拉伸流动作用下CFs/UHMWPE/HDPE共混物的制备及性能

介绍了一种拉伸流动支配的叶片挤出机的结构及其熔融塑化过程,利用该设备制备了碳纤维(CFs)/超高分子量聚乙烯(UHMWPE)/高密度聚乙烯(HDPE)共混物,研究了CFs和UHMWPE含量对共混物微观形貌、结晶性能和力学性能的影响。SEM图像表明,拉伸流动支配的叶片挤出机对CFs和UHMWPE有很好的分散混合效果;DSC分析结果表明,低含量的CFs和UHMWPE可以协同提高共混物的结晶度;加入适量的CFs和UHMWPE可使共混物的拉伸强度明显提升,当UHMWPE含量为8%、CF含量为12%时,CFs/UHMWPE/HDPE共混物拉伸强度与HDPE纯料相比,提高了23.4%;与CFs/HDPE共混物相比,加入UHMWPE可以有效缓解共混物冲击强度的降低,当UHMWPE含量为12%时,CFs/UHMWPE/HDPE共混物的冲击强度与CFs/HDPE共混物相比,提高了29.7%。     

HDPE/E-TMB共混物熔体的流变行为研究

用自制增韧母料(ETMB)与高密度聚乙烯(HDPE)通过热机械共混制得增韧高密度聚乙烯(HDPE/ETMB)共混物,用高压毛细管流变仪对此类共混物的流变行为进行了研究。结果表明,HDPE/ETMB共混物为假塑性流体;表观粘度随剪切速率和切应力的增大而减小,并随温度的升高而降低;粘流活化能随剪切速率的增大和母料中乙丙弹性体含量的增加均呈逐渐减小的趋势。     

塑料基体中MAPE/HDPE比例对木塑复合材料力学性能的影响

以高密度聚乙烯(HDPE)和马来酸酐接枝聚乙烯(MAPE)共混物为塑料基体,以木粉为填料,用注塑成型法制备木塑复合材料,研究MAPE/HDPE质量比变化对塑料基体和木塑复合材料力学性能的影响.结果表明:MAPE/HDPE比变化对MAPE/HDPE共混形成的塑料基体强度基本没有影响,但对由该共混物所制得的木塑复合材料的强度影响显著;在相同的木粉含量下,保持配方中MAPE和HDPE的总含量不变,木塑复合材料的拉伸强度随MAPE/HDPE比率增大先迅速增加,然后趋于平缓.冲击强度随MAPE/HDPE比增大逐渐减小.     

乙烯-醋酸乙烯酯共聚物/高密度聚乙烯的性能研究

讨论了不同高密度聚乙烯(HDPE)含量的乙烯-醋酸乙烯酯共聚物(EVA)/HDPE共混物的流变性能、热性能、相容性,以及共混纤维的可纺性、力学性能。实验结果表明:随着HDPE含量的增加,共混物的流动性变差;共混物的晶区是部分相容的。当共混物中HDPE的百分含量为15%时,共混物的可纺性及共混纤维的力学性能最佳;随着拉伸倍数的增加,共混纤维断裂强度增大、断裂伸长率降低。     

HDPE/TPU共混物的制备及性能

通过熔融共混方法,制备了高密度聚乙烯/热塑性聚氨酯弹性体(HDPE/TPU)共混物。使用电子万能试验机、冲击试验机和扫描电镜研究了共混物的力学性能与冲击断面的微观形貌;采用90#无铅汽油为介质研究了共混物的耐油性。力学性能测试表明,共混配比和相容剂的加入量对HDPE/TPU共混物的力学性能影响较大,当HDPE∶TPU为90∶10,相容剂LDPE-g-MAH和填料轻质碳酸钙的加入量分别为10%和20%时,共混物的拉伸强度、断裂伸长率、冲击强度比纯聚乙烯分别提高了70%、50%和35%;扫描电镜测试表明,相容剂可以有效改善HDPE与TPU的界面作用,提高二者的相容性;耐油性实验表明,当HDPE∶TPU∶LDPE-g-MAH=90∶10∶10,轻质Ca CO3用量为20%～30%时,共混物的耐油性最佳。     

原位增容等规聚丙烯/高密度聚乙烯共混物的制备及性能研究

以自由基支化反应为基础,在等规聚丙烯/高密度聚乙烯(iPP/HDPE)共混物中加入过氧化物、自由基调节剂和多官能度丙烯酸酯类单体进行共支化反应,以经济便捷的方式原位生成了长链支化共聚物,对iPP/HDPE共混物进行高效增容。结果表明:加入少量的添加剂就能大幅度提升iPP/HDPE共混物的力学性能,如原位增容使iPP/HDPE(50/50)共混物的断裂伸长率和缺口冲击强度提升约3倍。此外,与纯iPP/HDPE共混物相比,改性样品的耐环境应力开裂时间大幅提高,iPP与HDPE的Tg靠近,且球晶尺寸变小,表明原位增容极大地改善了iPP/HDPE共混物中iPP与HDPE的相容性。     

