Nanostructure of Potato Starch,Part I: Early Stages of Retrogradation of Amorphous Starch in Humid Atmosphere as Revealed by Simultaneous SAXS and WAXS

Crystallization experiments on amorphous, injection-molded starch in a humid atmosphere are reported. The crystallization mechanisms have been studied using simultaneous SAXS and WAXS during a temperature stepwise increase. In contrast to the crystallization of linear synthetic polymers, in starch the WAXS peaks are observed at low temperature before the appearance of the SAXS maximum. The initial state of crystallization is dominated by the amylose (AM) component of the potato starch alone. After the initial formation of large (16 nm) uncoordinated individual crystallites, stacks of lamellae and finally, an insertion of thinner lamellae within the stacks are observed. Results indicate that only if all AM is converted into a semicrystalline structure and if the secondary starch network of double helices of AM and amylopectin (AP) is molten by a temperature increase above 70°C, crystallization of AP also occurs. Because the AM crystals act as nuclei for the AP component, a common superstructure is developed. Within a spherulite, alternating AM and AP lamellae develop radially from the center of the AP molecule. Results suggest that the AM is distributed inhomogeneously with respect to the AP molecules, leaving approximately one half of the AP fraction free, which means not crystallized to a spherulitic structure together with AM.     

Cold Crystallization of PLLA Studied by Simultaneous SAXS and WAXS

Summary: The cold crystallization process of initially amorphous poly(L ‐lactic acid), PLLA, with two different molecular weights, during a heating at 2 °C/min, was investigated by DSC and time‐resolved simultaneous SAXS and WAXS, using synchrotron radiation. Equatorial scans of the isotropic 2D‐SAXS patterns showed that the average Bragg long period (L_B) of PLLA samples was approximately constant with the development of cold crystallization up to a temperature that corresponded to a melt/re‐crystallization process that took place before the nominal melting peak seen by DSC. L_B values were found to be higher for the high molecular weight material. This was in accordance with the higher melting temperature observed in the high molecular weight PLLA that implied the existence of thicker lamellae. WAXS results showed that the molecular weight did not apparently affect the crystal form and the final degree of crystallinity of PLLA. The Avrami parameters from WAXS and DSC were consistent, showing that the non‐isothermal cold crystallization of the two PLLA samples corresponded mainly to a three‐dimensional growth, although an imperfect crystallization process was involved at early times. The crystallization rate of PLLA, observed both by WAXS and DSC, decreased with increasing molecular weight.

SAXS profiles of PLLA2 as a function of temperature. The inset shows the 2D‐SAXS pattern obtained at 180 °C.     

Development of crystallinity in NEW-TPI polyimide

Development of crystallinity in NEW-TPI semicrystalline polyimide has been studied using differential scanning calorimetry (DSC), wide (WAXS), and small angle X-ray scattering (SAXS). Crystallinity of the fully imidized powder, pellet, or film processed NEW-TPI can occur from the melt, and depends upon the holding temperature of the melt. Repetitive exposure to elevated temperatures supresses the development of crystallinity from the melt state. In amorphous pellets and film, crystallinity can also develop by cold crystallization from the rubbery amorphous state. SAXS results show that during cold crystallization, NEW-TPI develops a periodic structure consistent with formation of alternating crystalamorphous stacks, but with crystals only a few molecular repeat units thick. Kinetics of nonisothermal crystallization were studied as a function of heating rate and could be described using the Ozawa analysis. Non-isothermal crystallization proceeds at a slower rate in NEW-TPI than in other high temperature thermoplastics such as PEEK, and with a much narrower processing window. The maximum degree of crystallinity that could develop during heating was 0.34, which occurred at a rate of 5°C/min. Similar degrees of crystallinity could be introduced by heating amorphous NEW-TPI film in N-methylpyrrolidone.     

