Effect of Piperazine Concentration on the Properties of Lower Purity Dimer Acid-Synthesized Polyamide Hot-Melt Adhesive

Abstract

Polyamide hot-melt adhesive was synthesized from lower purity, i.e., 75% purity dimer acid, sebacic acid, ethylenediamine and piperazine. The effect of piperazine content on the properties of polyamides, such as thermal properties: heat of fusion (H _f), heat of crystallization (H _c), softening point (T _s) and glass transition temperature (T _g); mechanical properties: tensile strength and hardness; adhesion properties: lap shear strength (LSS) and T-peel strength (TPS); and rheological properties was investigated. Concentration of piperazine was varied from 12.5 to 37.5 molar %. It was found that H _f, H _c, T _s, T _g, tensile strength, hardness, LSS, TPS and viscosity all increased with decrease in molar percentage of piperazine. This is due to increase in crystallinity of the polyamide with decrease in piperazine, giving better packing of molecules in the adhesive, thus giving better properties.     

Synthesis and properties of polyamide derived from piperazine and lower purity dimer acid as hot melt adhesive

Polyamide hot melt adhesive was synthesized from lower purity dimer acid (composition: ∼23% trimer acid, ∼75% dimer acid and ∼3% monomer acid), sebacic acid, ethylenediamine and piperazine. The effect of piperazine and dimer acid concentration on properties of polyamides such as thermal properties: fusion temperature (T_f), heat of fusion (H_f), crystallization temperature (T_c), heat of crystallization (H_c), softening point (T_s) and glass transition temperature (T_g), mechanical properties: tensile strength and hardness, adhesion properties like lap shear strength (LSS) and T-peel strength (TPS), and rheological properties were investigated. Concentration of piperazine was varied from 12.5 to 37.5 mol% while that of dimer from 37.5 to 42 mol%. Piperazine has one hydrogen atom on each of its two nitrogen atoms in the ring structure. When it undergoes reaction with acids to form polyamide, these hydrogen atoms get consumed, making the amide linkage unable to form hydrogen bonding with the neighboring polyamide polymer chains. This leads to decrease in crystallinity of the polyamide. Thus, as the mole percentage of piperazine in the polyamide increases, it becomes more amorphous, decreasing T_f, H_f, T_c, H_c, T_s, T_g, tensile strength, hardness, LSS, TPS and viscosity. Dimer acid and trimer acid are bulky compounds. As their percentages in the polyamide increase, it becomes difficult for the neighboring polyamide chains to come closer. Thus, inter-molecular hydrogen bonding decreases. This leads to decrease in crystallinity of the polyamide, lowering T_f, H_f, T_c, H_c, T_s, T_g, tensile strength, hardness, LSS, TPS and viscosity.     

Synthesis,characterization, and properties of novel fluorine containing aromatic polyamides

A series of novel fluorine containing aromatic polyamides were synthesized by the direct polycondensation of various fluorine containing aromatic diamines and commercially available 5‐t‐butyl isophthalic acid. These polyamides have good solubility in several organic solvents such as dimethylformamide, N,N‐dimethylacetamide, 1‐Methyl‐2‐pyrrolidone, dimethyl sulfoxide, and tetrahydrofuran. The synthesized polymers exhibited inherent viscosities up to 0.93 dL/g and M_w up to 1,52,000 with PDI of 2.49. The polyamides exhibited good thermal stability up to 489°C for 10% weight loss in nitrogen and high glass transition temperature up to 273°C. Dynamic mechanical analysis showed a very good retention of storage modulus up to the glass transition temperature. The tan δ peak value at 1 Hz was used to calculate the T_g and these values are in good agreement with differential scanning calorimetry data. The polyamide films were flexible with tensile strength up to 72 MPa, elongations at break up to 14%, and modulus of elasticity up to 1.39 GPa depending on the exact repeating unit structure. X‐ray diffraction measurements indicate that these polyamides are semicrystalline. Rheology study showed same trend of melt viscosity behavior with different shear rate for all polymers. Water absorption study indicates the hydrophobic nature of the polymer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal behavior of aliphatic–aromatic poly(ether-amide)s

