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A series of polyurethane elastomers (PUEs) were prepared by the reaction of hydroxyl-terminated polybutadiene (HTPB) and toluene diisocyanate (TDI), the resultant PU prepolymer was extended with polydimethyl siloxane (PDMS). The conventional spectroscopic characterization of the synthesized samples using Fourier transform infrared spectrophotometer confirmed the structure of the proposed PDMS-based PU. Thermogravimetric analysis (TGA) was carried out to determine the thermal stability of the prepared PU samples. Surface properties of the synthesized material were studied determining the percentage of water absorption and equilibrium degree of swelling. The results revealed that by increasing the mole ratio of PDMS, the synthesized PUEs showed hydrophilic behavior while placing them in water and dimethyl sulfoxide solvent. [ABSTRACT FROM AUTHOR]

The present research work was performed to study the properties of siloxane-based polyurethane (SPU) elastomers using aliphatic diisocyanate. SPU samples constituting of hexamethylene diisocyanate, hydroxyl-terminated polybutadiene, and polydimethylsiloxane (PDMS) were synthesized by two-step polymerization technique. Molecular engineering and surface characterization were carried out, and the outcome of the results was discussed. The conventional spectroscopic characterization of the synthesized samples using Fourier transform infrared spectroscopy confirms the existence of the proposed SPU structure. Surface properties of the synthesized material were studied determining the percentage of water absorption and equilibrium of the degree of swelling. It was found that by increasing the mole ratio of PDMS, the synthesized PU samples showed hydrophobic behavior while placing them in water and in dimethylsulfoxide solvent. [ABSTRACT FROM AUTHOR]

Abstract: Hydroxy terminated polybutadiene (HTPB)-chitin based polyurethanes (PUs) with controlled hydrophobicity were synthesized using HTPB and toluene diisocyanate (TDI). The prepolymer was extended with different mass ratios of chitin and 1,4-butane diol (BDO). The effect of chitin contents in chain extender (CE) proportions on surface properties was studied and investigated. Incorporation of chitin contents into the final PU showed decrease in contact angle value of water drop, water absorption (%) and swelling behavior. The antibacterial activity of the prepared samples was affected by varying the chitin contents in the chemical composition of the final PU. The results demonstrated that the use of prepared material can be suggested as non-absorbable suture. [Copyright &y& Elsevier]

Polyurethanes (PUs) prepolymer was prepared by the reaction of toluene-2,4-diisocyanate (TDI) and poly caprolactone diols and the chain was further extended with 1,4-butane diol (1,4-BDO) to get final polyurethane (PU). FTIR spectra of the monomers, PU prepolymer, chain extender and final PU confirmed the reaction progress. A series of blends were prepared by varying the percent compositions of prepared PU, procured polymethyl methacylates (PMMA) and titanium dioxide (TiO). Pellets were formed from the prepared blends (PU-PMMA/TiO) using a self-designed mechanical tool. Scanning electron microscope (SEM) images were also taken to confirm the incorporation of the TiO contents into the prepared blends. Mechanical properties such as hardness and compressive strength were studied and discussed. The results of the study reveal that the blended sample having 80% PU, 20% PMMA content with 2.5 g TiO in 100 g mixture of PU and PMMA is very suitable for suggesting dental materials. [ABSTRACT FROM AUTHOR]

Abstract: Chitin based polyurethane bio-nanocomposites (PUBNC) were prepared using chitin, Delite® HPS bentonite nanoclay enriched in montmorillonite (MMT), 4,4′-diphenylmethane diisocyanate (MDI) and polycaprolactone polyol CAPA 231 (3000g/mol−1). The prepolymers having different concentration of Delite HPS bentonite nanoclay were extended with 2moles of chitin. The structures of the resulted polymers were determined by FT-IR technique. The effect of nanoclay contents on mechanical properties and in vitro biocompatibility was investigated. The mechanical properties of the synthesized materials were improved with increase in the Delite HPS® bentonite nanoclay contents. Optimum mechanical properties were obtained from the PU bio-nanocomposite samples having 4% Delite HPS® bentonite nanoclay. The results revealed that the final PU bio-nanocomposite having 2% Delite HPS® bentonite nanoclay contents is ideal contenders for surgical threads with on going investigations into their in vitro biocompatibility, non-toxicity, and mechanical properties. [Copyright &y& Elsevier]