VC／BA共混物增容PVC／HDPE共混体系的研究

采用氯乙烯—丙烯酸丁酯(VC/BA)共混物作为聚氯乙烯(PVC)/高密度聚乙烯(HDPE)共混物的增容剂,通过冲击实验、拉仲实验、动态力学分析,系统地研究了共混体系性能与其结构之间的关系。通过Brabender流变仪测定了VC/BA共混物增容PVC/HDPE共混体系的流变性能。结果表明,VC/BA共混物是PVC/HDPE共混体系的良好增容剂。在一定范围内,VC/BA共混物与HDPE对PVC有协同增韧效应。vC/BA和HDPE的加入改善了PVC的塑化和流变性能     

茂金属聚乙烯的共混改性研究

对三种茂金属聚乙烯 (mPE)做了DSC研究。将茂金属聚乙烯同传统聚烯烃 (HDPE ,PP ,LDPE)进行了共混研究 ,结果表明mPE的加入提高了LDPE的拉伸性能 ,使HDPE和PP的拉伸强度下降 ,但mPE含量在 2 0 %～2 5 %的范围内 ,拉伸强度和断裂伸长率下降很小。mPE的加入大大提高了PP和HDPE的冲击性能。对mPE/LDPE共混物吹膜进行了研究 ,测定了共混物的熔体流动速率 ,探索了吹膜的工艺条件 ,以及薄膜的拉伸性能、撕裂性能与共混组成比的关系。     

POE-g-MAH对HDPE/EVOH共混物形态与性能的影响

通过双螺杆熔融挤出制备了高密度聚乙烯/乙烯-乙烯醇共聚物/马来酸酐接枝乙烯-辛烯共聚物(HDPE/EVOH/POE-g-MAH)三元共混物。固定基体HDPE与分散相的比例为70:30,考察了EVOH与POE-g-MAH含量变化时,共混物形态与力学性能、流变特性以及结晶行为之间的关系。结果表明:因EVOH与POE-g-MAH之间的反应,POE-gMAH能有效地调控共混物的形态和性质。随POE-g-MAH含量的增加,共混物中分散相形态从颗粒状和纤维状共存向全部颗粒状过渡,分散相尺寸变小,界面黏附力增强,HDPE的韧性得以明显改善。当HDPE/EVOH/POE-g-MAH为70:20:10时,三元共混物的冲击强度最高为60 kJ/m~2,是纯HDPE的4.3倍,拉伸强度保留率为92%。     

E-TMB中弹性体含量对HDPE/E-TMB共混物性能的影响

以高密度聚乙烯(HDPE)为基体树脂,(乙烯/丙烯)共聚物和(苯乙烯/丁二烯)共聚物为增韧剂研制出5种弹性体含量不同的聚乙烯增韧母料(E-TMB),将E-TMB与HDPE热机械共混制得弹性体总含量均为6.3%的5种HDPE/E-TMB共混物,研究了E-TMB中弹性体含量对共混物力学性能和热性能的影响。结果表明,当E-TMB中弹性体含量为44%时,共混物的综合力学性能最好,悬臂梁缺口冲击强度是HDPE的5.65倍,拉伸屈服强度和弯曲弹性模量保留率分别为90.8%和73.7%;共混物的熔点和热分解温度随E-TMB中弹性体含量的增加而升高,结晶温度随E-TMB中弹性体含量的增加而降低。     

废塑料配煤炼焦实验研究

利用2kg焦炉实验,研究废塑料配煤炼焦产物的特性．研究结果表明,废塑料代替瘦煤配煤炼焦对改善焦炭强度效果明显．废塑料代替瘦煤比例为1％～5％,焦炭的反应性和反应后强度呈现劣化趋势,但当废塑料比例为3％时,焦炭的反应性和反应后强度仍优于纯煤焦化所得焦炭,焦油中的芳香环结构物质增加,焦油出现轻质化趋势,焦炉煤气的热值有明显的提高,具有显著的工业应用前景．     

The effect of plastic size on coke quality and coking pressure in the co-carbonization of coal/plastic in coke oven

