Synthetic Process of Bio-Based Phenol Formaldehyde Adhesive Derived from Demethylated Wheat Straw Alkali Lignin and Its Curing Behavior

Lignin is a natural biopolymer with a complex three-dimensional network, commercially obtained from wasteliquid of paper pulp and bioethanol production, and could be a candidate for preparation of environment-friendlybio-based polyphenol material. In the present work, the demethylated wheat straw alkali lignin (D-Lig), preparedby demethylation of wheat straw alkali lignin (Lig) using an in-situ generated Lewis acid, was used to synthesizebio-based phenol formaldehyde resin adhesive (D-LPF) applied in plywood. Effects of synthetic process’s factors,including lignin substitution for phenol, NaOH concentration and molar ratio of formaldehyde to phenol, on thebonding strength and free formaldehyde content of D-LPF were investigated in detail, and the optimum syntheticprocess of D-LPF was obtained as following: Lignin substitution for phenol 60%, NaOH concentration 5.0% andmolar ratio of formaldehyde to phenol 2.0, and under the optimum reaction condition, the D-LPF presented lower free formaldehyde content (0.18%) and higher bonding strength (2.19 MPa), which was better than those ofcontaining-lignin phenol formaldehyde resin adhesive (LPF). Additionally, the curing behavior of the adhesivewas studied by differential scanning calorimetry (DSC) combined with gel time. It can be obtained that D-LPFresin adhesive had the shortest gel time, and fastest curing rate, compared with those of PF and L-PF resin adhesives. The curing kinetics data was fitted well by Kissinger model using non-isothermal DSC method, and theaverage activation energy value was 85.3 kJ/mol, slightly higher than that of commercial PF resin, while lowerthan that of LPF (90.2 kJ/mol). Finally, based on the analytical results of high temperature fourier transform infrared spectroscopy (FTIR), a possible curing mechanism of D-LPF was proposed.

Verification of Applicability of the Polyurethane Adhesive Based on Castor Oil in the Manufacture of Glued Laminated Bamboo

The current concern with the environment promotes the development of new technologies for production with use of alternative materials, from renewable resources, and changes in production processes, having as main objective the reduction of environmental impact. One of the alternatives for cleaner production is the use of castor oil derivatives instead of non-renewable sources, such as adhesives based on PVA （polyvinyl acetate）, applied in the manufacturing process of glued laminated bamboo. Based on the versatility of the bamboo laminate and the castor oil, and from the perspective of sustainability, this study aims to contribute to the application of new materials and processes, used in the manufacturing industry, by proposing the use of the polyurethane adhesive based on castor oil for glued laminated bamboo manufacturing, which can later be used in the manufacture of several products. To verify the applicability of the polyurethane adhesive based on castor oil in the glued laminated bamboo manufacture, mechanical tests of traction and shearing of the glue sheet were performed in specimens of the said material, and the results were compared with the Cascorez 2590 and Waterbond adhesives. The results showed that the polyurethane adhesive based on castor oil, in the traction test, has superior performance than the Waterbond adhesive and slightly below than the Cascorez 2590 adhesive, but in the shear test, the polyurethane adhesive based on castor oil presented a slightly inferior performance than the other two adhesives used in the comparison.

Control on Gradient Adhesive Loading of Porous Laminate:Effects on Multiple Performance of Composites with Bamboo Bundle and Sliver

Elementary units“bamboo bundle”and“bamboo sliver”were processed and cross-linked as“bamboo-bundle veneer(BBV)”and“bamboo-sliver veneer(BSV)”for preparation of laminated composites.The concept of“high-content-adhesive surface treatment”was raised to improve boards’performance,rather than increasing adhesive absorption of every layer’s porous unit.That is,some BBVs experienced an extra“dipping&drying”to absorb more resin(named“HBBV”).The effect of the amount of knitting threads was also discussed for influencing BBV’s quality.Results indicated that light transmittance of BBVs decreased as the amount of threads added from 3 to 8,while mechanical stiffness increased.Adding two skin layers of HBBVs symmetrically was helpful to enhance 24-hour underwater and 28-hour“boil-dry-boil”dimensional stability for boards with BSVs as core,while more than two pairs of HBBVs were needed to improve 28-hour“boil-dry-boil”dimensional stability of boards with BBVs as core.Two symmetrical surface layers of BBVs/HBBVs provided BSV-boards/BBV-boards with greater bending resistance,while such“surface treatment”would not raise shearing strength of BSV-boards upon 28-hour“boil-dry-boil”treatment.Besides,the data obtained from drop-hammer impact test indicated that more than two pair of surface BBVs or HBBVs were required for significant improvement in anti-impact property.

