可生物降解的半芳香聚酯聚碳酸丙烯酯共聚物/聚己二酸-对苯二甲酸丁二酯共混物的制备及性能表征

采用转矩流变仪对半芳香聚酯聚碳酸丙烯酯共聚物(poly(propylene carbonate-co-phthalate,PPC-P)和聚己二酸-对苯二甲酸丁二酯(poly(butylene adipate-co-terephthalate,PBAT)进行熔融共混,制备了不同比例的PPC-P/PBAT共混物.研究了不同共混温度和PBAT含量对共混物的力学性能、流变特性、热性能、微观形貌和阻隔性能的影响.结果表明,PPC-P/PBAT共混物的性能受共混温度和共混物组分的影响.在PPC-P和PBAT熔体黏度相当的温度下进行共混时得到的共混物性能最佳,扫描电子显微镜(SEM)图像显示在该温度下制备的共混物中2种聚合物能均匀分散且相容性较好;PBAT的加入能够大幅提升材料的热稳定性、断裂伸长率等性能,但同时也会降低材料对水、氧的阻隔性能.综合考虑,PBAT含量为30%~50%的PPC-P/PBAT共混材料是性能优异的食品/药品包装材料,具有优异的拉伸和阻隔性能.

Development of an orally bioavailable selective inhibitor of the menin-MLL

The protein–protein interaction between menin and mixed lineage leukemia(MLL)plays an important role in the development of human hepatocellular carcinogenesis(HCC)and is associated with poor prognosis of HCC patients.1,2 Hence,interrupting the menin-MLL interaction is an attractive strategy in cancer treatment,particularly for liver cancer.3,4 In this study,we identified complex C1 as the first rhodium(III)-based orally bioavailable selective inhibitor of the menin-MLL interaction for HCC.

Architecting Branch Structure in Terpolymer of CO_(2),Propylene Oxide and Phthalic Anhydride:An Enhancement in Thermal and Mechanical Performances

Poly(propylene carbonate phthalate)(PPC-P)is a chemically modified poly(propylene carbonate)(PPC)biodegradable thermoplastic by introducing phthalic anhydride(PA)as the third monomer into the copolymerization of propylene oxide(PO)and CO_(2).To enhance the thermal and mechanical properties of PPC-P,a branching agent pyromellitic anhydride(PMDA)was introduced into the terpolymerization of PO,PA and CO_(2).The resulting copolymers with branched structure,named branched PPC-P,can be obtained using metal-free Lewis pair consisting of triethyl borane(TEB)and bis(triphenylphosphine)iminium chloride(PPNCl)as catalyst.The products obtained were analyzed by NMR spectroscopy and their thermal,mechanical properties and melt processability were evaluated by DSC,TGA,tensile test and melt flow index(MFI)measurement.The obtained branched PPC-P has a high molecular weight up to 156.0 kg·mol^(-1).It shows an increased glass transition temperature(Tg)higher than 50℃and an enhanced tensile strength as high as 38.9 MPa.Noteworthily,the MFI value decreases obviously,indicative of an improved melt strength arising from the branched structure and high molecular weight.What is more,the branched PPC-P exhibits reasonable biodegradability,which demonstrates the great potential as a new green thermoplastic for the family of biodegradable plastics.

不同序列结构的二氧化碳/环氧丙烷/邻苯二甲酸酐三元共聚物的可控合成及性能研究

利用非金属催化体系,分别通过一锅两步法和一锅一步法,实现了二氧化碳(CO_(2))、环氧丙烷(PO)和邻苯二甲酸酐(PA)的本体聚合.通过反应条件优化获得了3种聚酯(PE)链段摩尔组成和分子量较为相近,但分别具有嵌段、梯度和无规序列结构的聚酯-聚碳酸酯共聚物(PPC-P).通过示差扫描量热法(DSC)、热重分析(TGA)以及拉伸试验对3种不同序列结构的PPC-P进行了热性能和力学性能的比较,其中嵌段PPC-P存在2个玻璃化温度(43和54℃),而梯度、无规PPC-P只存在一个玻璃化温度(分别为51和50℃).嵌段PPC-P的5%失重温度比无规和梯度PPC-P的低10℃,说明其热分解稳定性稍差一些.3种序列结构的PPC-P抗拉性能相当,拉伸强度达到35 MPa,都属于硬而脆的材料.

