Co-extruded multilayer shape memory materials: Nano-scale phenomena

Shape memory polymers (SMPs), which demonstrate the ability to possess multiple shapes, are traditionally produced from copolymers and recently from blends. These materials often have phase separated morphologies that possess domain sizes on either the nano- or micro-scale. The observed properties, specifically the shape memory behavior, can be significantly altered by a change in the domain size; however, doing this often requires modification to the materials or material production process. Forced assembly multilayer co-extrusion was used to produce shape memory materials with a continuous layered structure that can be easily tailored to cover layer thicknesses ranging from the nano- to the micro-scale. Upon decreasing the layer thickness of polyurethane/polycaprolactone (PU/PCL) layered films, improvement in the shape fixity and recovery ratios tracked with layer thickness. The improvement in properties was attributed to a change in the PCL crystal orientation from randomly oriented in microlayers to in-plane lamella orientation in nanolayers.     

A novel type of shape memory polymer blend and the shape memory mechanism

A novel styrene-butadiene-styrene tri-block copolymer (SBS) and poly(?-caprolactone) (PCL) blend were introduced for its shape memory properties. Compared to the reported shape memory polymers (SMPs), this novel elastomer and switch polymer blend not only simplified the fabrication process but also offer a controllable approach for the study of mechanisms and the optimization of shape memory performances. Microstructures of this blend were characterized by differential scanning calorimetry (DSC), AFM microscope observation and tensile test. DSC results demonstrated the immiscibility between SBS and PCL. AFM images and stress-strain plot further confirmed the two-phase morphology within the blend. It was found that the SBS and PCL continuous phases contributed to the shape recovery and shape fixing performances, respectively. A detailed shape memory mechanism for this type of SMP system was then concluded and an optimized SMP system with both good recovery and fixing performances was designed from this mechanism.     

Physical characterization and rheological behavior of polyurethane/poly(ϵ-caprolactone) blends,prepared by solution blending using dimethylacetamide

Blending effects of thermoplastic polyurethane based on polycaprolactone diol, PU (PCL diol), and poly (ϵ-caprolactone) (PCL) on the rheological properties and morphological behavior of the solvent-cast blends were investigated by parallel plate rheometer. The amount of PCL was varied from 20 to 50% by weight. Fourier transform infrared (FTIR) results showed existence of hydrogen bonding in PU/PCL blends. From FTIR, we also found the increase of PCL composition tends to reduction of intermolecular hydrogen bonding and enhancing of microphase separation in blends. Differential scanning calorimetry (DSC) indicated that these blend systems are partially miscible. Based on rheological characterization, decrease can be seen in the moduli, zero shear viscosity and plateau modulus of blends, as compared with net PU. Using Cole-Cole plots and composition dependencies of η₀ and the other viscoelastic functions expressed variation of morphology of blends due to increase of PCL content. Frequency sweep tests on PU/PCL (80/20) at five temperatures showed validity of time-temperature superposition in this blend. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Porous inorganic-organic shape memory polymers

Thermoresponsive shape memory polymers (SMPs) are a type of stimuli-sensitive materials that switch from a temporary shape back to their permanent shape upon exposure to heat. While the majority of SMPs have been fabricated in the solid form, porous SMP foams exhibit distinct properties and are better suited for certain applications, including some in the biomedical field. Like solid SMPs, SMP foams have been restricted to a limited group of organic polymer systems. In this study, we prepared inorganic-organic SMP foams based on the photochemical cure of a macromer comprised of inorganic polydimethylsiloxane (PDMS) segments and organic poly(ε-caprolactone) (PCL) segments, diacrylated PCL(40)-block-PDMS(37)-block-PCL(40). To achieve tunable pore size with high interconnectivity, the SMP foams were prepared via a refined solvent-casting/particulate-leaching (SCPL) method. By varying design parameters such as degree of salt fusion, macromer concentration in the solvent and salt particle size, the SMP foams with excellent shape memory behavior and tunable pore size, pore morphology, and modulus were obtained.     

