Synthesis,characterization, and kinetics study of thermal decomposition of epoxidized soybean oil acrylate

The synthesis of epoxidized soybean oil acrylate (ESOA) from epoxidized soybean oil (ESO) had been carried out by reacting acrylic acid with the oxirane group in ESO. The acrylated ESO products were characterized using a variety of analytical techniques. The oxygen value, iodine value, and acid value were obtained to know the amount of unsaturation in the synthesized product. Infrared and proton NMR spectra were carried out to confirm the participation of oxirane group in the acrylation reaction. Free‐radical initiators, benzoyl peroxide and tertiary butyl peroxy benzoate, were used for the curing of ESOA resin. Thermal decomposition kinetics of ESOA was studied by the methods of Ozawa, Kissinger, and Horowitz‐Metzger, and the kinetic parameters were compared. The thermal decomposition data of the cured ESOA resin was analyzed by thermogravimetric analysis (TGA) at different heating rates. TG curves showed that the thermal decomposition of the ESOA system occurred in one stage. The apparent activation energies determined by the Ozawa, Kissinger, and Horowitz‐Metzger methods are 122.69, 95.347, and 126.20 kJ/mol, respectively. The results show that there was a reasonably good agreement between the calculated activation energies for stage one in the above methods. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Dynamic mechanical and thermal behavior of epoxy resins based on soybean oil

Mechanical and thermal properties of materials prepared by curing epoxidized soybean oil with various cyclic acid anhydrides in the presence of tertiary amines were investigated by dynamic mechanical thermal analysis and thermogravimetry. All samples presented thermoset material characteristics that were dependent upon the type of anhydride, the anhydride/epoxy molar ratio, and epoxy group content. The thermosets obtained from anhydrides with rigid structures as such phthalic, maleic, and hexahydrophthalic showed higher glass transition temperatures (Tg) and cross-linking densities. As expected, the Tg decreased as the anhydride/epoxy ratio decreased. The influence of the degree of epoxidation of soybean oil on the mechanical properties and Tg was also investigated. It was found that the higher the epoxy group amount, the higher the Tg and hardness. Cured resins exhibited thermal stability up to 300°C, except for those prepared with dodecenyl succinic anhydride, which began to decompose at lower temperature. They presented excellent chemical resistance when immersed in 1% wt/vol NaOH and 3% wt/vol H₂SO₄ solutions but poor chemical resistance in the presence of organic solvents.     

Synthesis and properties of polyurethane elastomers based on renewable castor oil polyols

In this contribution, castor oil polyols with functionality of f = 2.7 and f = 2 are used as soft segments (SS) for synthesizing polyurethane elastomers (PUEs) without addition of petroleum-based polyol. The effect of molar ratio of castor oil polyols on structure and properties of PUEs has been investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, X-ray diffraction, tensile, swelling, and water absorption tests. The results reveal that hydrogen bonding mainly exists in hard segments (HSs) and weakens with decreasing the molar percentage of castor oil polyol (f = 2.7) in SS. T _g of SS decreases while T _g of HS remains constant as molar percentage of castor oil polyol (f = 2.7) decreased. The initial degradation temperatures (T_5%) are above 300 °C and independent of the molar ratio of castor oil polyols. However, the temperature at 50% weight loss (T_50%) decreases significantly as molar percentage of castor oil polyol (f = 2.7) decreased. Moreover, PUEs exhibit very low water absorption rate, <1%, after immersing in water for 140 h at room temperature. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47309.     