Nanostructure of potato starch. II. Structure of a highly crystalline gel obtained by retrogradation using X‐ray diffraction techniques

A highly crystalline gel (65% crystal portions) was prepared by retrogradation of injection‐molded potato starch in humid atmosphere. The different components of the nanostructure were identified by means of successive melting processes using “in situ” simultaneous wide and low angle X‐ray diffractions. At low temperatures, structural changes such as annealing phenomena or evaporation of water, giving rise to a thickening of the gel, are observed. In the range of 55–75°C, a first transition due to melting of a layered structure of concentric sphere‐like alternating crystalline and amorphous lamellar shells (amylopectine, AP, being the crystalline component) is detected. Analysis of results reveals that the AP crystallization contributes 25% to the overall crystal fraction. A spherulitic structure of alternating radial lamellae from amylose (AM) or AP melts in a higher temperature region between 75 and 86°C. This modification represents the major contribution to crystallinity of about 40%. Unexpectedly, the crystalline blocks of such a structure are abnormally anisometric; i.e., they are thicker than their width. This has been related to a contraction of the AMAP‐co‐spherulite due to an excessive growth of the AP‐shell crystals. The anisometry of the blocks of the AMAP lamellae vanishes at the beginning of the melting of the AP shell crystals, just when the total crystallinity decreases below 50% at 60°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 689–696, 2007     

Relationships between crystalline structure and the thermal behavior of poly(ethylene 2,5‐furandicarboxylate): An in situ simultaneous SAXS‐WAXS study

Poly(ethylene 2,5‐furandicarboxylate) (PEF) is an emerging bio‐based polymer with interesting thermal and barrier properties. In this study, the melting behavior of PEF was investigated in situ by means of simultaneous wide and small angle X‐ray scattering (WAXS and SAXS) measurements coupled with DSC measurements. This study gives the first evidence of what happens from a structural point of view during the multiple melting behavior of PEF, which is composed of three distinct events, taking into account the nature of the initial crystalline phase present. The first result is that the α′ form, induced at low crystallization temperature, does not undergo any phase transformation upon heating revealing its stable character. Second, the comparison of the SAXS and WAXS results with the DSC ones showed that the multiple melting behavior observed is attributed to a melting–recrystallization–melting process. Third, this work also definitely shows that the low amplitude melting endotherm observed in the DSC thermograms is ascribed to the melting of secondary crystals. Finally, SAXS‐WAXS results led to the conclusion that the secondary crystals cannot be depicted by the commonly accepted lamellar insertion model. Another microstructural representation of these secondary crystals is proposed. In this model, the secondary crystals consist of bundles of macromolecules, which formed small crystalline entities located between the primary crystalline lamellae stacks. POLYM. ENG. SCI., 59:1667–1677 2019. © 2019 Society of Plastics Engineers     

Thermal properties,structure and morphology of PEEK/thermotropic liquid crystalline polymer blends

The dynamic crystallization and subsequent melting behaviour of poly(aryl ether ether ketone), PEEK, and its blends with a thermotropic liquid crystalline polymer, Vectra^®, have been studied using differential scanning calorimetry, optical microscopy and wide‐angle and small‐angle X‐ray diffraction (WAXS and SAXS) techniques in a wide compositional range. Differences in crystallization rates and crystallinities were related to the structural and morphological characteristics of the blends measured by simultaneous real‐time WAXS and SAXS experiments using synchrotron radiation and optical microscopy. The crystallization process of PEEK in the blends takes place in the presence of the nematic phase of Vectra and leads to the formation of two different crystalline families. The addition of Vectra reduces the crystallization rate of PEEK, depending on composition, and more perfect crystals are formed. An increase in the long period of PEEK during heating was generally observed in the blends at all cooling rates. Copyright © 2003 Society of Chemical Industry     

Isothermal crystallization kinetics of PEEK/Vectra® blends by DSC and time‐resolved synchrotron X‐ray diffraction

Thermal properties of blends of poly(aryl ether ether ketone), PEEK, with a thermotropic liquid crystalline polymer, Vectra®, were investigated by differential scanning calorimetry and X‐ray diffraction techniques. Isothermal crystallization experiments were performed over a wide range of crystallization temperatures and compositions to follow the effect of Vectra® content on the crystallization kinetics of PEEK. A reduction in the crystallization rate of PEEK was related to a change in the mechanism of crystallization of PEEK, controlled in turn by the concentration of Vectra® in the blend. The addition of Vectra® resulted in a significant enhancement in the crystallization rate of PEEK. In addition, a reduction in this parameter is shown at a blend of 30% of Vectra®. Differences in the crystallization behavior of PEEK are related to structural properties of these systems measured by simultaneous real time WAXS and SAXS experiments using synchrotron radiation. Results of melting behavior of PEEK, subsequent to isothermal crystallization, were interpreted based on the effects of Vectra® on the formation of two crystal families of PEEK. Melting temperatures of PEEK and crystallinity calculated from double endotherm are influenced by blending. POLYM. ENG. SCI., 46:1411–1418, 2006. © 2006 Society of Plastics Engineers     