Triple one-way and two-way shape memory poly(ethylene-co-vinyl acetate)/poly(ε-caprolactone) immiscible blends

Triple one-way and two-way shape memory polymers (1W-SMPs and 2W-SMPs) are highly desirable for many practical applications due to the multiple shape transformation. In this work, the blend with co-continuous structure is fabricated based on poly(ethylene-co-vinyl acetate) (EVA) and poly(ε-caprolactone) (PCL), which shows excellent triple one-way and two-way shape memory properties. It is found that the blends have two independent crystallization peaks and two independent melting peaks. With the increase of dicumyl peroxide (DCP) content, the crystallization temperature, melting temperature, and crystallinity of both EVA and PCL in the blends gradually decreases. The blends show great dual and triple one-way shape memory property, and the phenomena of elongation induced by oriented crystallization and contraction induced by melting are clearly seen. Moreover, the blends exhibit remarkable and recyclable triple two-way shape memory performance, with an average shape recovery magnitude of 97.3% and an average actuation magnitude of 50.6%. In terms of the excellent triple one-way and two-way shape memory performance, the EVA/PCL blends may have potential applications in the fields of soft robotics, actuators, and cranes. The new preparation method of triple 2W-SMPs can be used to fabricate other triple 2W-SMPs with commercial polymers.     

Advance application of Raman spectroscopy for quantitative analysis of noncrystalline components in thin films of poly(ε-caprolactone)/poly(butadiene) blends

A quantitative analysis method for the distribution of noncrystalline poly(butadiene) component in poly(ε-caprolactone)/poly(butadiene) (PCL/PB) binary blends have been analyzed by advance application of Raman spectroscopy, optical microscopy, and differential scanning calorimetry (DSC) techniques. Thin films of different compositions of PCL/PB binary blends were prepared from solution and isothermally crystallized at a certain temperature. After calibration with real data, quantitative analyses by Raman spectroscopy revealed the amorphous PB are trapped inside the PCL crystals. Polarized optical microscopy and real time atomic force microscopy were used to collect data for the crystal morphology and crystal growth rate. For pure PCL crystals, a morphology of truncated lozenge shape was observed, independent of crystallization temperature and regardless of the blends compositions. For the pure PCL and their blends, almost unique crystal growth rate was found. The miscibility behaviors using DSC were drawn through melting point depression method. The Hoffman-Weeks extrapolations of the blends were found to be linear and identical with those of the neat PCL. The interaction parameter for the blends indicating that the PCL and PB blends have no intermolecular interaction, confirming the blends are immiscible. Despite the immiscibility of the blend, the PCL crystals do not bend during the growth process and do not reduce the growth rate as they do for miscible blend systems.     

Poly(ether ether ketone)/poly(aryl ether sulfone) blends: Relationships between morphology and mechanical properties

Mechanical properties such as the tensile modulus, yield (break) strength, and elongation to break (or yield) are measured for multiphase poly(ether ether ketone) (PEEK)/poly(aryl ether sulfone) (PES) blends. Specimens with three different levels of thermal histories (quenched, as‐molded, and annealed) are prepared in order to study their effects on the mechanical properties of PEEK/PES blends. Synergistic behavior is observed in the tensile modulus and tensile strength of the blends in almost the whole range of compositions. The ductility of quenched blends measured as the elongation to break (yield) shows an unexpected synergistic behavior in the blend containing 90 wt % PEEK, although a negative deviation from additive behavior is observed in the rest of the compositions. A ductile–brittle transition is observed between 50 and 75 wt % PEEK in the blend. The ductile–brittle transition in as‐molded blends shifts to 75–90 wt % PEEK. Annealed blends show predominantly brittle behavior in the whole composition range. The experimental data are further correlated with the theoretically predicted results based on various composite models. Although the prediction based on these equations fails to fit the experimental data in the whole composition range, the simplex equations that are normally used for blends showing synergistic behavior produced a reasonable fit to the experimental data. The mechanical properties obtained for different blend compositions are further correlated with their morphology as observed by scanning electron microscopy. Morphological observation shows a two‐phase morphology in PES‐rich blends, which is an interlocked morphology in which the disperse phase is not clearly visible in PEEK‐rich blends, and a cocontinuous type of morphology for a 50/50 composition. Considerable permanent deformation of both the disperse and matrix phase, especially in the case of quenched tensile specimens, demonstrates the remarkable adhesion present between the two phases. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2887–2905, 2003     

Triple-shape memory properties of thermoplastic polyurethane/olefin block copolymer/polycaprolactone blends

