热塑性塑料基/稻壳粉复合材料燃烧特性研究

应用锥形量热仪研究了稻壳粉填充常见热塑性塑料聚乙烯(PE)、聚丙烯(PP)、聚氯乙烯(PVC)复合材料在燃烧过程中的燃烧行为.结果表明:在热辐射功率50 kW/m2下,PVC/稻壳粉的点燃时间最大;PE/稻壳粉和PP/稻壳粉的热释放速率曲线出现两个放热峰,而PVC/稻壳粉热释放速率曲线出现三个放热峰,其中PE-稻壳粉放热峰峰值最大;总热释放量由大到小依次为PE/稻壳粉、PP/稻壳粉和PVC/稻壳粉;在燃烧的早期阶段,PVC/稻壳粉质量损失率较大;但燃烧后PVC/稻壳粉的残余质鼍率最大.分析比较得出PE/稻壳粉和PP/稻壳粉复合材料两者的燃烧特性相近,而PVC/稻壳粉复合材料燃烧特性明显不同于前两者.     

PP/稻壳粉复合材料的等温结晶行为研究

采用差示扫描量热法研究了聚丙烯(PP)及PP/稻壳粉复合材料的等温结晶行为,同时利用Avrami方程分析了纯PP和PP/稻壳粉复合材料的等温结晶动力学。结果表明:结晶温度对PP及PP/稻壳粉复合材料的结晶行为具有明显的影响,随着结晶温度的升高,结晶时间延长、结晶速率下降;在等温结晶过程中得到的Avrami指数在2.03~2.5之间,PP及PP/稻壳粉复合材料的晶体为二维盘状生长;稻壳粉在复合材料中起到了良好的异相成核作用,显著地提高了PP的结晶速率。     

稻壳粉/PP复合材料性能的研究

分别将未处理和经过表面处理的稻壳粉填充到聚丙烯(PP)中,制备了稻壳粉/PP填充复合材料。探讨了稻壳粉改性及其含量对该复合材料性能的影响。结果表明:当稻壳粉含量为40 phr时,稻壳粉/PP复合材料的综合性能较好;另外,相对于未经表面改性处理的稻壳粉,改性稻壳粉的PP填充复合材料的力学性能、热性能、流动性能均有不同程度的提高。     

聚氯乙烯/植物纤维木塑复合材料的性能研究

以植物纤维、聚氯乙烯(PVC)为原材料制备植物纤维/PVC木塑复合材料,研究了植物纤维种类与含量及偶联剂含量对复合材料洛氏硬度、冲击强度、弯曲强度以及拉伸强度等力学性能的影响。结果表明,20%含量稻壳粉填充PVC木塑复合材料的硬度最大,40%含量稻壳粉填充PVC木塑复合材料硬度最小,复合材料的硬度几乎不随花生壳粉含量的变化而变化,20%含量稻壳粉填充PVC木塑复合材料的拉伸强度和弯曲强度都最大。植物纤维/PVC木塑复合材料的吸水性能随着稻壳粉和花生壳粉等植物纤维含量的增加而增强,50%含量稻壳粉/PVC木塑复合材料的吸水率最大。添加偶联剂的稻壳粉填充PVC木塑复合材料的力学性能有所提高,吸水性降低,在一定程度上提高材料的耐磨性能,降低损耗。     

聚氯乙烯/植物纤维木塑复合材料的性能研究

以植物纤维、聚氯乙烯(PVC)为原材料制备植物纤维/PVC木塑复合材料,研究了植物纤维种类与含量及偶联剂含量对复合材料洛氏硬度、冲击强度、弯曲强度以及拉伸强度等力学性能的影响。结果表明,20%含量稻壳粉填充PVC木塑复合材料的硬度最大,40%含量稻壳粉填充PVC木塑复合材料硬度最小,复合材料的硬度几乎不随花生壳粉含量的变化而变化,20%含量稻壳粉填充PVC木塑复合材料的拉伸强度和弯曲强度都最大。植物纤维/PVC木塑复合材料的吸水性能随着稻壳粉和花生壳粉等植物纤维含量的增加而增强,50%含量稻壳粉/PVC木塑复合材料的吸水率最大。添加偶联剂的稻壳粉填充PVC木塑复合材料的力学性能有所提高,吸水性降低,在一定程度上提高材料的耐磨性能,降低损耗。     

PVC/稻壳粉复合材料的老化特性研究

通过甲基丙烯酸甲酯(MMA)在微波作用下改性稻壳粉,研究了聚氯乙烯(PVC)/稻壳粉复合材料在力、热化学、光、氧老化对木塑复合材料性能影响.结果表明,随着加工时间的延长,PVC/稻壳粉复合材料力学性能逐渐变劣,材料的颜色也逐渐变深.在户外紫外光作用下木塑复合材料出现失去光泽,变色、龟裂和脆化等,使聚合物的使用性能逐渐下降.通过适当加入抗热老化氧化剂及紫外线吸收剂能有效改善材料的耐热老化性能.     