Effect of hydrolytic degradation on the microstructure of quenched,amorphous poly(glycolic acid): an X-ray scattering study of hydrated samples

The effect of hydrolytic degradation on the microstructure of unoriented, quenched poly(glycolic acid) (PGA) was investigated using simultaneous small- and wide-angle X-ray scattering (SAXS/WAXS). Samples were analysed immediately after removal from the degradation media in order to prevent dehydration. Analysis showed that the material initially contained a small degree of crystallinity. On degradation, the material rapidly crystallized, developing a broadly similar morphology to samples crystallized from the melt. The behaviour of these new structures on degradation was similar to that observed in the precrystallized samples previously reported. The crystal density remained constant and little change was seen in the lateral extent of the crystal lamellae. Both the crystallinity and SAXS scattering power (or invariant) increased during the first 30 days which may be due to the preferential removal of amorphous material and further crystallization of amorphous chains. The crystallization of amorphous material was facilitated by plasticization due to the ingress of water and the cleavage of amorphous chains. In both quenched and precrystallized material, the average lamellar spacing fell and then rose during degradation. It is not possible to interpret this unambiguously from the SAXS data alone. It may be partially the consequence of a two-stage removal of amorphous material. Alternatively, the behaviour may be explained by changes in the osmotic potential of the amorphous layer on degradation, together with insertion crystallization. © 1999 Society of Chemical Industry     

Structure development during crystallization and solid‐state processing of poly(glycolic acid)

DSC and time‐resolved WAXS and SAXS are used to study the structure development during isothermal crystallization of poly(glycolic acid) (PGA) in the temperature range 180–195°C. It is shown that the crystallization rate increases with degree of supercooling in the temperature range of consideration. WAXS and DSC crystallinity measurements agree well and a final crystallinity of 50% is found independently of the crystallization temperature. In‐situ SAXS measurements indicate that for PGA the final crystal thickness approaches a limiting value of 70 Å independent of the crystallization temperature in the range 195–180°C. The material develops a well‐defined lamellar structure during crystallization at the highest crystallization temperature under study (195°C). We show that by increasing the degree of supercooling it is possible to hinder the formation of the lamellar structure and crystals, resulting in a less ordered structure. We report that PGA fibers with elastic modulus in the range 20–25 GPa can be prepared by adequate control of the structure before solid‐state plastic deformation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Creation of functional materials by use of a slow crystallization process in the nonequilibrium state. I. porous polyamide microparticles

Recently a number of investigations have focused on the self‐organization process from the nonequilibrium state as a new technique that may be used to develop many functional materials. In many cases, amorphous polymers were used and semicrystalline polymers were seldom used in spite of their importance. In this study, we basically investigated the crystal structure, crystalline process, and inner structures of polyamide by using slow phase separation and crystallization process from the nonequilibrium state of the polymer solution. We were able to observe the crystalline lamella growing twisted from the center of the particle. Between these lamella layers, narrow pores were created. From this investigation, we developed a new method to create functional materials of polyamide, the semicrystalline polymer. Porous spherical particles may be properly applied to functional materials such as adsorption materials, catalyst support materials, and so on. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2428–2432, 2003     

Gas barrier changes and structural alterations induced by retorting in a high barrier aliphatic polyketone terpolymer

Analysis of the consequences of a typical humid thermal plastic food packaging sterilization (retorting) process over the crystalline morphology and gas barrier properties of a high barrier aliphatic polyketone terpolymer was carried out by in situ simultaneous synchrotron WAXS and SAXS experiments an by DSC, ATR‐FTIR spectroscopy, and oxygen transmission rate measurements. From a structural view point, it was observed that the retorting process led to a less crystalline material; however, crystallinity was fully restored by a postdrying process. The humid thermal treatment also favored the sorption of moisture in the amorphous phase to a saturation level, i.e., 2% water uptake. As a result, the oxygen permeability at 21°C was observed to increase by about nine times immediately after the humid treatment, but the barrier character was observed to quickly recover over time. From the results, it is suggested that a simple postdrying process at moderate temperatures can restore morphology and barrier properties. In the overall, it is also suggested that aliphatic polyketones withstand far better the process of retorting in comparison with, for instance, other high barrier polymers such as ethylene‐vinyl alcohol copolymers reported earlier and can therefore offer even as a monolayer an alternative in retortable food‐packaging applications. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3348–3356, 2006     

