Preparation and characterization of polyacrylate/polymerized rosin composite emulsions by seeded semicontinuous emulsion polymerization

Polyacrylate/polymerized rosin composite emulsions were prepared by seeded semicontinuous emulsion polymerization of acrylate monomers in which polymerized rosin was dissolved. The effects of polymerized rosin content on the polymerization stability, monomer conversion, polymer structure, and adhesive properties were studied. Polyacrylate/polymerized rosin composites were characterized by gel permeation chromatograph (GPC), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogracvimetry (TG). The results showed that with an increase of polymerized rosin content from 0 to 6 wt %, gel fraction and sol molecular weight decreased obviously but monomer conversion was basically unchanged. In contrast, with a further increase of polymerized rosin content, the decreasing rates of gel fraction, and sol molecular weight were slowed down. Meanwhile, monomer conversion decreased remarkably. Moreover, interface failure changed into cohesive failure after the addition of polymerized rosin, and the peel adhesion and shear resistance of composite latex films declined with the increase of polymerized rosin content. Thermal analysis showed that polymerized rosin and polyacrylate were compatible and the composite latex films had good thermal stability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mechanical and thermal properties of coal gasification fine slag reinforced low density polyethylene composites

Coal gasification fine slag (CGFS) was processed via a grading technique. The CGFS products (CGFS‐S1, CGFS‐S2, CGFS‐S3) with different sizes were obtained. Effects of particle size and unburned carbon on tensile properties of filled low density polyethylene (LDPE) were studied within the CGFS weight fractions ranging from 10 to 50 wt %. The tensile strength was found to increase with decreasing CGFS size, and the tensile properties exhibited good performance, owing to unburned carbon. The tensile strength of the composites increased with increasing CGFS‐S3 weight fraction. The analysis of mathematical model and SEM revealed that the firm improvement of tensile strength resulted from the strong interactions between LDPE polymer chains and CGFS‐S3 particles, and good dispersion of CGFS‐S3 in resin. Thermogravimetric analysis proved obvious reinforcement in thermal‐oxidative stability by incorporation of CGFS‐S3. The degree of crystallinity of LDPE/CGFS‐S3 showed the first increased and then decreased variation tendency. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46203.     

An Epoxy Adhesive Crosslinked through Radical-Induced Cationic Frontal Polymerization

UV-initiated cationic frontal polymerization is exploited as a solvent-free, extremely fast, and low-temperature technique to obtain epoxy-based adhesives. Epoxy formulations are prepared by blending commercial resins at different weight ratios and adding photo and thermal initiators at different percentages. In addition, the influence of other critical parameters, including the joint thickness, the nature of the adherends, and the temperature, is studied. As the reaction front is thermally sustained, the boundary conditions play a key role during the curing process and heat dissipation through the adherends in particular. The thermal properties of the epoxy formulation are studied through differential scanning calorimetry analysis, and the joint strengths are investigated by carrying out single lap off-set shear tests under compression. The results demonstrate the feasibility of obtaining joints by means of the radical induced cationic frontal polymerization of the epoxy adhesives, which exhibit comparable epoxy group conversion and mechanical performances to the ones cured by traditional energy-intensive techniques.     

Thin Ag films adhesive onto flexible substrates with excellent properties for multi-application

Here, thin Ag films with excellent properties were successfully prepared on flexible substrates through surface grafting and assembling followed by simple spray-assisted deposition process. The constructed molecule brushes provide the interfacial adhesion for Ag layers onto polymer substrates. The mechanical and electrical properties of the conductive Ag coated PET could be tuned by changing the spraying passes. As the electromagnetic interference shielding material, the composite PET possesses a highest shielding efficiency of 45 dB. In addition, the Ag coated PET with the thickness of 0.1 mm would maintain the 72% electrical conductivity even been folded even at a minimum diameter of 0.2 mm. It was demonstrated that uniform and fine cracks would generate when the Ag coated PET was stretching, but Ag films still retain continuous networks to maintain the high electronic conductivity even stretching to 100%. Simple finite element modeling results prove that the stress by stretching would concentrate in corner of the crack and the deformation is mainly at stress side. The Ag layers were also produced on TPU substrates to detect the stretching, showing its potential applications for strain sensors and health monitoring systems.     