Abstract: Chitin based polyurethane bio-nanocomposites (PUBNC) were prepared by emulsion polymerization. A mixture of polymer and bentonite clay enriched in montmorillonite (MMT) was formed in emulsion polymerization, in which MMT dispersed differently depending on interaction of MMT with polymer chains. Cation exchange capacity (CEC) of bentonite clay enriched in montmorillonite was found 74meq/100g. The existence of the intercalated clay by PU in the hybrid was confirmed using optical microscope (OM) technique. Optical microscope (OM) photographs verified the well dispersed ordered intercalated assembles layers of bentonite in PU matrix. [Copyright &y& Elsevier]

Abstract: Chitin based polyurethane bio-nanocomposites (PUBNC) were prepared by emulsion polymerization. The existence of the intercalated clay by polyurethane (PU) in the hybrid was confirmed using X-ray diffraction (XRD), dynamic mechanical measurements and optical microscope (OM) techniques. The values of enthalpies changes (ΔH) associated with different bentonite nanoclay contents are much consistent with the crystalline pattern of the synthesized PUBNC samples. These results revealed that pure silicate disappear in PU/bentonite nanoclay hybrid and a set of new peaks appears corresponding to the basal spacing of PU/bentonite clay bio-nanocomposites. The values of tan δ versus temperature recorded using dynamic mechanical measurements were also in accord with crystalline pattern of the PUBNC samples. [Copyright &y& Elsevier]

Abstract: Chitin-based polyurethane elastomers having potential for biomedical applications with tunable mechanical properties were synthesized by step growth polymerization techniques using poly(ɛ-caprolactone) (PCL) with different diisocyanates. The prepolymer was extended using chitin and/or 1,4-butane diol (BDO). The structures of the resulted polymers were determined by Fourier transform infrared (FTIR), 1H NMR and 13C NMR spectroscopic techniques. The effect of structure of diisocyanates and chain extenders on mechanical properties and in vitro biocompatibility were investigated. The results revealed that the final polymers extended with chitin are preferred candidates for surgical threads with on going investigations into their in vitro biocompatibility and non-toxicity. [Copyright &y& Elsevier]

Abstract: Chitin based polyurethane elastomers with potential as biomedical implants with tunable mechanical properties were synthesized by step growth polymerization techniques using poly(ɛ-caprolactone) (PCL) and 4,4′-diphenylmethane diisocyanate (MDI). The prepolymer was extended with different mass ratios of chitin and 1,4-butane diol (BDO). Molecular characterization was done using FTIR, 1H NMR and 13C NMR techniques. The mechanical properties of these polymers were improved with increase in the chitin contents. Optimum mechanical properties were obtained from elastomers extended with chitin in comparison to elastomers extended with BDO. Cytotoxicity of the synthesized polyurethane samples was affected by varying the chitin contents in the chemical composition of the final polyurethane (PU). It is revealed that the final polymers extended with chitin are preferred candidates for surgical threads with on going investigations into their in vitro biocompatibility and non-toxicity. [Copyright &y& Elsevier]

In this study, we evaluated the morphological behavior of polyurethane elastomers (PUEs) by modifying the soft segment chain length. This was achieved by increasing the soft segment molecular weight (Mn = 400–4000 gmol−1). In this regard, polycaprolactone diol (PCL) was selected as the soft segment, and 4,4′-cyclohexamethylene diisocyanate (H12MDI) and 1,6-hexanediol (HDO) were chosen as the hard segments. The films were prepared by curing polymer on Teflon surfaces. Fourier transform infrared spectroscopy (FTIR) was utilized for functional group identification in the prepared elastomers. FTIR peaks indicated the disappearance of −NCO and −OH groups and the formation of urethane (NHCOO) groups. The morphological behavior of the synthesized polymer samples was also elucidated using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The AFM and SEM results indicated that the extent of microphase separation was enhanced by an increase in the molecular weight of PCL. The phase separation and degree of crystallinity of the soft and hard segments were described using X-ray diffraction (XRD). It was observed that the degree of crystallinity of the synthesized polymers increased with an increase in the soft segment's chain length. To evaluate hydrophilicity/hydrophobicity, the contact angle was measured. A gradual increase in the contact angle with distilled water and diiodomethane (38.6°–54.9°) test liquids was observed. Moreover, the decrease in surface energy (46.95–24.45 mN/m) was also found to be inconsistent by increasing the molecular weight of polyols. [ABSTRACT FROM AUTHOR]

