Heterophasic Copolymers Research Articles

Development of a Polypropylene-Based Material with Flame-Retardant Properties for 3D Printing.

In this study, a nanocomposite based on a heterophasic polypropylene copolymer containing 5 wt% of nanoclays and 3 wt% of compatibilizer was formulated via melt compounding to obtain a material suitable for Fused Filament Fabrication (FFF) processing with enhanced flame-retardant properties. From rheological analyses, the nanocomposite showed an important increase in the non-Newtonian behavior, and, therefore, improved FFF printability compared to the pristine PP COPO. A filament with suitable characteristics for FFF was produced using a single-screw extruder and subsequently 3D printed. Finally, cone calorimeter and UL94 tests were carried out on both 3D-printed and compression-molded specimens. The obtained results showed that the 3D-printed samples exhibited even better flame-retardant properties than the compression-molded ones, thus demonstrating not only the possibility of successfully developing and using functionalized PP-based filaments in 3D printing but also the possibility of obtaining enhanced flame-retardant properties compared to conventional compression molding.

Role of polymorphism in solid-state production of double-melting expanded polypropylene beads

The production of expanded polypropylene (EPP) beads is of great significance for its wide range of industrial applications. However, it requires special grades of polypropylene with high melt strength (HMS-PP) and the capability of forming double-melting expanded beads to enable sintering during post-processing of EPP. In this study, conventional Ziegler-Natta PP grades of heterophasic ethylene-propylene copolymer, random propylene-ethylene-butene-1 terpolymer, and their 50 wt% blends were studied in a wide range of foaming conditions from solid to semi-liquid state. While, all the polypropylenes were capable of producing EPP beads with double-melting behavior when foamed in a semi-liquid state, in solid-state foaming, the double-melting behavior appears only in polymorphic polypropylenes with low temperature and high temperature melting peaks associated with γ and α phase crystals, respectively. The EPP samples foamed in the solid-state show a closed-cell morphology with high cellular density (>1010 number of cells/cm3) and low cell size (0.3–5 μ m) resulting from the high extensional strength of the polymeric matrix when foamed at a temperature prior to the initial melting. Using polymorphism to induce double-melting behavior and performing the expansion in solid-state is promising for producing nano cellular EPP beads.

Pressure- and Temperature-Dependent Crystallization Kinetics of Isotactic Polypropylene under Process Relevant Conditions

In this study, a non-nucleated homopolymer (HP) and random copolymer (RACO), as well as a nucleated HP and heterophasic copolymer (HECO) were investigated regarding their crystallization kinetics. Using pvT-measurements and fast scanning chip calorimetry (FSC), the crystallization behavior was analyzed as a function of pressure, cooling rate and temperature. It is shown that pressure and cooling rate have an opposite influence on the crystallization temperature of the materials. Furthermore, the addition of nucleating agents to the material has a significant effect on the maximum cooling rate at which the formation of α-crystals is still possible. The non-nucleated HP and RACO materials show significant differences that can be related to the sterically hindering effect of the comonomer units of RACO on crystallization, while the nucleated materials HP and HECO show similar crystallization kinetics despite their different structures. The pressure-dependent shift factor of the crystallization temperature is independent of the material. The results contribute to the description of the relationship between the crystallization kinetics of the material and the process parameters influencing the injection-molding induced morphology. This is required to realize process control in injection molding in order to produce pre-defined morphologies and to design material properties.

Designing 3D printable polypropylene: Material and process optimisation through rheology

A polypropylene-based material has been formulated to be suitable for fused deposition modelling (FDM). In fact, the high volumetric shrinkage and the rheological behaviour are main problems whereby polypropylene (PP) is not commonly used as a 3D printing filament. Experimental results have evidenced how material modifications have a strong impact on rheological behaviour, providing critical features that permit and improve material printability. An optimised 20 wt% talc filled heterophasic PP copolymer has been developed. The peculiar properties of the materials have been assessed by thermal characterisation and rheological analysis. Several process parameters (extrusion temperature, screw speed, cooling conditions) have been evaluated in order to obtain a proper filament. Finally, a model part has been printed using different settings to check printing quality by morphological analysis.

New Insights into Crystallization of Heterophasic Isotactic Polypropylene by Fast Scanning Chip Calorimetry.

