
Gerrit W M PetersEindhoven University of Technology | TUE · Department of Mechanical Engineering
Gerrit W M Peters
PhD
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398
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Introduction
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January 1987 - July 2019
Position
- Professor (Full)
January 1996 - December 2011
Publications
Publications (398)
While crystallization behavior of isotactic polypropylene homopolymers had been subject to a wide range of experimental and modeling studies, this is not the case for propylene-ethylene random copolymers (PPR). This class of polymers offers up to now significant challenges, both from an experimental as well as a modeling perspective. The ethylene i...
The extrusion of highly filled elastomers is widely used in the automotive industry. In this paper, we numerically study the effect of thixotropy on 2D planar extrudate swell for constant and fluctuating flow rates, as well as the effect of thixotropy on the swell behavior of a 3D rectangular extrudate for a constant flowrate. To this end, we used...
In this paper, an experimental strategy is presented to characterize the rheological behavior of filled, uncured rubber compounds. Oscillatory shear experiments on a regular plate-plate rheometer are combined with a phenomenological thixotropy model to obtain model parameters that can be used to describe the steady shear behavior. We compare rate-...
Filament stretching rheometry is a prominent experimental method to determine rheological properties in extensional flow whereby the separating plates determine the extension rate. In literature, several correction factors that can compensate for the errors introduced by the shear contribution near the plates have been introduced and validated in t...
Viscosity controls an important issue in polymer processing. This paper reports on the terminal viscosity behavior of a polymer melt containing grafted nanosilica particles. The melt viscosity behavior of the nanocomposites was found to depend on the interaction between the polymer matrix and the nanoparticle surface. In the case of polycarbonate (...
This paper provides a model of the crystallization kinetics of polyamide 6 (PA6), including primary and secondary crystallization, lamellar thickness distribution, and the evolution of the mobile and rigid fractions of the amorphous phase. The kinetics includes the two-phase structure, the monoclinic α-phase and the pseudo-hexagonal γ-meso phase, o...
A finite element model is presented to describe the flow, resulting stresses and crystal-lization in a filament stretching extensional rheometer (FiSER). This model incorporates nonlinear viscoelasticity, nonisothermal processes due to heat release originating from crystallization and viscous dissipation as well as the effect of crystallization on...
We present a rheometer that combines the possibility to perform in situ X-ray experiments with a precise and locally controlled uniaxial extensional flow. It thus allows us to study the crystallization kinetics and morphology evolution combined with the rheological response to the applied flow field. A constant uniaxial deformation rate is ensured,...
Conclusions The rheological response measured with our rheometer for LDPE is in agreement with the linear viscoelasticity (LVE) and data from commercial devices. Furthermore the results of the in-situ X-ray experiments demonstrate that the crystallization kinetics, and the evolution of crystal structure and morphology, during and after uniaxial ext...
The effect of shear flow on the crystallization of homopolymers has been widely studied, however more complex systems such as nanocomposites or polymer blends nanocomposites (PBNANOs) have received less attention. In this work, the effect of pressure and shear flow on the crystallization process of polypropylene-based nanocomposites and polypropyle...
The influence of stress, temperature, and relative humidity on plasticity‐controlled failure of molded and laser‐sintered polyamide 12 (PA12) has been investigated. Ree–Eyring's flow theory is employed and modified to take into account the effect of relative humidity on the deformation kinetics. By introducing the concept of critical strain, time t...
Being able to properly model the material structure formation during processing is a fundamental step to predict final product properties, especially for semicrystalline polymers, like isotactic PolyPropylene (iPP), which can develop a multiplicity of different crystalline phases and morphologies. For this reason, in the present work a complete mod...
The objective of this work is to investigate the effect of the molecular mobility and resin formulation of UV‐curable acrylate systems on conversion and ultimate mechanical properties. Thin single‐layer films are produced from a series of nine mixtures of bisphenol A ethoxylate diacrylate, having different molecular weights (BisDAn = 2, BisDAn = 4,...
To provide knowledge to improve the mechanical performance of Polyamide 12 (PA12) sintered products, we have studied experimentally the mechanical response and structure development under constant strain rate of compression moulded and laser sintered PA12 by means of in situ small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD...
We report on the role of temperature and shear on the melt behavior of iPP in the presence of the organic compound N1,N1′-(propane-1,3-diyl)bis(N2-hexyloxalamide) (OXA3,6). It is demonstrated that OXA3,6 facilitates a viscosity suppression when it resides in the molten state. The viscosity suppression is attributed to the interaction of iPP chains/...
