氯化聚乙烯/废旧轮胎胶粉共混发泡性能研究

采用模压法进行发泡,以氯化聚乙烯（CM）为基体,研究了胶粉用量、硫化温度、硫化助剂对CM发泡体的泡体性能、泡孔结构的影响。结果表明,CM发泡体随着胶粉用量的增加,发泡密度逐渐增加,泡孔体积及发泡倍率逐渐减少。综合CM发泡体的泡体性能及泡孔结构,当胶粉用量为10份,170℃下硫化7min,使用TCHC作硫化助剂时,可得到发泡效果好,断面均匀分布,泡孔结构明显的CM发泡体。     

Transport studies of peanut shell powder reinforced natural rubber composites in aromatic solvents

This article investigates the transport behavior of three aromatic organic solvents, viz. benzene, toluene, and xylene in natural rubber (NR) composite membranes containing peanut shell powder (PSP) as filler at different temperatures by conventional weight‐gain experiments. PSP used in compounding the NR was processed in two particle sizes. The solvent swelling characteristics of NR composites containing both untreated and alkali‐treated fillers were investigated. The computed sorption characteristics were discussed in terms of PSP content, particle size, nature of solvent, and temperature. All the NR‐PSP composites were found to decrease with the uptake of aromatic solvents than NR, but the effect was more significant in the case of alkali‐treated PSP composites. Furthermore, the uptake of solvent decreased with decrease in penetrant size. The estimated Arrhenius activation energies (E_D) for the processes of sorption, diffusion, and permeation showed that E_D was generally highest in xylene at the filler contents investigated. The thermodynamic parameters of the sorption process were also evaluated. The relationship between the transport behavior and the morphology of the system was examined. The mechanism of diffusion is found to be close to Fickian trend in toluene and xylene and Fickian trend in benzene. Comparison between theoretical and experimental diffusion results was made to understand the mechanism of diffusion. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

废旧轮胎胶粉/PP复合材料的研究

研究了不同含量的废旧轮胎胶粉对聚丙烯力学性能的影响,并采用脱硫、自由基聚合反应改善两相的相容性。结果表明：加入未经处理的胶粉时,复合材料拉伸强度和断裂伸长率随着胶粉含量的增加而降低。当胶粉含量为70 ％(质量分数,下同)时,拉伸强度由37 MPa降至7 MPa,断裂伸长率由108 ％降至35 ％左右。冲击强度随着胶粉含量的增加呈现先升后降趋势,当胶粉含量为20 ％时,冲击强度达到14 kJ/m2。加入处理后的胶粉,拉伸强度随胶粉含量的增加而降低的趋势变缓。冲击强度和断裂伸长率随着胶粉含量的增加呈现先升后降趋势。胶粉含量为30 ％时,冲击强度可达18.5 kJ/m2,断裂伸长率约为320 ％.     

Sorption and diffusion of alcohols in amorphous polymers

The effects of polymer composition and penetrant molecular size on the solubility and diffusivity of alcohol vapors in a series of well characterized isoprene-methyl methacrylate copolymers and their corresponding homopolymers has been investigated at room temperature. The rate of sorption behavior changes progressively from Fickian to non-Fickian, to Case II to “Super Case II” transport with increasing methyl methacrylate (MMA) content in the polymers. The equilibrium solubility of the alcohols increases linearly with increasing penetrant molecular size for polymers which are above their glass transition temperature and decreases for polymers which are below their T_g. The solubility also initially increases as an approximately linear function of MMA content in the copolymers. At about 55 mole percent MMA, the sorbed concentration either levels off or passes through a maximum depending on the size of the penetrant. The apparent “diffusion coefficients” (D) decrease with increasing molecular volume of the penetrants. An exponential dependence was found between these two variables for PMMA. These “diffusion coefficients” also decrease exponentially with increasing MMA content in these polymers. However, at 55 mole percent MMA the copolymer undergoes a rubber to glass transition at the temperature of the experiments. On this basis, it is suggested that the hindered chain segmental motion contributes to the sorption process in addition to strictly thermodynamic considerations. Free volume theory can be used to explain the mechanism of diffusion through the rubbery polymers while the “hole” theory can be applied to explain the transport of the penetrants through the glassy polymers.     