A series of polyurethane elastomers (PUEs) based on 4,4′-cyclohexamethylene diisocyanate (H 12 MDI)/1,2-ethanediol as hard segment with the soft segments having different molecular weights of polycaprolactone diols, were effectively polymerized by two step technique. The structural characterization was performed by FT-IR spectroscopy. The X-ray diffraction (XRD) technique was used to study the crystallinity and hydrophilicity of the prepared polymer films. It was found that crystallinity and hydrophilicity increased with increasing the chain length of soft segments. The effect of molecular weight of polyols on the contact angle, water absorption (%) and swelling behavior of the synthesized polyurethanes were also studied. Moreover, the scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques revealed that the degree of micro-phase separation increases with increasing molecular weight of polyol which confirmed the results pattern shown by XRD diffractogram. [ABSTRACT FROM AUTHOR]

The present study describes a novel ecofriendly series of chitin/curcumin/1,4-butane diol (BDO) blend derived polyurethanes (PUs), using hydroxy terminated polybutadiene (HTPB) and hexamethylene diisocyanate (HDI) along with different mole ratio of chitin, curcumin and BDO. The structural and morphological elucidation of the prepared films was done by FTIR and SEM techniques. The swelling behavior of the films was analyzed in both water and DMSO, which showed that incorporation of chitin increases the hydrophobicity and decreases the rate of swelling. Thermal analysis of synthesized PU blends revealed better thermal stability with following mole ratio 1:0.5:0.5 of chitin: curcumin: BDO as determined by TGA and DSC techniques. [ABSTRACT FROM AUTHOR]

In this work, new hexamethylene diisocyanate (HMDI) and hyroxylterminated polybutadiene (HTPB) based polyurethanes (PUs) were prepared following step growth polymerization by the introduction of varying mole ratio of chitosan (CH) and curcumin (CUR). Structural study of blends through infrared spectroscopy confirmed the incorporation of CH and CUR into the backbone of the PU. The scanning electron microscopic (SEM) study confirmed the well dispersion of incorporated chitosan/curcumin and homogeneity of surface of synthesized samples. Thermogravimetric analysis (TGA) of PU blends indicated a better thermal stability with 0.25 M:0.75 M of chitosan to curcumin. Mechanical properties such as modulus and tensile strength of PU blends were found to be better with higher contents of chitosan and curcumin. The same extender composition (1 mol BDO, 075 mol chitosan and 0.25 mol curcumin) based PU showed higher substantial of antimicrobial activity as compared to the all other PUs. On the whole, this work is actually a step towards the generation of novel biocompatible materials preferably useful for biomedical applications. [ABSTRACT FROM AUTHOR]

Polysaccharides derived from plants are one of the largest groups of natural compounds that offer potentially beneficial functions and properties. Glucomannan, a bioactive polymer belonged to mannan family of polysaccharides is fairly abundant in nature along with superior gelling and film forming properties. Glucomannan and its derivative with several synthetic polymers are used in a biomedical and food sector especially. Polyurethanes (PUs), a commercially useful class of polymers are extensively used in both industry and everyday life because they retain exceptional properties of both plastics and elastomers. This review addresses the properties and applications of glucomannan based materials with the aim to be explored this less attempted polymer further. Furthermore this paper also presents an overview of current status and perspectives of glucomannan based polyurethane materials. [ABSTRACT FROM AUTHOR]

Chitin and chitosan are amino polysaccharides having massive structural propensities to produce bioactive materials with innovative properties, functions and diverse applications particularly in biomedical field. The specific physico-chemical, mechanical, biological and degradation properties offer efficient way to blend these biopolymers with synthetic ones. Polyurethane (PU) gained substantial attention owing to its structure-properties relationship. The immense activities of chitin/chitosan are successfully utilized to enhance the bioactive properties of polyurethanes. This review shed a light on chitin and chitosan based PU materials with their potential applications especially focusing the bio-medical field. All the technical scientific issues have been addressed highlighting the recent advancement in the biomedical field. [ABSTRACT FROM AUTHOR]

