Hydroxylated Tung oil (HTO) based nonionic polyurethane dispersion (HTO-NPUD) were synthesized using dicyclohexyl methane diisocyanate (HMDI) and HTO as main hydrophobic materials whereas polyethylene glycol-800 (PEG-800) as hydrophilic chain extender. To effectively study the effects of HTO on properties of NPUD, polypropylene glycol-400(PPG-400) based NPUD was prepared by HMDI reacting with PPG-400 and PEG-800. The structures of those novel nonionic polyurethane dispersions were characterized by FTIR and 1H NMR. Moreover, particle size and size distribution, cloud point and surface tension had been investigated. Results showed that, by comparing with PPG based NPUD (PPG-NPUD), the introduction of HTO into NPUD result in larger particle size and more uniformed particle size distribution, higher cloud point and lower surface tension.
Waterborne polyurethanes or polyurethane dispersions (PUDs) are a class of polymer dispersions with excellent comprehensive performance which exhibit a wide range of advantages such as low volatility of organic solvent, non-toxic, non-flammability and energy saving. It is for this reason that PUDs have been gaining thorough study and will be further developed into more environmental, biodegradable and functional materials. Among all types of PUDs, nonionic PUD (NPUD) without ion dangling on its molecular chain is provided with improved acid and alkali resistance, electrolyte sexual tolerance and can be applied in the development of synthetic leather surfactant and textile finishing agent [
Tung oil [
The HTO prepared by first method (through ester) has functionality of two and can be reacted with isocyanate. This passage aims to synthesize a novel HTO-based NPUD used for macromolecule surfactant with conjugated double bonds. Compared with micromolecule surfactants, whose residues after emulsification may harm the polymer matrix, macromolecule surfactants have properties of perfect dispersity, film-forming ability, environmental friendliness, stability [
The present study aims to develop novel, biobased HTO-NPUD with post crosslinking function, based on the HTO that is hydroxylated via ester mentioned above. Firstly, NPUD was synthesized from HMDI reacting with HTO and PEG-800. Then, the structures of the NPUDs were characterized by IR and NMR, and the influence of HTO on the performance of NPUD were studied and analyzed including particle size, cloud points and surface tension. In order to make better investigation analysis for effect of HTO on PUD, PPG-NPUD was selected to compare with HTO-NPUD. The reason to use PPG-NPUD as comparison is that PPG-400 is a kind of common material in synthesis of polyurethane and provides similar molecular weight with HTO.
Polyethylene glycol-800 (PEG-800, Bayer, Germany), polypropylene glycol-400 (PPG-400, Haian petrochemical plant, China). Reagents above were dealt with vacuum drying oven at certain temperature before use. HTO was kindly provided from US A-line Company. Dicyclohexyl methane diisocyanate (HMDI) was purchased from Wanhua Chemical Group Company. N-methyl pyrrolidone (NMP) was purchased from Shanghai Chemical Reagent Company of China Pharmaceutical Group, freed from moisture using anhydrous 4A molecular sieve. Distilled water was used as the dispersing phase.
The recipes for NPUD are showed in
HTO, PEG and HMDI were simultaneously added into a 500 mL four-necked flask equipped with stirrer and thermometer. The reaction was carried out in the protection of nitrogen gas and under a constant temperature at 80˚C - 90˚C heating with oil bath. When the NCO group content reached to a designed value, distilled water was added and the stirring rate was raised after the temperature was lowered. Then HTO-NPUD was obtained by the
Samples | The Basic Recipes | Mn(g/mol) | Cloud Point (˚C) | |||
---|---|---|---|---|---|---|
PPG-400 | HTO | PEG-800 | HMDI | |||
PPG-NPUD | 1 | 0 | 1 | 2 | 7800 | 34 |
HTO-NPUD | 0 | 1 | 1 | 2 | 8200 | 69 |
emulsification of HTO-NPU prepolymer. In this reaction process, a small amount of NMP was added to adjust the viscosity. The synthesis of PPG-NPUD was similar to that of HTO-NPUD. The synthesis process of NPUDs is showed in
All infrared spectra of NPUDs were obtained using a SHIMADZU FTIR-8700 Spectrophotometer. The frequency range covered was from 4000 to 400 cm−1 by averaging 16 scans at a resolution of 4 cm−1. 1H NMR spectra were recorded on a Bruker AvanceⅢ-400MH superconducting NMR Spectrometer using DMSO-d6 as the solvent at a concentration of ~5% (w/v). All spectra were recorded at room temperature (298 K). Chemical shifts (δ) are given in parts per million with tetramethylsilane (TMS, 0.1%) as internal standard. Coupling constants (J) are given in Hertz.