The crystallization kinetics of metallocene-catalyzed heterophasic isotactic polypropylene composed of a matrix of isotactic polypropylene (iPP) and rubbery particles made of random ethylene–propylene copolymers (EPC), often denoted as heterophasic iPP copolymers, was analyzed as a function of the cooling rate and supercooling in nonisothermal and isothermal crystallization experiments, respectively. Fast scanning chip calorimetry (FSC) allowed assessing crystallization at processing-relevant conditions, and variation of the content (0–39 wt %) and composition (0–35 wt % propylene counits) of the EPC particles revealed qualitatively new insight about mechanisms of heterogeneous crystal nucleation. For neat iPP homopolymer, the characteristic bimodal temperature dependence of the crystallization rate due to predominance of heterogeneous and homogeneous crystal nucleation at high and low temperatures, respectively, is reconfirmed. At high temperatures, in heterophasic iPP, the here studied ethylene-(C2)-rich EPC particles accelerate crystallization of the iPP-matrix, with the acceleration or nucleation efficacy correlating with the EPC-particle content. The crystallization time reduces by more than half in presence of 39 wt % EPC particles. An additional nucleating effect of the EPC particles on iPP-matrix crystallization is detected after their crystallization, suggesting that liquid/rubbery particles are less effective than solid/semicrystalline particles in affecting crystallization of the surrounding iPP-matrix. At low temperature, homogeneous crystal nucleation in the iPP-matrix outpaces all heterogeneous nucleation effects, and the matrix-crystallization rate is independent of the sample composition. The obtained results lead to the conclusion that the crystallization kinetics of iPP can be affected significantly by the content and composition of EPC particles, even towards superfast crystallizing iPP grades.

Copolymer Structure and Performance Consequences of High‐Impact Ethylene–Propylene Copolymers Based on a Ziegler–Natta Catalyst with Novel Internal Donor

AbstractCatalyst development for advanced isotactic polypropylene copolymer grades cannot be considered without parallel work on the polymerization process, especially when multi‐phase high‐impact ethylene‐propylene copolymers (also called heterophasic copolymers, HECOs) of complex composition are considered. Using a Ziegler–Natta type catalyst produced in an emulsion process and using citraconate ester as internal donor, a series of such high‐impact copolymers is first produced in a bench‐scale reactor. At this stage, the content of ethylene‐propylene copolymer (EPC) phase is varied in a wide range for understanding the catalyst performance as well as the resulting structure‐property relations, using three‐stage polymerization to emulate multiple reactors. Selected compositions are subsequently scaled up to a multi‐reactor pilot plant, demonstrating composition effects on mechanical performance. Both stages are accompanied by structural investigations using 13C‐NMR spectroscopy and atomic force microscopy. The novel catalyst is found to be capable of synthesizing HECOs in a wide range of elastomer (EPC) content, achieving free‐flowing polymer powders up to an elastomer content as expressed by the xylene cold soluble fraction of 37 wt%.

Polymerization of heterophasic propylene copolymer with Me2Si(2-Me-4-PhInd)2ZrCl2 supported on SiO2 and SiO2-MgCl2 carriers

Me2Si(2-Me-4-pbind)2ZrCl2 supported on SiO2/MgCl2 binary support was prepared for the preparation of heterophasic copolymer of polypropylene. The bi-support underwent surface treatment with various alkyl aluminum compounds such as trimethylaluminum (TMA), triethylaluminum (TEAL), and triisobutylaluminum (TIBA) before supporting the metallocene catalyst for 3 or 24 hours and were used for homopolymerization. It was notable that the generated SiO2/MgCl2 bi-support had lower surface area, pore volume and size as compared to the conventional SiO2. Impact polypropylene copolymers (IPCs) were obtained using two-step polymerization in one reactor with the presence of metallocene catalyst supported on SiO2. Propylene was polymerized in the reactor to produce the iPP matrix followed by polymerization of ethylene resulting to heterophasic material. It is apparent that the molecular weight of the polymer increased with longer PE polymerization time and as the polymerization time was more than 40 min, PP peak appeared near 147.9–149.2 °C, and a new peak emerged at 116.9–119.9 °C which could be attributed to the melting temperature of iPP crystallites and a less intense peak to either chains of ethylene-propylene copolymers. SEM images also confirmed that spherical PE particles were deeply embedded in the crystalline PP matrix and a large amount was produced as the polymerization time of the second stage ethylene polymerization was increased.