Effect of Thermal Treatment on CFRP Parts Before and After Adhesive Bonding

Numerous non-destructive techniques are being investigated for assuring quality of the adhesive bonds.The research presented here is focused on non-destructive assessment of carbon fibre reinforced polymer(CFRP)parts.The surface condition directly influences the performance of adhesive bonds.The structural joints should ensure safe usage of a structure.However,some modifications of the surface may lead to weak bond that cannot carry the desired load.This is why there is a search for methods of surface assessment before bonding.Moreover,reliable techniques are required to allow to verify the integrity of the adhesive bond after manufacturing or bonded repair.We focus on the laser induced fluorescence(LIF)method for assessing the surface state.The LIF is a noncontact measurement method.In the context of adhesive bond assessment the electromechanical impedance(EMI)method is studied.The EMI uses surface bonded piezoelectric sensors for excitation and sensing.The investigated samples were made of CFRP layers.The samples were treated at elevated temperatures.The influence of the thermal treatment was studied using LIF.The thermal treatment at 220℃could be clearly distinguishedrom the rest of the considered samples.The thermally treated plates were bonded to untreated plate and then they were measured with the EMI method to study the influence of the treatment on the adhesive bond.The changes of EMI spectra were significant for the treatment at 280 ℃ and for some thermally treated samples that were later contaminated with de-icing fluid.

Design and Lamination Process of Composite Fabric for Automobile

The composite fabric is a new type of automobile fabric in recent years.The three-layer composite fabric was made of different materials that were linen weaving fabric,knitting fabric and warp-knitted spacer fabric.Through testing performances of three different adhesives,the thermoplastic urethanes(TPU)hot melt powder was selected to adhere every fabric.Then,the laminating process was designed and applied.The optimized process conditions were following:the temperature was 150℃,the pressure was 2.0 N·cm-2,the time was 80 s,and the dosage of adhesive was 20 g·m-2.This new laminated fabric has multi-functions,such as comfortability,permeability and physic mechanical properties.This lamination process will be used to be the basis for the study of functional laminated car seat fabric.

Influence of angiotensin blocker-Ⅰ-converting enzyme inhibitors on processes of formation of posttraumatic adhesions in murine model

The Renin-Angiotensin System(RAS)plays an important role in post-surgical adhesion formation.Angiotensin-Ⅱ is synthesized in uterus and plays an important role in intraorganic connective tissue proteins metabolism and blood vessels regeneration.The studies found that longterm introduction of ACE blockers(captopril)to rats that undergwent single talc intraperitoneal injection with the aim of stimulation of adhesion formation,promotes development of inflammation and fibrosis in the uterus and activation of the adhesion formation.Stimulation of posttraumatic adhesions in female rats treated with an ACE is accompanied by inhibition of neoangiogenesis in the injured tissues.

婴幼儿头皮医用粘胶相关性皮肤损伤防护方案的构建与应用

目的降低视频脑电图监测婴幼儿头皮医用粘胶相关性皮肤损伤。方法采用历史对照设计,将2018年1月至2019年12月入住癫痫监测单元行头皮视频脑电图监测的患儿856例纳入对照组,实施常规皮肤护理;将2021年1月至2022年12月入住癫痫监测单元行头皮视频脑电图监测的患儿851例纳入观察组,构建和实施医用粘胶相关性皮肤损伤防护方案。比较两组头皮医用粘胶相关性皮肤损伤发生率。结果观察组头皮医用粘胶相关性皮肤损伤发生率显著低于对照组(P<0.05)。结论婴幼儿头皮医用粘胶相关性皮肤损伤防护方案的应用,可有效降低婴幼儿头皮医用粘胶相关性皮肤损伤发生率。

国产飞机蒙皮底漆工艺适应性研究

为了验证国产飞机蒙皮底漆的工艺适应性,从壶装寿命、基材适用性、固化性能、底漆相容性以及面漆相容性等方面对该底漆展开了工艺研究。经过验证,国产飞机蒙皮底漆工艺性能够很好地适应现有民机材料施工要求。试验结果可以为该底漆的涂装工艺提供施工技术指导,具有重要的工程实践意义。

