Effect of chain extender structure on the properties and morphology of polyurethanes based on H12MDI and mixed macrodiols (PDMS–PHMO)

The effect of chain extender structure on properties and morphology of α,ω‐bis(6‐hydroxyethoxypropyl) polydimethylsiloxane (PDMS) and poly(hexamethylene oxide) (PHMO) mixed macrodiol‐based aliphatic polyurethane elastomers was investigated using tensile testing, differential scanning calorimetry (DSC), and dynamic mechanical thermal analysis (DMTA). All polyurethanes were based on 50 wt % of hard segment derived from 4,4′‐methylenecyclohexyl diisocyanate (H₁₂MDI) and a chain extender mixture. 1,4‐Butanediol was the primary chain extender, while one of 1,3‐bis(4‐hydroxybutyl)tetramethyldisiloxane (BHTD), 1,3‐bis(3‐hydroxypropyl)tetramethyldisiloxane (BPTD), hydroquinonebis(2‐hydroxyethyl)ether (HQHE), 1,3‐bis(3‐hydroxypropyl)tetramethyldisilylethylene (HTDE), or 2,2,3,3,4,4‐hexafluoro‐1,5‐pentanediol (HFPD) each was used as a secondary chain extender. Two series of polyurethanes containing 80 : 20 (Series A) and 60 : 40 (Series B) molar ratios of primary and secondary chain extenders were prepared using one‐step bulk polymerization. All polyurethanes were clear and transparent and had number‐average molecular weights between 56,000 and 122,100. Incorporation of the secondary chain extender resulted in polyurethanes with low flexural modulus and high elongation. Good ultimate tensile strength was achieved in most cases. DSC and DMTA analyses showed that the incorporation of a secondary chain extender disrupted the hard segment order in all cases. The highest disruption was observed with HFPD, while the silicon‐based chain extenders gave less disruption, particularly in Series A. Further, the silicon chain extenders improved the compatibility of the PDMS soft segment phase with the hard segment, whereas with HFPD and HQHE, this was not observed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2979–2989, 1999     

The effect of soft‐segment structure on the properties of novel thermoplastic polyurethane elastomers based on an unconventional chain extender

Thermoplastic polyurethane elastomers (TPUs) are now widely used because of their excellent properties that include high tensile and tear strength, and good abrasion, impact and chemical resistance. TPUs are multiblock copolymers with alternating sequences of hard segments composed of diisocyanates and simple diols (chain extenders) and soft segments formed by polymer diols. Commonly used hard segments for TPUs are derived from 4,4′‐diphenylmethane diisocyanate (MDI) and aliphatic diols. The aim of our research was to examine the possibility of obtaining TPUs with good tensile properties and thermal stability by using an unconventional aliphatic‐aromatic chain extender, containing sulfide linkages. Three series of novel TPUs were synthesized by melt polymerization from poly(oxytetramethylene) diol, poly(ε‐caprolactone) diol or poly(hexane‐1,6‐diyl carbonate) diol of number‐average molecular weight of 2000 g mol^?1 as soft segments, MDI and 3,3′‐[methylenebis(1,4‐phenylenemethylenethio)]dipropan‐1‐ol as a chain extender. The structure and basic properties of the polymers were examined using Fourier transfer infrared spectroscopy, X‐ray diffraction, atomic force microscopy, differential scanning calorimetry, thermogravimetric analysis, Shore hardness and tensile tests. It is possible to synthesize TPUs from the aliphatic‐aromatic chain extender with good tensile properties (strength up to 42.6 MPa and elongation at break up to 750%) and thermal stability. Because the structure of the newly obtained TPUs incorporates sulfur atoms, the TPUs can exhibit improved antibacterial activity and adhesive properties. Copyright © 2011 Society of Chemical Industry     

Low‐modulus siloxane–polyurethanes. Part II. Effect of chain extender structure on properties and morphology

