关于对国家标准塑料密度测试计算方法的商榷

国家标准《塑料密度和相对密度试验方法》（GB1033—1998）规定了5种测定塑料密度的方法。第一种方法浸渍法又规定了当被测试样密度小于浸渍液密度时的测定方法与计算公式，标准中4．1．3．2计算公式（3）为：     

塑料材料的测试

为了正确地选用塑料材料,必须了解它们的机械性能、热性能、电性能等。ASTM——美国材料测试学会制订了一些标准测试方法。测试时,制备试样的方法以及试样的形状,都会影响测试结果。聚烯烃类塑料材料(例如聚乙烯和聚丙烯)主要测试流动速度或熔融指数以及树脂密度等,而像聚苯撑硫等工程塑料还要测试螺旋流动速度等。     

热塑性塑料熔密度的测定

本文对常见的几种热塑性塑料的熔融密度进行了测定,以弥补高熔体流动速率自动测试方法之不足。     

塑料密度温度系数的测定

对HDPE、LDPE、PP、PS、ABS、EVA、PVC等常见塑胶粒的密度温度系数进行了测定。采用本文所测得的密度温度系数值,将常温下测得的密度值校正到指定温度下的密度值,这种方法可以满足塑料密度常规检验的要求。     

单螺杆塑料挤出机标准测试机头

本文介绍了单螺杆塑料挤出机标准测试机头的用途、规格、使用范围、结构及相关测试仪表、测试方法，挤出机技术性能曲线，测试结果和曲线的处理方法及标准测试机头在新型螺杆开发方面的应用。     

塑料滑动轴承综合性能测试系统研制

研制了自润滑塑料滑动轴承综合性能测试系统并对聚四氟乙烯(PTFE)基复合材料滑动轴承进行了实际测试。该系统能够实现滑动轴承工作过程中载荷、速度、表面温度、摩擦力信号的在线测量并计算摩擦系数和工作PV值,利用该系统可以完成不同设计参数的塑料滑动轴承综合性能和承载能力测试与评价。     

影响塑料密度测量准确性因素的探讨

分析了影响塑料密度测量准确性的几种因素。从制样、取样、测量等方面进行了详细分析,探讨了注塑工艺条件及塑料含水率对塑料密度的影响,取样时尽量选取样品中部,测量时不可忽视悬丝质量等细节的影响,指出了提高密度测量准确度的正确操作方法。只有严格控制制样及测量中的各个环节,才可以保证塑料密度测量的准确性。     

生物分解塑料测试标准现状

生物分解塑料要健康发展，它的评价体系包括标准和测试技术相当关键，这是生物分解塑料产品推广的基础和产业化的前提。对此，世界主要工业国家及国际标准化组织（ISO）都制定了相关测试标准。[编者按]     

关于埋地塑料管的受力情况研究分析

本文介绍了埋地塑料管道的施工运用及塑料管道在土壤下的受力分析;重点介绍了埋地排水管道与土壤共同作用下的指标确定、影响埋地管道的重要参数,并研究分析管道的埋填要求,包括埋填材料要求,尺寸要求等。     

Wood/plastic copyrolysis in an auger reactor: Chemical and physical analysis of the products

Previous studies observed that slow copyrolysis of wood and plastic in enclosed autoclaves produced an upgraded raw bio-oil with increased hydrogen content. We now demonstrate that fast simultaneous pyrolyses of 50:50, w/w, pine wood/waste plastics in a 2 kg/h lab scale auger-fed reactor at 1 atm, with a short vapor residence time, generates higher heating value upgraded bio-oils. Three plastics: polystyrene (PS), high density polyethylene (HDPE) and polypropylene (PP) were individually copyrolyzed with southern yellow pine wood at 525, 450 and 450 °C, respectively, to generate modified bio-oils upon condensation. These liquids exhibited higher carbon and hydrogen contents, significantly lower oxygen contents, higher heats of combustion and lower water contents, acid values and viscosities than pine bio-oil. The formation of cross-over wood/plastic reaction products was negligible in the oils. Simultaneous pyrolysis process design requires using a temperature at which the plastic’s thermal decomposition kinetics produce vapors rapidly enough to prevent vaporized plastic from condensing on wood chars and exiting the reactor.     