The average particle size and distributions of NPUDs were measured with a Malvern ZEN3690 laser particle sizer (UK). The cloud points of aqueous polyurethane were measured using distilled water measurement according to GB/T5559-1993. Samples were regularly diluted to different concentrations and the surface tensions were investigated with DATAPHYSICS DCAT21 automatic interface tensiometer.
The FTIR spectra of PPG-NPUD and HTO-NPUD are shown in
The absorption peak at 1110 cm−1 are due to hydrophilic C-O-C stretching vibration. No peak at around 2250 cm−1, which is character peak of free NCO group, indicates that NCO in this product has totally reacted. The above characteristic spectra prove that the resultants are the expected polyurethanes. The absorption peaks of N-H at 3346 cm−1, 3337 cm−1 illustrate that N-H possibly formed hydrogen bond with C=O. And this phenomenon is proved by the fact that the absorption peaks of C=O are at 1719 cm−1 and 1717 cm−1 instead of 1732 cm−1 which is the characteristic peak of free C=O. In comparison with PPG-NPUD, there is one more peak at 993 cm−1 that represents characteristic peak of conjugated double bond in the spectrum of HTO-NPUD, suggesting that HTO is successfully introduced into NPUD structure.
The 1H NMR spectra of PPG-NPUD and HTO-NPUD are presented in
PUD is macromolecule of polyurethane dispersing in water in the form of latex particle whose diameter is particle size. Particle size and its distribution have a direct effect on the emulsion’s properties such as the color, transparency and stability. The decrease in particle size will result in an increase in transparency, stability [
It is evident from
The cloud point is a temperature at which a homogenous surfactant solution separates into two coexisting phases. It is basically affected by its molecular structure [
hydrogen bonds have profound impact on cloud point [
As is indicated in
The surface tension is induced by the liquid surface shrinkage that is an important property of surfactant.
in the same conditions, which indicates that the surface tension of NPUD is significantly affected by the introduction of HTO. On the surface of NPUD aqueous emulsion, hydrophilic groups combine with water inside, while hydrophobic chains arrange outside, whose repulsion destroy the power among water molecules. So the surface tension reduction may be induced by the introduction of long oleophyllic alkyl chain as side chain of HTO into NPUD.
A type of novel NPUDs have been successfully synthesized by the reaction of HMDI with HTO/PPG-400 and PEG-800. HTO with three conjugated double bonds had been introduced into the NPUD. In spite of the fact that the particle size of HTO-NPUD was much larger than that of PPG-NPUD, the introduction of HTO may improve the stability of NPUD emulsion owing to the more uniformed particle size distribution. The cloud point of HTO-NPUD was remarkably higher than that of PPG-NPUD, indicating that HTO significantly improved thermal stability of NPUD. Furthermore, the surface tension of the emulsion was reduced by the introduction of hydrophobic chain from HTO. The lower surface tension suggested that HTO-NPUD had obvious surface active property and provided possibility of using HTO-NPUD as surfactant. And the three conjugated double bonds would endow more excellent performance that is worth to be further studied.
This work is supported by the National Nature Science Foundation (21074030).
Xiaomin Yang,Baixia Ren,Zhiyong Ren,Lei Jiang,Wentao Liu,Chengshen Zhu, (2015) Synthesis and Properties of Novel Non-Ionic Polyurethane Dispersion Based on Hydroxylated Tung Oil and Alicyclic Isocyanates. Journal of Materials Science and Chemical Engineering,03,88-94. doi: 10.4236/msce.2015.31013