A series of six polyurethanes were prepared to study the effect of silicon chain extender structure on properties and morphology of siloxane–polyurethanes. Polyurethanes were prepared by a two‐step bulk polymerization without a catalyst. The soft segment of the polyurethanes was based on an 80:20 (w/w) mixture of α,ω‐bis(6‐hydroxyethoxypropyl) polydimethylsiloxane (PDMS, MW 966) and poly(hexamethylene) oxide (MW 714). The hard segment was based on 4,4′‐methylenediphenyl diisocyanate (MDI) and a 60:40 molar mixture of 1,4‐butanediol (BDO) and a silicon chain extender. Silicon chain extenders (SCE) investigated were 1,3‐bis(4‐hydroxybutyl)1,1,3,3‐tetramethyldisiloxane (BHTD), 1,3‐bis(3‐hydroxypropyl)1,1,3,3‐tetramethyldisiloxane (BPTD), 1,4‐bis(3‐hydroxypropyl)1,1,3,3‐tetramethyldisilylethylene (HTDE), 1,3‐bis(6‐hydroxyethoxypropyl)1,1,3,3‐tetramethyldisiloxane (BETD). All polyurethanes were clear and transparent with number average molecular weights between 72,000 to 116,000. Incorporation of the silicon chain extender resulted in polyurethanes with low‐modulus and high elongation. This was achieved without significant compromise in ultimate tensile strength in all cases, except BETD. Differential scanning calorimetry (DSC) results showed that the silicon chain extenders did not significantly disrupt the hard segment crystallinity, but exhibited a unique morphological feature where SCE‐based hard segments formed separate domains, which may be the primary reason for achieving low modulus without significant compromise in strength. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1092–1100, 2003     

Reactively Modified Poly(lactic acid): Properties and Foam Processing

Summary: In order to produce modified poly(lactic acid) (PLA) resins for applications requiring high melt viscosity and elasticity (e.g., low‐density foaming, thermoforming), a commercial PLA product has been reactively modified in melt by sequentially adding 1,4‐butanediol and 1,4‐butane diisocyanate as low‐molecular‐weight chain extenders. By varying amounts of the two chain extenders associated to the end group contents of PLA, three resulted samples were obtained. They were then structurally characterized by FTIR spectroscopy and molecular structure analysis. Their thermal, dynamic mechanical thermal properties and melt viscoelastic properties were investigated and compared along with unmodified PLA. The results indicated that chemical modification may be characterized as chain scission, extension, crosslinking, or any combination of the three depending on the chain extender amounts. The increase of PLA molecular weight could be obtained by properly controlling amounts of two chain extenders. The samples with increased molecular weights showed enhanced melt viscosity and elasticity. Such property improvements promised a successful application for modified PLA in a batch foam processing by producing foams with reduced cell size, increased cell density and lowered bulk foam density in comparison with plain PLA foam.

Cellular morphology of a modified PLA foam.     

Chain extension and branching of poly(ethylene terephthalate) (PET) with di- and multifunctional epoxy or isocyanate additives: An experimental and modelling study

The effect of two difunctional chain extenders, 1,6-diisocyanatohexane (NCO) and 1,4-butanediol diglycidyl ether (EPOX), in the reactive melt-processing of a post-consumer poly(ethylene terephthalate) (r-PET) was investigated. The torque evolution during processing in a batch mixer and the molecular weight of the chain-extended r-PET, as determined by SEC analysis, were comparatively evaluated. A simple mathematical model proposed here was used to fit the obtained molecular weights. Two polyfunctional chain extenders, poly(phenyl isocyanate-co-formaldehyde) (P-NCO) and a styrene-acrylate copolymer bearing epoxide groups (P-EPOX), were also used and their reactivity was compared with that of the difunctional ones by analysing torque and melt flow rate data. The different reactivity of the two functional groups and the structure of the final polymer (either linear or branched depending on the type of chain extender) affect both crystallization behaviour and tensile properties of the modified r-PET. Fine tuning of the latter properties by suitable chain extender(s) selection and formulation is anticipated.     

浇注型端羟基聚丁二烯聚氨酯弹性体的合成及性能研究

采用不同分子量的端羟基聚丁二烯（ＨＴＰＢ）和甲苯二异氰酸酯为主要原料合成预聚物，以Ｎ，Ｎ－Ｍ（２－羟丙基）苯胺为扩链剂制备了浇注型聚氨酯弹性体，并着重研究了预聚体中游离异氰酸酯基含量、扩链剂用量、ＨＴＰＢ分子量以及不同分子量ＨＴＰＢ并用和扩链剂并用对弹性体力学性能的影响，还对弹性体的结构与形态进行了初步分析和探讨。结果表明，预聚体中游离异氰酸酯基含量为９．０％时，拉伸强度最大，且综合性能最佳；扩链系数为０．８９时，拉伸强度、定伸应力、硬度出现最大值；ＨＴＰＢ分子量增大，弹性体力学性能有下降趋势，不同分子量ＨＴＰＢ并用时分子量大的ＨＴＰＢ增多，力学性能下降；当ＨＴＰＢＭｎ＝３１００，游离异氰酸酯基含量为９．０％，扩链系数为０．８９时，弹性体综合性能最佳。电子显微镜照片显示ＨＴＰＢ型聚氨酯有微相分离，且软硬键段分布不规整。     