Thermoplastic polyurethane (TPU)/olefin block copolymer (OBC)/polycaprolactone (PCL) blends (70/20/10 and 50/30/20) were melt-blended to form the first environmental OBC-based triple-shape memory polymer blends. In this work, PCL with low crystalline temperature (switching phase), OBC with medium crystalline temperature (switching phase), and TPU with high crystalline temperature (fixed phase) could form an alternative triple-shape memory polymer (TSMP). Two compatibilizers, OBC-g-glycidyl methacrylate (OBC-g-GMA) and dicumyl peroxide, were confirmed to show a synergistic effect in enhancing the compatibility further through the morphological observation. Crystallinity of both OBC and PCL in the blends with or without modification decreased in comparison with that of pure resin. For dual-shape behaviors, the shape fixing ratio (R_f) and shape recovery ratio (R_r) were up to 96.3% and 91.2% for the GMA and peroxide-modified blends (50/30/20). The higher amount of TPU didn’t give higher recovery ratio, but instead slightly lower R_r due to the morphology difference. For triple-shape behaviors, both TPU/OBC/PCL blend compositions with or without GMA or peroxide modifications gave high R_f(C→B) values in the first fixing stage, but slightly lower values R_f(B→A) in the second fixing stage, especially for (70/20/10) case. On the other hand, a reverse trend was observed for two recovery stages. To enhance the R_f(B→A) in the second fixing stage, higher deformation temperatures were considered, and a measurable increment on R_f(B→A) was attained. Through this subtle adjustment on the temperature difference between high and low deformation temperatures, the theoretical multi-shape memory shape could be readily tailored to meet different applications.     

Crystallization,morphology, and mechanical behavior of polylactide/poly(ε‐caprolactone) blends

Optically pure polylactides, poly(L ‐lactide) (PLLA) and poly(D ‐lactide) (PDLA), were blended across the range of compositions with poly(ε‐caprolactone) (PCL) to study their crystallization, morphology, and mechanical behavior. Differential scanning calorimetry and dynamic mechanical analysis (DMA) of the PLA/PCL blends showed two T_gs at positions close to the pure components revealing phase separation. However, a shift in the tan δ peak position by DMA from 64 to 57°C suggests a partial solubility of PCL in the PLA‐rich phase. Scanning electron microscopy reveals phase separation and a transition in the phase morphology from spherical to interconnected domains as the equimolar blend approaches from the outermost compositions. The spherulitic growth of both PLA and PCL in the blends was followed by polarized optical microscopy at 140 and 37°C. From tensile tests at speed of 50 mm/min Young's modulus values between 5.2 and 0.4 GPa, strength values between 56 and 12 MPa, and strain at break values between 1 and 400% were obtained varying the blend composition. The viscoelastic properties (E′ and tan δ) obtained at frequency of 1 Hz by DMA are discussed and are found consistent with composition, phase separation, and crystallization behavior of the blends. POLYM. ENG. SCI., 46:1299–1308, 2006. © 2006 Society of Plastics Engineers     

Hybrid Electroactive Shape Memory Polymer Composites with Room Temperature Deformability

Polymeric blend shape memory polymers (SMPs) can be constructed from two immiscible polymeric matrices. The shape recovery behavior of these composite systems can be easily controlled by varying the ratio of the polymer blends. It has been recently discovered that the functionality of SMPs can be further enhanced with electroactive ability through the use of conductive fillers. However, the fillers may negatively interact with the SMPs and cause a reduction in the elongation at failure thereby diminishing the shape recovery performance. It is proposed that a plasticizer can be utilized to alter the microstructure of the SMPs with conductive fillers. In this study, a new hybrid SMP is developed by combining single‐walled carbon nanotubes (SWCNT) into a poly(lactic acid) (PLA) and thermoplastic polyurethane (TPU) SMP system containing poly(ethylene glycol) (PEG) plasticizer. The incorporation of PEG is able to lower the activation temperature, while enhancing dispersion of SWCNT. The presence of SWCNT can stabilize the SMP system and significantly enhance the shape‐fixing capability after deformation at room temperature conditions. By carefully controlling the formulation, an electroactive SMP can be created by optimizing the amount of SWCNT and PEG plasticizer.     