The thermal properties of a set of experimental aliphatic–aromatic polyamides containing ether linkages were examined as a function of their chemical structure. Variations of the glass transition temperature (T_g) and melting temperature (T_m) could be correlated with the length of the aliphatic spacers and with the orientation of the phenylene rings. Polymers with a high concentration of p-oriented phenylene units showed a higher T_g than those containing mainly m-oriented ones; T_g values ranged from 110 to 155°C. Surprisingly, a negligible dependence of T_gs on the nature of flexible spacers was observed. For all of the polymers, the thermal stability was virtually the same, about 440°C, when tested by dynamic thermogravimetric analysis (TGA). However, quite different levels of thermal stability were found by isothermal TGA analysis for polyamides with different flexible spacers. Moreover, the poly(ether-amide)s described here compare fairly well with wholly aromatic polyamides when measured by dynamic TGA; but isothermal TGA measurements clearly demonstrated that they decompose faster than aromatic polyamides. Treatment of the TGA curves by the method of McCallum provided kinetic data that confirmed a better long-term stability for poly(ether-amide)s with a higher proportion of para-oriented phenylene rings. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:975–981, 1998     

Lower purity dimer acid based polyamides used as hot melt adhesives: synthesis and properties

Hot melt polyamides exhibit high adhesive strength. The polyamides synthesized from dimer fatty acids and diamines can present low crystallinity and a broad range of melting temperatures. In this work, polyamides with different compositions of dimer fatty acids, piperazine, ethylenediamine, sebacic acid and stearic acid and different content of secondary diamine (piperazine) and primary diamine (ethylenediamine) were synthesized. Polyamides with higher purity of dimer acids showed greater molecular weight, adhesion performance and a better mechanical resistance evaluated in stress/strain test. Softening point increased with increase in monomers content. By differential scanning calorimetry analysis, it was observed that polyamides with low percentage of monomer content show only one narrow melting peak in 100 °C. The increase in the acids monomer content leads to a larger temperature range of melting peak. The use of dimer fatty acid with a low content of monomers (up to 6%) in the polyamides synthesis promotes the formation of hot melt adhesives with good adhesion performances. The lowest monomer content leads to an increase in molecular weight, viscosity and mechanical properties of polyamide. Increase in the content of primary amines in polyamides increases crystallinity, viscosity and mechanical properties due to the higher number of hydrogen bonds formed by amide groups.     

Synthesis and characterization of polyesteramide based hot melt adhesive obtained with dimer acid,castor oil and ethylenediamine

Polyesteramide based hot melt adhesives were synthesized from high purity dimer acid (composition: ~1% trimer acid, ~98% dimer acid and ~1% linoleic acid), ethylenediamine and castor oil. The effect of castor oil content on the properties of the hot melts, such as thermal properties: glass transition temperature (T_g), melting temperature (T_m), enthalpy of melting (H_m), crystallization temperature (T_c), enthalpy of crystallization (H_c) and softening point (T_s); mechanical properties: tensile strength, elongation at break and Shore D hardness; adhesion properties: lap shear strength (LSS) and T-Peel strength (TPS); and rheological properties were investigated. Ethylenediamine was replaced by 5%, 10% and 15% (molar basis) of castor oil. It was found that T_g, T_m, H_m, T_c, H_c, T_s, LSS, TPS, tensile strength, Shore D hardness and viscosity, all decreased with increased concentration of castor oil. This is due to the decrease in the crystallinity of the polyesteramide caused by conversion of amide linkages by ester linkages and increased distance between two ester linkages (due to the bulky nature of castor oil).     

Aromatic polyamides. V. Substituent effect on thermal properties

Some wholly aromatic polyamides derived from unsubstituted and chloro- and nitro-substituted diamines have been studied from the viewpoint of their thermal stability, thermo-oxidative stability, and thermal transitions. General relationships between thermal stability of a polymer and its chemical structure are described. Decrease in thermal stability of poly(1,3-phenyleneisophthalamide) and poly(1,4-phenyleneterephthalamide) due to substituents has been explained and supported in part by infrared spectral data. The effect of electron-withdrawing substituents such as chloro and nitro in increasing the thermo-oxidative resistance of the polyamides is pointed out. The thermal transitions (T_g and T_m) of these polymers are also reported. All the polyamides exhibit a broad exothermic peak in the 630–700°C temperature range, which probably corresponds to reactions (crosslinking and cyclization) responsible for the high char yield of these systems.     