硅烷化、锆化、硅锆化预处理膜的性能对比

[目的]旨在为碳钢涂装开发性能优良的环保型预处理工艺。[方法]在Q235碳钢表面分别制备了硅烷化、锆化和硅锆化预处理膜,并通过中性盐雾试验、电化学测试、拉拔试验和微观形貌分析,考察了它们的性能。[结果]3种预处理工艺都有效提升了基材的耐蚀性,2 h中性盐雾试验后未处理的碳钢表面腐蚀严重,硅锆化处理的试样表面仅有不超过10%的面积被腐蚀。电化学极化曲线测量的结果显示,预处理后试样的腐蚀电位都正移了,硅锆化试样的腐蚀电流密度只是未处理试样的1/38。电化学阻抗谱测试结果表明预处理后基材的腐蚀反应阻力变大,锆化和硅锆化能令材料的表面粗糙度增大。环氧涂层在3种预处理Q235钢表面的附着力均超过10 MPa,完全符合一般涂装应用的要求。[结论]3种预处理工艺均能有效提升碳钢基体耐蚀性和涂层附着力,其中硅锆化处理的效果最好。

针织运动裤裤腰压胶工艺参数研究

为提高针织运动裤松紧带压胶裤腰性能,对其裤腰使用热压贴合熔接并优化压胶工艺参数。选用针织涤仿棉双面布,对热压温度、热压时间、机器压力以及松紧带的拉伸长度4项压胶工艺参数设置单因素试验,探究各工艺参数对剥离强度的影响。结果表明:在热压温度150~170℃、热压时间20~30s、机器压力0.5~0.6MPa、拉伸长度22.5~30.0cm(松弛长度为80.0cm)条件下,压胶裤腰剥离强度最大;4项参数对剥离强度均有显著影响;热压温度、机器压力、拉伸长度对剥离强度在一定程度上具有比较显著的线性关系。

折叠式手机玻璃的现状及发展

从直板机到折叠式机,随着手机的更新换代,推动了手机玻璃的发展。为适应折叠式手机要求,手机玻璃盖板必须具有柔性、韧性,可以弯曲折叠20~25万次,相当每天500次而不破裂,为此可选用叠层复合材料。叠层复合材料是由UTG超薄玻璃和CPI聚酰亚胺类型高分子材料保护膜通过热熔胶或热压贴合工艺形成的增强材料,利用UTG的刚性和CPI的塑性组合成韧性的叠层复合材料,从而提高折叠式手机玻璃盖板的抗冲击能力,将是今后手机玻璃的发展方向。

丙烯酸酯型端羟基聚醚双固化黏合剂的合成及打印成型固化机理

以聚四氢呋喃醚二醇(PTHF)和3-甲基-3-丙烯酰氧甲基氧杂环丁烷(MMO)为原料,通过阳离子开环聚合反应机理,设计、合成了丙烯酸酯型端羟基聚醚黏合剂(MAPTHF),再与六亚甲基二异氰酸酯缩二脲固化剂(N-100)、2,4,6-三甲基苯甲酰基二苯基氧化膦(TPO)和1,4-丁二醇(BDO)组成光-热双固化黏合体系,通过光固化、热固化双步骤获得了光-热双固化弹性体。采用FTIR、NMR和GPC表征了MAPTHF的结构组成和物性参数,探究了光-热双固化黏合体系最佳的固化工艺参数和较优的物料配比,考察了光-热双固化弹性体的力学性能和热稳定性。结果表明,MAPTHF光-热双固化黏合体系可在紫外光照(5 W,395 nm)下5 s快速固化,在加热(65℃)3.0 h内实现完全固化,具有快速固化成形和短时间内完全固化特征;光-热双固化弹性体的拉伸强度为3.15 MPa,断裂伸长率为350%。该光-热双固化黏合体系用于3D打印复合推进剂,得到了较优异的打印成型效果。

