Rubber solution adhesives for wood-to-wood bonding

Rubber solutions were prepared and used for bonding wood pieces. The effect of the variation of chlorinated natural rubber (CNR) and phenolformaldehyde (PF) resin in the adhesive solutions on lap shear strength was determined. Natural rubber and neoprene-based adhesive solutions were compared for their lap shear strength. The storage stability of the adhesive prepared was determined. The change in lap shear strength before and after being placed in cold water, hot water, acid, and alkali was tested. The bonding character of these adhesives was compared with different commercially available solution adhesives. The room-temperature aging resistance of wood joints was also determined. In all the studies, the adhesive prepared in the laboratory was found to be superior compared to the commercial adhesives. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1185–1189, 1998     

Studies on the adhesives for rubber to rubber bonding

Novel adhesive compounds for bonding natural rubber vulcanizates and NR/BR (natural rubber/polybutadiene) blend vulcanizates were developed. It has been shown that reclaimed latex waste can replace natural rubber in the adhesive, either partially or fully. The adhesives were found to retain their bond strength even after 5 weeks of aging at 30°C.     

Effect of temperature on sulfur prevulcanization of natural rubber latex

Sulfur prevulcanization of natural rubber latex was conducted at 60, 70, 80, and 90°C for different periods. The extent of crosslinking was assessed. Tensile properties, water absorption, leaching, and stress-relaxation characteristics of the films were also evaluated. The volume fraction of rubber (Vr), which is a measure of crosslink density of the films, showed a maximum when prevulcanization was conducted at 80°C for 2 h or at 90°C for 1 h. At lower temperatures, the rate of reaction was slow. At each temperature, tensile strength and elongation at break decreased when the prevulcanization time increased, whereas the modulus increased up to a maximum crosslinking and thereafter decreased. Water absorption and leaching were more rapid in prevulcanized film than in postvulcanized film. The rate of stress relaxation slightly increased as the extent of prevulcanization increased. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1913–1920, 1997     

样品制备工艺对石材干挂胶性能测试结果的影响

探讨了石材干挂胶性能测试中样品制备工艺对钢/钢拉剪强度和冲击强度测试结果的影响。结果表明,制备钢/钢拉剪样品时用垫丝控制胶层厚度的方法,控厚更精确,测试结果重复性好;相比于硅胶模具,钢模具制2备的试样冲击强度要高出0.5~0.8 k J/m,样品制备中不同的表面找平方法对冲击强度的影响相对较小。     

Acetylene-terminated polyimide adhesives

In a research programme to develop an addition polyimide adhesive that is easily processed and exhibits good retention of strength after long term ageing, three different acetylene-terminated polyimide adhesives systems were prepared and characterized. The most promising system, a polyimidesulphone, was selected for a long term ageing study. The results indicate that this polyimidesulphone has improved strength retention over LARC-13 after ageing for extended time at high temperatures. In addition, it exhibited surprising adhesive strength for a short time at 593°C. The synthesis and characterization of these adhesives are discussed.     

Initial evaluation of novel polyamide-imides and their copolymers as adhesives

—An adhesive screening study was performed at NASA Langley Research Center on two linear aromatic polyamide-imide (PAI) homopolymers and two linear aromatic PAI copolymers. The homopolymers were made with either of two amide diamines, 3,3'- or 4,4'-diaminobenzanilide (DABA), and 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA). The two copolymers studied were prepared with a combination of 3,3'-DABP and amide diamines. These aromatic PAIs possess high thermal stability because of intermolecular hydrogen bonding and chain stiffness. Lap shear strength (LSS) tests, conducted at room temperature, 177, 204 and 232°C, were the primary criterion for evaluation of the polymers as adhesives. Included in the study were measurements of the glass transition temperature made on fractured specimens for each bonding condition and a visual determination of the type of bond failure for specimens at each test temperature. Of the four adhesive candidates investigated, the best LSS values were obtained with the PAI copolymer identified as LARC-TPI(25% 3,3'-DABA). However, the LSS values were higher for the LARC-TPI polyimide with which the adhesive strengths were compared. The combination of a high molecular weight and the increased interchain electronic interaction associated with the amide group appears to contribute to the poor flow properties observed.     