New thermoplastic segmented polyurethanes with hard segments derived from 4,4′‐diphenylmethane diisocyanate and methylenebis(1,4‐phenylenemethylenethio)dialcanols

New thermoplastic poly(ether–urethane)s and poly(carbonate–urethane)s were synthesized by a one‐step melt polymerization from poly(oxytetramethylene) diol (PTMO) and poly(hexane‐1,6‐diyl carbonate) diol (PHCD) as soft segments, 4,4′‐diphenylmethane diisocyanate, and 2,2′‐[methylenebis(1,4‐phenylenemethylenethio)]diethanol, 3,3′‐[methylenebis(1,4‐phenylenemethylenethio)]dipropan‐1‐ol or 6,6′‐[methylenebis(1,4‐phenylenemethylenethio)]dihexan‐1‐ol as unconventional chain extenders. The effects of the kind and amount of the polymer diol and chain extender used on the structure and properties of the polymers were studied. The polymers were examined by Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction analysis, atomic force microscopy, differential scanning calorimetry, thermogravimetric analysis (TGA), TGA coupled with FTIR spectroscopy, and Shore hardness and tensile testing. The obtained high‐molecular‐weight polymers showed elastomeric or plastic properties. Generally, the PTMO‐based polymers exhibited significantly lower glass‐transition temperatures (up to ?48.1 vs ?1.4°C), a higher degree of microphase separation, and ordering in hard‐segment domains in comparison with the corresponding PHCD‐based ones. Moreover, it was observed that the polymers with the PTMO soft segments showed poorer tensile strengths (up to 36.5 vs 59.6 MPa) but higher elongations at break. All of the polymers exhibited a relatively good thermal stability. Their temperatures of 1% mass loss were in the range 270–320°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The effect of average soft segment length on morphology and properties of a series of polyurethane elastomers. I. Characterization of the series

A series of eight thermoplastic polyurethane elastomers were synthesized from 4,4′-methylene diphenyl diisocyanate (MDI) and 1,4-butanediol (BDO) chain extender, with poly(hexamethylene oxide) (PHMO) macrodiol soft segments. The soft segment molecular weights employed ranged from 433 g/mol to 1180 g/mol. All materials contained 60% (w/w) of the soft segment macrodiol. Differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), wide angle x-ray diffraction (WAXD), and small angle x-ray scattering (SAXS) techniques were employed to characterize morphology. Tensile and Shore hardness tests were also performed. Materials were tested in the annealed state. It was found that an increase in segment length was accompanied by an increase in the degree of microphase separation, average interdomain spacing, hard domain order, hardness, stiffness, and opacity. DSC experiments showed the existence of several hard segment melting regions that were postulated to result from the disordering or melting of various hard segment length populations. For the system and composition ratio employed, it was found that optimum tensile properties (UTS and breaking strain) were achieved when a PHMO molecular weight of between 650 and 850 was utilized. © 1996 John Wiley & Sons, Inc.     

端羟基聚乳酸的扩链改性研究

乳酸与2,2-(1,3-亚苯基)-二恶唑啉(1,3-PBO)直接熔融缩聚成端羟基乳酸预聚物(PLBO),以聚乙二醇(PEG)和六亚甲基二异氰酸酯(HDI)聚合制得的端异氰酸酯基聚乙二醇(PEG-NCO)为扩链剂,以二月桂酸二丁基锡为催化剂,对PLBO进行扩链以制备可完全生物降解的聚酯氨酯(PEU)。采用乌氏黏度法、FTIR、DSC、XRD、TG、SEM等方法对各聚合物的结构和性能进行了表征。结果表明:以n(—OH)/n(—NCO)=1的比例投料、反应温度165℃、反应压力0.096 MPa、反应时间20 min为PLBO扩链反应的最佳条件;PEU的最大黏均分子量为44 700;PEG的引入使得PEU的玻璃化转变温度均小于PLA与PLBO,且柔韧性提高;PEU热稳定性提高,分解过程分为两步,第一步为PEU链段中的PLA失重,第二步为PEG-NCO链段的降解;PEU的结晶度降低,进一步说明扩链后聚合物的柔韧性增强。     