可溶解热塑性聚酰亚胺薄膜的制备和性能研究

为了改善传统热塑性聚酰亚胺(TPI)的溶液加工性并提高其耐热性和粘接性,采用不同的商品化二酐单体分别与自制的主链含有吡啶和二苯醚结构及活性苯酚侧基或苯侧基的二胺单体通过两步法制备了一系列可溶解热塑性聚酰亚胺(TPI)树脂,随后制备了相应的TPI薄膜以及挠性覆铜板(FCCL)。通过溶解性试验和凝胶渗透色谱(GPC)分析TPI树脂的性能,然后测试分析了TPI薄膜的结构、吸水率、力学性能、热学性能和介电性能,并对其FCCL的相关性能进行测试。结果表明:TPI树脂均能溶解于NMP等强极性有机溶剂,相应薄膜的玻璃化转变温度(T_(g))均为236.8~325.6℃,5%热失重温度(T_(5%))为508.7~553.7℃,800℃残留率(R_(800))均高于64%,热膨胀系数(CTE)为56.36×10^(-6)~78.30×10^(-6)℃^(-1),拉伸强度为64.93~109.18 MPa,断裂伸长率为9.09%~24.60%,吸水率为0.74%~3.75%。综合性能相对较优的TPI-4的介电常数和介质损耗因数也相对较低,相应FCCL的剥离强度达到0.95 N/mm,但只能通过288℃/10 s的耐浮焊测试。此外,TPI-4中极性的苯酚侧基不仅保证了其有机溶解性,对其耐热性和机械强度也有明显的增强作用,同时还降低了其CTE值。具有反应活性的苯酚侧基为TPI的后续化学改性提供了极大的便利,通过加入少量的氰酸酯树脂(CE01)对其进行改性可以明显改善其与热固性PI薄膜或铜箔的粘接性能并提高相应FCCL的耐浮焊性。

工艺参数对轻质热防护组件胶接装配性能的影响

可重复使用运载器采用轻质热防护材料和应变隔离垫作为飞行器的热防护系统,轻质热防护组件通过硅橡胶胶黏剂粘接至碳纤维复合材料蒙皮表面。为提高可重复使用飞行器轻质热防护系统粘接质量,通过实验方法研究了加压压力、加压时间、表面处理方式等对轻质热防护组件与碳纤维复合材料的粘接强度的影响。结果表明:轻质热防护组件与碳纤维复合材料的粘接强度随加压压力的增大而增大,随加压时间的增长先迅速增大,当加压时间超过7 h时缓慢增大;打磨或涂处理剂表面处理方式均能提高粘接强度,同时施加两种处理方式时提高粘接强度大于52%。

微波多腔体外壳导电胶粘接覆铜板失效原因分析与解决

[目的]某微波多腔体外壳(可伐材料)镀镍/金后,在通过导电胶粘接覆铜板时出现导电胶与可伐腔体不浸润、导电胶开裂、覆铜板从可伐腔体外壳上剥离等不良现象。[方法]通过建立故障树,结合能谱分析、水滴试验和剪切力测试,对上述问题的主要影响因素逐一进行分析。[结果]导电胶粘接失效的主要原因是镀金后浸泡金保护剂工艺参数不当,以及转运过程中所用包装盒上的微量硅油沾污了外壳表面。[结论]在导电胶粘接前对微波多腔体外壳进行化学清洗,以及禁用含硅油的包装盒后,未再出现粘接失效现象。

体能训练器械用胶粘剂的改性与性能研究

采用乳化分散工艺和超声分散工艺对体能训练器械用石墨烯/环氧树脂胶粘剂进行预分散处理,研究了氧化石墨烯对环氧树脂胶粘剂的改性作用,并分析了其含量对各项性能的影响。结果表明,改性胶粘剂的储能模量会随着氧化石墨烯含量增加而逐渐增大,当氧化石墨烯含量为2.0%时取得储能模量最大值。随着氧化石墨烯含量的增加,氧化石墨烯改性胶粘剂的冲击强度和硬度整体呈现先增后减;氧化石墨烯含量对胶粘剂抗拉强度的影响规律与对胶粘剂硬度的影响规律相同,即氧化石墨烯含量为1.8%时具有较高的抗拉强度和硬度。对于体能训练器械用胶粘剂而言,适宜的氧化石墨烯添加量为1.8%。