Thermal and mechanical properties of cast polyurethane resin based on soybean oil

The soy polyols were prepared from epoxidation of soybean oil followed by ring opening of oxirane obtained by using methanol as the ring opener. Polyols of hydroxyl (OH) numbers ranging from 128 to 174 mg of KOH/g were obtained by the variation of epoxidation time of soybean oil. A novel cast polyurethane resin has been synthesized by these polyols and 2,4‐toluene diisocyanate. Swelling of networks in toluene showed that the sol fraction varies from 1.13 to 72.06%. The thermal and mechanical properties of cast resins were characterized by differential scanning calorimetry and thermogravimetric analysis. The results showed that the glass transition temperature increases with the increase of OH number and that the thermal stability of the resins was slightly decreased with the increasing OH number. The tensile strength at break increases with the increase of OH number. Polyols with OH number of 174 mg of KOH/g gave glassy polymers, whereas those below this value gave rubbers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and properties of boron-containing soybean oil based thermosetting copolymers

The first example of boron-containing soybean oil based copolymers was prepared from soybean oil, styrene, divinylbenzene and 4-vinylphenyl boronic acid by cationic polymerization using boron trifluoride etherate as initiator. Soxhlet extraction and NMR spectroscopy indicate that the copolymers consist of a crosslinked network plasticized with varying amounts of oligomers and unreacted oil. The thermal degradation mechanism was studied and the thermal, dynamomechanical and flame retardant properties of these materials were examined. Thermosets with glass transition temperatures ranging from 43 to 60 °C, which are thermally stable below 350 °C and with LOI values from 23.7 to 25.6 were obtained. The LOI tests indicate that the flame retardant properties of vegetable oil can be improved by adding boron covalently bonded to the polymer.     

Crosslinked latex blends based on gelatin: Synthesis,morphology, thermal,and mechanical properties

Latex blends of different compositions of poly(methyl methacrylate-co-n-butylacrylate) and gelatin have been synthesised in latex form with crosslinking agents. These latex blends were characterized by thermal and mechanical properties. The morphology of cross-linked latex blends were studied by scanning electron microscopy (SEM).     

Dynamic mechanical properties of magnetorheological elastomers based on polyurethane matrix

Magnetorheological elastomers (MRE) are mainly composed of soft magnetic particles and rubber‐like matrix. Previous studies have shown that the matrix has a greater impact on mechanical properties of MRE. In this article, a new kind of polyurethane material was fabricated and used as the matrix of MRE. The effect of several factors on the mechanical properties of MRE samples was experimentally studied, such as fabrication condition, content of iron particles, different weight ratio of castor oil and diphenylmethane diisocyanate, plasticizer. Their microstructures were observed, and the mechanical properties were measured using a testing system in the presence of an external magnetic field. The experimental results demonstrate that these factors have different impact on shear storage modulus, magneto‐induced modulus, MR effect and damping property. In addition, the damping property of these MRE is also higher than that of MRE based on the other matrix. This study can hopefully be applied to optimize the mechanical properties of MRE. POLYM. COMPOS., 37:1587–1595, 2016. © 2014 Society of Plastics Engineers     

Preparation,morphology, and mechanical properties of elastomers based on polydimethylsiloxane/ polystyrene blends

Polydimethylsiloxane/polystyrene (PDMS/PS) blends were prepared by radical copolymerization of styrene (St) and divinylbenzene (DVB) in the presence of α,ω‐dihydroxy‐polydimethylsiloxane (PDMS), using benzoyl peroxide as initiator. The PDMS/PS blends obtained by this method are a series of stable, white gums, when the feed ratio of PDMS to St is 60/40 and DVB to St is not more than 2.0 wt %. Elastomers based on PDMS/PS blends were formed by crosslinking PDMS with methyl‐triethoxysilicane (MTES). The MTES dosage was much larger than the amount necessary for end‐linking hydroxy‐terminated chains of PDMS, with the excess being hydrolyzed to crosslinked networks, which were similar to SiO₂ and acted as filler. Mechanical property measurements show that the elastomers thus formed exhibit superior mechanical properties with respect to pure PDMS elastomer and the elastomers based on PDMS/PS system we prepared before. Moreover, investigations were carried out on the elastomers by extraction measurement and scanning electron microscopy (SEM). The extraction data show that the sol‐fraction decreases with increasing the feed ratio of DVB to St. SEM observation demonstrates that the elastomer has a microphase‐separated structure consisting of dispersed PS domains within a continuous PDMS matrix, and the extracted material exhibits a porous structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and properties of thermoplastic elastomers based on PTMO and tetra-amide