Heterophasic ethylene-propylene copolymers: New insights on complex microstructure by combined molar mass fractionation and high temperature liquid chromatography

The present study investigates the changes in the microstructure of heterophasic ethylene propylene copolymers (HEPCs) with increasing ethylene content, before and after visbreaking. Three samples obtained from commercial gas process reactors at Sasol Polymers at varying times after the addition of the ethylene comonomer are further visbroken to produce three more samples. Bulk sample analyses indicate that the ethylene-rich rubber phase which is essential in aiding peroxide mobility during visbreaking as observed in narrower dispersities and lower peak molar masses with increasing ethylene content. Further investigations of the microstructure via offline coupling of preparative molar mass fractionation (pMMF) to advanced analytical techniques such as solvent gradient interaction chromatography (SGIC) reveal that ethylene-rich copolymer chains are not significantly affected by the peroxide as the polypropylene homopolymer. Consequently, the polypropylene (PP) homopolymer and polypropylene-rich fractions with high molar mass diminish after visbreaking. Furthermore, the increase in ethylene content was observed to reduce the impact of the peroxide on the fraction quantities before and after visbreaking implying that visbreaking affects more the polyolefin chains with more PP segments and less those with more ethylene comonomer.

Pseudo‐ductile behavior of poly(vinyl alcohol) fiber‐reinforced polypropylene

Composites based on two different polypropylene (PP) grades reinforced with poly (vinyl alcohol) (PVA) fibers were prepared by compounding and injection molding. Very high residual fiber length values of up to 2,500 μm were achieved. The impact performance of a PP homopolymer can be improved dramatically by reinforcement with the PVA fibers, even below the glass transition temperature of the matrix. For a high impact PP heterophasic copolymer, the fiber reinforcement interferes with the elastomer toughening. Scanning electron microscopy and X‐ray computer‐tomography analysis indicate that the specific composite microstructure has very long, entangled fibers and a low fiber matrix interaction allowing for pseudo‐ductility. Analysis of the micromechanical deformations by volume strain and acoustic emission measurements during tensile testing supports this hypothesis. POLYM. COMPOS., 40:4067–4078, 2019. © 2019 Society of Plastics Engineers

Unrevealing the effect of different dispersion agents on the properties of ethylene–propylene copolymer/halloysite nanocomposites

The properties of polyolefin nanocomposites strongly depend on the dispersion level of the nanoparticles and the addition of dispersion agents contributes to improving their performance. In this study, the morphology and the mechanical properties of heterophasic ethylene-propylene copolymer/halloysite nanocomposites were tailored by using two hydrogenated hydrocarbon resins: 90% and 100% hydrogenated and two compatibilizing agents: poly(propylene-g-maleic anhydride) and poly(ethylene-octene-g-maleic anhydride). The transmission electron microscopy indicated that the best dispersion of the halloysite nanotubes was achieved when hydrogenated hydrocarbon resins and poly(propylene-g-maleic anhydride) were used simultaneously. All nanocomposites showed an increase in mechanical stiffness and the most pronounced increase of 46% in the Young modulus was achieved with the system containing halloysite, poly(propylene-g-maleic anhydride) and the hydrocarbon resin with the higher degree of hydrogenation. Poly(ethylene-octene-g-maleic anhydride) caused the halloysite nanoparticles to concentrate preferentially in the rubber domains, wherein these hindered the crystallization of polypropylene and polyethylene chains, as showed by atomic force microscopy. In this case, the composite exhibited both high stiffness and improved toughness. These results highlight the key role of dispersion agents in promoting a good balance in the mechanical properties of resulting nanocomposites based on halloysite particles and heterophasic ethylene-propylene copolymers.

Structure-property relations of heterophasic ethylene-propylene copolymers based on a single-site catalyst

Structure-property relations of heterophasic ethylene-propylene copolymers based on a single-site catalyst

Crystallization behaviour of heterophasic propylene-ethylene copolymer at rapid cooling conditions

Abstract The crystallization kinetic of neat and nucleated heterophasic isotactic propylene(ethylene-propylene) copolymer (iPP-EPC) was analyzed by fast scanning chip calorimetry. On cooling neat iPP-EPC shows two exothermic events, one related to the solidification of the iPP component followed by the crystallization of the polyethylene (PE) part in the copolymer. The effect of the type of nucleating agent on the kinetic of structure formation of the iPP matrix was observed only in the high-temperature range of isothermal crystallization. The detected decrease of the minimum crystallization half-time due to the addition of nucleating agent, from 0.12 s in case of the neat copolymer to 0.01 s in case of the nucleated iPP-EPC, is in parallel to the increase of the critical rate of cooling for suppression of crystallization from 200 to 1000 K/s, respectively. The efficiency of the different nucleating systems in iPP-EPC solidified at slow cooling was qualitatively analyzed by light microscopy.

