Effect Of Chain Extender Research Articles

Investigating the Effect of Chain Extender on the Phase Separation and Mechanical Properties of Polybutadiene-Based Polyurethane.

The thermodynamic incompatibility between the soft and hard segments of thermoplastic polyurethane (TPU) results in a microphase-separated behavior and excellent mechanical properties. However, the effect of the chain extender on the degree of microphase separation (DMS) and the resultant mechanical properties of TPU have not been well studied because of the complex interactions between the soft and hard segments. Herein, hydroxyl-terminated polybutadiene-based TPUs(HTPB-TPUs) without hydrogen bonding between the soft and hard segments are synthesized using hydroxyl-terminated polybutadiene, toluene diisocyanate, and four different chain extenders, and the effect of the chain extender structure on DMS is analyzed experimentally using a combination of analytical techniques. Furthermore, the solubility parameters of the soft and hard segments, glass transition temperatures, and hydrogen-bond density of the HTPB-TPUs, are computed using all-atom molecular dynamics simulations. The results clearly reveal that the chain extender significantly affects the DMS and thus the mechanical properties of HTPB-TPUs. This study paves the way for studying the relationship between the structure and properties of TPU.

Study on the effect of chain extenders on aliphatic polyurethane and its application

AbstractThermoplastic polyurethane (TPU) has been applied to high‐performance laminated glass depending on its high impact strength and bonding properties. The utilization of various polyurethane molecular structures in laminated glass is scarcely reported. The selection and application of chain extenders are crucial for TPU performance. In this work, aliphatic polyurethane film with high strength has been successfully synthesized, incorporating chain extender of poly(propylene glycol) bis(2‐aminopropyl ether) (PEA230). The films with melting point above 80°C were prepared by adjusting the proportion of dimethylglyoxime (DMG), while simultaneously monitoring the thermal behavior of the samples by DMA. Results indicate that combining PEA230 and DMG in a 1:1 molar ratio yields the hydrogen bonding degree of 85.77%, toughness of 43.14 MJ m3, and shear stress of 1.8 MPa for the polyurethane film. Subsequently, laminated glasses based on the polyurethane film with different thermal properties were constructed successfully, and their super strong impact resistance was confirmed through falling ball impact experiments.

Effect of carbon black and chain extender on thermal, rheological and mechanical properties of fully biodegradable poly(butylene adipate‐co‐terephthalate)/poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) blends

AbstractDifferent carbon black (CB) contents in poly(butylene adipate‐co‐terephthalate) (PBAT)/poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P34HB) blends were prepared by melt blending using chain extender multifunctional styrene‐acrylic‐ epoxy random oligomer (ADR), as a compatibilizer. PBAT and P34HB were immiscible, and ADR could react with PBAT and P34HB to improve interfacial adhesion force and molecular entanglement. CB fillers were uniformly and selectively located in the PBAT matrix and could act as a nucleating agent to promote the nucleation of PBAT crystallization. At a CB content of 5 wt%, a percolation network structure of CB was formed. The most interesting result in the work was the achievement of composites with improved rheological and mechanical properties under the synergistic effect of chain extender and CB fillers. The viscoelasticity of the system was markedly improved and a transition from liquid‐like to solid‐like behavior was observed. Young's modulus and yield strength of chain extender modified PBAT/P34HB/CB composite with 10 wt% CB increased by 502% and 69% compared to neat PBAT, and by 89% and 43% compared to PBAT/P34HB binary blend. The combination of improved melt viscoelasticity and mechanical properties will further broaden the practical application of biodegradable polymers. © 2024 Society of Chemical Industry.