The crystallization of Polyamide 12 (PA12) has been investigated using a new experimental setup which allows in-situ synchrotron Wide Angle X-ray Diffraction (WAXD) during Flash-DSC measurements. The experimental results are used to parameterize and validate a new numerical model to quantify the quiescent crystallization kinetics, under isothermal...
The effect of processing conditions during injection on the structure formation and mechanical properties of injection molded polyamide 6 samples was investigated in detail. A large effect of the mold temperature on the crystallographic properties was observed. Also the the effect of pressure and shear flow was taken in to consideration and analyse...
This study presents the mechanical characterization of UV-curing acrylate systems. UV-curable polymers are commonly used in the stereolithography (SLA) technique to build multi-layered objects. Typically, the mechanical properties of the 3D-printed product are affected by the intrinsic material heterogeneity along the sample thickness. To understan...
Skin mechanics is of importance in various fields of research when accurate predictions of the mechanical response of skin is essential. This study aims to develop a new constitutive model for human skin that is capable of describing the heterogeneous, nonlinear viscoelastic mechanical response of human skin under shear deformation. This complex me...
The deformation and failure kinetics of polyamide 6 samples prepared by several thermal histories were investigated by tests at different temperatures and relative humidities. PA6 samples were produced in quiescent condition and multiple cooling procedure. A characterization was performed to investigate the effect of the different thermal histories...
We report on the effect of an aliphatic oxalamide based nucleating agent (OXA3,6) on the melt and crystallization behavior of isotactic polypropylene (iPP) under defined shear conditions. Through polarized optical microscopy, we demonstrate that OXA3,6 self-assembles from the iPP melt into rhombic crystals whereas their size and distribution proved...
Cross-nucleation is defined as the nucleation of one polymorph on the surface of another polymorph of the same substance. Although the description of this particular form of heterogeneous nucleation is mainly phenomenological, recently dedicated quantitative studies are performed on several systems. In this work we propose a model framework that ca...
Flow-induced crystallization of α- and γ- phases was studied for a propylene/ethylene random copolymer with 3.4 mol% ethylene at two high temperatures of 132 and 142 °C by combining a pressure-driven slit flow device with real-time synchrotron wide angle X-ray diffraction. At 132 °C, it was found that both α- and γ- phases were generated at shear s...
The skin is the largest organ of the human body. With its layered structure, it is mechanically a very complicated tissue. From the outer surface down, the main layers are the stratum corneum (10–15 μm), the viable epidermis (100–150 μm), dermis (subdivided into the papillary and reticular dermis, ≈2 mm), and hypodermis. Although the stratum corneu...
In this study, the influence of temperature and relative humidity on the plasticity controlled failure of polyamide 6 was investigated. Uniaxial tensile tests were performed at several temperatures, strain rates, and relative humidity; creep tests were performed at different relative humidity and applied load. In order to describe and predict the y...
This detailed study reveals the relation between structural evolution and the mechanical response of α -, β - and γ -iPP. Uni-axial compression experiments, combined with in situ WAXD measurements, allowed for the identification of the evolution phenomena in terms of phase composition. Tensile experiments in combination with SAXS revealed orientati...
Flow-induced crystallization at elevated pressure of a set of metallocene isotactic polypropylenes (iPP) possessing different molecular weight distributions is studied using extended dilatometry experiments in an apparatus able to apply elevated pressure (up to 1200 bar) and strong shear flow (shear rates up to 180 s⁻¹). The effect of flow on the c...
The glass transition temperature (Tg) is a crucial parameter for understanding the mechanical behavior of polyamide 6. It depends mainly on two aspects: hydration level and processing, i.e. the thermal history and the flow conditions. In this work, the effect of the thermal history on Tg was investigated by means of fast scanning calorimetry (flash...
A particular kind of heterogeneous nucleation, i.e., cross-nucleation, is sometimes observed in polymorphic substances, when a new crystal structure nucleates on the surface of a crystal of a different modification. Here we show a unique and apparently incongruous nucleation behaviour in polymorphic isotactic polypropylene (i-PP). The rate of cross...
Fibrin is a plasma protein with a central role in blood clotting and wound repair. Upon vascular injury, fibrin forms resilient fibrillar networks (clots) via a multi-step self-assembly process, from monomers, to double-stranded protofibrils, to a branched network of thick fibers. In vitro, fibrin self-assembly is sensitive to physicochemical condi...