不同填料及不同塑料基木塑复合材料的力学性能

以稻秸秆粉、稻壳粉、衫木粉、竹粉,PP、PE-HD、PE-LD膜为原材料,采用模压成型工艺制备不同填料及不同塑料基体的木塑复合材料,并对复合材料力学性能进行分析.结果表明:无油墨PP基复合材料的综合力学性能较好,而含油墨PE-LD基复合材料的冲击韧性较好.稻秸秆粉作为填料增强无油墨PP复合材料效果最佳,制得稻秸秆粉/PP综合力学性能较好,而稻壳粉/PP复合材料冲击韧性较好.     

超细硼酸锌对LDPE/IFR体系抑烟性能的影响

用锥形量热法研究了超细硼酸锌对膨胀型阻燃低密度聚乙烯(LDPE/IFR)体系燃烧时发烟量和气体(CO、CO2)释放量的影响。结果表明:在超细硼酸锌引入LDPE/IFR体系后,烟产生速率的峰值从0.0427m2/s降低到0.0151m2/s,总烟释放量由1340.95降低为719.6,烟产生速率峰值出现的时间推后,证明了超细硼酸锌具有显著的抑烟作用,同时对LDPE/IFR体系燃烧时产生的CO和CO2也具有显著的抑制作用。     

壳聚糖/聚磷酸铵膨胀阻燃PP的阻燃及抑烟性能

为了提高聚丙烯(PP)的阻燃和抑烟性能,将壳聚糖(CS)作为膨胀型阻燃剂的碳源、聚磷酸铵(APP)作为膨胀型阻燃剂的酸源和气源,在此基础上通过熔融共混的方法制备了PP/CS/APP复合材料。采用极限氧指数仪、锥形量热仪等仪器研究了PP/CS/APP复合材料的的抑烟性及阻燃性。研究结果表明:CS/APP添加量为30%时,复合材料的极限氧指数值最大可达28.1%;且复合材料在烟气释放总量、CO和CO_2排放上明显降低,抑烟性得到了提升;热释放速率峰值、平均热释放速率值、平均有效燃烧热值、总热释放量值降低,成炭率升高,PP/CS/APP复合材料更难点燃;火灾性能指数明显提高,阻燃性能得到了大幅度提升,火灾蔓延指数显著减小,同时火灾危险性也相应降低。     

PVC/稻壳复合材料塑化性能与动态黏弹特性研究

通过MMA在微波作用下改性稻壳粉研究了PVC/稻壳粉复合材料的塑化性能与动态黏弹特性。结果表明,加工温度为140℃时,凝胶化程度为零,物料塑化很差;85℃时,熔体凝胶化程度达85%。稻壳粉的加入大大提高了复合材料的刚性,40份稻壳粉的复合材料在60℃的储能模量仍与纯PVC常温时的模量相当;与纯PVC相比,MMA处理PVC/稻壳粉的复合材料损耗因子峰值明显减小。MMA改性稻壳粉的复合材料的α值比未改性的大,表明改性后复合材料相容性好。     

链条炉试烧稻壳成型颗粒的研究

研究采用20 t/h供暖链条炉,在不改变锅炉主体结构,并保证锅炉出力的前提下,试烧了稻壳成型颗粒。结果表明:随着生物质颗粒掺烧比的增加,排渣烧失量逐渐降低,排烟中CO浓度升高,排烟温度逐渐升高。其中生物质挥发分在对流受热面中燃烧是造成排烟温度升高的主要原因。燃煤链条锅炉改烧生物质颗粒,应该在锅炉前拱或者喉部增加流量小、压头大、速度高的二次风,增强烟气扰动,从而增强挥发分与空气的混合燃烧,达到减排SO₂和节约优质烟煤的目的。     

An alternative method for in vitro fire smoke toxicity assessment of polymers and composites using human lung cells

An alternative method for in vitro fire smoke toxicity assessment of polymers and composites using human lung cells has been investigated. A range of building and train interiors including polyethylene (PE), polypropylene (PP), polycarbonate (PC), polymethyl methachrylate (PMMA), polyvinyl chloride (PVC), fiberglass‐reinforced polymer (FRP), and melamine‐faced plywood (MFP) were studied. The exposure of combustion toxicants to human lung cells (A549) at the air/liquid interface was acquired using a Harvard Navicyte Chamber. Cytotoxic effects on human cells were assessed based on cell viability using the MTS assay (Promega). Cytotoxicity results were expressed as no observable adverse effect concentration (NOAEC), 10% inhibitory concentration (IC₁₀), 50% inhibitory concentration (IC₅₀), and total lethal concentration (TLC) values (mg/l). Mass loss data and toxic product yield were also determined. Results suggested that PVC (IC₅₀ 1.99 mg/l) was the most toxic materials followed by PP, FRP‐16, PC, PMMA, FRP‐10, PE, and melamine plywood. Some materials revealed to be more toxic under flaming combustion (PP, PC, FRP‐16, and FRP‐10), while others (PVC, PMMA, PE, and melamine plywood) appeared more toxic under non‐flaming combustion. The method developed can be used to screen the toxicity of materials which would be important information in building and mass transport material selection. Copyright © 2010 John Wiley & Sons, Ltd.     