Solvent‐ and thermal‐induced crystallization of poly‐L‐lactic acid in supercritical CO2 medium

The effect of different annealing treatments with supercritical carbon dioxide (SCCO₂) on the structural and mechanical properties of semicrystalline poly‐L ‐lactic acid (L ‐PLA) was investigated. 2000, 27,000, 100,000, and 350,000 g mol^?1 molecular weight L ‐PLA polymers were used in the study. The solid‐state processing of L ‐PLA at temperatures lower than the effective melting point led to solvent‐ and thermal‐induced crystallization. Solvent‐induced and isothermal crystallization mechanisms could be considered similar regarding the increase of polymer chain mobility and mass‐transfer in the amorphous region; however, quite different microstructures were obtained. SCCO₂ solvent‐induced crystallization led to polymers with high crystallinity and melting point. On the contrary, SCCO₂ thermal‐induced crystallization led to polymers with high crystallinity and low melting point. For these polymers, the hardness increased and the elasticity decreased. Finally, the effect of dissolving SCCO₂ in the molten polymer (cooling from the melt) was analyzed. Cooling from the melt led to polymers with high crystallinity, low melting point, low hardness, and low elasticity. Distinctive crystal growth and nucleation episodes were identified. This work also addressed the interaction of SCCO₂‐drug (triflusal) solution with semicrystalline L ‐PLA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Structural changes of injection molded starch during heat treatment in water atmosphere: Simultaneous wide and small‐angle X‐ray scattering study

Native starches with wide varying amylose content were processed by injection molding. The injection‐molded materials were conditioned in water for 20 days and sealed in glass capillaries. Simultaneous wide‐ and small‐angle X‐ray scattering (WAXS and SAXS, respectively) were recorded during thermal heating using a synchrotron source. Crystallinity, SAXS invariant, Q, and long period, L, were measured as a function of heating temperature. The injection‐molding process provokes a destruction of the crystal forms A (cereal starch) and B (tubercle starch) but favors a development of the crystal form V_h. After wet conditioning, WAXS of the injection‐molded samples shows again the appearance of the crystal forms A or B, and crystallinity reaches values similar or larger than those of native starch. A constant heating rate (5°C/min) was particularly used for a comparison of potato and corn starch with a similar amylose content. While the crystallinity associated to forms A and B slowly decreases below 55°C and then rapidly decreases until its disappearance at 85–90°C, the invariant shows a maximum around 40°C and rapidly decreases thereafter. The total nanostructure disappearance occurs at temperatures about 10°C higher for the case of potato starch. In addition, a recovery of the WAXS and SAXS maxima during the subsequent cooling process before reaching room temperature was observed only for potato starch. Analysis of WAXS and SAXS for the rest of the starch materials reveals clear differences in the structural parameters of the samples that cannot be easily explained solely on the basis of the amylose content. Thus, for Cerestar and Roquette, it is noteworthy that there was a continuous decrease of L until its total disappearance as well as the persistence of crystallinity (form B), presumably stabilized by the presence of the V_h structure (12–15%). Real‐time crystallization experiments on two amorphous injection molded samples, waxy maize (free amylose starch) and potato starch, are also discussed. It is shown that the absence of amylose delays the recrystallization of amylopectine during the experiment. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 301–309, 2004     