Polyurethanes (PUs) are considered currently as one of the established bio compatible and blood compatible biomaterials offering tremendous structure–property relationship. But few limitations such as low resistance to micro-emboli and thrombi are still associated with these biomaterials that restricted their applications and hence need to be modified. Heparin, a highly sulfonated and negatively charged member of glycosaminoglycan family is well established for their anti-thrombin, anticoagulant and many biological activities that make it a highly attractive candidate capable of modifying or tailoring polymer properties. Incorporation of heparin for the improvement of biocompatibility of PUs is an interesting approach and enabling emerging technology. This review focuses on the methods used for modification of PUs via heparin with their pros and cons. The major PU–heparin systems with the recent developments and their possible biomedical applications are discussed. [ABSTRACT FROM AUTHOR]

Recent advancements in material science and technology made it obvious that use of renewable feed stock is the need of hour. Polymer industry steadily moved to get rid of its dependence on non-renewable resources. Starch, the second largest occurring biomass (renewable) on this planet provides a cheap and eco-friendly way to form huge variety of materials on blending with other biodegradable polymers. Specific structural versatility design for individual application and tailor-made properties have established the polyurethane (PU) as an important and popular class of synthetic biodegradable polymers. Blending of starch with polyurethane is relatively a developing area in PU chemistry but with lot of attraction for researchers. Herein, various starch based polyurethane materials including blends, grafts, copolymers, composites and nano-composites, as well as the prospects and latest developments are discussed. Additionally, an overview of starch based polymeric materials, including their potential applications are presented. [ABSTRACT FROM AUTHOR]

The trend of using biopolymers in combination with synthetic polymers was increasing rapidly from last two or three decades. Polysaccharide based biopolymers especially starch, cellulose, chitin, chitosan, alginate, etc. found extensive applications for different industrial uses, as they are biocompatible, biodegradable, bio-renewable resources and chiefly environment friendly. Segment block copolymer character of polyurethanes that endows them a broad range of versatility in terms of tailoring their properties was employed in conjunction with various natural polymers resulted in modified biomaterials. Alginate is biodegradable, biocompatible, bioactive, less toxic and low cost anionic polysaccharide, as a part of structural component of bacteria and brown algae (sea weed) is quite abundant in nature. It is used in combination with polyurethanes to form elastomers, nano-composites, hydrogels, etc. that especially revolutionized the food and biomedical industries. The review summarized the development in alginate based polyurethanes with their potential applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] New chitosan based polyurethane elastomers (PUEs) were synthesized. [•] Molecular engineering was carried out during the synthesis using FT-IR. [•] The FT-IR confirms the existence of the proposed chitosan based PUEs structure. [•] Internal morphology of the prepared PUEs was studied using SEM analysis. [ABSTRACT FROM AUTHOR]

Abstract: Chitin based polyurethanes (PUs) using hydroxyl terminated polybutadiene (HTPB) as soft segment were prepared and the structure of the proposed PU was confirmed using FTIR spectrometer. PU prepolymer was prepared using HTPB and toluene-2,4-diisocyanate (TDI), and the chain was extended with different proportions of 1,4-butane diol (BDO) and chitin. During the detailed FTIR study, it was observed that tri-functional character of chitin results in the formation of network structure due to crosslinking of the material, whereas bi-functional aliphatic diol based polyurethane produced linear PU. Hydrogen bonding between the hard segments was identified by the IR spectroscopy. The scanning electron microscope (SEM) analysis also confirmed the cross-linked structure. [Copyright &y& Elsevier]

Abstract: Biodegradable polyurethane elastomers with tunable hydrophobicity were synthesized by step-growth polymerization techniques using poly(ɛ-caprolactone) (PCL) and 4,4′-diphenylmethane diisocyanate (MDI). The prepolymer was extended with different mass ratios of chitin and 1,4-butane diol (BDO). The effect of chitin contents in chain extenders (CE) proportion on surface properties was studied and investigated. Incorporation of chitin contents into the final PU showed decrease in surface free energy and its polar component. Simultaneously, the work of water adhesion to polymer decreases significantly by increasing the chitin contents in the synthesized polymer. Contact angle measurement, water absorption and swelling behavior of the synthesized polyurethane samples were affected by varying the chitin contents in the chemical composition of the final PU. The interactions of the final PU films with solvents on the surface were displayed clear dependent on the contents of chitin in to the final polyurethane formulation. The results of different tests demonstrated that the synthesized products are a potential candidate as non-absorbable suture as previously investigated into their in vitro biocompatibility and non-toxicity [K.M. Zia, M. Zuber, I.A. Bhatti, M. Barikani, M.A. Sheikh, Int. J. Biol. Macromol. 44 (2009) 18–22]. [Copyright &y& Elsevier]