热压工艺参数对TA2/CF/PEEK层板弯曲性能的影响

以TA2箔、碳纤维和PEEK材料体系为基础,探索钛箔-碳纤维布-PEEK薄片直接复合的热压法制备工艺。在对初始材料进行超声清洗除油、砂纸打磨等预处理后,手工铺层并放入自行设计的热压模具,基于不同温度(370和390℃)、压力(0.8、1.6和2.5 MPa)与保压时间(20和40 min)的热压法制备了TA2/CF/PEEK层板。利用三点弯曲实验方法探究了热压工艺参数对层板弯曲性能的影响。结果表明,较佳的热压工艺为:成形温度390℃、热压压力1.6 MPa、保压时间40 min且每侧铺设两片树脂薄膜。在此工艺下制备的TA2/CF/PEEK层板弯曲强度为681.68 MPa,弯曲模量为69.5 GPa。

铝镁合金砂带磨削工艺与粘附特性实验研究

铝镁合金以其质量轻、耐腐蚀等良好材料性能,广泛应用于各个领域。针对当前铝镁合金砂轮磨削加工存在的效率低、表面质量难以保证、砂轮表面易发生粘附等问题,提出采用砂带磨削技术对铝镁合金进行加工。为研究铝镁合金砂带磨削工艺规律以及在磨削过程中容易产生的粘附特性问题,运用36、60两种目数的氧化铝陶瓷、碳化硅和锆刚玉砂带进行铝镁合金磨削实验,分析不同磨削压力和砂带转速下的铝镁合金材料去除率、磨削噪声、磨削能耗和砂带材料粘附率的变化规律。结果表明:在相同磨削参数下,3种砂带中锆刚玉砂带因磨料韧性、抗冲击性、锋利程度更优,其材料去除率最高,粘附率最低,但磨削噪声和能耗更大,故在铝镁合金砂带磨削中,如果不考虑噪声和能耗的影响,可选择锆刚玉砂带以提高磨削效率;3种砂带的磨削压力达到20 N后,砂带粘附达到稳定形成阶段,磨屑堵塞磨粒间隙,使材料去除效率降低。这一结论可为铝镁合金砂带磨削压力参数的选取提供参考;在10~30 N、1 500~3 500 r/min的工艺参数范围内,磨削压力和砂带转速对材料去除率、粘附率都有很大影响,但砂带转速对磨削噪声的影响更大,磨削压力对磨削能耗的影响更大。研究结论可为提高铝镁合金砂带磨削效率与质量,降低磨削噪声与能耗提供一定参考。

水中构筑物表面生物膜形成物理化学过程

水中构筑物表面生物膜的形成会加速构筑物的腐蚀,严重影响其使用效率和寿命;成熟后的生物膜老化脱落或受水力剪切作用进入主体水中,会造成水体二次污染,对动植物生长和人类生活造成重大影响。生物膜的形成是由单个细菌黏附到表面开始的,经过可逆黏附到不可逆黏附的过渡后,细菌分泌的胞外聚合物(extracellular polymeric substances, EPSs)会加速表面微菌落的形成,再通过细菌间的群体感应(quorum sensing,QS)使细菌启动表型和基因型变化,最终促使成熟生物膜的形成。本文综述了生物膜形成的不同阶段所涉及的物理化学过程(薄膜形成阶段、细菌黏附阶段、胞外聚合物膜阶段、群体感应调节生物膜阶段和生物膜成熟与表征),分析总结了本领域各方向的最新研究进展,归纳并阐明了水中构筑物表面生物膜形成的机理和影响因素,为生物膜防控、清除和利用等相关研究领域提供了理论依据。

新型无醛淀粉胶黏剂制备刨花板的研究

为开发刨花板用无醛胶黏剂、满足广阔的市场需求,针对传统淀粉胶黏剂存在固含量低、黏度高和耐水胶接性能差等应用问题,采用新型无醛淀粉胶黏剂(DSA)制备刨花板,探讨其热压工艺、施胶量以及DSA和异氰酸酯(pMDI)胶黏剂复合使用对制造刨花板性能的影响。结果表明,以DSA制得刨花板的性能略低于以pMDI制得刨花板的性能,但DSA与pMDI复合使用时表现出节胶增效的协同作用,而且使用DSA可替代约20%的pMDI胶黏剂,同时热压因子可降低13.3%,有助于提升E_(NF)级刨花板的生产效率。DSA胶黏剂单独使用或与pMDI联用时,能够有效发挥黏结、填充、扩链、固化的作用,有助于解决传统淀粉胶黏剂工艺性能不佳、耐水胶接性能差等关键问题,有利于推动生物质绿色胶黏剂在人造板中的规模化应用。