Mechanically robust,electrically and thermally conductive graphene-based epoxy adhesives

This study develops a facile approach to fabricate adhesives consists of epoxy and cost-effective graphene platelets (GnPs). Morphology, mechanical properties, electrical and thermal conductivity, and adhesive toughness of epoxy/GnP nanocomposite were investigated. Significant improvements in mechanical properties of epoxy/GnP nanocomposites were achieved at low GnP loading of merely 0.5?vol%; for example, Young’s modulus, fracture toughness (K_1C) and energy release rate (G_1C) increased by 71%, 133% and 190%, respectively compared to neat epoxy. Percolation threshold of electrical conductivity is recorded at 0.58?vol% and thermal conductivity of 2.13?W m^?1 K^?1 at 6?vol% showing 4 folds enhancements. The lap shear strength of epoxy/GnP nanocomposite adhesive improved from 10.7?MPa for neat epoxy to 13.57?MPa at 0.375?vol% GnPs. The concluded results are superior to other composites or adhesives at similar fractions of fillers such as single-walled carbon nanotubes, multi-walled carbon nanotubes or graphene oxide. The study promises that GnPs are ideal candidate to achieve multifunctional epoxy adhesives.     

Elastomer modification of epoxy based film adhesives: adhesive and mechanical properties

Three approaches were employed to improve the flow and sandwich bonding properties of a nylon-carrier supported film adhesive based on carboxyl terminated butadiene acrylonitrile (CTBN)-modified novolac epoxy resin. These included the addition of a commercial acrylate flow modifier, replacement of novolac epoxy partly with solid diglycidyl ether of bisphenol A (DGEBA) resins, and replacement of CTBN partly with an epoxy functional acrylate terpolymer (EPOBAN). Adhesive properties such as lap shear strength (LSS), T-peel strength (TPS) and flatwise tensile strength (FTS) on honeycomb core bonded sandwich specimens were evaluated using aluminium adherends. The addition of the flow modifier in low concentrations enhanced the flexibility of the system and resulted in a marginal increase in LSS, TPS and FTS. Replacing novolac epoxy partly with solid DGEBA resulted in a less brittle system with enhanced LSS and TPS, but with reduced FTS due to the decreased flow characteristics. A substantial increase in FTS was observed when CTBN was partly replaced with EPOBAN. The introduction of EPOBAN resulted in good flow and fillet properties and the optimum FTS was obtained for the composition based on 25/75 CTBN/EPOBAN ratio. Mechanical properties of selected systems were also studied in addition to adhesive properties.     

HEMA接枝改性天然胶乳的制备及其粘接性能研究

以甲基丙烯酸羟乙酯(HEMA)作为天然胶乳(NRL)的接枝改性剂,采用乳液聚合法制备了NR-g-HEMA[HEMA接枝NR(天然橡胶)]胶乳;然后以此为基体,并以水溶性松香树脂为增黏树脂、邻苯二甲酸二丁酯(DBP)为增塑剂等,制备相应的NR-g-HEMA胶粘剂;最后,用该胶粘剂压制胶合板,并对胶合板的粘接性能进行了测定。结果表明:采用单因素试验法优选出制备NR-g-HEMA胶乳的最佳工艺条件为m(干态单体)∶m(NRL)∶m(引发剂)∶m(活化剂)∶m(交联剂)=20∶100∶0.2∶0.2∶0.1、反应时间为8 h和反应温度为16℃,此时相应胶合板的剪切强度(1.88 MPa)符合Ⅲ类胶合板的指标要求。     

