Papers by Keyword: Chain Extender

Abstract: 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 (T_g) and melting temperature (T_m) of rPET, indicating enhanced rigidity and thermal resistance. However, the crystallinity (X_c) 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.

Abstract: Chain extender plays a significant role in enhancing the final mechanical properties of thermoplastic polyurethane (TPUs) derived from polytetra methylene etherglycol (PTMG) and 4,4-diphenylmethane diisocyanate (MDI). In this research we focused on the effect that mixed chain extender of ethylene glycol (EG) and 1,4-butanediol (BDO) used has on the phase behavior and morphology of high hard block content TPUs. DSC, FTIR, and mechanical testing were mainly used to characterize the morphology and properties of the TPUs materials. Through this work we were able to show that mixed ratio of different chain extenders had dramatic effects on the properties of the TPUs. After mixing EG and BDO, the degree of hydrogen bonding, melting temperature, tensile strength, tear strength, and hardness of TPUs are all reduced, the glass transition temperature is increased. when the mixing ratio is 1: 1 , the elongation at break is increased to 672% . However, when the mixing ratio is n (EG): n (BDO) = 1: 2, the tensile strength is increased to 29.2 MPa, and the elongation at break is reduced to 353%.

Abstract: The effect of monoethylene glycol (mEG) acting as chain extender in polypropylene glycol (PPG-4000) and 4,4ʹ-diphenylmethane diisocyanate (MDI) reaction was investigated. Polyurethane elastomers (PUR) were changed from flexible to rigid materials by varying the mEG content. Results show that Shore A and D hardness values trend to increase with increasing mEG content. It appears that increasing the chain extender content increases the hard segment content in the polyurethane structure. Moreover, increasing the mEG content increases Young’s modulus and the tensile strength of PUR, while elongation at break decreases. The chemical structure of the hard segment of PUR was characterized by Infrared (IR) spectroscopy. IR spectra exhibited the bands typical for PUR consisting of –NH, CH₂– and C=O groups. The spectra reveal a few interactions between the polymeric chains that appear to be responsible for the shift of transmittance peak and decrease of some peak intensity. This may be due to the hard segment aggregating more to form domains in the PUR when mEG content was increased.

Abstract: The aim of this work was to compare and discuss the influence of multifunctional monomers as crosslinking agent (Triallyl Isocyanurate; TAIC) and chain extender (Joncryl ADR4368) on the gamma irradiated Polylactic acid (PLA). The modified PLA samples with varying amount of TAIC and Joncryl were characterized by observing the molecular characteristics and mechanical properties. The results showed that irradiated PLA had lower average molar mass and mechanical properties compared to non-irradiated PLA due to irradiation induced chain scission. Gel content was observed and increased with increasing irradiation dose for the TAIC modified sample, indicating that the further crosslink of irradiated PLA was occurring. Crosslinking and chain extension were responsible for the improved modulus and tensile strength of irradiated PLA, however the decrease in tensile strength at high irradiation dose was observed for crosslinked PLA.

Abstract: Ultraviolet (UV) curable waterborne polyurethane dispersions with comb branched structure were synthesized by prepolymer process. C=C bonds were incorporated into the branched chains of the polyurethane using chain extender, hence, the content of C=C bonds can be adjusted by the chain extender consumption. The chemical structure was identified by Fourier transform infrared spectroscopy (FTIR) and ¹H NMR. Effects of the chain extender content on the microstructure, rheological behavior, thermal property, mechanical and other properties of the UV cured films were researched.

Abstract: High molecular weight PLA was successfully synthesized by chain extension reaction of hydroxylated prepolymer using succinic anhydride as a chain extender. Hydroxylated prepolymer was prepared by direct condensation polymerization of L-lactic acid in the presence of 1,4-butanediol. Various molar ratios between hydroxylated prepolymer and succinic anhydride (i.e, 1:1, 1:2, 1:3) were investigated. The results showed that succinic anhydride can help increasing molecular weight of hydroxylated prepolymer approximately up to 47% as characterized by gel permeation chromatography (GPC) technique. Proton nuclear magnetic resonance (¹H-NMR) was used to investigate structure of chain-extended PLA. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to examine thermal properties while the crystallinity was investigated by X-ray diffraction (XRD).

Abstract: In this work, biodegradable plastics were produced from different poly(lactic acid) (PLA)/ poly(butylene succinate) (PBS) blend ratios in the presence of a fix loading (1 phr) of a commercial epoxy functionalised polymeric chain extender (Joncryl ADR-4300-S). The effects of blend ratio and chain extender on the tensile properties, thermal stability and morphology were investigated by the tensile testing, thermogravimetric analysis (TGA) and scanning electron microscopy, respectively. The results show that the incorporation of PBS and Joncryl into PLA apparently reduced the tensile strength and tensile modulus, but increased the elongation at break of the blends in a dose-dependent manner. However, their blends provide interesting materials for industrial packaging applications, due to their enhanced ductility by decreasing the tensile modulus and increasing the elongation at break. TGA analysis showed that thermal stability of the blends was lower than that of the pure PLA and PBS. Moreover, the chain-extended products exhibit two stages of thermal decomposition, the first was due to the degradation of PBS, and the second was due to the degradation of PLA.

Abstract: In this work pyromellitic dianhydride (PMDA) was used as the chain extender to increase the molecular weight of the recycled poly(ethylene terephthalate) (R-PET) and improve the rheological properties of the R-PET. The reaction was performed in a Brabender torque rheometer. The rheological and thermal characterization were performed by means of a fusion index instrument and a differential scanning calorimeter (DSC ) to compare the effectiveness of the chain extending reaction of different percentages of PMDA. The experimental results showed that compared with the unmodified R-PET, the addition of PMDA decreased the melt flow index and increased the viscosity of the R-PET. In addition, increased crystallization temperatures ( ) were observed with the modified R-PET. It was also found that the modified R-PET with the concentration of 1.0wt% PMDA exhibited the lowest MFI.

Abstract: In this work, hydroxyl-terminated lactic acid prepolymer was firstly prepared by adding diethylene glycol in the condensation of lactic acid. Molecular weight, acid value and structure of prepolymer were characterized. The results showed that the prepolymer was hydroxyl-terminated with weight average molecular weight (M_W) of 10,000 g/mol. After that, the chain linking polymerization of the prepolymer was carried out in a glass tube at 160 °C for 1 h employing 1,6-hexamethylene diisocyanate (HMDI) as a chain extender. By varying the hydroxyl/isocyanate ratio, it was found that the OH/NCO ratio of 1:2 seemed to be the most suitable ratio which gave PLA with the maximum M_W of 93,000 g/mol.

Abstract: Novel sterically hindered chain extender, 2-acetyl-ethylenediamine (MEDA) was synthesized by acetylating of ethylenediamine(EDA) with glacial acetic acid in presence of phosphoric acid, in order to reduce high reactivity of synthesizing polyurea and study its kinetics equation. Its chemical structure was confirmed through FTIR and 1H-NMR analysis. Polyureas were synthesized by reaction of 4,4’-diphe^{Superscript text}nylmethane diisocyanate(MDI), amine terminated polyether(D-2000) with different chain extenders. The reaction kinetics of polyurea curing process was studied by FTIR. The results showed that extending reaction with MEDA was second order kinetic mechanism, its apparent activation energy was 36.81 kJ•mol^-1.