NEW-TPI thermoplastic polyimide: Structure and relaxation using SAXS and TSDC

The thermoplastic polyimide Regulus^TM NEW-TPI has been studied using small-angle X-ray scattering (SAXS) and thermally stimulated depolarization current (TSDC). SAXS was used to study the development of lamellar structure during isothermal or nonisothermal crystallization. The one-dimensional electron-density correlation function was used to determine structural parameters. The long period, lamellar thickness, and amorphous layer thickness increase as crystallization temperature increases from 300 to 360°C. By combining melting-point data with SAXS results, we report the side and fold surface free energies of NEW-TPI crystals, which are 29 ± 3 and 41 ± 3 erg/cm², respectively. Real-time SAXS was carried during nonisothermal cold-crystallization at 5°C/min. The long period decreases, while lamellar thickness, linear crystallinity, and interphase thickness increase, with increasing temperature. These changes are explained by a crystal-insertion model. TSDC was used as a more sensitive probe of the amorphous phase structure below 300°C. Both semicrystalline and amorphous NEW-TPI exhibit complex TSDC behavior. Above the glass transition, amorphous NEW-TPI has a strong TSDC peak attributed to short-range-ordered structures, which may serve as nucleation sites for subsequent crystallization. This peak was not seen in semicrystalline material. At the glass transition, both amorphous and semicrystalline NEW-TPI have a strong TSDC peak. In the semicrystalline polymer, relaxation of the amorphous dipoles is slightly restricted by the crystals, which results in a smaller relaxation peak and a shift to higher temperature. Below T_g, another TSDC peak occurs which is not due to dipolar relaxation. This peak is attributed to the combined effects of space charge, electrode type, ionizable species, and interfacial charges. © 1995 John Wiley & Sons, Inc.     

Effects of zone drawing on the structure of metallocene polyethylene

The influence of zone drawing on bulk properties and structure of metallocene polyethylene (m‐PE) is reported. Two different m‐PE materials were subjected to tensile stresses above the yield point by zone drawing in the temperature range from 50 to 100°C. Drawn materials were characterized by using small‐ and wide‐angle X‐ray scattering (SAXS, WAXS), molecular retraction, and small‐angle light scattering (SALS). Structural changes were studied as a function of drawing temperature, engineering stress, and draw ratio. WAXS showed strong crystalline orientation in drawn samples, and only the orthorhombic crystal modification was observed. SAXS showed lamellar orientation in drawn samples. At low drawing temperatures of 50 or 60°C, draw ratio increased as a step function of stress. There is a stress barrier, which must be exceeded before high‐draw ratios can be achieved at these temperatures. At drawing temperatures of 70°C or above, the barrier stress is low enough that draw ratio increases nearly linearly as a function of stress. Below the stress barrier, spherulitic structure is observed by small‐angle light scattering (SALS). Elongation occurs via deformation of the interspherulitic amorphous phase. Molecular retraction was low for these samples, indicating mostly plastic deformation of the amorphous material. Above the stress barrier, SALS showed that spherulites are destroyed. Elongation occurs via deformation of the intraspherulitic amorphous phase. Molecular retraction for these samples was high, indicating elastic deformation of the amorphous material. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3492–3504, 2001     

Long Spacing in Polyblock Poly(ether ester)s—Origin and Peculiarities

Abstract

Poly(ether ester)s (PEE) based on poly(butylene terephthalate) (PBT) as hard segments and poly(ethylene glycols) (PEG) with different molecular weight as soft segments are studied by means of WAXS and SAXS in the drawn and undrawn state after annealing at various temperatures (T_a ). The repeatedly reported strong increase of the long spacing L with T_a is confirmed once again. In the same time the directly measured by WAXS crystallite size of PBT remains insensitive to T_a and the increase of L with T_a is the stronger, the higher the PEG content. It is concluded therefore that the rise in L is due to the expansion of the amorphous intercrystalline layers rather than to crystal thickening, the latter being the case of semicrystalline homopolymers.

The observed much stronger increase of L with T_a in undrawn samples than in drawn ones is explained by melting of less perfect crystallites at higher T_a and dephasing processes in the amorphous regions. The conclusions drawn seem to be valid for other segmented polyblock copolymers and suggest some specific features of the block copolymers in comparison to homopolymers.     

Study of As‐Spun Poly(ethylene terephthalate) Fibers Subjected to Thermal and Mechanical Treatments

As‐spun poly(ethylene terephthalate) filaments, subjected to mechanical and thermal treatments have been studied. Structural peculiarities investigated by the methods of thermo‐mechanical analysis (TMA), differential scanning calorimetry (DSC) and wide‐angle X‐ray scattering (WAXS) are presented. The influence of simultaneously applied thermal and mechanical treatments on the structural changes of the studied samples is discussed. It was shown that the structures obtained could be semicrystalline or entirely amorphous depending on the mechanical treatment.     

