抑制PVC制品中小分子增塑剂迁移的研究

采用气-固相氯化法和氯化原位接枝法对小分子增塑剂邻苯二甲酸二辛酯(DOP)进行了改性,得到的产物分别与PVC共混,并对其失重率、沸点、力学性能进行了研究。结果表明:氯含量为30%左右的氯化DOP,从PVC制品表面迁移出来的几率最小;DOP氯化原位接枝丙烯酸丁酯(BA)后作为PVC的增塑剂,当BA含量在1～10份时材料的失重较少,而BA含量在10份时材料的强度及韧性最好。     

CPE的接枝共聚及对PVC的增韧改性

采用氯化原位接枝法制备氯化聚乙烯接枝甲基丙烯酸甲酯（CPE-g-MMA）,并对其红外谱图进行了分析。与CPE相比,CPE-g-MMA具有良好的力学性能。研究了CPE-g-MMA与纳米CaCO3协同增韧PVC。实验结果表明：与CPE相比,CPE-g-MMA增韧效果显著;CPE-g-MMA与纳米CaCO3对PVC有协同增韧作用。     

一种用于PVC粘接的环氧树脂胶粘剂

为解决PVC的粘接问题,采用自制对软质PVC具有良好亲合作用的改性环氧树脂增韧树脂制备的环氧树脂胶粘剂,室温固化24h或70℃固化1h可以达到软质PVC材料破坏,使用温度80～100℃。     

CPE的接枝共聚及对PVC的增韧改性

采用氯化原位接枝法制备氯化聚乙烯接枝甲基丙烯酸甲酯(CPE-g-MMA),并对其红外谱图进行了分析,研究了CPE-g-MMA与纳米CaCO3协同增韧PVC.结果表明,CPE-g-MMA在1 730 cm-1处有明显的羰基吸收峰;与CPE相比,CPE-g-MMA具有良好的力学性能;CPE-g-MMA增韧效果显著; CPE-g-MMA与纳米CaCO3对PVC有协同增韧作用.     

氯化聚乙烯与纤维黏合性影响因素的探讨

以用H抽出法测定的帘线最大抽出力及扫描电镜为主要手段,对增强剂、增塑剂、稳定剂等影响涤纶或芳纶纤维与氯化聚乙烯(CM)黏合性的因素进行了探讨,考察了两种常用纤维与CM的黏合性。结果表明,在CM中涤纶的黏合效果优于芳纶。随增强剂用量的增加,CM与纤维的黏合强度存在最大值,白炭黑有助于芳纶与CM之间黏合性的提高。增塑剂对二者黏合性的影响不明显,包括其种类和用量。稳定剂用量影响CM与纤维的黏合性,适当增加稳定剂氧化镁的用量有助于提高二者的黏合性。     

氯化原位接枝含氟丙烯酸酯对PVC性能的影响

通过氯化原位接枝法制备了PVC/含氟丙烯酸酯接枝共聚物(以下简称改性PVC树脂),考察了含氟丙烯酸酯的种类和用量对改性PVC树脂性能的影响,以及改性PVC干混料加工性能的变化。结果表明:①在考察的4种含氟单体(丙烯酸三氟乙酯、丙烯酸六氟丁酯、丙烯酸八氟戊酯、丙烯酸十二氟庚酯)中,采用丙烯酸六氟丁酯生产的改性PVC树脂综合性能最好;②当m(丙烯酸六氟丁酯)∶m(PVC)=5∶95时,改性PVC树脂的综合性能较好;③改性PVC树脂的加工性能得到改善。     

复合内衬纸用胶粘剂的特性及应用研究

研究了三种内衬纸用胶粘剂的物理特性,分析其在不同涂布量和环境水分活度条件下的胶粘效果变化,为胶粘剂的应用提供指导。研究结果表明:三种胶粘剂的水分含量、黏度、粒径均具备显著差异;随着胶粘剂涂布固形物含量的增加(0～2.0 mg/cm²),铝箔纸的粘接强度呈现先增大后减少的趋势;三种胶粘剂的粘接强度峰值为1.064 3～1.597 2 N,涂布量均出现在1.30 mg/cm²附近,但峰形宽窄和尖锐程度具备显著差异。这种变化规律将影响到胶粘剂的应用效果,可能与胶粘剂分子粒径和颗粒聚集相关。低和高环境平衡水分活度(0.113和0.809)均会提升铝箔纸的粘接强度,这可能与胶粘剂分子在不同水分活度环境下和纸基分子的分子间相互作用类别和强度变化有关,影响粘接效果。     