Preparation and performance of urethane-modified polytriazole adhesives

Polytriazole adhesives are a new type of adhesives with excellent heat resistance, but the lap shear strength at room temperature is not ideal, which is about 15 MPa. In order to improve its adhesion performance at room temperature, a series of urethane-modified polytriazole (UPTA) adhesives were successfully synthesized via 1, 3-dipolar cycloaddition reaction between azides, and alkynes. Firstly, an alkynyl-terminated urethane monomer di(but-3-yn-1-yl) (1,3-phenylenebis(methylene)) dicarbamate (DBPMD) was synthesized and characterized. Then DBPMD was reacted with biphenyl dibenzyl azide (BPDBA) and N′,N′,N′,N′-tetrapropargyl-p,p′-diaminodiphenyl methane (TPDDM) to prepare UPTA adhesives. Curing behavior, thermal properties, bonding performance, and resistance to damp heat aging of UPTA adhesives were studied. The results show that the introduction of urethane group has almost no effect on the curing behavior. The glass transition temperature (T_g) and the 5% thermal weight loss temperature (T_d5) gradually decreased with the increased proportion of DBPMD added. T_g of UPTA adhesives ranged from 185 to 215°C and T_d5 of UPTA adhesives were all above 300°C, which indicated its outstanding thermal stability. The lap shear strength at room temperature of UPTA adhesives increased first and then decreased with the increasing amount of DBPMD, which ranged from 13.9 to 19.9 MPa. The highest lap shear strength of UPTA adhesives can reach 19.9 MPa, which was 31.8% higher than PTA adhesive. The lap shear strength retention rate of UPTA adhesives at 180°C was all over 75%. Lap shear strength retention rate of UPTA adhesives under 168 h damp heat aging time was all over 80%. UPTA adhesives have good bonding performance, heat resistance, and damp heat aging resistance, which can meet many complex construction requirements.     

影响水性聚氨酯复膜胶粘接性能因素的研究

探讨了影响水性聚氨酯复膜胶粘接性能的各种因素,并对它们的影响规律做了初步研究。发现低聚物多元醇、异氰酸酯和固化剂的种类及用量,以及胶本身的表面张力和固含量是影响粘接性能的主要因素。     

Effect of molecular weight of epoxidized natural rubber on shear strength of adhesives

The dependence of shear strength of epoxidized natural rubber (ENR)‐based adhesives on molecular weight of the rubber is studied using coumarone–indene resin, gum rosin, and petro resin as tackifiers. The adhesive was coated on polyethylene terephthalate (PET) film substrate using a SHEEN hand coater at various coating thickness. The shear strength of adhesives was determined by a Texture Analyzer. Results show a maximum at 6.63 × 10⁴ and 4.14 × 10⁴ for ENR 25 and ENR 50, respectively, after which the shear strength decreases with further increases in molecular weight for all the coating thickness. This observation is attributed to varying degree of cohesiveness which culminates at the respective optimum molecular weight of ENR. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Evaluation of adhesives for bonding printed wiring boards

The design considerations relating to the selection of adhesives for bonding printed wiring boards to heat sinks are discussed. On the basis of these considerations several film adhesives that do not require conventional high temperature and pressure laminating processes were evaluated. The performance properties investigated include adhesion, dielectric strength, solvent resistance and thermal conductivity.     

Soy proteins as plywood adhesives: formulation and characterization

Soybean proteins have great potential as bio-based adhesives. The objectives of our study were to develop and characterize formaldehyde-free soybean wood adhesives with improved water resistance. Second-order response surface regression models were used to determine the effects of soy protein isolate concentration, sodium chloride, and pH on adhesive performance. All three variables affected both dry and wet strengths of bonded wood specimens. The optimum operation zone for preparing adhesives with improved water resistance is at a protein concentration of 28% and pH 5.5. Sodium chloride had negative effects on adhesive performance. Soy adhesives modified with 0.5% sodium chloride had dry strength, wet strength, and boiling strength of bonded specimens comparable to nonmodified soy adhesives. Rheological study indicated that soy adhesives exhibited shear thinning behavior. Adhesives modified with sodium chloride showed significantly lower viscosity and yield stress. Sodium chloride-modified soy adhesives formed small aggregates and had low storage moduli, suggesting reduced protein–protein interactions. These formaldehyde-free soy adhesives showed strong potential as alternatives to commercial formaldehyde-based wood adhesives.     