Ionic liquid tailored interfaces in halloysite nanotube/heterophasic ethylene–propylene copolymer nanocomposites with enhanced mechanical properties

In this study, imidazolium ionic liquids (IL) were investigated as novel compatibilizers to improve the dispersion of halloysite nanotubes (HNT) in heterophasic ethylene-propylene copolymer (EPP) matrix to enhance the mechanical properties of the EPP/HNT nanocomposites prepared by melt-blending approach. The results highlight that the dispersion of HNT nanotubes and consequently the mechanical properties of nanocomposites depends on the surface modification of HNT with IL, which in turn strongly depends on the chemical structure of IL, i.e. anion and cation N-alkyl chain length, as well as on the adsorption conditions, e.g. solvent polarity and IL concentration adopted for the modification of HNT surface. In details the nanocomposites with HNT modified by IL (m-HNT) exhibited a more homogeneous HNT dispersion above all when the IL surface modification was conducted in less polar solvents as dichloromethane. Furthermore, the IL allowed to tuning the stiffness and the toughness with a right compromise. The EPP/m-HNT nanocomposites with bis(trifluoromethylsulfonyl)imide [NTf2] anion and 1-methyl-3-n-octadecylimidazolium cation-based IL, exhibited an improvement of elastic modulus of about 34% with respect to the pristine polymer, without loss of the impact properties at 23°C. The morphological and mechanical results confirm the IL acted effectively as compatibilizer, improving both the interfacial interaction and HNT dispersion into the EPP matrix.

Comparison of the effect of ethylene and hexene-1 co-monomers on the composition, microstructure, rheology, thermal and mechanical behaviour of randomized polypropylene hetero-phasic block co-polymers

Ethylene and hexene-1 co-monomers were applied to isotactic polypropylene reactor alloys to compare the effect of the co-monomer type on their interfacial interaction and impact strength.

Heterophasic Polypropylene Copolymer Grafted with Itaconic Acid: Molecular Structure Analysis Through Fractionation Techniques

SummaryThe functionalization of polypropylene (PP) through the grafting of unsaturated polar monomers such as maleic anhydride (MAH), acrylic acid and its derivatives, in the presence of organic peroxide as initiator, has received much attention over the past decades. However, up to now, only few studies have been reported on the effect of these polar monomers on crystallization and how they are distributed in the polymeric chain. In the present work heterophasic polypropylene copolymer was grafted with itaconic acid (AIt) using reactive extrusion. The main objective of this work was to evaluate the influence of itaconic acid in the rubber and crystalline phases in samples of PP. The separation of the different phases by xylene solubles analysis showed that the acid has preference to incorporate in the rubber fraction. The amount of itaconic acid was determinate by FTIR. It was concluded that the addition of peroxide and itaconic acid to the polymer causes changes of chemical and structural order in the generated material. The results showed a narrowing in the profile of crystallization of the samples analyzed by CRYSTAF resulting of a higher interaction between crystalline and amorphous phases, due to the presence of hydrogen bridges arising from the grafted acid.

The Influence of Copolymerization Condition on Rheology, Morphology and Thermal Behavior of Polypropylene Heterophasic Copolymers

In this work, the polypropylene impact copolymers were synthesized by a modified sequential polymerization process. The copolymerization of ethylene and propylene was carried out between two homopolymerization stages at two different pressures and temperatures and the rheology, morphology and thermal properties of reactor alloys were studied. It is found that the ethylene propylene rubber (EPR) content increased up to 32 wt% by increasing the copolymerization time to 20 min. At a fixed copolymerization time of 10 min, the addition of 50 ppm hydrogen (H2), increased the EPR content from 9.7 to 12.8 wt%. By doubling H2 concentration, no considerable change in EPR wt% was observed. It is found that the zero shear viscosity of the alloys is significantly under the influence of EPR wt%, not the molecular weight of matrix. The molecular weight of PP matrices determined by rheological data, mildly decreased from 463000 to 458000 g/mol by increasing the copolymerization time from 10 min to 15 min. At high copolymerization time/high H2 concentration, a melting peak in the differential scanning calorimetry test around 165°C for isotactic PP and also an endothermic peak around 127°C for the block copolymer with long ethylene segments, is observed. The study of interfacial strength by theoretical emulsion models showed that 15 min copolymerization time is optimum considering EPR wt%.