Polyamides incorporating furan moieties. 5. Synthesis and characterisation of furan-aromatic homologues

2,2′-Bis (5-chloroformyl 2-furyl) propane and various aromatic diamines were used as monomers in the study of their interfacial polycondensation and the properties of the ensuing furanic-aromatic polyamides. The effects of such variables as the nature of the organic phase, the temperature, the reaction time, and the type and concentration of the catalyst were investigated as well as the properties of the polyamides in terms of structure, average chain length, T_g, T_m and thermal stability.     

The effect of furan molecular units on the glass transition and thermal degradation temperatures of polyamides

Interfacial polymerization is used to prepare biobased furan polyamides from the carbohydrate‐derived monomer, 2,5‐furan dicarboxylic acid, aromatic diamines, and varying chain length aliphatic diamines. The molecular weights of the furan polyamides variations range 10,000–70,000 g/mol. These biobased polyamides have improved solubility relative to petroleum‐derived polyamides affording enhanced processability options. The glass transition temperatures (T_g) of the biobased furan polyamides are higher than that of aliphatic analogs, but lower than phenyl‐aromatic analogs. The T_g for these furan polyamides are as high as 280 °C. Also, the furan polyamide glass transition temperatures increase with decreasing aliphatic diamine chain length similar to results exemplified in petroleum‐based nylons. Group contribution parameters are determined for furans to enable simple prediction of the glass transition temperature and decomposition temperature of furan polyamides. The molar glass transition function for the furan is calculated to be 27.6 ± 1.5 K kg/mol. Thermal analysis measurements of the biobased furan polyamides have maximum thermal degradation temperatures at 350 °C or higher, similar to that of aliphatic polyamides when scaled with the number average molecular weight. The molar decomposition temperature functions are determined to be 37 K kg/mol for furans bonded to aliphatic units and 42 K kg/mol for furans bonded to phenyl units. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45514.     

A simple and efficient way to synthesize optically active polyamides by solution polycondensation of di‐O‐methyl‐L‐tartaryl chloride with diamines

A series of optically active polyamides containing di‐O‐methyl‐L ‐tartaryl moieties in the main chain were synthesized by polycondensation of di‐O‐methyl‐L ‐tartaryl chloride 5 with diamines and characterized by gel permeation chromatography, UV–vis, circular dichroism (CD), IR, and NMR spectroscopies. The polycondensation reaction could be carried out under mild conditions and the reaction time was short (2–3 h). The key monomer 5 prepared from L ‐tartaric acid via esterification, etherification, hydrolysis, and chlorination was easily purified by vacuum sublimation. These polyamides with number average molecular weights ranging from 14,000 to 35,000, displayed large optical activity in dimethyl sulfoxide solution, and their specific optical rotations oscillated between 87.2° and 210.7° depending on the structures of the diamines. The glass transition temperatures of these polyamides were in the range of 106–191°C, and the 10% mass loss occurred at temperature above 300°C. The polyamides derived from aromatic diamines exhibited higher T_g and thermal stability than those derived from aliphatic diamines. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of polyundecamethylene 2,6‐naphthalamide as semiaromatic polyamide‐containing naphthalene ring

A novel engineering plastic polyundecamethylene 2,6‐naphthalamide (PA11N) was prepared via a reaction of 2,6‐naphthalene dicarboxylic acid and 1,11‐undecanediamine through a three‐step procedure. The structure of synthesized PA11N was characterized by elemental analysis, Fourier transform infrared spectroscopy, and proton nuclear magnetic resonance (¹H‐NMR). The thermal behaviors were determined by differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. The solubility, water‐absorbing capacity, and mechanical properties of PA11N have also been investigated. Melting temperature (T_m), glass transition temperature (T_g), and decomposition temperature (T_d) of PA11N are 294, 139, and 493°C, respectively. The results show that the heat resistance and mechanical properties of PA11N are near to those of polynonamethylene terephthalamide, and PA11N is a promising heat‐resistant and processable engineering plastic. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Photo-Crosslinked Poly(ε-caprolactone fumarate) Networks: Roles of Crystallinity and Crosslinking Density in Determining Mechanical Properties

We present a material design strategy of combining crystallinity and crosslinking to control the mechanical properties of polymeric biomaterials. Three polycaprolactone fumarates (PCLF530, PCLF1250, and PCLF2000) synthesized from the precursor polycaprolactone (PCL) diols with nominal molecular weights of 530, 1250, and 2000 g mol⁻¹, respectively, were employed to fabricate polymer networks via photo-crosslinking process. Five different amounts of photo-crosslinking initiator were applied during fabrication in order to understand the role of photoinitiator in modulating the crosslinking characteristics and physical properties of PCLF networks. Thermal properties such as glass transition temperature (T_g), melting temperature (T_m), and degradation temperature (T_d) of photo-crosslinked PCLFs were examined and correlated with their rheological and mechanical properties.     