一种氯丁胶粘剂拉伸粘接强度降低的原因分析

研究了影响氯丁胶粘剂拉伸强度主要因素,探讨了混炼胶、溶剂、树脂等对氯丁胶粘剂拉伸粘接强度的影响。     

氯化原位接枝技术制备改性CPVC的研究

采用氯化原位接枝技术制备了改性CPVC,研究了在气固相中氯化接枝的规律,讨论了单体苯乙烯（St）和甲基丙烯酸甲酯（MMA）用量、氯含量以及氯化反应温度对产物性能的影响。结果表明,单体用量为10份左右时,改性CPVC的屈服强度高于CPVC的屈服强度;加入St改性后,氯化反应温度120℃时可得到屈服强度较高的CPVC—g—St;在135℃可得到维卡软化点较高的CPVC—g—St;单体用量适当,可同时提高改性CPVC的屈服强度和韧性。     

丙烯酸丁酯原位接枝PVC的合成与性能研究

采用溶胀聚合的方法在聚氯乙烯(PVC)颗粒内部原位接枝丙烯酸丁酯(BA),考察了反应配比m(BA)/m(PVC)对接枝反应的影响,并研究了接枝产物的相容性和形态结构.结果表明,在m(BA)/m(PVC)达到平衡溶胀度1.5时,接枝率和凝胶含量达到最大.m(BA)/m(PVC)=15/85时的产物相容性比m(BA)/m(PVC)=50/50的产物好,颗粒形态规整;共聚产物PVC-BA具有接枝交联结构.     

Surface treatment of wood polymer composites for adhesive bonding

An experimental study was undertaken to evaluate different surface treatment techniques for adhesive bonding of a Wood Polymer Composite (WPC) material. The surface treatment methods were flame, corona discharge treatment (CDT), mechanical abrasion (MA) and combination treatment of MA followed by the CDT. Surface analytical techniques used were contact angle analysis, Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Atomic Force Microscopy (AFM) and 2 dimensional profilometry. Adhesion pull-off test was used to assess the effects of surface treatments. The combination surface treatment, i.e. MA+CDT, was particularly effective in improving bonded joint strength. The adhesion pull-off strengths increased from 0.2 MPa for untreated substrate to 3.4 MPa for MA+CDT treated substrates. The carbonyl, hyroxyl and wood indices obtained from the ATR-FTIR spectra were valuable indicators for studying the nature of WPC substrates.     

A new pretreatment for the adhesive bonding of aluminium

A new pretreatment for the adhesive bonding of aluminium has been developed. Hard anodizing in sulphuric acid gave a dense, corrosion-resistant coating which was then textured by controlled dissolution in phosphoric acid. The topography and chemical properties of the surface were then suitable for adhesive bonding. The structure of the anodic film, the bond strengths obtained and the bond durability in humid atmospheres were assessed and compared with those from conventional treatments.     

Activation of wood surface by corona treatment to improve adhesive bonding

Oxidative activation of resinous wood surfaces by a corona treatment to improve adhesive bonding was studied. It was found that the wettability of the veneers, including hardwoods, softwoods, and tropical woods increased with an increase in the degree of treatment, and the gluability increased rapidly after the initial mild treatment. To elucidate the nature of any chemical change occurring on the wood surface, the dyeing examination of the wood and its components with Schiff's reagent was made, and the results showed a higher dyeing ability for corona-treated samples compared to untreated ones, indicating that aldehyde groups increased by the corona treatment. The treatment affected the alcohol-benzene extractives, and oxidized them to produce aldehyde groups. Especially, the neutral fraction in the extractives was significantly affected. On the other hand, negligible chemical effects of the treatment on the surface modification of the wood's main components were seen. Both the untreated and corona-treated samples adsorbed basic dye to the same extent of coloration. Thus, no measurable carboxyl groups increased on the surface of the samples. It seems that an increase in the wettability of corona-treated wood veneers resulted mainly from the oxidation of the high hydrophobic surface layer of neutral fraction substances in the extractives, and from the reduction in their hydrophobicity. © 1993 John Wiley & Sons, Inc.     

PVC wood: A new look in construction

As a result of the increasing environmental concern for forest protection, there is a rapidly growing demand for alternatives to wood products. PVC wood, which includes PVC foam and PVC/wood flour composite, shows improved performance over wood in the following properties: termite resistance, weathering aging, less moisture absorption, and ease of installation. It can be nailed, screwed, sawed, cut, and glued like wood by conventional tools without any special skills required. Although the bending strength of PVC wood is lower, it can be used for decorative applications, i.e., cornice, door, and siding.     