Contribution of soft segment entanglement on the tensile properties of silicone–urea copolymers with low hard segment contents

Novel, segmented thermoplastic silicone–urea (TPSU) copolymers based on rather high molecular weight aminopropyl terminated polydimethylsiloxane (PDMS) soft segments (<M_n> 10,800 and 31,500 g/mol), a cycloaliphatic diisocyanate (HMDI) and various diamine chain extenders were synthesized. Copolymers with very low urea hard segment contents of 1.43–14.4% by weight were prepared. In spite of very low hard segment contents, solution cast films showed very good microphase separation and displayed reasonable mechanical properties. Tensile strengths of TPSU copolymers showed a linear dependence on their urea hard segment contents, regardless of the structure of the diamine chain extender used. The modulus of silicone–urea copolymers is dependent on the urea concentration, but not on the extender type or PDMS molecular weight. When silicone–urea copolymers with identical urea hard segment contents were compared, copolymers based on PDMS-31,500 showed higher elongation at break values and ultimate tensile strengths than those based on PDMS-10,800. Since the critical entanglement molecular weight (M_e) of PDMS is about 24,500 g/mol, these results suggest there is a significant contribution from soft segment chain entanglement effects in the PDMS-31,500 system regarding the tensile properties and failure mechanisms of the silicone–urea copolymers.     

软硬段比对磺酸盐型水性聚氨酯性能的影响

以聚己二酸乙二醇酯二醇(PBA)、异佛尔酮二异氰酸酯(IPDI)和六亚甲基二异氰酸酯(HDI)为主要原料,以乙二胺基乙磺酸钠为亲水性扩链剂,合成了固含量为50%的磺酸盐型水性聚氨酯(WPU)乳液。考察了软硬段比对乳液黏度、粒径及其分布、聚合物重均相对分子质量(Mw)、胶膜结晶性以及力学性能等影响。结果表明:当软硬段比值为2.96时,可以制得固含量为50%的磺酸盐型WPU乳液,其平均粒径为146.0 nm、黏度为143 mPa.s,聚合物Mw为128 488,结晶熔融温度为50℃,结晶性相对最好;此时WPU胶膜的拉伸强度(31.6 MPa)和断裂伸长率(1 702%)相对较大;WPU胶粘剂的初始剥离强度(118.6 N/cm)和最终剥离强度(156.3 N/cm)相对最高。     

Degradation of crosslinked poly(ester‐urethanes) elastomers in distilled water: Influence of hard segment

Polyurethane elastomers are frequently used in wet conditions. Crosslinked polyurethanes based on poly(ethylene adipate) diol, 4,4′‐diphenylmethane diisocyanate, 1,6 hexane diisocyanate—with different hard‐segment compositions but with the same molecular weight soft segment—were degraded in distilled water at 37°C, in a specific environment; in the dark without exposure to enzymatic conditions and under the continuous circulation of water. The incubation of polymer samples took place over a period of maximum 30 days. The degradation process was evaluated by the changes in mechanical properties and surface relief observed by optical microscopy. The changes in hydrogen bonding were collected through attenuated total reflectance infrared (ATR‐FTIR) spectroscopy which indicated that aliphatic diisocyanates allow for a better formation of hydrogen bonds. The mechanical properties of the degraded films show that the crosslinked polyurethanes containing aromatic diisocyanate suffer a decrease in tensile strength between 33 and 56% depending on the chain extender and hard segment content. The hydrolytic degradation behavior of crosslinked polyurethanes was found to be dependent on the diisocyanate and chain extender structure, as well as on the hard segment content and chemical crosslinks. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