Recycling PET Bottles for 3D-Printing Filament: Effect of Chain Extender

This study investigates the effect of a chain extender on the properties of recycled polyethylene terephthalate (rPET) for 3D printing filament. The research focuses on the melt flow index (MFI), mechanical properties, thermal behavior, and crystallinity of rPET blends with varying chain extender concentrations. MFI analysis reveals that the viscosity of rPET is influenced by the grade and sources of the PET bottles. The addition of the chain extender decreases MFI, indicating increased viscosity. Mechanical testing shows a slight decrease in impact strength with increasing chain extender concentration, suggesting the presence of limitations or constraints within the material. Thermal analysis demonstrates that the chain extender elevates the glass transition temperature (Tg) and melting temperature (Tm) of rPET, indicating enhanced rigidity and thermal resistance. However, the crystallinity (Xc) decreases as the chain extender disrupts the regular packing of polymer chains within the crystalline regions. These findings provide valuable insights into the influence of the chain extender on the properties of rPET for 3D printing filament. The research contributes to the development of sustainable manufacturing practices and promotes the utilization of recycled materials in additive manufacturing applications, furthering the goals of the circular economy and environmental sustainability.

Effect of chain extender on the morphological, rheological and mechanical properties of biodegradable blends from PBAT and P34HB

Effect of chain extender on the morphological, rheological and mechanical properties of biodegradable blends from PBAT and P34HB

Investigation of the Effects of Chain Extender on Material Properties of PLA/PCL and PLA/PEG Blends: Comparative Study between Polycaprolactone and Polyethylene Glycol.

This study investigated the effect of the Joncryl concentration on the properties of polylactide/poly(ε-caprolactone) (PLA/PCL) and PLA/poly(ethylene glycol) (PEG) blends. The addition of Joncryl influenced the properties of both PLA-based blends. In the blend of PLA/PCL blends, the addition of Joncryl reduced the size of PCL droplets, which implies the compatibility of the two phases, while PLA/PEG blends showed a co-continuous type of morphology at 0.1% and 0.3 wt.% of Joncryl loading. The crystallinity of PCL and PEG was studied on both PLA/PCL and PLA/PEG blend systems. In both scenarios, the crystallinity of the blends decreased upon the addition of Joncryl. Thermal stabilities were shown to depend on the addition of Joncryl. The toughness increased when 0.5 wt.% of Joncryl was added to both systems. However, the stiffness of PLA/PCL decreased, while the stiffness of PLA/PEG increased with the increasing concentration of Joncryl. This study provides new insight into the effect of chain extenders on the compatibility of PLA-based blends.

Biodegradable blends from bacterial biopolyester PHBV and bio-based PBSA: Study of the effect of chain extender on the thermal, mechanical and morphological properties

Being aware of the global problem of plastic pollution, our society is claiming new bioplastics to replace conventional polymers. Balancing their mechanical performance is required to increase their presence in the market. Brittleness of bacterial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was attempted to be decreased by melt blending with flexible starch-based poly(butylene succinate-co-butylene adipate) (PBSA). An epoxy-functionalized chain extender was used to enhance interaction between both immiscible biopolyesters. Mechanical performance, morphology, rheology, and crystallization behavior of injection-molded PHBV-PBSA blends (70–30, 50–50, and 30–70 wt%) were assessed in the presence and absence of the chain extender. Crystallization of PHBV was hindered, which was reflected in the improvement of mechanical properties. When PBSA >50 %, the homogeneity of results increased within the same sample while for PHBV-PBSA 70–30 wt% the elongation was 45 % higher. During the flexural test, it changed from brittle to non-breakable. The additive did not change the type of morphology developed by each blend nor the toughening mechanisms, so impact strength was barely affected. However, it reduced the size of dispersed phase domains due to a viscosity change, improving their processability. The higher the PHBV in the blend, the higher the effect of the chain extender.