Investigation on pyrolysis of Moroccan oil shale/plastic mixtures by thermogravimetric analysis

Thermal degradation processes for a series of mixtures of oil shale/plastic were investigated using thermogravimetric analysis (TGA) at four heating rates of 2, 10, 20 and 50 K min^− 1 from ambient temperature to 1273 K. High density polyethylene (HDPE), low density polyethylene (LDPE) and polypropylene (PP) were selected as plastic samples. Based on the results obtained, three thermal stages were identified during the thermal degradation. The first is attributed to the drying of absorbed water; the second was dominated by the overlapping of organic matter and plastic pyrolysis, while the third was linked to the mineral matter pyrolysis, which occurred at much higher temperatures. Discrepancies between the experimental and calculated TG/DTG profiles were considered as a measurement of the extent of interactions occurring on co-pyrolysis. The maximum degradation temperatures of each component in the mixture were higher than those of the individual components; thus an increase in thermal stability was expected. In addition, a kinetic analysis was performed to fit thermogravimetric data. A reasonable fit to the experimental data was obtained for all materials and their mixtures.     

提高PMMA塑料光纤芯材耐热性的方法

介绍了提高以聚甲基丙烯酸甲酯(PMM A)为芯材的塑料光纤的耐热性的方法。     

Phenomenology of plastic recovery in high polymer glasses

Deformations in isotropic, strain-free polymer glasses are usually completely recoverable (at the test temperature or after warming to T_g), in sharp contrast with the behavior of low molecular weight glasses and crystals. The apparent ‘plastic strain’ which remains at the end of a creep or stress relaxation experiment does not recover at the test temperature, but only after the sample is heated. It is proposed that the long time scales needed for entanglement reorganization in the glass are responsible for this delayed recovery. A phenomenological network model for thermally activated strain recovery in polymer glasses is analyzed. A superposition relation between the stress and the strain history using a KWW (stretched exponential) memory kernel is employed. The recovery of plastic (i.e. residual) strain in non-crosslinked amorphous thermoplastics is a two-step process that may be interpreted in terms of the network model. In particular, recovery at sub-T_g temperatures is associated with entanglement slippage, while recovery near-T_g is believed to involve reorganization at or near chain ends.     

无定型玻璃态聚碳酸酯的塑性行为模拟

用常压分子动力学模拟和固定晶胞能量最小化计算程序,以及构型和能量分析研究了无定型玻璃态聚合物双酚—A—聚碳酸酯(BPA-PC)的塑性变形。计算结果和"势能面理论"架构吻合,此理论将塑性转换解释成"理想结构"之间的相互交叉和塌陷。本方法可以在晶胞尺度有限、高压缩比和低温下对聚合物材料进行模拟,密度、杨氏模量、屈服应变、屈服应力、激化能、激化体积都与BPA-PC的实验数据吻合。     

工程塑料行业形势发展分析

介绍了政府部门对行业发展的指导意见,并概述了国内工程塑料行业发展、市场发展、技术发展及企业发展.     

The density of cement phases

The densities of principal crystalline phases occurring in Portland cement are critically assessed and tabulated, in some cases with addition of new data. A reliable and self-consistent density set for crystalline phases was obtained by calculating densities from crystallographic data and unit cell contents. Independent laboratory work was undertaken to synthesize major AFm and AFt cement phases, determine their unit cell parameters and compare the results with those recorded in the literature. Parameters were refined from powder diffraction patterns using CELREF 2 software.A density value is presented for each phase, showing literature sources, in some cases describing limitations on the data, and the weighting attached to numerical values where an averaging process was used for accepted data. A brief discussion is made of the consequences of the packing of water to density changes in AFm and AFt structures.     

环保型聚氨酯塑胶跑道的研究

介绍了聚氨酯铺地材料在塑胶跑道浆料技术上的研究进展,将MDI体系与传统的TDI体系相比较,分析了MDI型聚氨酯体系代替TDI型体系在环保和性能上的优势。分别对聚氨酯塑胶跑道面层浆料的选择与配方及其物理性能进行了介绍与总结。为今后进一步研究环保型聚氨酯塑胶跑道提了一定的参考和借鉴。     

Co-gasification study of biomass mixed with plastic wastes

Fluidised bed steam gasification has proven to be a possible way of converting biomass and plastic undesirable wastes into fuel gases. The addition of plastics to pine wastes decreased CO content, but increased H₂ released, up to values of 50% (v/v). The highest gas yield obtained was 1.96 Nl/g daf for 98% of energy conversion, when 60% (w/w) of plastic was in the feedstock. The steam/waste mixture ratio seems to have a small effect on gas composition. Temperature is the parameter that most influenced gases composition. The rise of temperature favoured the formation of H₂ and decreased the formation of hydrocarbons, tars and char. At 885°C and in presence of 40% (w/w) of plastic, conversion to char was around 2%, whilst feedstock conversion to gas was around 90%. In this paper, the effect of experimental conditions on gasification process, with the aim of enhancing the gas production and improving its composition and energetic content was analysed.