车身反光贴用聚氨酯胶粘剂的研制

以结晶性聚酯多元醇、直链二醇扩链剂、异氰酸酯和纳米助剂等为主要原料,制备出一种高粘接强度、耐老化性能优良的车身反光贴用PU(聚氨酯)胶粘剂。分析了聚酯多元醇的种类及其Mr(相对分子质量)、扩链剂、异氰酸酯、纳米助剂和催化剂等对PU胶粘剂性能的影响。结果表明:当结晶性聚酯多元醇为Mr=3 000的聚己二酸-1,4-丁二醇酯、扩链剂为1,6-己二醇(HDO)、异氰酸酯为1,6-己二异氰酸酯(HDI)、催化剂为有机铋类(BiCAT 8108)且w(催化剂)=0.03%(相对于反应物总质量而言)、n(聚酯多元醇)∶n(扩链剂)=1∶0.3和w(气相白炭黑)=0.2%～0.3%(相对于反应物总质量而言)时,PU胶粘剂的综合性能相对最好。     

基于异氰酸酯衍生物的聚乳酸熔融扩链工艺、动力学及结构表征

以微波法氧化锌（ZnO）柱撑有机皂石催化丙交酯开环聚合的聚乳酸(PLA)为原料,分别采用二苯基甲烷二异氰酸酯 (MDI)和六亚甲基二异氰酸酯(HDI)进行熔融扩链反应,研究了扩链剂的用量和反应时间对PLA相对分子质量的影响,并对PLA的扩链动力学进行了研究。结果表明,最优的扩链反应工艺参数为：反应温度180 ℃,nNCO：nOH为2.5：1,MDI扩链时间为45 min,HDI扩链时间为30 min;MDI和HDI扩链反应的表观速率常数分别为6.081×10^3、6.98×10^3 g/(mol·min)。     

The phase mixing studies on moisture cured polyurethane-ureas during cure

Moisture cured polyurethane-urea (MCPU) is one of the industrially important polymers that shows good thermal, mechanical and weathering properties and is widely used in the reactive hot melt adhesives and coatings. Structural variation of the building blocks, i.e. soft, hard segment and chain extender structure on the phase mixing characteristics during cure in polyether based moisture-cured polyurethanes (MCPUs) has been investigated. Variations in the soft segment structure like polyethylene glycol (PEG), polypropylene glycol (PPG) and polytetramethylene glycol (PTMG) and hard segment like toluene diisocyanate (TDI) or isophorone diisocyanate (IPDI) were made. The effect of isocyanate content (NCO:OH ratio 1.6:1 and 2:1) as well as various aliphatic diol and aromatic diamine chain extenders were also compared. The phase mixing phenomenon during network growth was evaluated by differential scanning calorimetry (DSC) and a correlation was drawn for the degree of cure with the phase mixing property. The change in modulus and thermal stability with the cure advancement were measured by dynamic mechanical and thermal analysis (DMTA) and thermogravimetric analysis (TGA). A correlation was made for the soft, hard segment and chain extender structure to the phase mixing phenomenon during cure. The rate of phase mixing was found to be dependent on the subtle variations in molecular architecture.     

Synthesis and properties of waterborne polyurethane adhesives: effect of chain extender of ethylene diamine,butanediol, and fluoro-butanediol

Waterborne polyurethane (WBPU) adhesives were prepared using poly(tetramethylene oxide glycol), 4,4’-dicyclohexylmethane diisocyanate (H₁₂MDI), hydrophilic agent dimethylol propionic acid and chain extender of 2,2,3,3-tetrafluoro-1,4-butanediol (TFBD), ethylene diamine (EDA), and 1,4-butanediol. All three chain extenders have been used as single and mixed (different ratio) content during synthesis, and the effect of chain extender and their content to the properties of tensile strength, Young’s modulus, water swelling (%), and adhesive strength was investigated. The adhesive strength value was higher using EDA as a single-chain extender; however, the potentiality of adhesive strength under water was improved using mixed-chain extenders of EDA and TFBD in WBPU adhesives. The maxima potentiality was observed with 6.31 mole% TFBD and 2.10 mole% EDA in WBPU adhesives.     