Effect of chain extenders on the hydrolytic degradation of soybean polyurethane

AbstractThis publication highlights the effect that different chain extenders (CEs) have on the structure–property relationships of soy‐based polyurethanes that have been exposed to hydrolytic degradation for 480 and 960 h at 80°C. Gel content, crosslinking densities, surface energy, atomic force microscopy, dielectric, and dynamic mechanics were used for monitored structural changes. Polyurethanes (PU) is composed of a structure with minor phase separation when a chain extender is not used, maintaining all properties over time. However, when a chain extender, butane‐1.4‐diol (BDO), ethane‐1.2‐diol (MEG) our (2‐hydroxypropoxy)‐propane‐2‐ol are added, it is noted that there is a more significant degradation in the flexible domains, modifying the fraction between the initial rigid (HS)/soft (SS) segment that makes the polymer stiff and brittle. The hydrolysis degradation generates new Fourier transform infrared bands relative to urea (1640 cm−1) and amide (1800 cm−1). The reduction in band intensity of the C=Ofree at 1730 cm−1, while increasing the intensity of C=Obonded at 1710 cm−1 indicated a higher phase separation degree. After 960 h the TgS decreased, while the TgH was practically unchanged. The higher polarization observed in the PUs with BDO and MEG samples indicates the increased phase separation resulting in hydrolytic degradation.

Effect of chain extenders with different functionalities on the properties of single-component waterborne polyurethane ink binders.

Waterborne polyurethane (WPU) dispersions were prepared by post-chain extension and crosslinking reactions using 2-[(2-aminoethyl)-amino]ethyl sulfonic acid sodium (AAS), diethylenetriamine (DETA), triethylenetetramine (TETA) and AAS/DETA as post-chain extenders, and their influence on the properties of WPUs was studied. Results showed the introduction of trifunctional DETA chain extenders significantly improved the molecular weight, T-peel strength, and water resistance of WPUs, suggesting that DETA was an effective crosslinking agent. The WPU dispersions with a 2 : 3 molar ratio of AAS/DETA chain extenders exhibited excellent properties. At a molar ratio of 1.6 for NCO groups to OH groups, a stable WPU dispersion possessed higher solid content of 42.8%. Furthermore, only 4 wt% organic solvents were used in the preparation of WPU dispersions. Results revealed that the obtained WPU dispersions are a potential candidate for binders in water-based inks, without removing organic solvents. This study may provide some insight or guidance for the design and preparation of water-based ink binders.

Fully Biobased Reactive Extrusion of Biocomposites Based on PLA Blends and Hazelnut Shell Powders (HSP)

The production of biocomposites based on natural fiber waste and biopolymers is constantly increasing because of their renewability, biodegradability, and the accordance with the circular economy principles. The aim of this work is to contrast the disadvantages in the production of biocomposites, such as reduction of molecular weight through the use of biobased chain extenders. For this purpose, epoxidized soybean oil (ESO) and dicarboxylic acids (DCAs) were used to contrast the slight chain scission observed in a poly(lactic acid) (PLA)/poly(butylene succinate-co-adipate) (PBSA) binary blend caused by the melt mixing with hazelnut shell powder (HSP). Two different dimensions of HSPs were considered in this study as well as different concentrations of the ESO/DCA system, comparing succinic acid and malic acid as dicarboxylic acids. Melt viscosity parameters, such as torque and melt volume rate (MVR), were measured to investigate the chain extender effect during the extrusion. In addition, the reactivity of the ESO/DCA system was investigated through infrared spectroscopy. The effect of chain extenders on thermal properties, in particular on the crystallinity of PLA, and on mechanical properties of final biocomposites was investigated to understand their potentialities in industrial application. Results of this study evidenced a modest increase in melt viscosity due to ESO/malic acid chain extension system, but only for the HSP with the lower dimension (so the higher surface area) and adding 0.5 wt.% of ESO/malic acid. Thus, the slight chain scission of polyesters, not significantly affecting the final properties of these biocomposites, is the most relevant effect that was revealed in this complex reactive system.