Abstract: Biodegradable polyurethane elastomers with potential for biomedical application as non-absorbable sutures with improved hydrophobic properties were synthesized by the reaction of poly(ε-caprolactone) (PCL) and 4,4′-diphenylmethane diisocyanate (MDI), extended with different mass ratio of chitin and 1,4-butane diol (BDO). Their molecular engineering and structural transition due to the changes of hydrogen bonding was confirmed by using FT-IR, 1H NMR and 13C NMR. Involvement of chitin was evidenced by the appearance of new signals in both 1H NMR and 13C NMR spectra, and very strong peak at 1724cm−1 in FT-IR spectra. From the results, it was concluded that the reaction of the urethane group occurred mainly at C6of chitin in which strong intermolecular and intersheet hydrogen bonds are involved. Contact angle and surface tension measurement of the synthesized polyurethane as a function of chitin contents were investigated. Optimum hydrophobicity was obtained from elastomer extended with chitin in comparison to elastomers extended with BDO. The surface free energy was also affected by chemical composition of the final PU. Structure–property relationship for prepared elastomers showed that the main determining factors were hydrogen bonding, hydrophobicity and content of chitin in polyurethane backbone. [Copyright &y& Elsevier]

Bionanocomposites is an emerging class of biohybrid materials, have a significant impact in environmental and biomedical fields owing to their high performance, lightweight, unique, and ecofriendly properties. A major challenge in the multiphase bionanocomposites system is to subtle control over the performance by managing the individual properties of reacting components. Herein, we presented the preliminary investigation on bionanocomposite system based on graphene nanoplatelets (GNPs) and hydroxyethyl cellulose graft poly(lactic acid) copolymer-polyurethane (HLAC-PU) with the aim to understand the structure property correlation for proposed applications in electronics and medical areas. The HLAC was fabricated by graft copolymerization of hydroxyethyl cellulose (HEC) and lactic acid (LA) with dibutyltin dilaurate. The HLAC was used to get a bio-functionalized PU matrix reinforced with GNPs by step-growth polymerization method. The structural, surface, and thermal properties of the HLAC and GNPs-HLAC-PU bionanocomposites were studied. The spectroscopic techniques confirmed the structure of bionanocomposites by the identification of related bands. The SEM/EDX results demonstrated that the 0.3 wt% of GNPs dispersed well in the HLAC-PU matrix and offered higher crystallinity. The reinforcement of the 0.3 wt% of GNPs has meaningfully enhanced the thermal stability producing higher residue contents. The reinforced GNPs filler increased the water resistance of bionanocomposites by reducing their water vapor permeability. • HEC grafted PLA copolymer based on graphene nanoplatelets (GNPs) based PUEs are developed. • FTIR, 1HNMR, XRD techniques suggested that GNPs disrupted the order of the hard segments. • Surface morphology depicted strong interactions between GNPs and PU matrix. • The thermal resistance of the PU is enhanced at low contents of GNPs. • The higher contents of the GNPs turn the elastomers to be hydrophobic. [ABSTRACT FROM AUTHOR]

Highlights: [•] Chitin based polyurethane (PU) using (HTPB) was prepared. [•] The FT-IR analysis confirmed the crosslinking behavior of the material [•] The SEM images also confirmed the cross-linked and non-cross-linked structure. [•] EDX–SEM analysis also supported the FT-IR and SEM analysis. [Copyright &y& Elsevier]

Abstract: Chitin based polyurethane (PU) elastomers constituted on 4,4´-diphenylmethane diisocyanate (MDI), poly(ε-caprolactone) (PCL) and extended with blends of chitin/1,4-butane diol were synthesized via two step polymerization technique. The synthesized samples were irradiated for 50, 100 and 200h in an UV exposure chamber as such the spectral distribution of the light is good match for terrestrial solar radiation. The crystalline behavior of the irradiated PU samples were investigated by X-ray diffraction (XRD), differential scanning calorimetery (DSC) and dynamic mechanical thermal analysis (DMTA) techniques. The effect of irradiation time and chitin contents on crystallinity were studied and investigated. The maximum decrease in the crystalline behavior of samples after irradiation observed by XRD, DSC and tan δ peaks were found for the PU samples extended with lower contents of chitin (chitin/BDO; 0/100). In comparison with irradiation times the 200h irradiation showed maximum change in the crystalline behavior. [Copyright &y& Elsevier]