The morphology,properties, and shape memory behavior of polylactic acid/thermoplastic polyurethane blends

Biodegradable polylactic acid (PLA) was compounded with thermoplastic polyurethane (TPU) by twin‐screw extrusion at weight ratios of 90/10, 80/20, 70/30, and 60/40. The blends were investigated based on their phase morphology, thermal and mechanical properties, and shape memory properties. The tensile results showed that PLA was successfully toughened by TPU. When the TPU content was 40%, the elongation‐at‐break increased to 400%. The SEM morphology showed that TPU was dispersed uniformly in the PLA matrix; DMA and DSC results indicated that the two polymers were immiscible. Most interestingly, it was found that the blends exhibited a shape memory behavior and, unlike most of the existing shape memory polymers (SMPs), the PLA/TPU blends could be deformed at room temperature without an extra heating and cooling step. During the deformation process, TPU acted as a toughening agent that prevented the PLA/TPU blends from breaking; thus, the temporary shape could be kept and internal stress was stored in the blends. Upon heating to above the glass transition temperature of PLA (about 60°C), the deformed parts regained their original shapes quickly along with the release of the stress. POLYM. ENG. SCI., 55:70–80, 2015. © 2014 Society of Plastics Engineers     

Polycaprolactone-blended gelatin microspheres and their morphological study

Polycaprolactone (PCL)-blended gelatin microspheres were prepared in the size ranges of 5–20 μm as well as 70–340 μm and modified through different compositions of PCL to gelatin in the oil-in-water emulsion solvent evaporation method. The formation of the polymer particles and particle morphology, stability, crystallinity, and thermal behavior of the polymer blends were studied. The changes in physiochemical properties of the blends were also studied with the addition of very less amount of polyvinylpyrrolidone (PVP), as it enhances the particle size distribution of microspheres as well as the surface morphology. Differential scanning calorimetry analysis shows the shifting of exothermic peak in the PCL/gelatin blend, and the PCL/gelatin blend stabilized by PVP results in the decrease in crystallinity. PCL-blended gelatin microspheres were smooth with definite shape and fine dispersibility with the increased concentration of gelatin to the polymer while lower concentration of the gelatin caused agglomeration. Optimization of the gelatin and PVP ratio to the polymer matrix results in large-size spherical stable microparticles. The stabilizing ability of microsphere decreases with the increased concentration of PCL during the solvent evaporation method. The addition of PVP to the PCL/gelatin blend enhanced the particle size distribution of microspheres as well as the surface morphology.     

High-efficiency shape memory copolymers of polycaprolactone/thermoplastic polyurethane fabricated via in situ ring-opening polymerization

Shape memory blends of polycaprolactone/thermoplastic polyurethane (PCL/TPU) were prepared by in situ ring-opening polymerization (ROP) of ε-caprolactone (CL) and thermoplastic polyurethane (TPU). Fourier infrared spectrometer and ¹H-NMR were used to characterize the chemical structure of PCL/TPU copolymers. The results show that TPU has been involved in the ROP of CL, leading to the formation of copolymers with homogeneous morphologies. Besides, pure PCL and all the blends exhibit an excellent shape fixation ratio of 100%, due to their high crystallinity. When a small amount of TPU is introduced, the crystallinity of PCL decreases, and as a result, the shape recovery ratio of the copolymer is enhanced compared with pure PCL. However, with the increased loading of TPU, the content of PCL as the reversible phase decreases and the storage modulus of the PCL/TPU blend declines, so the driving force for the blends to return from the temporary shape to the initial shape becomes smaller, leading to a decrease in the shape recovery ratio. Notably, when the amount of TPU is only 5%, the shape recovery ratio of the blend could reach 83.3%, which is 26% higher than that of pure PCL, and meanwhile, the tensile strength of the blend decreases slightly. This study provides a new strategy for the design of shape-memory materials with high shape-memory properties.     

Preparation and characterization of two-way shape memory olefin block copolymer/silicone elastomeric blends

Very few olefin block copolymer (OBC)-based shape memory polymers (SMPs) studies were reported in the literature so far. This study investigated the preparation of OBC and silicone elastomeric blends (70/30 and 50/50) using a melt-blending technique to form the first two-way OBC-based SMPs, to our best knowledge. Two phr of ((2,5-bis(tert-butylperoxy)-2,5-dimethylhexane (DHBP) was used to prepare flexible OBC/silicone D2 (D2 representing 2 phr of DHBP) networks. DHBP not only assisted the curing of OBC and silicone but also increased their compatibility in the blends. Despite the very low crystallinity of the OBC elastomer component, 10.4%, corresponding to only ~7% based on total resins in the OBC/silicone D2 70/30 blend, the rare two-way shape memory behavior at such a low crystallinity was still envisaged. Regarding two-way shape memory results at various loads, both entropy-driven and crystallization-driven contributions to the overall actuation magnitude (R_act) were at the highest level under 450 kPa, attributing to the highest orientation of molecular networks in the blends. With increasing the applied stress, the R_act of OBC/silicone (70/30) sample increased from 4.1% to 23.7% due to the increased strain-induced crystallization effect confirmed by the XRD (X-ray diffraction) evaluation, while the recovery magnitude (R_rec) was maintained at the high level, close to 90%, without the hindrance of high load on the recovery due to high elasticity of silicone rubber. Besides, the crystallization-driven contribution to the overall actuation magnitude was higher for the blends containing the higher amount of crystalline OBC elastomer in the blends. On behalf of silicone with outstanding thermal stability, high elastic behavior, and high hydrophobicity, OBC/silicone SMP blends with versatile properties could meet different applications.     