Effect of chain extender on morphologies and properties of PBAT/PLA composites

Biodegradable poly(butylene adipate-co-terephthalate)/poly(lactic acid) (PBAT/PLA) composites were prepared by melt blending, and chain extender was used to improve the compatibility of PBAT/PLA blends through the chemical reaction. The influence of PLA and chain extender contents on mechanical properties, morphology, and rheological properties of PBAT/PLA composites was systematically investigated. The results revealed that the Young’s modulus and stress values gradually increased under the same strain, whereas the elongation at break decreased with the increase of chain extender content for PBAT/PLA (80/20) composites. Noteworthy, the presence of chain extender improves the interfacial compatibility between PLA and PBAT phases. At the chain extender content of 0.4, 0.6, and 0.8 wt.%, the extensional viscosity of the composites exhibited an increasing trend, whereas an obvious strain-hardening phenomenon emerged in the uniaxial extensional curves.

Synthesis of Mono Ethylene Glycol (MEG)-Based Polyurethane and Effect of Chain Extender on Its Associated Properties.

This study depicts the investigations of the effect of composition of aromatic polyester polyol produced from terephthalic acid (TPA) and different concentrations of mono ethylene glycol (mEG) as a chain extender on the mechanical properties of polyurethane (PU) elastomer. Aromatic polyester polyols are prepared via the poly-esterification of adipic acid, terephthalic acid, catalyst, and mono ethylene glycol; while a polyurethane elastomer is formulated via the pre-polymerization of polyol with pure monomeric Methylene diphenyl diisocyanate (MDI.) Mechanical properties of polyurethane elastomers are examined, such as hardness via shore A hardness, apparent density via ASTM (American Society for Testing and Materials) D1622–08, and abrasion wear resistance via a Deutches Institut fur Normung (DIN) abrasion wear resistance tester. Structural properties are investigated through Fourier-transform infrared spectroscopy (FTIR) analysis. Results reveal that the shore A hardness of the PU elastomer increases with an increasing concentration of mEG from 4g to 12g. Nevertheless, the elastomer’s density depicts a reduction with an increasing extender content. The abrasion wear resistance of polyurethane, however, increases with an increasing concentration of glycol. A structural analysis through FTIR confirms the formation of polyurethane elastomer through the characteristic peaks demonstrated.

Effect of chain extender on microphase structure and performance of self‐healing polyurethane and poly(urethane‐urea)

AbstractIn this work, four aliphatic chain extenders, hexanediol (HDO), hexane diamine (HDA), cystamine (CY), and cystine dimethyl ester (CDE), were chosen to synthesize four kinds of polyurethane and poly(urethane‐urea)s (PUs), respectively. HDO extended polyurethanes, HDA extended poly(urethane‐urea), CY extended poly(urethane‐urea), and CDE extended poly(urethane‐urea) were denoted as OPU, APU, CPU, and SPU, respectively. The effect of chain extender type on microphase structure and performance of four PUs was investigated. Our research showed that mechanical strength increased in the following order: OPU < SPU < CPU < APU, and self‐healing performance increased in the opposite direction. This result is attributed to the increasing degree of microphase separation: OPU < SPU < CPU < APU. The optimal sample SPU has not only excellent mechanical properties (tensile strength of 27.1 MPa and elongation at break of 397.7%), but also exhibits superior self‐healing performance (self‐healing efficiencies of 95.3% and 93.5% based on tensile strength and elongation at break). The moderate degree of microphase separation between the soft segments and the hard segments, the introduction of disulfide bonds and low degree of hydrogen bonding are responsible for preparing a polyurethane or poly(urethane‐urea) system with high mechanical strength and excellent self‐healing performance simultaneously. This work provides useful information for us to develop self‐healing polyurethane or poly(urethane‐urea) materials in the future.

Effect of chain extender on the morphology, thermal, viscoelastic, and dielectric behavior of soybean polyurethane

AbstractThe objective of this work was to determine the influence of different chain extenders (CEs) on the morphology, thermal, viscoelastic, and dielectric properties of soybean polyurethane (PU). The PU with ethane‐1.2‐diol showed a more organized structure, which was attributed to the smaller amount of methylene groups (CH2) and the shorter distance between the hydrogen bonds. While, PUs with dipropylene glycol, the free volume increased due to the less effective interactions formed between the hard and soft domains. The α, β, and γ transitions dipolar by conductive process, are probably associated with (a) local motions of the main chain, (b) the smaller groups rotation motions in the fatty acid chains in the soft phase, and (c) the CH2 group rotation motion in the amorphous region. The phase‐separated morphology is most evident at high temperatures due to the Maxwell–Wagner–Sillars interfacial polarization process.