Numerical analysis of the influence of a river on tunnelling-induced ground deformation in soft soil

When tunnels are constructed in coastal cities,they will inevitably undercross a river.Exploring the influence of rivers on tunnelling-induced deformation in costal soft soil is of great significance for controlling excessive settlement and protecting surrounding buildings.This paper presents a case study of twin tunnels undercrossing a river in soft soil in Hangzhou,China.The soft soil of Hangzhou refers to cohesive soil in a soft plastic or fluid plastic state with high natural water content,high compressibility,low bearing capacity,and low shear strength.Considering the influence of the river,the research region was divided into two parts,inside and outside the river-affected area,based on monitoring data of the Zizhi Tunnel.The development law of surface settlement is divided into three stages.In the first and second stages,the surface settlement within and outside the river-affected area showed a similar trend:the settlement increased and the growth rate of settlement in the second stage was smaller within the river-affected area.In the third stage,the surface settlement continued to increase within the river-affected area,while it converged outside the river-affected area.Within the river-affected area,there was an asynchronization of the sinking rate and stability of vault settlements and surface settlements.A numerical model was established by simulating different reinforcements of the tunnel.The numerical model revealed that the ground movement is influenced by the distribution and amount of the excess pore water pressure.The excess pore pressure was concentrated mostly in the range of 1.0H_(t)-3.0H_(t)(H_(t) is the tunnel height)before the tunnel face,especially within the river-affected area.Inside the river-affected area,the dissipation of excess pore water pressure needs more time,leading to slow stabilization of surface settlement.When undercrossing a river,a cofferdam is necessary to reduce excessive ground deformation by dispersing the distribution of excess pore water pressure.

Microstructure and mechanical properties of a Cr-Ni-W-Mo steel processedthermo-mechanical controlled processing

Experiments were conducted to evaluate the microstructure and tensile properties of a medium carbon Cr-Ni-W-Mo steel processedthermo-mechanical controlled processing(TMCP)with cooling at different conditions in water,oil,air or lime followedlow tempering.Compared to normal heat-treatment processing,TMCP with water-cooling after deformation enhances the yield strength and tensile strength of the steelabout 323 MPa and about 251 MPa,respectively,due to higher dislocation strengthening and grain boundary strengthening.Meanwhile,it increases the elongation by ;about 1.76%attributed to the increase in volume percentage of the retained austenite and the refined laths of tempered martensite.Slowing the cooling rate after deformation during TMCP leads to a decrease in the strength.This results the coupling effectsthe reduction in dislocation density and volume fraction of tempered martensite together with the coarseness in martensite sizes.However,cooling rate decreasing has less influences on ductility becathe improved elongation the increase in the volume fractions of both retained austenite and lower bainite together with dislocation density decreasing is compensatedthe reduced elongation coarsened grains.

Experimental study of the bearing capacity of a drainage pipe pile under vacuum consolidation

In this study,we propose a drainage pipe pile under vacuum consolidation to integrate foundation treatment and pile foundation engineering in soft soil areas.To study its bearing capacity characteristics and foundation treatment performance,single pile static load tests,vane shear tests,and water content tests were carried out for ordinary piles,perforated piles,and drainage pipe piles under conditions of static and vacuum consolidation.Based on the results,the concept of strong and weak reinforcement areas was proposed and used for bearing capacity prediction.The results showed that the drainage pipe pile did not become silted under vacuum consolidation.The single pile bearing capacity was much higher than that of an ordinary pile,and the pile side friction was exerted mainly in the middle and lower parts.Good results were achieved using the shear strength at the junction of the strong and weak reinforcement areas to estimate the ultimate bearing capacity of a single pile.This study provided important insights into the design and construction of drainage pipe piles in a soft soil foundation.

A Potential Alternative to Polystyrene: Ring-opening Terpolymerization of Different Epoxides with Phthalic Anhydride Using Metal-free Dual Catalysts

A series of semi-aromatic polyesters named as Poly(PO-CHO-PA) were facilely synthesized via ring-opening terpolymerization of biobased cyclohexane oxide(CHO)/propylene oxide(PO)/phthalic anhydride(PA) using economical U1/PPNCl as dual catalyst. The proportion of CHO-PA and PO-PA segments in polymer can be readily altered by changing the feed ratio of CHO/PO because the reactivity ratios of CHO and PO with PA calculated by Fineman-Ross method are comparable. All synthesized amorphous polyesters with various compositions show one Tg ranging from 62 ℃ to 133 ℃. Significantly, the mechanical, thermal and barrier properties of these amorphous semi-aromatic polyesters are also adjustable and investigated for the first time. The results indicate the semi-polyesters exhibit superior thermostability(T5% ranging from 306 ℃ to323 ℃) and high tensile strength(40.21-55.7 MPa) that is comparable with polystyrene(PS). Furthermore, Poly(PO-CHO-PA) films possess a promising prospect as packaging materials because of its colorless and highly transparent nature, along with low oxygen and water vapor transmission rate. All above performances may guarantee its potential alternative to commercial PS.