinized hemp seed oil (MHO) on the physical performance of polylactide (PLA) pieces. To this end, PLA pieces with varying MHO contents in the 0–10 wt% range were manufactured by twin-screw extrusion (TSE) followed by injection molding. The resultant pieces were characterized in terms of their mechanical, thermal, and thermomechanical properties. The obtained properties suggested that, unlike typical plasticizers, MHO does not only induce an increment in elongation at break and impact resistance but it also enhances both elastic modulus and tensile strength. In addition, a moderate decrease in the glass transition temperature (Tg) was observed. This was ascribed to simultaneous linear chain-extension, branching, and/or cross-linking phenomena due to the reaction of the multiple maleic anhydride (MAH) groups present in MHO with the terminal hydroxyl groups of the PLA chains. Furthermore, morphology characterization revealed that, though certain phase separation occurred at its highest content, MHO was finely dispersed as submicron droplets within the PLA matrix contributing to improving toughness. The use of multi-functionalized reactive vegetable oils thus represents a highly sustainable solution to reduce the intrinsic brittleness of PLA materials without compromising their mechanical resistance and the toughened biopolymer pieces described herein can find interesting applications in, for instance, rigid packaging.

The Grafting of PE-g-MA Chains on Graphene Derivatives to Improve Tensile Properties of Polyethylene

Abstract Polyethylene chains having functional maleic anhydride groups were grafted on several graphene derivatives. These chain grafted graphene derivatives were added to polyethylene and the properties of the obtained nano-composites were investigated. Modified Hummers' method was employed to produce graphite oxide (GO). Then amino-functionalized GO (AFGO) was prepared through the functionalization of GO by ethylenediamine. Thermally reduced GO (TRGO) was prepared by the heating of the GO in the presence of nitrogen. TRGO was amino-functionalized to obtain amino functionalized nano-graphite (AFNG). Low density polyethylene (PE) and polyethylene grafted maleic anhydride (PEgMA) nano-composites, containing 1 to 3 wt% of the obtained fillers, were produced by solution mixing. With the incorporation of amino-functionalized graphene into PEgMA, the amine groups on the graphene surface and the maleic anhydride in PE chains covalently bonded and improved the mechanical properties of the nano-composites; by comparing PEgMA nano-composite with 1 wt% AFGO and 1 wt% GO, a 155 percent enhancement in the elongation at break was observed. The modulus and tensile strength of these nano-composites increased over the pure matrix. In addition, the effect of PEgMA content in the 1 wt% AFGO nano-composites was studied and the optimum ratio of PEgMA to PE was found to be 0.40 to 0.60. At this ratio, the best mechanical properties were achieved. Also, at 2 wt% nano-filler the elongation at break of the AFNG nano-composite was higher than that of the TRGO nano-composite. AFNG created more chain grafting but AFNG exfoliates more. The electrical conductivity of TRGO powders by amino-functionalization decreased about 20 times. Therefore, the electrical conductivity of the graphene nano-composites was higher than amino-functionalized graphene nano-composites.

Cellulose nanofibres as biomaterial for nano-reinforcement of poly[styrene-(ethylene-co-butylene)-styrene] triblock copolymer

Cellulose nanofibres (CNFs) obtained from waste mango wood scrap were used for the preparation of nanocomposites with SEBS (poly[styrene-(ethylene-co-butylene)-styrene]) and SEBS-g-MA (SEBS-maleic anhydride grafted). Results revealed the incompatibility of CNFs with unmodified SEBS due to the lack of interaction between polar and nonpolar groups. The polar maleic anhydride groups in SEBS-g-MA (mSEBS) demonstrated a strong interfacial interaction with CNFs showing a compatible association. Nanocomposite films with very minute loading of CNFs [0.005 phr (parts per hundred resin)] resulted in a substantial increment in Young’s modulus (98% increment) and tensile strength (70% improvement) as compared to neat mSEBS film along with increment in elongation at break. The nanocomposite films showed the integration of CNFs as an interwoven thread-like structure in the polymer matrix at 0.001 phr. Polymer coated continuous foam/porous network microstructure was observed at 0.005 phr loading.

Peroxidase chemically attached on polymeric micelle and its reaction with phenolic compounds.

Horseradish peroxidase was chemically modified with comb-shaped polymaleic anhydride-alt-1-tetradecene (PMA-TD) in microemulsion systems to produce surface-active peroxidase that has capability to form micellar structures in aqueous solutions and can be concentrated at liquid/liquid interfaces without unfolding of the enzyme. For chemical modification oil-in-water (O/W) and water-in-oil (W/O) microemulsion systems composed of n-butyl acetate and a buffer solution were prepared because n-butyl acetate turned out to be less detrimental to the activity of peroxidase at high degree of modification compared to other organic solvents. The modification degree of amine groups on the surface of peroxidase by maleic anhydride groups on PMA-TD was reached at equilibrium after 1h reaction at 0°C, and 42% of amine groups were modified with 7-fold amount of PMA-TD to peroxidase (wt/wt). The activity of the PMA-TD-modified peroxidase measured with 2,4-dichlorophenol at pH 7.0 was increased by approximately 2-fold compared to native peroxidase. There was no significant shift in optimum pH after modification, and optimum pH measured with 2,4-dichlorophenol was observed at pH 7.0. For all six phenolic compounds tested, there was a significant increase in the reaction efficiency with the PMA-TD-modified peroxidase. The remarkable enhancement of the reaction efficiency by the modification was presumably because of micellar structures of PMA-TD that could concentrate hydrophobic phenolic oligomers into the core of the micelles. Overall, horseradish peroxidase chemically attached to the surface of PMA-TD micelles was found to be significantly effective for the oxidative polymerization of phenolic compounds.

Biocomposite Fiber-Matrix Treatments that Enhance In-Service Performance Can Also Accelerate End-of-Life Fragmentation and Anaerobic Biodegradation to Methane

Biodegradable resins can enhance the environmental sustainability of wood-plastic composites (WPCs) by enabling methane (CH $$_4$$ ) recovery via anaerobic digestion (AD). An under appreciated step in biocomposite AD is the role of cracking and fragmentation due to moisture uptake by the wood fiber (WF) fraction. Here, we use batch microcosms to simulate AD at end-of-life and to assess the effects of fiber-matrix treatments used to retard in-service moisture uptake. The composites evaluated were injection molded poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) with WF (0, 20%) using two fiber-matrix compatibilization treatments: (1) hydrophobic silane treatment of the wood fiber and (2) grafting of hydrophilic maleic anhydride groups to the PHBV matrix. Both treatments accelerated rates of mass loss and CH $$_4$$ production by a factor of 1.2–2.3 compared to neat PHBV. The fragmentation rate, as measured by mass loss, increased significantly for treated samples compared to untreated samples. A ranking of test samples from lowest to highest rates of mass loss gave the following sequence: neat PHBV $$\approx$$ maleated PHBV < PHBV plus untreated WF < maleated PHBV plus untreated WF < PHBV plus silane-treated WF. Compared to the untreated samples, maleic anhydride treatment increased the mass loss rate by 30%, and silane treatment increased the mass loss rate by 92%. Onset of cracking in silane-treated composites was observed at 2 weeks (using X-ray micro-computed tomography). At the same time, solid mass loss and CH $$_4$$ production peaked, implicating cracking and physical disintegration as the rate-limiting step for accelerated anaerobic degradation. When modified to account for bioplastic matrix degradation, a previously derived moisture-induced damage model could predict the onset of composite fragmentation at end-of-life. These results are significant for design of bio-WPCs and demonstrate that treatments designed to improve in-service performance can also improve end-of-life options.