氧化淀粉基水性胶粘剂的研究

以过硫酸钾-亚硫酸氢钠(KPS-NaHSO3)为引发剂,在木薯氧化淀粉上接枝苯乙烯(St)和丙烯酸丁酯(BA),并引入功能单体丙烯酸(AA),采用无皂聚合法合成了氧化淀粉基水性胶粘剂。考察了引发剂用量、单体与氧化淀粉配比、单体配比、功能单体用量、聚乙烯醇(PVA)用量和反应温度对胶粘剂性能的影响,并对接枝共聚物进行了红外光谱(FT-IR)表征。实验结果表明,当w(引发剂)=1.8%、m(单体)∶m(氧化淀粉)=3.0∶1、m(St)∶m(BA)=1.75∶1、w(AA)=2.0%和w(PVA)=3%～4%时,所制备的胶粘剂的综合性能最佳,其剥离强度为23.15 N/mm、拉伸强度为0.92 MPa。     

Dipping characteristics of layered silicates–natural rubber latex nanocomposites

The dipping characteristics of prevulcanized natural rubber latex containing three different types of silicates (fluorohectorite, bentonite, and English Indian clay) were studied using a semiautomatic dipping machine. The effect of variation in the speed of immersion and withdrawal of the glass former, dwell time, and concentration of the coagulant, etc. on the thickness of the latex deposit were investigated. Characterization of the composites was done using X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The viscosities of these compounds were measured using a Brookfield viscometer. The results of the studies showed that the deposit thickness depends on the withdrawal speed of the glass former, the concentration of the coagulant, dwell time, and the viscosity of the latex compound. Higher film thickness was noticed for the bentonite clay‐filled composites. This was believed to be due to the formation of clay network formation in the composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Peel and shear strength of pressure‐sensitive adhesives prepared from epoxidized natural rubber

Peel and shear strength of two grades of epoxidized natural rubber (ENR 25 and ENR 50)‐based pressure‐sensitive adhesive was studied. Coumarone‐indene resin was used as the tackifier, whereas toluene was chosen as the solvent throughout the experiment. The tackifier loading was varied from 0 to 80 parts per hundred parts of rubber (phr). A SHEEN hand coater was used to coat the adhesive on substrate to give a coating thickness of 30, 60, 90, and 120 μm. Peel strength and shear strength of the adhesive were determined by using a Lloyd adhesion tester and Texture analyzer, respectively. Results show that maximum peel strength occurs at 40 phr of coumarone‐indene resin for both ENRs studied an observation, which is attributed to the maximum wettability of the substrate. However, the shear strength shows a gradual decrease with increasing tackifier loading because of the decrease in cohesive strength of adhesive. ENR 25 consistently indicates higher peel strength and shear strength than ENR 50. Generally, peel and shear strength increases with coating thickness. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007.     

One-year bonding performance of one-bottle etch-and-rinse adhesives to dentin at different moisture conditions

Abstract

This study aimed to investigate the one-year bond strengths to dentin of one-bottle etch-and-rinse adhesive systems applied under different moisture conditions. Class V cavities were prepared in bovine incisors and randomly allocated (n?=?8) according to the type of adhesive system used – SB (Adper? Single Bond 2); PB (Prime & Bond 2.1); and XPB (XP Bond) – and the moisture condition kept in the cavity – moist, over-wet, and over-dry. Filtek? Z250 was used for teeth restoration. Specimens for microtensile bond strength (µTBS) test were obtained and stored in water for 24?h or 1?year, and submitted to mechanical testing. Data were analyzed using t-tests, ANOVA and the Holm–Sidak post hoc test (α?=?0.05). Weibull analysis was used to verify the reliability of specimens. The type of adhesive and the moisture condition of the substrate affected the µTBS. At 24?h, SB performed better under the moist and over-wet conditions. At 1?year, SB, PB, and XPB showed the greatest percentage reduction at the moist (～38%), over-wet (100%), and over-dry (100%) conditions, respectively. The reliability of adhesives was affected by the variable factors tested. In conclusion, the solvent composition of adhesives and the moisture condition of the substrate play an important role in the bond strength and bonding stability of resin-based restorations, as well as on the reliability of the adhesive interfaces over time.     

橡胶金属粘合剂耐热性能研究

本文研究了不同种类的粘合剂在100℃至150℃温度下,预固化5分钟至15分钟对于天然橡胶金属复合件的粘合强度的影响。结果表明：预涂在金属表面的粘合剂经过适当的预固化处理后,对于成品取得高强度粘接性能是有帮助的。最佳的预固化温度不宜高于120摄氏度,时间不超过10分钟。