国内卷烟胶生产概况

简要回顾了国内卷烟胶的发展历程,介绍了各主要生产单位及其技术特征。     

影响胶带用聚丙烯酸酯压敏胶乳液性能的因素分析

分析了影响聚丙烯酸酯压敏胶乳液产品性能的主要因素,并通过实验分析了反应温度、种子乳液量和阻聚剂量与产品性能之间的关系。结果表明:胶带用聚丙烯酸酯压敏胶乳液的反应温度在83～88℃,种子乳液量在10%时,乳液的初粘力、剥离力、持粘力达到平衡。     

Nano-SiO_2/PU胶黏剂的制备及性能研究

文章采用硅烷偶联剂(KH550、KH560和KH570)改性纳米SiO2,并利用超声设备将其分散在聚醚二醇中,再加入TDI进行预聚反应,得到-NCO封端的预聚体。利用二乙烯三胺扩链得到A组分,加入固化剂B组分,制得醇溶型纳米SiO2/PU胶黏剂。并对改性后的胶黏剂进行了微观结构分析和性能测试。测试结果表明:经偶联剂改性后的纳米SiO2能够与聚氨酯达到很好的纳米尺度的复合,且掺杂SiO2后的聚氨酯胶黏剂剪切强度和耐水性进一步提高。     

Rheological investigation of cure kinetics and adhesive strength of polyurethane acrylate adhesive

In this work, we used rheological techniques to study both the cure characteristics and the degree of cure of polyurethane acrylate adhesive, a type of reactive adhesive used in hard disk component assembly. These results were then correlated with the tensile shear strengths of adhesives. Here, the cure characteristics of polyurethane adhesive were investigated at isothermal conditions ranging from 25 to 120°C. From the rheological results, the gelation time, the vitrification time, as well as the time required to reach the maximum degree of cure, decreased when increasing the curing temperature. The cure rates of adhesive increased with temperature in three temperature ranges, which were retardation zone, vitrification zone, and reaction‐controlled zone. The cure rates in these zones were controlled by slow diffusion, fast diffusion, and the rate of reaction, respectively. From the temperature sweep of fully‐cured adhesives, we found that the crosslinking level of adhesives increased with curing temperatures at different rates depending on the temperature zones as well. Moreover, the adhesive strength measured by tensile shear test was found to also increase correspondingly with the adhesives' T_g, indicating that the crosslinking level directly affected the adhesive strength. The strong dependence of adhesive strength with crosslinking level indicates that the crosslinking level was essential for high adhesive strength. The correlation of cure characteristics and adhesive strengths at various curing temperatures performed in this study can further provide useful information for planning appropriate curing schemes of polyurethane acrylate adhesives used in electronic and other industries. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Development of Polyaniline/Epoxy Composite as a Prospective Solder Replacement Material

In this paper we present a novel application of a conducting polymer, polyaniline, as a conductive filler for the development of isotropically conductive adhesives. We have developed isotropically conductive adhesives using protonic acid-doped polyaniline as the conducting filler in an anhydride-cured epoxy system. Fundamental material characterization like DSC, TGA and SEM of the samples was conducted to study their properties. Conductivity of these materials was measured by the four probe method while impact properties were studied by lap shear and drop tests. Samples were aged at 85°C/～100% RH for more than 500 h and the effects of aging were studied. Conductivity value of 10^?3 S/cm was obtained at 25% PANI filler concentration. These results demonstrate the potential of such systems to function as isotropically conductive adhesives.     

车用胶粘剂对车内空气质量的影响

以车用胶粘剂作为研究对象,重点探讨了其VOC(挥发性有机物)含量和气味性能对车内空气质量的影响,并提出了相应的改善措施。研究结果表明:焊装用胶的主要成分为丁基橡胶、加工油和炭黑,三者对VOC含量的影响依次为加工油>炭黑>丁基橡胶,其气味等级(3～4级)属于难闻和反感级别;涂装用胶的主要成分为糊状PVC(聚氯乙烯)树脂、DOP(邻苯二甲酸二辛酯)增塑剂和有机溶剂等,其对整车车内VOC含量影响较大,并且涂装用胶的气味等级(4级)属于反感级别;总装用胶的主要成分为异氰酸酯、聚醚多元醇等,其乙苯含量相对最高,对整车车内的VOC含量影响极大,并且总装用胶的气味等级(1级)属于无法忍受级别。