Understanding the complex crystallization behavior of isotactic polypropylene (iPP) in conditions comparable to those found in polymer processing, where the polymer melt experiences a combination of high shear rates and elevated pressures, is key for modeling and therefore predicting the final structure and properties of iPP products. Coupling a un...
In this study, the mechanical performance of the different polymorphs of isotactic polypropylene, typically present in iPP crystallized under industrial processing conditions, is assessed. Different preparation strategies were used to obtain samples consisting of almost solely α, β, or γ crystals. X-Ray measurements were used to validate that the d...
Nucleation of semi-crystalline polymers is very sensitive to perturbations of the melt state. In contrast to the case of flow, the influence of pressure changes on nucleation has been almost neglected so far. In this work we explore the effect of the pressure history on isotactic polypropylene crystallization by applying a brief step-like increase...
The crystallization behavior of poly(lactic acid) (PLA) has been studied extensively, and this has resulted in different reported values for the nucleation densities (Ns) and crystal growth rates (Gs) for similar grades. These inconsistencies may be magnified when they are used in subsequent modeling studies. Therefore, the quiescent crystallizatio...
During industrial processing, polymer melts are exposed to local high cooling rates, strong deformation rates and high pressures. Nowadays, research in the field of semi-crystalline polymers still strives towards an accurate prediction of the evolution and final appearance of the crystalline morphology in polymer products. After all, the amount, nu...
In this paper we demonstrate the advantage of applying viscoelastic materials instead of purely viscous materials as damping medium in mechanical dampers. Although the loss modulus decreases as function of frequency in case of viscoelastic behavior, which can be interpreted as a decrease of damping, the viscoelastic behavior still leads to an incre...
A numerical model is presented that describes all aspects of flow-induced crystallization of isotactic polypropylene at high shear rates and elevated pressures. It incorporates nonlinear viscoelasticity, including viscosity change as a result of formation of oriented fibrillar crystals (shish), compressibility, and nonisothermal process conditions...
Understanding and controlling physical aging below the glass transition temperature (Tg) is very important for the long-term performance of plastic parts. In this article, the effect of grafted silica nanoparticles on the physical aging of polycarbonate (PC) below the Tg is studied by using the evolution of the enthalpy relaxation and the yield str...
To elucidate the mechanism of formation of shish-kebab, flow-induced crystallization of isotactic polypropylene is investigated using model slit-flow experiments in combination with in situ small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD). The results, consistent with nucleation and growth theory, show that a brief but in...
Flow-induced shish formation in semicrystalline polymers is an important phenomenon since shish can strongly influence final material properties. The formation, dissolution, and re-emergence of flow-induced shish were studied for a polyethylene system with a broad molecular weight distribution using time-resolved synchrotron small-angle X-ray scatt...
A modeling framework is presented to describe flow-induced crystallization of isotactic polypropylene at elevated pressures in multiple crystal phases and morphologies. By combining two models for flow induced crystallization developed in previous work, all parameters but one are a priori fixed. In the present work only one additional parameter was...
The chapter describes the work that was performed in the soft tissue biomechanics laboratory at Eindhoven University of Technology on the biomechanics of skin. A rationale is given for the changes from standard testing methods to inverse methods, from in vitro to in vivo and back to in vitro testing and for the more detailed studies on individual s...
The on-line morphological development during film blowing of 2 different linear low density polyethylenes (LLDPE) and a blend of LLDPE with low density polyethylene (LDPE) has been investigated, for the first time, using synchrotron Small Angle X-Ray Scattering (SAXS). The processing conditions, blow-up ratio and take-up ratio, have been varied and...
A strategy is presented to predict the yield kinetics following from different thermomechanical histories experienced during processing in non-isothermal quiescent conditions. This strategy deals with three main parts, i.e. processing, structure and properties. In the first part the applied cooling conditions are combined with the crystallization k...
In industrial processes, polymer melts are often exposed to a combination of fast cooling rates, high flow fields, and high pressures. The processing conditions have an ultimate impact on the structure that develops during cooling. The final structure at the nano- and microscopic level determines the properties of the final polymer product. Small a...
Nascent polyamide-6 shows a peculiar and irreversible effect; the quiescent crystallization kinetics on cooling are accelerated upon deformation in the melt, even after full relaxation of the melt. This phenomenon, known as the orientation (or better, deformation) induced memory effect of polyamide materials, is explored in a step-by-step manner us...
The primary and secondary crystallization kinetics of a homogeneous linear low-density polyethylene were characterized as function of cooling rate, pressure and flow strength. Our approach to describe primary crystallization is based on nucleation and growth of spherulites, quantified well below the melting temperature using small-angle light scatt...