In the recycling process of waste plastics using coke ovens, coals and added plastics are carbonized and changed into coke, tar, oil and coke oven gas in a coke oven chamber. In this study, the effect of added plastic size on coke quality and the effect of plastic addition on coking pressure was investigated. In the case of a plastic addition rate of 2%, the coke strength reached a minimum at the particle size of 10 mm for polyethylene (PE) and 3 mm for polystyrene (PS). The mechanism was attributed to the weak coke structure formed on the interface between plastic and coal. The result indicates that large or small plastic particles are favorable in order to add waste plastics to blended coals for coke making without affecting coke strength . Furthermore, it was also shown that a 1% addition of large size agglomerated waste plastics to blended coals did not increase coking pressure. Based on this fundamental study, and considering the ease of handling plastics, we have determined that the size of waste plastic used in a commercial-scale recycling process of waste plastics using coke ovens is about 25 mm. Nippon Steel Corporation started to operate a waste plastic recycling process using coke ovens at Nagoya and Kimitsu works in 2000 and at Yawata and Muroran works in 2002. Now the total capacity is 120,000 tons per year as of 2003 and this process is operating smoothly.     

Basic study on separate charge of coal and waste plastics in coke oven chamber

Nippon Steel Corporation started to operate a waste plastic recycling process using coke ovens at Nagoya and Kimitsu Works in 2000 and at Yawata and Muroran Works in 2002. Now the total capacity is 120,000 tons per year and the recycling process is operating smoothly. In this process, coals and added plastics are carbonized and changed into coke, tar, oil and coke oven gas in a coke oven chamber. At present, upper limit of the addition rate of waste plastics to blended coals is 1% so that the plastic addition does not affect coke strength. However, the amount of waste plastics in Japan is as much as about 10 million tons per year and there is a real need for increasing the amount of waste plastics treated by the waste plastic recycling process using coke ovens. We investigated a method of increasing the addition rate of waste plastics without affecting coke strength by charging coal and plastic separately in a coke oven chamber. In the case of the same plastic addition rate, charging the plastic in the bottom or the top part of the coke oven chamber can decrease the deterioration of coke strength compared with charging a homogeneous mixture of coal and plastic. Charging the plastic in the bottom decreases the coke strength to a greater extent than charging the plastic in the top. This is because the decomposition of the plastic charged in the bottom decreases the bulk density of the upper coal layer. The results suggest that charging the coal and waste plastics separately increases the amount of waste plastics treated in the waste plastic recycling process using coke ovens. In order to commercialize this method, further studies are necessary concerning the charging method, device and the effect of this method on the coke oven operation.     

Feedstock recycling of plastic wastes/oil mixtures in cokemaking

Two lubricating oils, a plastic waste composed mainly of polyolefins (95%) and their mixtures (1:1 w/w) were assessed for possible use as minor components of coal blends for metallurgical coke production. The addition of 2 wt% plastic waste causes a decrease in the maximum fluidity of the coal developed during thermal heating between 400 and 500 °C. At the same addition rate, the two oils are good additives for mixing with coal/plastic blends in order to partially restore the caking ability of the co-carbonizing systems. Co-carbonizations of the coking blend with the different wastes were carried out in a movable wall oven of 15 kg capacity. Although the bulk density remained unchanged, the addition of the plastic waste produced an increase in coking pressure to values that were too high for it to be considered as a safe blend. At the same time the mechanical strength of the partially gasified coke was improved as reflected by the CSR index. The oils, however, had the effect of reducing bulk density and the coking pressure generated during the process. When blended with the coal and the plastics, the oils appeared to act as good solvents of the polyolefins and also proved to be effective in decreasing coking pressure without negatively affecting coke quality.     

铁烧结矿富氢还原动力学

通过还原实验并结合热力学和动力学分析,研究了高炉富氧喷煤条件下炉缸煤气(H2-CO-N2)中H2体积分数变化时烧结矿的富氢还原行为. 结果表明,还原气体中H2含量为10%时,700, 900和1000℃下烧结矿的还原度分别比H2含量为0时提高15.3%, 11.5%和11.4%;温度越高还原速率越快,还原结束时间大幅度提前,由700℃时的180 min缩短到1000℃时的90 min;H2含量为10%时Fe2O3和FeO转变速度加快. 动力学分析表明,还原初期为界面反应控制,中后期为内扩散和界面化学反应混合控制.     

Coal blend moisture—a boon or bane in cokemaking?