Segmented copolymers based on T6T6T-dimethyl (two-and-a-half repeating unit of nylon-6,T) and PTMO or extended PTMO₁₀₀₀/DMT that are thermoplastic elastomers were made via polycondensation. The materials have a good solvent resistance, are melt-processable and transparent. The polymers all have a low glass transition temperature (−60 to −0 °C). The rubbery plateau is wide and extremely flat and the melting temperature is sharp and high. The shear modulus of the rubbery plateau (3.3-14.5 MPa) and the flow temperature (183-220 °C) increase with increasing T6T6T content (5-16 wt%), corresponding to increasing crystallinity. The undercooling, as measured by DSC, is 20-30 °C. The compression set at room temperature is low (6-7%) and decreases slightly with decreasing T6T6T content. With AFM it was shown that the crystalline T6T6T units form long threads or ribbon like structures with a high aspect ratio in the amorphous PTMO matrix.     

HTBN／PTMG基聚氨酯脲弹性体的结构与性能

以端羟基丁腈液体橡胶（HTBN）和聚四氢呋喃醚二醇（PTMG）共混软段并加入交联剂,制备一系列聚氨酯弹性体（PUU）,对其力学性能进行测定,并采用差示扫描量热分析（DSC）和热失重分析（TG）对材料进行热力学分析。结果表明,HTBN与PTMG以8：2的质量比共混时,制得的PUU的拉伸强度为25MPa,耐热性能也较优越;用三羟甲基丙烷（TMP）为交联剂制得交联网络结构的PUU,力学性能和热性能都有所提高;2,5-二甲基-2,5-双（叔丁过氧基）己烷（简称双二五）打开HTBN主链上的双键,进一步加强了聚氨酯的交联,使其力学及耐热性能进一步提高。     

蓖麻油作交联剂的聚氨酯弹性体的合成及性能

以不同摩尔比的四氢呋喃均聚醚（PTMG）和1,6-亚己基二异氰酸酯（HDI）合成聚氨酯（PU）预聚体,再分别用丁二醇（BD）、蓖麻油（CO）以及BD和CO混合物进行扩链交联,合成了一系列不同CO含量的PU.通过FTIR、AFM、拉伸实验和TGA,对不同硬段含量和CO含量PU的氢键化程度、相形态结构、力学性能和热性能进行了比较。结果表明,二异氰酸酯和扩链剂的种类及用量对PU的性能均有很大的影响。随着PU中二异氰酸酯用量的增加,其力学性能和热稳定性能提高。随着扩链剂中CO用量的增加,PU氨酯键的氢键化程度降低,其软、硬段的微相分离程度降低,导致其力学性能降低。但CO用量的增加会提高PU分子链的交联和支化,因而其热稳定性能得到提高。     

1,5-萘二异氰酸酯型聚氨酯弹性体的制备及性能

通过预聚法合成了以己二酸乙二醇丙二醇二酯、聚四氢呋喃二醚、1,5-萘二异氰酸酯(NDI)、甲苯二异氰酸酯(TDI)、1,4-丁二醇及4,4'-二氨基-3,3'-二氯二苯甲烷为主要原料的聚氨酯弹性体。通过水解后弹性体的拉伸、撕裂等力学性能保持率的比较,发现NDI型聚氨酯弹性体比TDI型具有更好的水解稳定性;通过不同温度下和热空气老化后弹性体力学性能保持率的对比,证明NDI型聚氨酯弹性体的耐热稳定性要优于TDI型。     

Preparation, characterization and mechanical properties of epoxidized soybean oil/clay nanocomposites