Enzymatic degradation of blends of poly(ε‐caprolactone) and poly(styrene‐co‐acrylonitrile) by Pseudomonas lipase

In polymer blends, the composition and microcrystalline structure of the blend near surfaces can be markedly different from the bulk properties. In this study, the enzymatic degradation of poly(ε‐caprolactone) (PCL) and its blends with poly(styrene‐co‐acrylonitrile) (SAN) was conducted in a phosphate buffer solution containing Pseudomonas lipase, and the degradation behavior was correlated with the surface properties and crystalline microstructure of the blends. The enzymatic degradation preferentially took place at the amorphous part of PCL film. The melt‐quenched PCL film with low crystallinity and small lamellar thickness showed a higher degradation rate compared with isothermally crystallized (at 36, 40, and 44°C) PCL films. Also, there was a vast difference in the enzymatic degradation behavior of pure PCL and PCL/SAN blends. The pure PCL showed 100% weight loss in a very short time (i.e., 72 h), whereas the PCL/SAN blend containing just 1% SAN showed ～50% weight loss and the degradation ceased, and the blend containing 40% SAN showed almost no weight loss. These results suggest that as degradation proceeds, the nondegradable SAN content increases at the surface of PCL/SAN films and prevents the lipase from attacking the biodegradable PCL chains. This phenomenon was observed even for a very high PCL content in the blend samples. In the blend with low PCL content, the inaccessibility of the amorphous interphase with high SAN content prevented the attack of lipase on the lamellae of PCL. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 868–879, 2002     

Cover Image,Volume 138, Issue 9

Blends of polypropylene (PP), polyamide 6 (PA6), and biodegradable polymers (BPs) such as poly(D,L-lactic acid) (PDLLA), poly(lactic acid-co-ε-caprolactone) (poly[LA-co-ε-CL]) and poly(ε-caprolactone) (PCL) were prepared using a twin-screw mini-extruder. The composition of the blend PP/PA6 was fixed at a mass proportion of 70/30, and the compatibilized blends contain 5 wt% of each BP. The morphology observed through scanning electronic microscopy, the dynamic mechanical thermal properties (DMTA), and the biodegradation test after composting and performing optical microscopy (OM) of the blends were investigated. The blend PP/PA6 compatibilized with polypropylene grafted with maleic anhydride (PPMA) was also obtained and used as a reference. The results showed that the PP/PA6/PPMA revealed a more homogeneous morphology and resulted in higher modulus; nevertheless, the sample obtained with the lower molar mass PDLLA as an alternative for PPMA showed a storage modulus behavior close to the reference material. Poly(LA-co-ε-CL) and PCL also showed changes in the morphology of the PA6 dispersed phase. Positive results were observed in the biodegradation test examined by OM for all samples containing BPs. The novelty of this work was to employ BPs as compatibilizing agents of the blends comprising PP/PA6, producing ternary blends with superior mechanical properties due to the better dispersion of the phases.     

Miscibility and crystallization behavior of biodegradable poly(ε‐caprolactone)/tannic acid blends

