Tough thermosetting polyurethanes and adhesives from rubber seed oil by hydroformylation

Rubber seed oil (RSO), extracted from the seeds of rubber trees, is inedible oil with high free fatty acid content. In order to add value to RSO, we prepared a polyol with primary OH groups via hydroformylation/hydrogenation. Free hydroxy fatty acids formed in the process were utilized as reactive diluents, viscosity reducers, and adhesion promoters through hydrogen bonding with the substrate. The structures of the oil and polyol were analyzed using a range of analytical methods. The polyol had a hydroxyl number of 244 mg KOH g⁻¹ and an acid number of 21 mg KOH g⁻¹. The polyurethane prepared from this polyol and diphenylmethane diisocyanate was a highly crosslinked, tough material with a glass transition at 44 °C, high tensile strength and elongation, and attractive electrical properties. When used as a wood adhesive, it displayed extraordinary shear strength characterized by substrate wood failure rather than cohesive failure of the polymer. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48509.     

Surface modification of synthetic vulcanized rubber

Surface modifications produced by treatments (mainly halogenation) of synthetic vulcanized styrene-butadiene rubber (SBR) leading to increased adhesion properties with polyurethane adhesives have been studied. T-peel tests, scanning electron microscopy (SEM), advancing contact angle measurements, infra-red (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and differential scanning calorimetry (DSC) were used to analyze the nature of surface modifications produced in the rubber. Although some surface heterogeneities were created, physical treatments (ultrasonic cleaning, solvent wiping, abrasion) did not noticeably increase the adhesion strength because certain abhesive substances (e.g. zinc stearate, paraffin wax) cannot be removed from the rubber surface by such treatments. Chemical treatment (chlorination) was carried out using ethyl acetate solutions of trichloroisocyanuric acid (TCI) (1,3,5-trichloro-1,3,5-triazine-2,4,6-trione). Chlorination of SBR with trichloroisocyanuric acid produced a significant improvement in T-peel strength, due to the contribution of mechanical (surface roughness, microcracks), thermodynamical (increase of polar contribution to the surface energy) and chemical (removal of abhesive substances, creation of polar groups) rubber surface modifications. The strong adhesion between the chlorinated SBR surface and the polyurethane adhesive was due to the presence of oxidized species of >C=O, -C-OH and -COR type. Chlorination of SBR is a fast reaction which needs only a small concentration of chlorination agent (< 1 wt% TCI/ethyl acetate) to produce high adhesion levels. An increased amount of TCI facilitated the chlorination reaction progressing from the exterior to the internal rubber bulk; however, although a thicker layer of chlorinated rubber created no further increase in adhesion strength was obtained.     

空气等离子体处理芳纶纤维及其与天然橡胶/乳聚丁苯橡胶的黏合性能

考察了空气等离子体处理对芳纶纤维表面结构形态的影响,研究了空气等离子体和间苯二酚-甲醛-胶乳(RFL)浸胶处理芳纶纤维与天然橡胶(NR)/乳聚丁苯橡胶(ESBR)的黏合性能,并对经处理的芳纶纤维与NR/ESBR体系的界面层作了动态力学分析。结果表明,芳纶纤维经空气等离子体处理后,表面粗糙度增大,表面积增加,结晶度减小,但处理功率过大、处理时间过长时,芳纶纤维的表面又变得比较光滑、结晶度又呈增大趋势。随着等离子体处理时间的延长,芳纶纤维与NR/ESBR的黏合性能增强,但处理时间过长时,芳纶纤维与NR/ESBR的黏合性能下降;等离子体处理芳纶纤维经RFL进一步浸胶处理后,芳纶纤维与NR/ESBR的黏合性能大幅度提高。芳纶纤维与NR/ESBR的界面存在介于高模量芳纶纤维和低模量橡胶之间的过渡层。     

Improved adhesion of silicone rubber to polyurethane by induced surface reconstruction