废旧轮胎橡胶粉/苯乙烯-丁二烯-苯乙烯嵌段共聚物/石油树脂复合改性沥青的制备及性能

以苯乙烯-丁二烯-苯乙烯嵌段共聚物（SBS）、废旧轮胎橡胶粉和石油树脂制备复合改性沥青,并对复合改性沥青的储存稳定性、温度敏感性、高温流变性能、抗车辙性能和黏度等进行了考察。结果表明,复合改性沥青中,SBS、废旧轮胎橡胶粉及石油树脂的最佳质量分数分别为4.5%、14.0%和4.5%;石油树脂/SBS/废旧轮胎橡胶粉复合改性沥青具有较好的储存稳定性、温度敏感性和抗车辙性能。     

Water sorption and desorption in 2-hydroxyethylmethacrylate/methylmethacrylate copolymers

Cross-linked copolymers of 2-hydroxyethylmethacrylate/methylmethacrylate HEMA/MMA) with different HEMA contents have been prepared. Water sorption and desorption kinetics have been studied at a temperature of 37°C. The results indicate that the rate controlling step of sorption and desorption is the Fickian diffusion in the swollen polymer. The diffusion coefficient is a function of the water concentration and decreases to zero below a critical value of water content, which depends on the HEMA content.     

Studies of the chemical modifications of wool and their effects on the wool–water relationship. Part II. Wool-water relationships of modified and unmodified wool

The wool–water relationships of the modified wools prepared as described in Part I of this series have been studied. The drained water content of fabric and the solution isotherms and diffusion constants of water vapor into untreated and modified wools have been measured. Most of the treated wool fabrics showed considerable decreases in the drained water contents compared with the untreated wool. However, the degree of improvement depended markedly on the conditions of modification, particularly with the styrene grafted materials. In some cases values close to those of a comparable polypropylene fabric were found. The sorption isotherms also showed that the modifications reduced, substantially in some cases, the regains even when calculated on the wool content only. The diffusion constants were difficult to measure because of the heats of sorption causing temperature changes during the sorption; however, at lower regains this effect could be corrected. It was found that both the direct chemical modification and the grafted wools showed a diffusion behavior which was more characteristic of hydrophobic materials in that the diffusion constants tended to decrease with increasing concentration. At low humidities the diffusion constants were larger than in the untreated wool, but at higher humidities lower diffusivities were found with the modified wools.     

基于废旧轮胎胶粉的热塑性弹性体的制备及发泡性能研究

通过沥青改性胶粉及采用相容剂与聚丙烯共混制备了性能优良的热塑性弹性体(TPE)材料,并以超临界流体为发泡剂对其发泡性能进行了研究。实验结果表明,胶粉通过沥青改性后,可以明显地提高TPE的拉断伸长率,并且发泡TPE的泡孔平均直径增大,泡孔密度减少,相对密度减小,但是随着沥青用量的增加,材料的粘度降低,从而出现泡孔破裂和塌陷现象,最后导致泡孔平均直径和泡孔密度减小,相对密度增加。相容剂苯乙烯嵌段共聚物接枝马来酸酐(SEBS-g-MA)可以提TPE的拉断伸长率并改善泡孔结构。温度的升高和饱和压力的增大,都导致了发泡弹性体的泡孔增大,泡孔密度和相对密度减小。     

聚氯乙烯/丁腈胶粉共混型热塑性弹性体

将聚氯乙烯与废丁腈胶粉经高温机械共混，制备了动态交联的共混型热塑性弹性体。讨论了共混比，硫化体系及其用量，废胶粉品种（丁腈胶粉，轮胎胶粉）等因素对热塑性弹性体性能的影响，同时将聚氯乙烯／丁腈胶粉与聚氯乙烯／轮胎胶粉制备的共混型热塑性弹性体的性能进行了比较。结果表明，以聚氯乙烯100份（质量份，下同），邻苯二甲酸二辛酯50份，丁腈胶粉80份，丁腈橡胶20份，过氧化二异丙苯0．5份，氧化锌5份及适量其他助剂可制得综合性能较好的共混型热塑性弹性体。扫描电镜结果显示该共混型热塑性弹性体具有较好的相容性。     

Transport properties of dichloromethane in glassy polymers. I. Atactic polystyrene films