Effect of chain extender and light stabilizer on the weathering resistance of PBAT/PLA blend films prepared by extrusion blowing

Biodegradable poly (butylene adipate‑co‑terephthalate)/polylactic acid (PBAT/PLA) films were prepared by melt blending and blowing technology under the presence of a chain extender and two different light stabilizers. A comparison of the infrared spectra of the film with and without these additives before and after the weathering tests showed that the addition of chain extender and light stabilizer improved the polymer weathering resistance significantly. Without PLA, PBAT underwent serious chain scissions and crosslinking during the weathering. PBAT/PLA film chain scissions were weakened as the PLA content increased. After 200 h of the weathering, the machine direction (MD) tensile strength as well as MD and transverse direction (TD) elongation at break of both PBAT and PBAT/PLA films decreased, while their TD tensile strength changed only slightly. The film with the 85:15 PBAT:PLA ratio containing 1.5 phr of chain extender showed much better flexibility without any changes to its tensile strength. The addition of 0.6 phr of light stabilizer (Chimassorb2020 or Irganox 1010) to this blend showed significantly improved weathering resistance. Better weathering improvement was observed when Chimassorb2020 was added. The tensile strength of PBAT/PLA/ADR/ Chimassorb2020 sample in the machine and transverse directions decreased by 8.4 and 28%, respectively, after 200 h of weathering.

Effect of chain extender on structural and mechanical properties of poly(butylene succinate‐co‐adipate)/halloysite nanotube bionanocomposites

AbstractBionanocomposites comprising poly(butylene succinate‐co‐adipate) (PBSA) and halloysite nanotubes (HNTs) were fabricated via melt extrusion using different HNT loadings. These nanocomposites were characterized through Fourier transfer infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, and mechanical, thermal, and rheological tests. Adding a chain extender (CE) ensured homogeneous dispersion of HNTs in the PBSA matrix because the epoxy‐based CE and HNTs reacted with the carboxyl groups of PBSA, leading to effective interfacial interactions between the matrix and reinforcing filler. Differential scanning calorimetry results revealed that HNTs had a nucleating effect on PBSA, thereby increasing the crystallization of PBSA and percentage crystallinity of the composites. Nevertheless, the CE did not cause any change in the crystallinity of the nanocomposites. Further, the thermal stability of PBSA without and with the CE reduced, depending on the HNT loading. The HNTs and CE also increased the melt strength of PBSA. Additionally, HNTs and CE enhanced the mechanical properties owing to the increased molecular weight and formation of long‐chain branched structures.

Effect of the Trifunctional Chain Extender on Intrinsic Viscosity, Crystallization Behavior, and Mechanical Properties of Poly(Ethylene Terephthalate)

In this work, poly(ethylene terephthalate) (PET) chain-extending products with different molecular weights were prepared by reactive extrusion using isocyanate trimer (C-HK) as the trifunctional chain extender. The effect of the chain extender C-HK on the intrinsic viscosity, melt flow property, crystallization behavior, crystallization morphology, and mechanical property of PET was investigated. The results showed that when the content of the chain extender was increased from 0.6 to 1.4 wt%, the viscosity average molecular weight of PET was effectively increased from 2.36 × 104 to 5.46 × 104 g·mol–1. After the chain extending, the crystallinity and the time of semicrystallization of PET were significantly decreased. After the isothermal crystallization at 220 °C for 5 min, the spherulites formed by pure PET became larger. With the increase in molecular weight of PET after chain extension, its spherulite size was significantly decreased without changing the crystalline structure. The chain-extended PET also exhibited more excellent bending-resistant and impact-resistant properties. While the tensile strength of PET after chain extension was slightly decreased, the bending strength was increased by a maximum value of 56.8%, and the impact strength was increased by a maximum value of five times.