Synthesis and properties of bismaleimide resins containing ether bonds

New bismaleimides containing ether bonds were prepared. The thermal properties of the bismaleimides were investigated by differential scanning calorimetry (DSC). The effects of structure of the bismaleimides and curing conditions on the thermal and mechanical properties of the cured resins such as initial decomposition temperature (T_d), glass transition temperature (T_g), and flexural strength were studied. The introduction of ether bonds to bismaleimide resins decreased the brittleness of the resins without reductions in their heat-resistant properties.     

Polyamides based on diamines containing aryloxy groups: Structure-property relationships

Aromatic polyamides containing different numbers of p-oxyphenylene groups and different catenated positions in the benzene rings were prepared from terephthalic acid (TPA) and isophthalic acid (IPA) with various aryloxy-containing diamines by means of the phosphorylation polycondensation reaction. Most of the polyamides were moderately to highly crystalline, as indicated by X-ray diffraction and DSC measurements. Polyisophthalamides were readily soluble in polar amide-type solvents such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc). Some non-crystalline polyamides could afford tough films by solution casting. Most polyisophthalamides revealed discernible glass transition on their DSC curves, and their T_g values were recorded in the range of 215–238 °C. No discernible glass transitions were observed for the polyamides of TPA by DSC. The thermal stability of these polymers did not show clear dependence on the structure of the diacid or the diamine. In addition, a series of polyamides having pendant groups was synthesized from the polycondensation of TPA and IPA with 1,4-bis(4-aminophenoxy)benzene and its derivatives with methyl, tert-butyl, or phenyl substituent on the central benzene ring. In most cases, the incorporation of pendant groups generally resulted in an enhanced solubility and a decreased T_g and crystallinity.     

The effect of urea bond on structure and properties of toughened epoxy resins

In this article, modified poly(oxypropylene) diamines were synthesized and used as a new flexible curing agent for epoxy resins. The purpose of modification is to introduce urea group into epoxy resins. The reaction rate, mechanical properties, glass transition temperature (T_g), and fracture surface morphology of these toughened epoxy resins were investigated. Because of urea groups, the reactivity between poly(oxypropylene) diamines and epoxy resins was significantly enhanced. At the same time, the urea groups resulted in strong intersegmental hydrogen bonding between modified poly(oxypropylene) chain, which reduced the compatibility of poly(oxypropylene) with epoxy resins and resulted in higher T_g of toughened epoxy. The modified sample had tensile strength of 15.8 MPa and ultimate elongation of 118% at room temperature, whereas the unmodified sample only had 6.2 MPa and 70%. The scanning electron microscope analysis showed that the modified system displayed tough fracture feature, whereas the unmodified system showed typical brittle fracture. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Epoxy thermosetting systems: Dynamic mechanical analysis of the reactions of aromatic diamines with the diglycidyl ether of bisphenol A

Dynamic mechanical behavior during the reactions of four aromatic diamines (m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfone, and benzidine) with the diglycidyl ether of bisphenol A was studied by torsional braid analysis under isothermal conditions. Depending on the cure temperature, three types of behavior were observed: (I) below T_gg (the glass transition temperature of the reactive systems at the gel point); (II) between T_gg and T_g∞ (the glass transition temperature of the ultimately cured polymers); (III) above T_g∞. Overall activation energies and apparent overall rate constants of the cure reactions based on third-order overall kinetics were determined before gelation, after gelation but before vitrification, and after vitrification, using gelation time, relative rigidity, and glass transition temperature T_g(t) of the polymers as kinetic terms. The influence of cure temperature and structure of the diamines on the kinetic parameters is discussed.     