New epoxidized soybean oil (ESO)/clay nanocomposites have been prepared with triethylenetetramine (TETA) as a curing agent. The dispersion of the clay layers is investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM data reveal the intercalated structure of ESO/clay nanocomposites has been developed. The thermogravimetric analysis exhibits that the ESO/clay nanocomposites are thermally stable at temperatures lower than 180 °C, with the maximum weight loss rate after 325 °C. The glass transition temperature, T_g, about 7.5 °C measured by differential scanning calorimetry (DSC) and T_g about 20 °C measured by dynamic mechanical study have been obtained. The difference in the T_g between DSC and dynamic measurements may be caused by different heating rate. The nanocomposites with 5-10 wt% clay content possess storage modulus ranging from 2.0×10⁶ to 2.70×10⁶ Pa at 30 °C. The Young's modulus (E) of these materials varies from 1.20 to 3.64 MPa with clay content ranging from 0 to 10 wt%. The ratio of epoxy (ESO) to hydrogen (amino group of TETA) greatly affects dynamic and tensile mechanical properties. At higher amount of TETA, the nanocomposites exhibit stronger tensile and dynamic properties.     

Polymers from renewable resources. IX. Interpenetrating polymer networks based on castor oil polyurethane poly(hydroxyethyl methacrylate): Synthesis,chemical, thermal,and mechanical properties

A number of polyurethanes were synthesized by reacting castor oil with hexamethylene diisocyanate, varying the NCO/OH ratio. The polyurethanes were reacted with 2-hydroxyethyl methacrylate (HEMA) to prepare the interpenetrating polymer networks (IPNs) using benzoyl peroxide as the initiator and ethylene glycol dimethacrylate (EGDM) as the crosslinker. The IPNs are partly soluble in some of the solvents and are less resistant to alkali, but more resistant to acid. The solvent absorption is more pronounced in benzene than in toluene. A novel computerized LOTUS package was used to calculate the kinetic parameters. All the IPNs decomposed with 2–4% weight in the temperature range of 0 to 200°C; 10% weight loss occurs at 300°C and 40% weight loss occurs at 400°C. There is a rapid weight loss from 10 to 90% in the temperature range of 400–500°C. From the kinetic data, it is clear that the degradation process of the IPNs is slower in the temperature range 300–400°C and faster in the temperature range of 440–560°C. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 671–679, 1997     

Blends of polyamide 6 and epichlorohydrin elastomers. II. Thermal,dynamic mechanical,and mechanical properties

The mechanical blending of polyamide 6 and epichlorohydrin elastomers, polyepichlorohydrin, PEPI, and poly(epichlorohydrin‐co‐ethylene oxide), ECO, is accompanied by grafting copolymerization. In this work the influence of the graft copolymer on the thermal and mechanical properties of the blends is investigated. The blends are immiscible and the crystallinity degree normalized to the polyamide 6 contents in the blends is higher than expected. The X‐ray diffraction results show that the grafting copolymer is also crystalline; hence, the presence of crystalline phase of copolymer can be responsible for the apparent enhancement of crystallinity. The DMA analysis reveals the presence of a shoulder in the peak corresponding to the PA 6 glass transition, as observed by loss modulus curves, which was assigned to relaxations of the grafting copolymer. Tensile tests show that the blends are more fragile than the PA 6, despite the graft copolymer. These results were attributed to the mechanical fragile interface constituted by a network type structure of the graft copolymer. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1835–1841, 1999     

Synthesis of a novel lignin-based epoxy resin curing agent and study of cure kinetics,thermal, and mechanical properties

In this contribution, first of all, the methoxy groups of organic solvent lignin (OSL) was converted to phenolic hydroxyl groups through demethylation reaction for the purpose of fabricating demethylated organic solvent lignin (DOSL). In addition, the resulting DOSL was utilized as a renewable material to synthesize a novel esterified lignin (EDOSL) by reacting with isobutyryl chloride for curing of epoxy resin. Finally, commercial liquid diglycidyl ether of bisphenol A was cured by EDOSL in the presence of 4-dimethylaminopyridine (DMAP) used as a catalyst based on dual-curing mechanism. Dual curing is a processing methodology based upon the alliance of two diverse and compatible polymerization reactions occurring sequentially or simultaneously. According to the FTIR spectra and ¹H-NMR analyses, the demethylation of OSL, esterification of DOSL, and the curing reaction of epoxy resin with EDOSL were successfully conducted. The value of the phenolic hydrogen in the DOSL was approximately 4.89 mmol/g, which increased by 12.64% after demethylation. The thermal and mechanical performances of these cured epoxy samples were measured by DSC, DMA, TGA, and tensile testing. The epoxy system cured by 10%wt esterified lignin with 1%wt DMAP possessed the tensile strength of 71.54 ± 7.50 MPa and the initial degradation temperature (T_5%) of 370°C, which can compete fairly with commercial aromatic curing agents or other lignin-based agents studied currently for the curing of epoxy systems.     