Induced surface reconstruction of silicone rubber by blending polydimethylsiloxane (PDMS) reactants with bifunctional PDMS-hydroxyl terminated polybutadiene (PDMS-b-HTPB) copolymers and curing with appropriate mold material was attempted to improve the adhesion of chemically inert silicone rubber to polyurethane (PU). Surface characterization using Fourier transform infrared-attenuated total reflectance indicated that the surface of the silicone rubber possessed a controlled amount of HTPB. The surface was enriched with HTPB by using mold materials having high critical surface tension, such as aluminum. A dynamic surface rearrangement occurred during a 1-h heating cycle at 70°C, changing from an HTPB-enriched surface to a PDMS-enriched surface. The peel strength between the silicone rubber and PU was found to increase with decreased propanol residue and with an increase in critical surface tension of the molding materials. The increased content of surface HTPB was suggested to account for the improved adhesion of silicone rubber to PU. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1669–1675, 1998     

Kinetics of nonisothermal thermal degradation of styrene-butadiene rubber

The kinetics of thermal degradation of styrene-butadiene rubber (SBR) was studied by conventional thermo-gravimetric technique with various heating rates under nitrogen. A kinetic model which accounts for the effects of scission of polymeric chain at any time was proposed to describe the thermal degradation of SBR. Results showed that the contribution of the thermal degradation of zero-order reaction is greater than that of first-order and second-order reactions. The activation energy of the thermal degradation of SBR was calculated to be 172 kJ/mol using the Arrhenius equation.     

Crosslinking of styrene-butadiene rubber with polyurethanes bicapped with benzyocyclobutene

Summary A polyurethane prepared from 1,9-nonanediol and toluene-2,4-diisocyanate with M_n=11,840, was capped on both ends in a reaction with 4-(benzocyclobutenyl) methanol. The polyurethane was used to crosslink styrene-butadiene rubber through Diels-Alder reactions on the benzocyclobutene functionality. The synthesis and characterization of 4-(benzocyclobutenyl) methanol, a molecule not reported previously, is presented. The crosslinking reaction was carried out on intimate mixtures of the telechelic polyurethane and SBR at elevated temperature and pressure. Various physical properties of the crosslinked material were studied.Work done at the Department of Chemistry, University of Akron, Akron, OH 44325, USA     

MEK wiping prior to chlorination to improve the adhesion of vulcanized SBR rubber containing paraffin wax

In this study, it was shown that the degree of effectiveness produced by halogenation with trichloroisocyanuric acid (TCI) was influenced by previous methyl ethyl ketone (MEK) wiping of a synthetic vulcanized styrene-butadiene rubber (R2) surface. The MEK wiping of the R2 rubber surface prior to chlorination with TCI removed the paraffin wax layer from the surface, which favoured the chlorination and oxidation reactions of the rubber. Chlorination with TCI decreased the contact angle values (increased the wettability) mainly due to the creation of C–Cl and C=O moieties, as well as roughness. The amount of these chemical moieties increased when the MEK wiping was applied prior to chlorination, so higher degrees of chlorination and oxidation were obtained on the R2 rubber surface. T-peel strength values increased more markedly if the MEK wiping was carried out before chlorination with TCI, in agreement with the higher degree of modifications produced in the R2 rubber surface. In fact, a cohesive failure in the R2 rubber was obtained in the adhesive joint produced with MEK wiped + TCI chlorinated R2 rubber.     

A new organofunctional methoxysilane bilayer system for promoting adhesion of epoxidized rubber to zinc: Part 1: Optimization of practical adhesion

Practical adhesion of rubber to zinc cords is measured for various zinc silanization treatments. Aminopropyltrimethoxysilane (APS) alone or both APS and mercaptopropyltrimethoxysilane (γ-MPS) were used as coupling agents for zinc and epoxidized natural rubber (ENR). It is shown that special chemical and physical conditions are required to provide strong practical adhesion. With APS alone, best results are obtained when the zinc is silanized with 1% APS in isopropanol–water, cured at 110 °C for 1 h in air and vulcanized with ENR (20% epoxy groups) at 170 °C for 15 min. The adherence is further improved by double silanization with γ-MPS (0.5%) and then APS (1%). In both cases, the concentration of silanes, the cure temperature of the silane layers, the ageing and acidity of the silane solutions are the main parameters which must be thoroughly optimized. In the case of double silanization, the highest practical adhesion seems to be correlated with a true γ-MPS/APS bilayer structure which is achieved for a specific application of the γ-MPS. It is suggested that this layer is bound to zinc through its thiol function, and the APS layer (on the γ-MPS layer) is cross-linked to γ-MPS and ENR through silanol and epoxy groups, respectively. When the silanized zinc surface was vulcanized and the rubber then peeled off the zinc surface, XPS analysis of the bare zinc areas indicates a rupture characteristic of an adhesive failure in the case of silanization by APS alone, and a cohesive failure in the case of the double silanization.     