Miscibility, isothermal melt crystallization kinetics, spherulitic morphology and growth rates, and crystal structure of completely biodegradable poly(ε‐caprolactone) (PCL)/tannic acid (TA) blends were studied by differential scanning calorimetry, polarized optical microscopy, and wide angle X‐ray diffraction in detail in this work. PCL and TA are miscible as evidenced by the single composition dependent glass transition temperature over the whole compositions range and the depression of equilibrium melting point of PCL in the PCL/TA blends. Isothermal melt crystallization kinetics of neat PCL and an 80/20 PCL/TA blend was investigated and analyzed by the Avrami equation. The overall crystallization rates of PCL decrease with increasing crystallization temperature for both neat PCL and the PCL/TA blend; moreover, the overall crystallization rate of PCL is slower in the PCL/TA blend than in neat PCL at a given crystallization temperature. However, the crystallization mechanism of PCL does not change despite crystallization temperature and the addition of TA. The spherulitic growth rates of PCL also decrease with increasing crystallization temperature for both neat PCL and the PCL/TA blend; moreover, blending with TA reduces the spherulitic growth rate of PCL in the PCL/TA blend. It is also found that the crystal structure of PCL is not modified in the PCL/TA blend. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Binary and ternary blends of polylactide, polycaprolactone and thermoplastic starch

In this study binary and ternary blends of polylactide (PLA), polycaprolactone (PCL) and thermoplastic starch (TPS) are prepared using a one-step extrusion process and the morphology, rheology and physical properties are examined. The morphology and quantitative image analysis of the 50/50 PLA/TPS blend transverse phase size demonstrate a bimodal distribution and the addition of PCL to form a ternary blend results in a substantial number of fine dispersed particles present in the system. Focused ion beam irradiation, followed by atomic force microscopy (AFM) shows that dispersed PCL forms particles with a size of 370 nm in PLA. The TPS phase in the ternary blends shows some low level coalescence after a subsequent shaping operation. Dynamic mechanical analysis indicates that the temperature of the tan δ peak for the PLA is independent of TPS blend composition and that the addition of PCL in the ternary blend has little influence on the blend transitions. Both the α and β transitions for the thermoplastic starch are highly sensitive to glycerol content. When TPS of high glycerol content is blended with PLA, an increase in the ductility of the samples is achieved and this effect increases with increasing volume fraction of TPS. The ternary blend results in an even greater ductility with an elongation at break of 55% as compared to 5% for the pure PLA. A substantial increase in the notched Izod impact energy is also observed with some blends demonstrating three times the impact energy of pure PLA. The mechanical properties for the ternary blend clearly indicate a synergistic effect that exceeds the results obtained for any of the binary pairs. Overall, the ternary blend approach with PLA/TPS/PCL is an interesting technique to expand the property range of PLA materials.     

Preparation and characterization of shape memory polymer networks based on carboxylated telechelic poly(ɛ-caprolactone)/epoxidized natural rubber blends

Shape memory polymer networks were prepared from blends of end-carboxylated telechelic poly(?-caprolactone) (XPCL) and epoxidized natural rubber (ENR). The XPCL/ENR blends can form cross linked structure via interchain reaction between the reactive groups of each polymer during molding at high temperature. Degree of crosslinking of the blend network and their thermomechanical properties were characterized by gel content measurement, DSC and DMA. We found that the degree of crosslinking and crystalline melting transition temperatures was dependent upon the blend compositions as well as the molecular weight of the XPCL segment in the blends. The blends showed a good shape memory behavior such as good shape fixity as well as a high final recovery rate when they exhibit crystalline melting transition with a sufficiently high degree of crosslinking. And the response temperature of the recovery was well matched with T_m of the samples.     

The physical properties and morphology of poly-ϵ-caprolactone polymer blends

The compatibility, morphology, and mechanical properties of poly-?-caprolactone (PCL) blended with poly(vinyl chloride), nitrocellulose, and cellulose acetate butyrate are described in this study. Methods used in this investigation included differential scanning calorimetry, dynamic mechanical testing, small-angle light scattering, light microscopy and stress–strain testing. Blends of PCL with poly(vinyl chloride) (PVC) are shown to be compatible in all proportions. In the PCL concentration range 40–100%, the PCL crystallizes in the form of negative spherulites. The spherulites were found to be volume filling with as much as 35% PVC. The nitrocellulose blends with PCL exhibited the glass transition behavior of a compatible system over the composition range of 50–100% PCL. At lower PCL concentrations, phase separation was apparent. The PCL crystallinity was present only in the nitrocellulose blends with more than 50% PCL, and it was in the form of rod-like super-structures. Blends of PCL with cellulose acetate butyrate were shown to be phase separated, with one phase having nearly equal proportions of the two polymers. The PCL crystallinity was in the form of negative spherulites and was formed with PCL compositions as low as 50%. Stress–strain results show polycaprolactone to be an effective plasticizer for poly(vinyl chloride) and the cellulose derivatives studied.