This paper presents the use of a state of the art damper for high-precision motion stages as a sliding plate rheometer for measuring linear viscoelastic properties in the frequency range of 10 Hz–10 kHz. This device is relatively cheap and enables to obtain linear viscoelastic (LVE) fluid models for practical use in precision mechanics applications...
High hydrostatic pressure pulses, up to 80 MPa, have been imposed for different time and at various temperatures on molten iPP during cooling. The absence of any effect on the crystallization behavior after pressure release and further cooling demonstrates either that no nucleation precursor is produced by this thermo-mechanical history or that the...
Polypropylene-based impact copolymers are a complex composition of matrix material, a dispersed phase and many optional modifiers. The final heterophasic morphology of such systems is influenced significantly by the processing step, adding an additional level of complexity to understanding the structure-property relation. This topic has hardly been...
The mechanical properties determine to a large extent the functioning of a blood clot. These properties depend on the composition of the clot and have been related to many diseases. However, the various involved components and their complex interactions make it difficult at this stage to fully understand and predict properties as a function of the...
A model is presented to describe flow-induced crystallization in isotactic polypropylene at high shear rates. This model incorporates nonlinear viscoelasticity, compressibility, and nonisothermal process conditions due to shear heating and heat release due to crystallization. Flow-induced nucleation occurs with a rate coupled to the chain backbone...
Structure formation during flow, a common phenomenon driving polymer processing, can have a major effect on the rheological behavior of a polymer melt. This can cause large increases of the pressure and thus large changes in thermodynamical properties which, in turn, will strongly influence the structure formation. Consequently, a complex, mutual,...
Reproducibility is a well-known issue in research involving electrospun materials, and, therefore, it is one of the main obstacles preventing this processing technique to prevail into the industry. Controlling environmental parameters during the electrospinning process helps in drastically reducing variability of results and, at the same time, has...
Flow-induced structure formation is investigated with in situ wide-angle X-ray diffraction with high acquisition rate (30 Hz) using isotactic polypropylene in a piston-driven slit flow with high wall shear rates (up to ≈900 s(-1) ). We focus on crystallization within the shear layers that form in the high shear rate regions near the walls. Remarkab...
Blood clot formation is important to prevent blood loss in case of a vascular injury but disastrous when it occludes the vessel. As the mechanical properties of the clot are reported to be related to many diseases, it is important to have a good understanding of their characteristics. In this study, a constitutive model is presented that describes...
We studied experimentally the structure development during film blowing for three different low-density polyethylenes at four different processing conditions. For this, we combined blown film extrusion with in situ X-ray diffraction at a synchrotron radiation beam line. The measurements were performed at rheological similar conditions at the die ex...
Flow-induced crystallization is investigated through short-term shear flow experiments on poly(1-butene) in the RheoDSC device. We demonstrate that the DSC signal shows contributions from spherulitic morphology in the center of the sample and oriented structures at the edge of the sample, the latter being induced by edge effects at the free surface...
Using a unique slit flow device and in situ synchrotron X-ray methods, the entire evolution of flow induced crystallization in isotactic polypropylene (iPP) was studied from the start-up of flow up to completion of crystallization. Two WAXD detectors, including the ultrafast Pilatus and the two-dimensional Frelon, were combined to achieve a suffici...
We have studied the formation of nanoparticles in lead sulfide (PbS)-doped borosilicate glass subjected to
a two-step nucleation and growth heat treatment using in situ small-angle X-ray scattering (SAXS). The
microstructure produced was subsequently characterized using X-ray powder diffraction (XRD) and
transmission electron microscopy (TEM). Whil...
A model is presented for the crystallization kinetics of flow-induced shish-kebab structures in isotactic polypropylene. The model accounts for two phenomena that affect the crystal growth of kebab structures. First, the temperature of the material increases due to latent heat release. Second, polymer chains are deformed in such a way that growth o...
Blood clot formation is crucial to maintain normal physiological conditions but at the same time involved in many diseases. The mechanical properties of the blood clot are important for its functioning but complicated due to the many processes involved. The main structural component of the blood clot is fibrin, a fibrous network that forms within t...
This chapter gives an overview of work on porcine adipose tissue that was performed at Eindhoven University of Technology. It demonstrates that only at very small strains, far away from the physiological strains we experience in daily live, the behavior is more or less linear and can be described with standard constitutive models. Long term oscilla...
