非石油基食品包装生物降解塑料的 研制方法及关键技术

利用天然高分子(淀粉、纤维素、甲壳素等)制作的非石油基生物降解塑料具有显著的资源和环境优势,已被广泛应用于食品包装领域.现代高分子设计方法使科研人员摆脱了开发新聚合物时所需的大量实验工作,寻找到了一条合成改性的新捷径,从而加快了获得新聚合物的速度.天然高分子材料的改性技术、绿色合成技术和低成本技术是进一步发展非石油基食品包装生物降解塑料的三大关键技术.     

木塑复合刨花板制造技术及其应用

从环境安全型人造板产品的市场需求及废弃塑料膜资源化利用的角度,阐述了木塑复合刨花板制造技术开发的必要性和意义;介绍了木塑复合刨花板的基本制造工艺流程、胶合特点及技术关键。木塑复合刨花板耐水性好、力学性能好,且不使用含醛胶黏剂,可用于制造环境安全性好且防水性要求高的家具、橱柜、地板和复合门等,具有非常好的应用前景。     

生物可降解脂肪芳香共聚酯增韧改性聚乳酸

以自主研发合成的生物可降解脂肪芳香共聚酯——聚(丁二酸丁二醇-对苯二甲酸丁二醇)酯(PBST)(以1,4-丁二酸、1,4-丁二醇和对苯二甲酸为单体原料)为增韧改性剂,对脆性的聚乳酸(PLA)进行共混增韧改性,研究了PBST加入量对PLA/PBST共混物力学性能的影响,并结合DSC曲线研究了PLA/PBST共混物的结晶度和结晶能力的变化,从微观形态阐述了PBST对PLA的宏观增韧改性机理。实验结果表明,当m(PLA)∶m(PBTS)=60∶40~40∶60时,PLA/PBST共混物具有较高的力学强度(拉伸屈服应力最大可达31.6 MPa)、较大的断裂伸长率(与纯PLA相比,增大了近50倍)和较高的缺口冲击强度(最大可达8.16 kJ/m2),是一类力学综合性能优异的生物可降解塑料。     

Stiffness and Strength Evaluations of a Shear Connection System for FRP Bridge Decks to Steel Girders

This paper reports on research investigating a nongrouted sleeve-type connection used to attach fiber-reinforced polymer (FRP) decks to steel girders. The connection system was investigated for stiffness, strength, fatigue resistance, and degree of composite action. Static and fatigue tests were conducted first at the component level on push-out specimens to obtain P-Δ (load-displacement) and S-N (stress range–fatigue life) relationships, from which design formulas were developed. Then tests were conducted at the system level on a 1∶3 scaled-bridge model by using this sleeve-type connection, and the results showed this shear connection can satisfy requirements from AASHTO specifications for fatigue, strength, and function. Further, three-point bending tests were conducted on a T-section model cut from the scaled bridge, and approximately 25% composite action was achieved for two different connection spacings. The structural efficiency of this shear connection is shown, and this connection design is applied in practice.     

Numerical Optimization of a Compact and Reusable Pretensioning Anchorage System for CFRP Tendons

Efficient use of pultruded carbon fiber–reinforced plastic profiles (CFRP tendons) to prestress high-performance concrete (HPC) highly depends on the performance of the anchorage system and on material choice. For current applications, a prestressing degree of approximately 40% of the CFRP material strength is utilized in pretensioned concrete elements. A higher prestress implicates lower costs of fully prestressed concrete elements. The present project aimed to optimize the design of a removable and reusable pretensioning anchorage system for sand-coated CFRP rods. The optimized design was achieved by means of finite-element calculations in which parametric studies were complemented with extensive experimental work for validation. Analytical results demonstrated a reduction up to 25% for the relevant stress peaks in the tendons. The static rupture load under laboratory conditions increased by 25%, and the pretensioning level on-site could be increased by 50%. This improvement in production efficiency can be explained by easier applicability of the new system, i.e., failure tolerant assembly and prestressing process.     

废塑料与煤粉升温过程中的燃烧特性

试验研究废塑料燃烧特性。在空气和氧气的不同条件下,研究了不同品种废塑料颗粒和对比煤粉的燃烧特性。结果表明：在氧气条件下,不同品种废塑料升温时尾气中CO含量明显升高的温度都比在空气中的低30℃,CO2含量比在空气中的显著升高;在空气或氧气同一条件下,废塑料的CO2最大含量都比煤粉大幅提高,废塑料完成燃烧的温度比煤粉的低300~500℃。     

多层塑料复合板废料改性聚丙烯的结构与性能

硅烷偶联剂KH550、KH560、KH570处理的多层塑料复合板废料(WGFRP)与增容剂并用后,通过与聚丙烯(PP)熔融共混,制备了PP/WGFRP/相容剂复合材料。采用热重分析(TGA)、扫描电子显微镜(SEM)和力学性能测定,研究了复合材料的结构与性能。结果表明,当用质量分数1%的硅烷偶联剂KH570处理的WGFRP(100 mesh)为20份,相容剂为2份时,复合材料的冲击强度比纯PP提高约113%,拉伸强度变化不大。SEM观察到PP/WGFRP/相容剂复合材料在断裂过程中发生塑性变形,其韧性较好。TGA结果表明,随着WGFRP用量的增加,复合材料的热稳定性提高。     

冻融循环下CFRP锚杆粘结性能试验

通过冻融循环、拉伸试验研究了冻融作用对碳纤维CFRP锚杆强度、弹性模量、延伸率等基本力学性能及粘结性能的影响,并利用粘结应力—滑移线性回归方法预测冻融循环后CFRP锚杆不同筋材直径、不同锚固长度下滑移值.试验及分析结果证明:CFRP锚杆在冻融循环作用下强度变化、弹性模量、延伸率等变化不大;粘结剂环氧砂浆抗压强度提高13.68％,弹性模量降低约13.8％;冻融循环作用后CFRP锚杆粘结滑移增大,粘结性能降低.     

CFRP加固受损钢管混凝土轴压柱试验研究

采用4个受损轴压钢管混凝土柱试件和4个用碳纤维复合材料(carbon fiber reinforced plastics,CFRP)加固的受损轴压钢管混凝土试件进行对比试验研究,分析两者的受力机理,评价CFRP加固受损轴压钢管混凝土承载力提高效果.结果表明:由于CFRP的环向约束,受损钢管混凝土的钢管和核心混凝土的径向变形受到了限制,受损钢管混凝土轴压承载力有不同程度提高,且其提高效果随着长细比的增加而变小;提出了加固前后受损钢管混凝土承载力计算方法,其计算结果与试验结果吻合良好.     

Preparation and Properties of Asphalt Modified with a Composite Composed of Waste Package Poly（vinyl chloride） and Organic Montmorillonite

A composite composed of waste package poly（vinyl chloride）（WPVC） and organic montmorillonite（OMMT） was prepared by coextrusion, which is used for modifying asphalt. The micromorphology of the WPVC/OMMT composite and its effect on the macroscopic properties of asphalt were studied using a fluorescent microscope and an X-ray diffractometer（XRD）. The introduction of OMMT allows the WPVC to be good dispersed in the asphalt matrix, as demonstrated by differential scanning calorimetry（DSC） and Fourier transform infrared spectroscopy（FTIR） analysis. The results indicate that asphalt modified by WPVC/OMMT composites with low OMMT content results in better high-temperature storage stability and physical properties of modified asphalt.