A new formaldehyde-free wood adhesive from renewable materials

A formaldehyde-free adhesive that consists of soy flour (SF) and a new curing agent (CA) was developed and evaluated for making interior plywood. Three types of plywood panels (seven-ply maple/white fir/pine/white fir/pine/white fir/maple, five-ply yellow poplar, and five-ply aspen) were prepared with the SF–CA adhesives and evaluated for their water resistance. The CA was derived from the reaction of epichlorohydrin (ECH) and ammonium hydroxide in water. Effects of the reaction time, reaction temperature, NaOH usage, heat treatment of CA, addition order of reactants in the preparation of the CA, and storage time of the CA on the water resistance of plywood panels bonded with SF–CA adhesives were investigated. The reaction time required for the completion of the reaction significantly decreased as reaction temperatures increased. The addition of NaOH to the SF–CA adhesive improved the water resistance and dry shear strength of the five-ply aspen panels. All plywood panels met the requirements for interior plywood when the CAs were prepared at 45–60 °C no matter whether the CA was heat-treated or not. Mixing ECH and ammonium hydroxide all at once resulted in better water resistance of the resulting plywood panels than adding either of ECH or ammonium hydroxide to the other dropwise. The viscosity of heat-treated CA was comparable to that of untreated CA when the CA was prepared at 50 °C. Both heat-treated and untreated CAs could be stored at room temperature for at least two months without compromising the water resistance of the resulting plywood panels.     

Influence of wood extractives on two-component polyurethane adhesive for structural hardwood bonding

ABSTRACT

When bonding wood for structural applications, the wood–adhesive bond is influenced by a variety of factors. Besides the physical and mechanical properties of wood species, their chemical composition, e.g. wood extractives, can play a role in bonding wooden surfaces. A two-component polyurethane system (2C PUR) was chosen to better adapt to the current adhesion problem. The influence of extractives on crosslinking was determined by Attenuated Total Reflection-Fourier Transform Infrared Spectrometer (ATR-FTIR) and on the rheological behavior in terms of gel point and storage modulus. Therefore, 2C PUR was mixed with 10% of eight common wood extractives separately. Furthermore, the mechanical properties of beech wood (Fagus sylvatica L.) bonded with extractive enriched adhesive were tested by means of tensile shear strength tests and evaluation of wood failure. These results of ATR-FTIR clearly show that the majority of crosslinking was terminated after 12 hr. Acetic acid and linoleic acid expedited the isocyanate conversion during the first 2.5 hr. The curing in terms of gel point and storage modulus of 2C PUR was accelerated by starch, gallic acid, linoleic acid, and acetic acid. Heptanal, pentanal, 3-carene, and limonene decelerated the curing. All extractives lowered the storage modulus determined after 12 hr. The bonding of beech wood with extractive–adhesive blends showed a slight decrease of the mechanical properties, with the exception of a marginal increase in the case of linoleic acid and pentanal.

In summary, it can be said that 2C PUR is sensitive to the influence of wood extractives and can therefore be partly held responsible for adhesion problems occurring when extractives in surface-wide and higher contents are available.     

Primers for adhesive bonding to polyolefins

When polypropylene (PP) and low density polyethylene (LDPE) are coated with about 100 nm of triphenylphosphine (TPP) or cobalt acetylacetonate (CaAcac₂) primers, adhesive bonds can be made using ethyl cyanoacrylate (CA) adhesive. These bonds are sufficiently strong so that the bond strength exceeds the bulk shear strength of the polyolefin, and are sufficiently durable as to withstand immersion in boiling water for long periods of time. The dependence of adhesive bond performance on primer thickness, application solvent, aging of primed surface, and the durability of bond, are explained on the basis of a model where the primer dissolves in the polymer surface and facilitates interpenetration of the polyolefin and the monomeric CA. The primer catalyzes cure of the CA, resulting in entanglement of adhesive and adherend chains. This model is tested using infrared (IR) spectroscopic, x-ray spectroscopic (XPS), and microscopic (SEM) analysis. © 1993 John Wiley & Sons, Inc.     

金属与橡胶粘接用双组份胶液的研制

研制了一种酚醛-丁腈橡胶型双组份胶液,主要应用于橡胶与金属之间、橡胶与橡胶之间及橡胶与其他非金属材料之间的胶接。该胶既可以冷粘、又可以热硫化粘接;且粘接强度较高、耐介质、耐老化等综合性能优良。     

Development of a chitosan‐based adhesive. Application to wood bonding

The potential of chitosan (CS) as wood adhesive was investigated in this study. The measurement of the bond strength of different CS‐based formulations was carried out using double‐lap shear tests. The best formulation tested was an adhesive composed of 6% of CS, 1% of glycerol, and 5 mmol/L of trisodium citrate dehydrate. Best bond strength from this formulation was found to be equal to 6.0 MPa in dried conditions and 1.6 MPa in wet conditions (specimens immersed for 3 h at 30°C in water). The failure in the double‐lap joint tests mainly occurred in wood. Finally, the penetration of the rhodamine‐labeled CS at 4% in the pinewood matrix was also studied using microtome and microscopy techniques to show interactions between CS‐based adhesive and wood. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013