Understanding the effect of chain extender on poly(butylene adipate-co-terephthalate) structure

We investigated poly(butylene adipate-co-terephthalate) (PBAT), a biodegradable polymer, under the influence of a chain extender (a multifunctional epoxide oligomer, Joncryl ADR-4370S®, ADR) at different concentrations, and correlated their properties concerning the molecular interaction between the active sites of the structures. Several studies have used ADR in poly(lactic acid)-PBAT blends; however, the effect of ADR in terms of chemical and physical interaction with PBAT is not investigated in-depth, which can limit its applications. The chain extender is usually applied to improve the mechanical and thermal properties and PBAT resistance to thermal degradation. The developed materials were evaluated by high-resolution solid-state nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), mechanical and thermal properties, and rheological measurements. NMR and FTIR indicate an interaction between the carboxylic sites of PBAT and the epoxy sites of ADR. PBAT-2%ADR shows higher tensile properties, probably due to the hydrogen bonds and interactions of π–π nature between the materials; in this case, the ADR can act as a reinforcing agent. High contents of chain extender can change the nature of the interaction and influence the final properties of the polymer. The effect of this additive was found to be strongly dependent on the content used and the polymer processing. It was observed that ADR could act as an internal lubricant during processing (due to the low molecular weight of this additive), demonstrating the importance of processing parameters control.

Elucidating the effect of chain extenders substituted by aliphatic side chains on morphology and gas separation of polyurethanes

Novel poly(urethane-urea) (PUU) membranes were developed as the aim of a structure-property relationship study to enhance gas permeation. Designing the PUUs was followed by three synthesized chain extenders with different length-alkyl side chains, polytetramethylene glycol, and isophorone and hexamethylene diisocyanates. The longest substituted PUU indicated higher phase separation and lower glass transition temperature. Pure and mixed gas permeabilities of prepared membranes grew as phase separation of PUU material increased, while fractional free volume decreased by lengthening the side chain of the PUUs. The reasons for this event were the migration of the side chains to the surface of hard domain, thereby shielding it and filling the soft/hard interface. Enhanced permeability of materials with longer side chains is attributed to its plasticizing effect. The highest CO2 permeability (287 barrer) was obtained for the longest substituted PUU. The findings revealed an increase in gas permeation without a significant reduction of selectivity by longer substituted PUUs.

Effects of chain extender and uniaxial stretching on the properties of PLA/PPC/mica composites

Poly(lactic acid) (PLA)/poly(propylene carbonate) (PPC)/mica composites with different amount of chain extender (CE) were melt compounded and then processed via two routes (compression molding and uniaxial stretching) into sheets and films. The tensile, thermal, and oxygen barrier properties of all the samples were investigated. Tensile test showed that the tensile strength and elongation at break of all films were much higher than that of all sheets, especially for PLA/PPC/mica with 0.9‐wt% CE composite (CM3(CE)0.9) film. The crystallinity of all films increased significantly after uniaxial stretching of sheet samples. The Fourier transform infrared spectroscopy (FTIR) results proved the chemical reactions occurred between PLA/PPC and CE. Scanning electron microscope (SEM) analysis revealed that compatibility and interfacial adhesion of all samples were improved after adding mica and CE, and they were further enhanced after uniaxial stretching. The addition of CE was not favorable to improve the oxygen barrier performance of PLA/PPC/mica sheet samples. However, the oxygen barrier performance of film samples was significantly improved after uniaxial stretching. In particular, the CM3(CE)0.9 film had the lowest oxygen permeability coefficient (1.4 × 10−15 cm3·cm/(cm2·s·Pa)), and this was the best oxygen barrier properties reported in the literature for PLA‐based composites, which was comparable with PA film. This study demonstrated the high efficiency of uniaxial stretching on improvement of properties of composites, which would promote the application of biodegradable polymers in oxygen sensitive food packaging.