Effect of bonding systems on the adhesion of butyl rubber to polyester fabric

An adhesion promoter system composed of hexamethylene tetramine, resorcinol, and hydrated silica was compounded with butyl rubber mix. This mix was spread over untreated polyester fabric. The resorcinol was also replaced by o-aminophenol, m-aminophenol, or m-phenylene diamine. The rubber-fabric materials were subjected to aging or exposed to ionizing radiation. The peel strength, permeability, dielectric constant, and electrical resistivity were examined.     

Use of an aliphatic hydrocarbon to improve adhesion in butyl rubber-proofed polyester fabric

An aliphatic hydrocarbon resin (Escoraze) was used as an additive in four bonding systems. These systems were based on (i) resorcinol, (ii) o-aminophenol, (iii) m-aminophenol, and (iv) m-phenylene diamine. Escoraze caused a significant additional adhesion force between the butyl rubber and the polyester fabric. The rubber-proofed fabric was subjected to an ionizing radiation. This led to better adhesion properties of the product. The permeability, the dielectric constant, and the electrical resistivity of the rubber-proofed fabric were measured.     

生物卤化反应的新领域

介绍了卤化物在生物系统的应用，综述了目前已探明的卤化反应及一些用于卤化反应中的生物催化酶。指出生物基因技术应用于卤化反应酶的生产中，能够产生一系列更有价值的卤化衍生物。生物卤化合成具有广阔的应用前景。     

环保型丁苯橡胶与传统丁苯橡胶性能对比

对比考察了环保型丁苯橡胶与传统丁苯橡胶的相对分子质量及其分布、微观结构、混炼胶的硫化特性、硫化胶的物理机械性能及加工性能,结果表明,环保型丁苯橡胶SBR 1500 E与SBR 1500、环保型丁苯橡胶SBR 1502 E与SBR 1502及环保型丁苯橡胶SBR 1712 E与SBR 1712的相对分子质量及其分布、分子...     

Synthesis and characterization of waterborne polyurethane adhesive from MDI and HDI

A series of waterborne polyurethane adhesives (WPUAs) were prepared from diphenylmethane‐4,4′‐diisocyanate (MDI), 1,6‐hexamethylene diisocyanate (HDI), poly(1,4‐butanediol adipate) diol (PBA), 1,4‐butanediol (BDO), and internal‐emulsifying agents by the prepolymer mixing method. The viscosity, mechanical properties, thermal properties, and adhesion strength of the samples were measured. The structure–property relationship was discussed primarily. The results indicated that the MDI/HDI and PBA/BDO molar ratio influenced these properties. The WPUA exhibited excellent T‐peel strength and mechanical properties at a suitable MDI/HDI (or PBA/BDO) molar ratio. Moreover, higher MDI/HDI (or PBA/BDO) molar ratio resulted in higher thermal stability. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Ice adhesion to rubber materials

The aim of this study was to investigate the interfacial shear strength between ice and rubbers. Different rubber materials containing only a polymer and curing agent (peroxide) were tested with regard to surface wettability and interfacial shear strength. The effect of different grades and amounts of carbon black filler was also studied. The wettability was determined from contact angles, using water and diiodomethane as test liquids, measured on carefully cleaned and mirror smooth rubber sheets. The test showed that there is a correlation between ice adhesion and rubber substrate wettability. Below a water contact angle of 90°, the interfacial shear strength of ice decreases linearly with increasing contact angle. For contact angles above 90°, the interfacial shear strength of ice stays practically the same. The presence of high surface energy additives such as reinforcing carbon black (e.g. N220 ISAF) significantly increases the interfacial shear strength. The highly hydrophobic behaviour of different plant surface textures was also investigated regarding ice adhesion strength. The combination of a submicrometer textured surface and a hydrophobic surface characteristic showed an abrupt decrease in the adhesion force of a water droplet at measured macroscopic contact angles above approximately 150°. Despite this water repellency, the ice adhesion strength is not nil. However, it was among the lowest values experienced in the test.     