The effect of controlled degradation on the molecular characteristics of heterophasic ethylene–propylene copolymers

ABSTRACTA commercial heterophasic ethylene–propylene copolymer (HEPC) produced by Sasol Polymers using a Ziegler‐Natta catalysed gas‐phase process was vis‐broken (controlled degradation) to various degrees by making use of an organic peroxide. The effects of the amount of vis‐breaking on the molecular characteristics and physical properties were subsequently studied by making use of preparative Temperature Rising Elution Fractionation (p‐TREF), Nuclear Magnetic Resonance (NMR), Differential Scanning Calorimetry (DSC), High Temperature Size Exclusion Chromatography (HT‐SEC), and deposition of the SEC fractions via the LC Transform Interface (SEC‐FTIR). It was found that by increasing the amount of organic peroxide, the molecular characteristics of the heterophasic copolymer are severely affected and hence influence the physical characteristics of the polymer dramatically. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41783.

Defining the distribution of ethylene-propylene copolymer phases in heterophasic ethylene-propylene copolymers by a sequential xylene extraction method: Chemical and morphological analysis

Sequential xylene extraction (SXE) in combination with scanning electron microscopy (SEM) and high temperature solvent gradient interaction chromatography (HT-SGIC) were employed for the detailed visualisation and understanding of the evolution of phase morphology in heterophasic ethylene-propylene copolymer (HEPC) particles. The study focused on sequentially extracting the soluble EP rubber phase and EP block or segmented copolymers by SXE at various temperatures. Major changes in the particle morphology (significant increase in both size and number of voids in the particles) after SXE were revealed using SEM imaging. These void structures are believed to result from the amorphous phase (EPR) being removed during the xylene extraction which was further confirmed by differential scanning calorimetry (DSC), high temperature 13C NMR spectroscopy and HT-SGIC. The extractables obtained at 100 °C were found to be a mixture of EP random copolymers, semi-crystalline EP (block or segmented) copolymers, as well as iPP and PE homopolymers. Upon complete dissolution of the particles by SXE at 100 °C, significant amounts of the EP rubber fractions were obtained. Our results show a very heterogeneous distribution of EPR components with varying chemical compositions in HEPC particles produced by dual-reactor processes. For the layered structure observed from this study, truly amorphous EP rubber was found in the outer most regions followed by continuous regions of EP random copolymers having increasing ethylene contents. Propylene-rich EPR, extracted at temperatures of 100 and 130 °C, was observed as the inner EPR phase. Semi-crystalline EP (segmented or block copolymer) and PE homopolymer were detected as intermediate structures between these two EPR regions, inside and outside the pores of the iPP particles. Based on these findings a modified multi-layered core–shell structure was proposed. The results obtained by the proposed SXE fractionation method and its combination with various analytical approaches are found to be very effective for the investigation of the phase composition present in HEPC particles. The present approach is general and can also be used for other multiphase semi-crystalline polyolefins.

Poly(propylene) Heterophasic Copolymers: Molecular Structure Analysis through Fractionation Techniques

SummaryHeterophasic poly(propylene) copolymers obtained by sequential polymerization are multi‐component products formed by a crystalline matrix of poly(propylene) and an ethylene‐propylene rubber phase. Some crystalline polyethylene and poly(ethylene‐co‐propylene) are formed in the rubber synthesis step by copolymerization of ethylene and propylene. These multi‐component systems present a complicated microstructure and heterophasic morphology. In this study, two heterophasic copolymers with the same total amount of rubber but different composition and molecular weight, were thoroughly analyzed. The morphology was evaluated by SEM and AFM techniques. The complexity of the system required some attention in the fractionation methodology to perform an accurate interpretation of results and different methodologies of fractionation, especially for obtaining PE fractions as free of PP as possible, were performed in order to better characterize the crystalline polyethylene fractions in the copolymers. Preparative TREF was used to obtain fractions for further analysis by 13C‐NMR, DSC and GPC. Also samples were submitted to Cross Fractionation Chromatography (CFC). Results obtained by the different methodologies were compared.