Maximizing the utility of bio-based diisocyanate and chain extenders in crystalline segmented thermoplastic polyester urethanes: Effect of polymerization protocol

High molecular weight semi crystalline thermoplastic poly(ester urethanes), TPEUs, were prepared from a vegetable oil-based diisocyanate, aliphatic diol chain extenders and poly(ethylene adipate) macro diol using one-shot, pre-polymer and multi-stage polyaddition methods. The optimized polymerization reaction achieved ultra-high molecular weight TPEUs (>2 million as determined by GPC) in a short time, indicating a very high HPMDI – diol reactivity. TPEUs with very well controlled hard segment (HS) and soft segment (SS) blocks were prepared and characterized with DSC, TGA, tensile analysis, and WAXD in order to reveal structure–property relationships. A confinement effect that imparts elastomeric properties to otherwise thermoplastic TPEUs was revealed. The confinement extent was found to vary predictably with structure indicating that one can custom engineer tougher polyurethane elastomers by “tuning” soft segment crystallinity with suitable HS block structure. Generally, the HPMDI-based TPEUs exhibited thermal stability and mechanical properties comparable to entirely petroleum-based TPEUs.     

Biodegradable polyurethanes: Comparative study of electrospun scaffolds and films

The development of elastomeric, bioresorbable, and biocompatible segmented polyurethanes (SPUs) for use in tissue‐engineering applications has attracted considerable interest in recent years. In this work, nonporous films and microfiber/nanofiber scaffolds, which were prepared from two different poly(?‐caprolactone)‐based SPUs previously synthesized from 1,6‐hexamethylene diisocyanate and novel chain extenders containing urea groups or an aromatic amino acid derivative, were studied. Their thermal properties were influenced by both the different chemical structures of the hard segments and the processing conditions. The mechanical properties of the scaffolds (the elastic modulus, ultimate strain, and tensile stress) were adequate for engineered soft‐tissue constructs (e.g., myocardial tissue). The film samples displayed a low swelling degree (<2 wt %) in a phosphate‐buffered solution at 37°C. The introduction of the amino acid derivative chain extender with hydrolyzable ester bonds contributed to greater degradation. The fibrous scaffolds exhibited higher hydrolytic stability than the films after short assay times because of their more crystalline structures and higher degrees of association by hydrogen bonding, but they also experienced higher mass losses under accelerated conditions (70°C). This suggested that the degradation rate was not constant but depended on the degradation time and the processing technique. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Reactive Extrusion of Polyamide 6 Using a Novel Chain Extender

Polyamide 6 (PA6) is an important engineering thermoplastic, very widely used but prone to thermal degradation during extrusion at temperature not far from its melt temperature (220°C). Typically, and as measured in this study, PA6 extruded at temperature of 300°C shows a 40% decrease in tensile modulus compared with non‐extruded PA6. To rebuild PA6 molecular weight, the easiest and cheapest method is to use an appropriate chain extender. Many chain extenders have been used in the past but they are essentially suited to nucleophile induced degradation, targeting split PA6 chains carboxyl COOH and amine NH₂ end groups. What have been lacking are effective chain extenders for thermally only induced degradation, i.e. for the practical cases where the PA6 is thoroughly dried before extrusion. For such a case, the degradation reaction mechanism dictates that the solution is to develop chain extenders that target the split PA6 chains amide CONH₂ groups not the carboxyl COOH and amine NH₂ end groups. As amide groups strongly react with anhydride functionalities, we test the effectiveness of a novel chain extender, Joncryl® ADR 3400, a styrene maleic anhydride copolymer with multiple, repeating anhydride functionality. Assessment of chain extension in this study is done as with previous work, using rheology, mechanical and thermal properties of PA6 extruded on its own and with the chain extender. The viscoelastic data conclusively show the efficacy of such chain extender with more than 10‐fold changes in the comparative values of the extruded sample storage modulus G’ and as much as an 85% increase in the tensile modulus. POLYM. ENG. SCI., 59:E25–E31, 2019. © 2018 Society of Plastics Engineers     

Poly(ester amide)s derived from 1,4-butanediol, adipic acid and 6-aminohexanoic acid. Part II: composition changes and fillers

BAK poly(ester amide)s differing in the amide/ester ratio have been synthesized and characterized, considering spectroscopic data and both thermal and mechanical properties. Degradability under different media (water at 70 °C, acid or enzymatic catalysis at 37 °C) has also been studied by evaluating the changes in intrinsic viscosity, in the NMR spectra and in the surface texture of samples. The use of chain extenders, such as hexamethylene diisocyanate and 1,3-butadiene diepoxide, has been investigated and the optimal reaction conditions are reported here. Changes on mechanical properties due to the incorporation of biodegradable reinforces have also been evaluated. Finally, the synthesis and determination of thermal properties of related poly(ester amide)s constituted by glutaric or succinic acid instead of adipic acid have been investigated.