The parallel plates geometry is often deemed unsuitable for nonlinear viscoelasticity measurements because the strain field, and thus the nonlinear response, varies across the sample. Although cone–plate and Couette geometries are designed to circumvent this problem by ensuring a uniform strain field, it is not always easy to shape the material to...
Recent developments on the experimental infrastructure and the acquisition of new detectors on the Dutch–Belgian beamline BM26B at the ESRF offer novel and promising possibilities for synchrotron X-ray experiments in the field of polymer crystallization under processing-relevant conditions. In this contribution, some of the most recent experiments...
The so-called “short-term flow” protocol is widely applied in experimental flow-induced crystallization studies on polymers in order to separate the nucleation and subsequent growth processes [Liedauer et al. Int. Polym. Proc. 1993, 8, 236–244]. The basis of this protocol is the assumption that structure development during flow can be minimized and...
A modeling framework for flow-enhanced nucleation of polymers is applied to a broad set of data from literature. Creation of flow-induced pointlike nuclei is coupled to chain stretch of the high-molecular weight tail of the material, calculated with a rheological constitutive model. As the flow-induced nuclei grow, the crystalline volume fraction i...
The anisotropic yielding of injection molded polyethylene is discussed, specifically focusing on the differences between the tensile and compressive yield stress as a function of loading angle and strain rate. For the first time, it is demonstrated that a strong Bauschinger effect exists in polymers that possess molecular orientation due to melt-pr...
Molecular properties are reflected in the rheological and crystallization behavior. The first task is to design and use some well‐defined experiments that reveal all these features. Second, the experimental findings should be translated into mathematically formulated physical models, suited to be implemented in numerical codes for simulation...
Using dilatometry combined with shear flow at conditions comparable to realistic processing conditions, the flow-induced crystallization of polymers is modelled. The model describes the kinetics of quiescent nucleation, flow-enhanced point nucleation, fibrillar growth, and the time evolution of the dimensions of the resulting crystalline structures...
Crystallization of an isotactic polypropylene (iPP) homopolymer and two propylene/ethylene random copolymers (RACO), induced by high-stress shear, was studied using in situ synchrotron wide-angle X-ray diffraction (WAXD) at 137 °C. The “depth sectioning” method (Fernandez-Ballester, Journal of Rheology 53:5 (2009), pp. 1229−1254) was applied in ord...
It is shown that predictions of local mechanical properties in a product can be made from the orientation only using an anisotropic viscoplastic model. Due to processing-induced crystalline orientations, the mechanical properties of injection-molded polymer products are anisotropic and exhibit strong variations within a product. The tensile respons...
Skin is a complex multi-layered tissue, with highly non-linear viscoelastic and anisotropic properties. Thus far, a few studies have been performed to directly measure the mechanical properties of three distinguished individual skin layers; epidermis, dermis and hypodermis. These studies however, suffer from several disadvantages such as skin damag...
Key issue in studying the crystallization process of semi-crystalline polymers, is the need for controlled (or known) boundary and initial conditions. Here dilatometry (PVT) is used to reveal the crystallization kinetics and the resulting morphology of isotactic polypropylene homopolymer as a consequence of the combination of non-isothermal cooling...
The influence of cooling rate on the structure and resulting mechanical performance is explored for a set of isotactic polypropylenes with varying molecular weight, insertion of counits, and addition of a nucleating agent. A continuous variation of crystal type (α–mesomorphic phase competition) and structural features is obtained with cooling rate....
The structure of semi-crystalline polymers is strongly influenced by the conditions applied during processing and is of major importance for the final properties of the product. A method is presented to quantify the effect of thermal and pressure history on the isotropic and quiescent crystallization kinetics of four important structures of polypro...
This paper describes the features of new membranes that can act as local biomedical devices owing to their peculiar shape in the form of mesh structure. These materials are designed to provide significant effects to reduce local inflammations and improve the tissue regeneration. Lamellar Hydrotalcite loaded with Diclofenac Sodium (HTLc-DIK) was hom...
This paper is focused on the formulation and characterization of
membranes that can act as biomedical devices with a mesh sample
structure to reduce local inflammation and improve the tissue
regeneration. These systems were realized homogenously dispersing
lamellar Hydrotalcite loaded with Diclofenac Sodium (HTLc-DIK) in a
polymeric matrix of Poly-...
Nature uses mechanochemical transduction processes to achieve diverse and vital functions, such as hearing, cellular adhesion and gating of ion channels. One fascinating example of biological mechanotransduction is the emission of light on mechanical stimulation. However, molecular-level transduction of force into luminescence in a synthetic system...