Adhesion of flame-treated polyolefins to styrene butadiene rubber

Samples of polyethylene and polypropylene have been submitted to repeated short duration (75 ms) flame treatments, at optimum flaming conditions. Surface energies of untreated and flamed specimens were determined by liquid contact angle measurements. It appears that the surface energy of polyethylene increases much more than that of polypropylene after flame treatment. The flamed polymer surfaces were further examined by electron spectroscopy, Fourier Transform IR spectroscopy and secondary ions mass spectrometry. The adhesion properties of modified polymer surfaces were studied by testing in peel the bonded Styrene Butadiene Rubber/polyolefins assemblies. Scanning electron microscopy (SEM) and water contact angle measurements have been used to observe the locus of failure. Good correlations were obtained between surface energy and adhesion strength, the increase in adhesion strength being particularly important for flamed PE/SBR assemblies. In addition, the peeling in a liquid medium allowed the determination of the respective contribution to adhesion of chemical and physical interactions. It is shown that a major part of the adhesion strength increase is of chemical origin, particularly for the bonded flamed PE/SBR assemblies.     

聚酯帘线与胶料粘合性能研究

研究不同预浸渍方法对聚酯帘线与胶料粘合性能的影响.结果表明,用水溶性环氧树脂和邻苯二甲酸酐或氯化亚锡作为预浸渍液,然后用RFL浸渍液处理聚酯帘线,帘线H抽出力比只用RFL浸渍液处理提高7～12 N;红外光谱分析表明,环氧树脂作为媒介与聚酯帘线表面及RFL胶层发生了化学作用;经两步浸渍处理的抽出帘线附胶量较大,粘合强度提高.     

全卤制碱新工艺

叙述２０ｋｔ／ａ全卤隔膜法制烧碱工艺;探讨３０ｋｔ／ａ全卤离子膜法制烧碱工艺的两个方案。针对全卤隔膜法烧碱工艺存在４个关键问题提出新的工艺方案并已用于工业生产     

合成橡胶卤化改性的研究进展

合成橡胶经卤化改性后,具有了许多新的优良特性,从而拓宽了它们的应用领域.当今人们已经对多种橡胶的卤化改性进行了研究,部分产品实现了工业化生产.卤化技术的发展方向是效率高、无污染、连续化、结构可控.本文介绍了国内外合成橡胶卤化改性的研究进展,提出了我国应加强合成橡胶的卤化改进研究.     

Enhancement of hydrolytic stability and adhesion of waterborne polyurethanes

A new type of polyester polyol, with alkyl side groups, viz. poly(2,4‐diethyl‐1,5‐pentamethylene adipate) glycol (PDPAd) was synthesized and used to improve the hydrolytic stability of waterborne polyurethanes (PU). The results compared favorably with poly(tetramethylene adipate) glycol (PTAd)–based PU and blends of the two types of PU in terms of particle size, thermal, XRD, mechanical, dynamic mechanical, and swell behavior of the dispersion cast films in addition to hydrolytic stability and adhesion properties. Blends of PTAd‐based PU and PDPAd‐based PU gave significantly improved green (immediate) adhesion and hydrolytic stability due to the synergistic effects of crystallinity (heat of crystallization, high density) and amorphous regions (tack, high thermal stability). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1961–1969, 2005     

Improved adhesion of silicone rubber to polyurethane by surface grafting

Polyurethane (PU) has widespread applications in implantable devices because of its excellent mechanical and biocompatible properties, whereas weak biostability limits its long‐term implantation. The introduction of silicone rubber (SR) onto the PU surface is an effective method for improving the biostability of PU, but the adhesion of these two polymers is unsatisfactory. In this study, the surface modification of PU via grafting through the introduction of vinyl and Si H groups onto the PU surface was attempted to improve the adhesion of PU to SR. Fourier transform infrared, energy‐dispersive X‐ray spectroscopy, and X‐ray photoelectron spectroscopy were employed to investigate the graft reaction on the PU surface. The interfacial and surface morphology was characterized with scanning electron microscopy. Different PU/SR interfaces after oscillation and shear were compared as well. The results indicated that the PU surface was activated by diisocyanate, which generated free isocyanate groups for the further grafting of vinyl and Si H groups. When addition‐type, room‐temperature‐vulcanized SR was poured onto the PU surface, the vinyl and Si H groups on the PU surface underwent an addition reaction, which improved the adhesion of PU and SR by connecting them with chemical bonds. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011