POLYPROPYLENE/STARCH BLENDS: STUDY OF THERMAL AND MORPHOLOGICAL PROPERTIES

SUMMARY Polypropylene/starch blends were prepared using starch of different botanical source. The influence of starch type and starch content on thermal properties and morphology of polypropylene/starch blends was studied. Corn and potato starches were used as starch source. The starch content in the blends was 7 and 15 wt-%. Characterization of PP and PP/starch blends by (DSC), (TGA), and (SEM) was carried out to obtain information on miscibility among PP and starch. The starch domains exhibited characteristic voids be due to thermal degradation.Two types of PP, PP 1 poly(propylene- co -ethylene), random copolymer, and PP 3 poly(propylene- co -ethylene), heterophasic copolymer were studied Keywords: Polypropylene, starch, blends, characterization INTRODUCTION Blends are a mixture of two or more polymers obtained by melting or in solution. Its objective is the preparation of a material that posses the combination of properties of their components, not compassable by separated. The development of a blend with an adequate behavior, especially with respect to their mechanical and physical properties, depends on the interfacial adhesion among the phases. A compatible blend is that in which the dispersed or minority phase is found homogeneously distributed in the matrix or majority phase and in which the adhesion among the same is strong. In this type of blends, a force applied is transmitted among the components of the phases (1).Polypropylene (PP), a synthetic polymer is an economical material that offers a combination of outstanding physical, mechanical, thermal, chemical properties that are not found in any other thermoplastic polymer (2)The great number of polyolefinic products has caused harmful consequences to the nature due to the low degradation rates reached by the traditional polyolefins, e.g. low-density polyethylene (LDPE) and isotactic polypropylene (iPP).By this way, researchers have studied the incorporation of biodegradable polymers, such as the starch, to the traditional polyolefins, which is justified by the presence of hydrolyzable groups in the natural polymer that are able to induce the biodegradation of the polyolefins (3-5).Ramis et al. (6) evaluated the biodegradability of iPP/starch blends under simulated soil and observed the materials decomposition under nitrogen and oxygen atmosphere, by different mechanisms of degradation. The biodegradation affected the starch but not the iPP matrix.When dealing with starch-derivative materials, this last can present a thermoplastic characteristic (commonly called thermoplastic starch or TPS) when incorporating glycerin to it, acting as a plasticizer (7).Moreover, the use of glycerin, as described by Carvalho (7) can increase the fragmentation rate of the material (morphological structure), obtaining though materials with many different characteristics just by varying the amount of glycerin on the starch.In general, it is said that in order to let the polyolefins more susceptible to degradation, some kind of modification is necessary, such as modifications on the crystallinity degree (8), chemical degradation and reduction on the molar mass of polymers to create short molecules that are capable of being absorbed by microorganisms (9).The inclusion of such materials allows products traditionally produced from non-renewable and environmentally persistent petroleum-based materials, to be produced from materials made from renewable resources which may also provide a degree of degradability to the final product. Starch, in particular, has been used since the 1970s as a filler in plastics (10) and has recently been plasticized and extruded with traditional plastics (11) used as a baked foam for thin walled applications (12), and used as packaging foams (13). Dry granular starch and baked starch, which is pressed and molded, have limited processability and can be used in only a limited range of applications. Plasticized starch, however, is more versatile and can be blended with various polymeric materials for numerous applications.Starch is an abundant, naturally occurring polysaccharide that is obtained from various plant sources, such as corn, potato, rice, and cassava [14]. Starch is a semi-crystalline polymer comprised of glucose monomer units. its granular form is comprised of linear amylose or branched amylopectin macromolecules with amylose content of ranging from 20-30% (see Scheme 1). Dry granular starch, by itself, cannot be processed like a plastic; however, it can be heated and blended with several different small polar molecules (water, glycerol) or polar oligomers (polyols), giving a thermoplastic material, generally called (PLS). This process, known as gelatinization, breaks up the granular structure of starch by disrupting hydrogen bonding between adjacent glucose molecules and essentially destroys its crystallinity [15].