影响聚丙烯基木塑复合材料力学性能因素

研究了偶联剂、相容剂、木粉用量和木质填料种类对以聚丙烯（PP）为基体树脂制备小塑复合材料力学性能的影响。结果表明，以硅烷偶联剂处理木粉或直接加入相容剂均使复合材料力学性能得到提高；木粉用量的提高使复合材料冲击强度下降，弯曲强度、弯曲模量、拉伸强度则大幅提高；在分别以粒径为0．14mm木粉和0．22mm木粉、竹粉、花生壳粉、稻壳粉制备复合材料，以粒径为0．14mm木粉与PP制备的复合材料力学性能最好。     

废旧聚丙烯编织袋回收料改性应用研究

废旧聚丙烯(PP)编织袋回收料分别与回收聚乙烯(PE)、回收橡胶粉、木粉共混,制备了增韧PP材料、热塑性弹性体和木塑复合材料,采用力学性能测试、SEM和DSC分析等手段对其性能和结构进行了表征。结果表明:随着回收聚乙烯(PE)含量的增加,回收PP/PE共混物的拉伸强度和冲击强度迅速提高;回收PP/橡胶粉共混物中加入聚丙烯接枝马来酸酐(PP-g-MAH)能起到增容的效果,随PP-g-MAH含量的增加,共混物的拉伸强度上升,永久变形减小;在回收PP/木粉复合材料中加入PP-g-MAH后,复合材料的冲击强度明显提高。     

稻壳粉填充聚乙烯复合材料的研究

采用稻壳粉对高密度聚乙烯(HDPE)进行改性，研究了稻壳粉用量对。HDPE力学性能、耐热性、流动性及硬度的影响，并观察了稻壳粉在HDPE中的分散状况。结果表明：复合材料的弯曲强度、硬度、维卡软化温度随稻壳粉用量的增加而增加，而加工流动性能、拉伸强度、断裂伸长率和冲击强度则随稻壳粉用量的增加而下降；稻壳粉在HDPE中的分散不均匀，用量较大时易出现聚集现象，两相间的粘接性变差。     

表面处理剂对PVC仿木复合材料性能的影响

使用4种不同类型的含高活性反应基团的聚氨酯处理剂对木粉表面进行处理,并制备了聚氯乙烯(PVC)/木粉复合材料,研究了表面处理剂的交联度、不同用量和高活性反应基团—NCO的含量对复合材料性能及结构的影响。结果表明,使用聚氨酯处理剂对木粉表面进行处理可以明显改善复合材料的流变性能,并明显提高复合材料的力学性能;扫描电镜观察表明,木粉经聚氨酯处理剂改性后与PVC的相容性明显得到改善。     

KINETICS OF RICE HULL CHAR BURNOUT IN A BENCH-SCALE FLUIDIZED-BED REACTOR

Rice hull, also known as husk, is a by-product of the rice milling process; it is a significant alternative energy resource for the milling industries of rice producing countries. Apart from its high energy content, the residual ash from complete combustion of rice hull at moderate temperatures in a combustor, e.g., a fluidized-bed reactor, is also a potential cement extender. The regeneration of steam for parboil rice and for other process activities makes combustion an attractive means of disposing rice hull in the rice milling industries, which otherwise is a menace to the rice miller.

In the present work, the combustion kinetics of Guyana rice hull char was studied in a bench-scale fluidized-bed reactor. The salient features of the combustion of the char were observed, and the temporal history of burnout was traced at temperatures of 973 and 1173 K. The oxygen concentrations of the inlet fluidizing gas were maintained at 2.3 and 4.6% by regulating the mixing of nitrogen and air.

The rates of combustion of the residual char generated from rice hull through rapid devolatilization were determined to range from 3.18 × 10^-6 to 9.04 × 10^-6kg/s. By fitting the conversion data with various heterogeneous reaction models, it appears that the data could be described, to some extent, by the unreacted core model with ash layer diffusion control. However, the complexity of the carbon/silica arrangement in the residual char results in uncertainties in model selection.     

Rice hull ash adsorbent performance under commercial soy oil bleaching conditions

Rice hull silica and a rice hull carbon ash were evaluated as adsorbents for the soy oil bleaching process under commercial temperature and pressure conditions. Their performance in adsorbing pigment, phospholipid, free fatty acids, and peroxides was compared with that of a commercial bleaching clay and silica hydrogel. With the exception of phospholipid binding, rice hull-derived adsorbents were ineffective. Rice hull silica showed potential as a phospholipid adsorbent but was not as effective as the synthetic silica hydrogel on an adsorbent weight basis. However, it was a superior adsorbent when the data were expressed as adsorbate bound per unit surface area. The low surface area of the rice hull silica limits its commercial viability. It may have value in areas of the world where rice hulls are plentiful and an inexpensive phospholipid adsorbent is required for oil processing. Research is in progress to increase the surface area of rice hull silica for commercial oil processing.