Synthesis,properties, and dyeing application of nonionic waterborne polyurethanes with different chain length of ethyldiamines as the chain extender

This study deals with the synthesis of some nonionic waterborne polyurethanes (PUs), using ethyldiamines of different chain length, such as ethylenediamine (EDA) and diethyltriamine (DETA), as the chain extender in the reaction, and examines the thermal properties, mechanical properties, and dyeing properties of the PU products and their blends. As far as each PU by itself is concerned, we found that the T_g of the one made with DETA is the highest, followed by that with EDA, and the one with 1,4‐butanediol (1,4‐BD) is the lowest. The PU made with 1,4‐BD as the chain extender has no T_m, while the two others, using diamines as chain extenders, have a clear T_m, the one with DETA being higher than that with EDA. However, the enthalpy data are just the opposite. The tensile strengths of the two PUs, made with diamines as the chain extender, are larger than that made with 1,4‐BD, but their respective elongation properties are just the opposite. A comparison within PUs made with diamines showed that the one made with EDA is greater in both strength and elongation categories than that made with DETA. However, the one made with DETA is far superior to both of those made with 1,4‐BD and EDA in their dye‐exhaustion ratio, color yield (K/S), fixation rate, and color fastness. In respect to the various PU mixtures that we examined, we found that both PUs synthesized with EDA or DETA as the chain extender would have their T_g's greatly increased by blending in some PU made using 1,4‐BD as the chain extender. Among them, in particular, a blend of PU, made separately with DETA and 1, 4‐BD as the chain extender, showed great improvements in both tensile strength and elongation and also demonstrated better dyeability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2824–2833, 2003     

Synthesis and study of some newer polyamides for semipermeable membrane

A series of novel polyamides was prepared by low temperature solution polycondensation of N-(p/m-aminobenzoyl aminoacetyl)-N'-(4/3-aminobenzoyl) hydrazine with different diacid chlorides in dry N,N-Dimethylacetamide (DMAC). The properties of the polyamides for membrane processing were studied with the help of infrared spectra, inherent viscosity, differential thermal, and thermogravimetric analysis. The inherent viscosities were measured in concentrated sulfuric acid at 25±5°C and were in the range of 0.35–0.89 dL/g. The thermogravimetric data in air indicate that the initial decomposition temperature was in the range of 175–200°C. The polymer melt temperature (T_m) and glass transition temperature (T_g) were in the range of 230–450°C and 153.3–300°C, respectively.     

Synthesis and properties of nylon 6 modified with various aromatic polyamides

In this study, flexible nylon 6 was reinforced by the following rigid-chain aromatic polyamides: poly (m-phenylene isophthalamide) (PmIA), poly(4,4′-diphenylsulfone terephthalamide) (PSA), poly( p-diphenyloxide terephthalamide) (POA), and poly(p-diphenylmethane terephthalamide) (PMA). Various high-molecular-weight block copolyamides were synthesized by solution polymerization using p-aminophenylacetic acid (p-APA) as a coupling agent. Their thermal properties have shown that the block copolyamides exhibit higher T_g and T_m and better thermal stability than those of nylon 6, especially PmIA-modified nylon 6. The order of their thermal properties of aromatic modified nylon 6 copolyamides is PmIA > PMA > POA > PSA. Besides, the T_g and T_m of multiblock copolyamides are higher than those of triblock copolyamides. From the wide-angle X-ray diffraction pattern, it is found that the triblock copolyamides have two diffraction peaks (i.e., 2θ = 20.5 and 24°). However, the multiblock has only one at 2θ = 20°, indicating a different crystal structure for multiblock copolyamides. This can be further confirmed from scanning electron microscopy. It shows that the triblock copolyamides are a dispersed phase structure, although the multiblock copolyamides exhibit a homogeneous texture rather than an aggregated one. For the mechanical properties, it is found that the multiblock copolyamides have a more significant reinforcing effect than the triblock copolyamides. Also, the order of their physical properties of aromatic modified nylon 6 copolyamides, such as tensile strength, is PmIA > PMA > POA > PSA; but for the elongation, the order is PSA > POA > PMA > PmIA. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1031–1043, 1998     

Polyamides incorporating furan moieties: 4. Synthesis,characterisation and properties of a homologous series

Interfacial polycondensation of 2,2′‐bis[2‐(5‐chloroformylfuryl)]propane with various diamines gave high yields of a novel series of furanic polyamides with high inherent viscosities. The properties of these polymers (T_g, surface energy, crystallinity, thermal stability) were assessed and examined in terms of the role of the specific structure of the bridging group borne by the diamines. Only three polyamides were partially crystalline, whereas all the others were amorphous. Thermogravimetric analysis revealed that thermal decomposition began above 300 °C in all instances. © 2001 Society of Chemical Industry