A by-product coke making plant is required to supply sufficient coke of good quality and adequate gas of high calorific value for the integrated steel plant to be a going concern. The one element that influences the handling of coal and impacts the operation and efficiency of the plant is moisture. Compared to other important properties of the coal blend, moisture can be easily manipulated. The coal moisture can be increased simply by adding water through hose pipes. Also, it can be reduced to 5–6 mass percent using Coal Moisture Control (CMC) and 2–4 mass percent using Dry-cleaned & Agglomerated Pre-compaction System (DAPS). Moisture content is one among the many variables affecting the bulk density of coal blend and those controlling the coke qualities and yield. Increase in moisture reduces coal grindability, coking pressure and internal gas pressure; helps in dust suppression during charging and hence reduces jamming of ascension pipes and hydraulic main. Batteries charging coals with high moisture content are not troubled with roof carbon deposits. It was observed that when moisture content in coal blend of SAIL-Bokaro Steel Plant increased to more than 8.50%, the calorific value of coke oven gas improved. In the working moisture range of 9–11%, the increase of the yield of coke oven gas per 1% of working moisture is 5.2 m³. Studies have shown, however, that the increase in moisture content of coal beyond 8% hampers strong coke formation. Pre-carbonization preheating process generally showed an increase in the proportion of 40–80 mm coke, compared with wet charges. For SAILBokaro coke ovens, driving out 1% moisture from coal blend requires 125 Mega-calories of heat/oven. With lesser moisture, the emission of NO _x in atmosphere will also be low. On using dry to low moisture coal blend, the swelling of coke mass increases leading to difficulty in oven pushings. Hence, an optimum level of moisture content of charge coal needs to be maintained for improving coke oven productivity, coke quality and operational smoothness. The coke oven managers all around the globe maintain this optimum level according to their requirement, the operating conditions, the quality of product and by products, the oven health & age and the ease of handling.     

Plastic wastes, lube oils and carbochemical products as secondary feedstocks for blast-furnace coke production

Two plastic wastes (polyolefin-enriched and multicomponent), two lube oils (paraffinic and synthetic) and one coal-tar were assessed as individual and combined additives to coal blends for the production of blast furnace coke. The effects of adding 2 wt.% of these additives or their mixtures (50:50 w/w) on the coking capacity of coal, coking pressure and coke quality parameters were investigated. It was found that the two plastic wastes reduce fluidity, whereas the addition of oils and tar helps to partially restore the fluidity of the coal-plastic blend. From the co-carbonization of the coking blend with the different wastes in a movable wall oven of over 15 kg capacity, it was deduced that polyolefins have a detrimental effect on coking pressure. The addition of oils and tar to the coal-plastic blend has different modifying effects. Whereas paraffinic oil eliminated the high coking pressure caused by the polyolefins, polyol-ester oil had a weak reducing effect unlike coal-tar which had a strong enhancing effect. The compatibility of the oils/tar with plastics and coal and the beneficial influence of these combinations on coking pressure is discussed in relation to the miscibility of the plastic and the oily and bituminous additives, and the amount and composition of the volatile matter evolved from each additive during pyrolysis as evaluated by thermal analysis. Furthermore, it was found that coke reactivity towards CO₂ (CRI) and coke strength after reaction with CO₂ (CSR) are heavily dependent on the composition of the plastic waste, with polystyrene (PS) and polyethylene terephthalate (PET) having a clear negative effect. The porosity of the cokes obtained from blends containing plastic wastes is always higher, but the pores are smaller in size.     

废塑料配煤炼焦实验研究Ⅱ-焦炭质量分析

利用焦炭反应性装置对在2kg焦炉上实验所得的废塑料配煤炼焦焦炭进行热强度分析,结果表明:废塑料的配入量为1%～5%时,各配煤样品所得的焦炭的反应性和反应后强度均呈现下降趋势。用废塑料代替3%以内的瘦煤炼焦,所得焦炭的反应性和反应后强度指标均有所改善,但是废塑料代替其他煤种炼焦所得焦炭的热性能指标均有所降低。     

高磷铁矿含碳团块直接还原-磁选提铁

采用直接还原?磁选工艺从湖南某地高磷铁矿含碳团块中提铁,研究了还原温度、还原时间、团块碱度、还原剂焦粉用量、添加剂Na2SO4用量和废塑料替代焦粉量等因素对磁选精矿指标的影响. 结果表明,在还原温度1150℃、还原时间40 min、团块碱度0.8、碳氧摩尔比0.9的条件下,添加4% Na2SO4同时添加废塑料替代25%焦粉,可得到金属化率为88.77%的焙烧矿,磁选后可得到铁品位91.99%、金属化率92.26%及P含量0.20%的金属铁粉,铁回收率达86.74%.     

高磷铁矿含碳团块直接还原动力学

研究了基准条件(不添加Na2SO4和废塑料)、添加4% Na2SO4和添加4%Na2SO4同时废塑料替代25%焦粉直接还原高磷铁矿含碳团块的动力学. 结果表明,不同条件下还原高磷铁矿含碳团块的限制性环节均为气相扩散. 与基准条件相比,高磷铁矿含碳团块中加入4% Na2SO4后,活化能由204.92 kJ/mol降低至158.81 kJ/mol,添加4% Na2SO4同时废塑料替代25%焦粉后,活化能由204.92 kJ/mol降至172.89 kJ/mol.