Abstract: A series of polyurethane elastomers were prepared by the reaction of poly ε-caprolactone and 4,4′-diphenylmethane diisocyanate. The prepolymer was extended using α, ω-alkane diols as chain extenders having 2–10 methylene units in their structure. The synthesized samples were irradiated for 50, 100 and 200h in an ultra violet (UV) exposure unit. Modifications in the chemical structure before and after irradiation were characterized using Fourier Transform Infrared spectroscopy. The thermal and mechanical properties were affected by the ultra violet irradiation time and the number of methylene units in the chain extenders. The experimental results indicated that the morphological structure changed during irradiation as a consequence of hard segment and soft segment degradation. [Copyright &y& Elsevier]

Abstract: Chitin based polyurethane elastomers (PUEs) were synthesized by step growth polymerization techniques using poly (ε-caprolactone) (PCL), 4, 4′- diphenylmethane diisocyanate (MDI) and blends of chitin and 1,4-butanne diol (BDO). The conventional spectroscopic characterization of the samples with FT-IR, 1H NMR and 13C NMR were in accordance with proposed PUEs structure. The crystalline behavior of the synthesized polymers were investigated by X-ray diffraction (XRD), differential scanning calorimetery (DSC), optical microscopic technique and loss tangent curves (tan δ peaks). Results showed that crystallinity of the synthesized PUEs samples was affected by varying the chitin contents used as chain extender. The contents of chitin favors the formation of more ordered structure, as higher peak intensities were obtained from the PU extended with chitin than 1,4-butane diol (BDO). X-ray diffraction experiments results correlates with optical microscopy findings. The higher ΔH value; 41.57(Jg−1) was found in the samples extended with chitin than BDO (31.32Jg−1). [Copyright &y& Elsevier]

Abstract: Polyurethane elastomers (PUEs) based on 4,4′-diphenylmethane diisocyanate (MDI), poly (ɛ-caprolactone) (PCL) and extended with series of chain extender (CE) were synthesized via two step polymerization technique. The synthesized samples were irradiated for 50, 100 and 200h in an UV exposure unit as such the spectral distribution of the light is good match for terrestrial solar radiation. The modifications in the chemical structures of the PU before and after irradiation were characterized using Fourier transform infrared (FT-IR) technique. The effect of irradiation time and chain extenders length on surface properties were studied and investigated. Photo-oxidation of PU surface leads to fast increase in surface free energy and its polar component. Simultaneously, the work of water adhesion to polymer increases significantly during UV-irradiation. The higher changes in surface properties, observed by water absorption (%), equilibrium degree of swelling, as well as monitored by ATR-FT-IR and contact angle measurement, were found for the PU samples extended with higher number of methylene unit and irradiation time. [Copyright &y& Elsevier]

Abstract: Chitin-based polyurethane elastomers (PUEs) were synthesized by step growth polymerization techniques using poly(ɛ-caprolactone) (PCL) varying diisocyanate and chain extender structures. The viscosity average molecular weight (M v) of chitin was deduced from the intrinsic viscosity and found; M v =6.067×105. The conventional spectroscopic characterization of the samples with FTIR, 1H NMR and 13C NMR were in accordance with proposed PUEs structure. The crystalline behavior of the synthesized polymers were investigated by X-ray diffraction (XRD), differential scanning calorimetery (DSC) and loss tangent curves (tan δ peaks). The observed patterns of the crystalline peaks for the lower angle for chitin in the 2θ range were indexed as 9.39°, 19.72°, 20.73°, 23.41° and 26.39°. Results showed that crystallinity of the synthesized PUEs samples was affected by varying the structure of the diisocyanate and chain extender. Crystallinity decreased from aliphatic to aromatic characters of the diisocyanates used in the final PU. The presence of chitin also favors the formation of more ordered structure, as higher peak intensities was obtained from the PU extended with chitin than 1,4-butane diol (BDO). The value of peak enthalpy (ΔH) of chitin was found to be 47.13Jg−1. The higher ΔH value of 46.35Jg−1 was found in the samples extended with chitin than BDO (39.73Jg−1). [Copyright &y& Elsevier]