Mechanical,thermal, and electric properties of polyurethaneimide elastomers

Linear polyurethaneimide elastomers (PUI) were obtained from polyether- or polyester-diols, diphenylmethane diisocyanate or bitolylene diisocyanate and pyromellitic acid dianhydride. It was found that these polymers have considerably better mechanical properties than typical linear polyurethanes (PU). The elastic modulus and stress at break increase with contents of the hard polyimide segments. The softening temperatures and thermal stability of the PUI at 500°C were higher than the ones of PU with similar hard segment contents. Electric properties of PUI were close to the ones of conventional PU. It was shown that cellular PUI had considerably lower dielectric constant. T_g's of the soft segments PUI were less than T_g's corresponding to PU. It is connected with greater phase separation of the hard imide segments from the soft polyether– or polyester–urethane matrix.     

Influence of molecular weight on the thermal and mechanical properties of polyurethane elastomers based on 4,4′-diisocyanato dicyclohexylmethane

Two series of segmented polyurethane elastomers based on 4,4′-diisocyanato dicyclohexylmethane were investigated with respect to their thermal properties and deformation behavior. We used a crystallizable soft segment, 1,4-poly(tetramethylene glycol), for one series and a noncrystallizable soft segment, 1,2-poly(propylene glycol), for the other. Both systems exhibited mechanical self-reinforcement that depended strongly on the deformation rate. We propose a mechanism for the observed stress/strain behavior in terms of two competing processes: (1) the buildup of orientation caused by deformation and (2) the loss of orientation caused by plastic slippage and segmental relaxation during deformation. The kinetics of these processes depend stronly on the deformation rate and overall molecular weight.     

Aliphatic polycarbonate‐based polyurethane elastomers and nanocomposites. II. Mechanical,thermal, and gas transport properties

Thermal, thermomechanical, tensile and gas transport properties of aliphatic polycarbonate‐based polyurethanes (PC‐PUs) and their nanocomposites with bentonite for organic systems were studied. Hard segments are formed from hexamethylene diisocyanate and butane‐1,4‐diol. All PC‐PUs and their nanocomposites feature high degree of the phase separation. Three phase transitions were detected by temperature‐modulated differential scanning calorimetry (TMDSC) and dynamic mechanical thermal analysis. TMDSC revealed the filler affinity both to soft and hard segments, even though the affinity to hard segments is much stronger. Elongation‐at‐break at ambient temperatures is mostly over 700%, which leads together with high tensile strength (in some cases) to very high toughness values (over 200 mJ/mm³). The addition of 1 wt % of bentonite does not practically affect mechanical properties implying its very good incorporation into the PU matrix. Permeabilities and other gas transport properties depend on regularity of PC‐diol and on hard segment content, but the variations are insignificant. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Multifunctional deoxybenzoin-based epoxies: Synthesis,mechanical properties,and thermal evaluation

We describe 2,4,4′,6-tetrahydroxydeoxybenzoin (THDB) as a multifunctional cross-linker in conjunction with bis-epoxydeoxybenzoin (BEDB), affording new resins that combine excellent physical and mechanical properties with low flammability. The char residue and heat release capacity values of the cross-linked epoxies were measured by thermogravimetric analysis (TGA) and pyrolysis combustion flow calorimetry (PCFC), respectively. Resins fabricated from THDB exhibited low total heat release (13 kJ/g) and high char yields (34%), as well as good mechanical properties, making them suitable candidates for consideration in high performance adhesive applications. The desirable heat release and char yield properties of these structures are realized without the presence of any conventional flame retardant, such as halogenated structures or inorganic fillers that are commonly utilized in commercial materials.