Structural evolution of tensile deformed high-density polyethylene at elevated temperatures: Scanning synchrotron small- and wide-angle X-ray scattering studies

The structural evolution of an ice-quenched high-density polyethylene (HDPE) subjected to uniaxial tensile deformation at elevated temperatures was examined as a function of the imposed strains by means of combined synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) techniques. The data show that when stretching an isotropic sample with the spherulitic structure, intralamellar slipping of crystalline blocks was activated at small deformations, followed by a stress-induced fragmentation and recrystallization process yielding lamellar crystallites with their normal parallel to the stretching direction. Stretching of an isothermally crystallized HDPE sample at 120 °C exhibited changes of the SAXS diagram with strain similar to that observed for quenched HDPE elongated at room temperature, implying that the thermal stability of the crystal blocks composing the lamellae is only dependent on the crystallization temperature. The strain at a characteristic transition point associated with the first indication for the occurrence of a fibrillar structure remains essentially constant in spite of the large changes in drawing temperature and crystalline thickness. In addition, WAXS experiments were used to probe the texture changes accompanying the uniaxial elongation and yield the relationship between the orientational order parameters associated with the crystallites and the amorphous chain segments, and the imposed strain. The results support the existence of intralamellar slip processes from the very beginning of tensile deformation.     

Theoretical and experimental studies of anisotropic shrinkage in injection moldings of semicrystalline polymers

A novel approach to predict anisotropic shrinkage of semicrystalline polymers in injection moldings was proposed using flow‐induced crystallization, frozen‐in molecular orientation, elastic recovery, and PVT equation of state. The anisotropic thermal expansion and compressibility affected by the frozen‐in orientation function and the elastic recovery that was not frozen during moldings were introduced to obtain the in‐plane anisotropic shrinkages. The frozen‐in orientation function was calculated from amorphous and crystalline contributions. The amorphous contribution was based on the frozen‐in and intrinsic amorphous birefringence, whereas the crystalline contribution was based on the crystalline orientation function, which was determined from the elastic recovery and intrinsic crystalline birefringence. To model the elastic recovery and frozen‐in stresses related to birefringence during molding process, a nonlinear viscoelastic constitutive equation was used with temperature‐ and crystallinity‐dependent viscosity and relaxation time. Occurrence of the flow‐induced crystallization was introduced through the elevation of melting temperature affected by entropy production during flow of the viscoelastic melt. Kinetics of the crystallization was modeled using Nakamura and Hoffman‐Lauritzen equations with the rate constant affected by the elevated melting temperature. Numerous injection molding runs on polypropylene of various molecular weights were carried out by varying the packing time, flow rate, melt temperature, and mold temperature. The anisotropic shrinkage of the moldings was measured. Comparison of the experimental and simulated results indicated a good predictive capability of the proposed approach. POLYM. ENG. SCI., 46:712–728, 2006. © 2006 Society of Plastics Engineers     

Mechanical investigation of confined amorphous phase in semicrystalline polymers: Case of PET and PLA

The effect of confinement onto the mechanical properties of the amorphous phase of Polyethylene terephthalate (PET) and poly(lactic acid) (PLA) was investigated. These polymers have the advantage of being in bulk amorphous or in semicrystalline state allowing mechanical and physical investigation of the amorphous phase on bulk and confined configuration. Based on small angle X‐ray scattering (SAXS), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) experiments, the micro‐structural arrangement of the amorphous and crystalline phase, the rigid amorphous fraction, and the visco‐elastic mechanical properties of the different semicrystalline samples were investigated. DSC results help quantifying the rigid amorphous fraction dependence on the crystallinity. DMA measurements lead to quantify the viscoelastic properties of the free and confined amorphous phases for PET and PLA polymers. Indeed, based on the DMA tests, where the maximum of tan(δ) peak is usually related to the glass transition temperature, shifts upon crystallization, the mechanical properties of the restricted and mobile amorphous phase were determined. This result was correlated along with the amorphous phase thickness distribution determined by SAXS results. This observation was bolstered based on literature results about geometrical confinement configurations and their effect on the glass transition temperature of polymeric materials. POLYM. ENG. SCI., 55:397–405, 2015. © 2014 Society of Plastics Engineers