Sorption and diffusion of dichloromethane vapor were measured in atactic polystyrene films, obtained with different cooling conditions and after controlled aging times at different temperatures. The diffusional behavior is characterized by three zones, depending on temperature and penetrant activity. In Zone I, at low activity, the diffusion coefficient is independent of vapor concentration; Zone II is characterized by concentration-dependent diffusion, whereas in Zone III structural transformations are possible. The study of diffusion at three temperatures allowed building of a temperature-penetrant concentration diagram, which is very useful to visualize the different zones of behavior. The aging at room temperature has no effect on the curve of sorption as a function of vapor activity, whereas it determines two effects on the diffusion: a decrease of the zero concentration diffusion coefficient and a more and more anomalous behavior with the aging time. The aging at 70°C produces the same effects on the diffusion behavior as the aging at room temperature; in addition, a decrease sorption is observed at low penetrant activity. The possible presence of ordered domains, impermeable to the vapor, in the samples stored at 70°C, was suggested on the basis of sorption results.     

渗透汽化膜分离MeOH/MTBE混合物的传质分析——单组分在膜中的扩散

用石英晶体微平衡法测定了298.15 K、305.75 K、312.95 K下MeOH（甲醇）和MTBE（甲基叔丁基醚）在CA（醋酸纤维素）膜中的吸着平衡数据和吸着动力学数据.结果表明：MeOH和MTBE在CA膜中的传质过程属于Fick扩散类型;MeOH在CA膜中的平衡吸着量和扩散系数都比MTBE大,说明CA膜对MeOH/MTBE混合物有较好的分离性能;同一吸着温度下,吸着速度和平衡吸着量均随着吸着蒸气压的升高而升高;可用Eyring的扩散“空穴”理论解释MeOH和MTBE在膜中的扩散行为.     

Experimental and theoretical investigation of solubility and diffusion of ethylene in semicrystalline PE at elevated pressures and temperatures

The solubility and diffusivity of ethylene in semicrystalline polyethylene were experimentally measured using a magnetic suspension microbalance. The sorption measurements were carried out at temperatures up to 80°C and pressures up to 66 atm. The experimentally measured solubilities were found to decrease with increasing temperature and increased with ethylene pressure in good agreement with the predictions of the Sanchez–Lacombe lattice‐fluid model. The diffusivity of ethylene in semicrystalline polyethylene films was estimated from the reduced sorption curves using the half‐time method. The experimentally determined diffusivities were compared with theoretical values predicted by a new molecular hybrid model, which combines the characteristic features of the Pace–Datyner diffusion model with those of the Kulkarni–Stern free‐volume model. The ethylene diffusion coefficient was found to increase with temperature and/or the ethylene‐sorbed concentration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 953–966, 2003     

有氧再生废轮胎橡胶粉的制备与表征

在管式炉中对废轮胎橡胶粉进行了有氧再生,并考察了气氛、再生温度和再生时间对废轮胎橡胶粉有氧再生过程的影响。结果表明,有氧条件下橡胶粉的质量损失和溶胶质量分数均随温度升高而增大,溶胶中合成胶分子链之间易发生二次重组再交联反应,天然橡胶分子链则主要发生断裂。240 ℃下橡胶粉在有氧条件下再生10 min时,溶胶质量分数达55.9%。橡胶主链和交联键断裂主要发生了氧化反应,生成含羰基和亚砜基的化合物,同时伴有水和二氧化碳等生成,说明橡胶粉中的橡胶分子链有效断链。     

Sorption of Brilliant Red HE-3B Reactive Dye from Aqueous Solution onto Seashells Waste: Equilibrium and Kinetic Studies

The potential of waste seashells powder, as a new adsorbent for Brilliant Red HE-3B reactive dye removal from aqueous solutions, was examined by the batch technique. The Freundlich, Langmuir, and Dubinin-Radushkevich adsorption models were applied to describe the equilibrium sorption data and to determine the corresponding isotherm constants. The values of the thermodynamic parameters, ΔG, ΔH, and ΔS, indicate that the sorption of reactive dye is a spontaneous and endothermic process. The kinetic data evaluated by pseudo-first order, pseudo-second order, and intraparticle diffusion kinetic models suggested that the sorption of reactive dye onto seashell is a complex process and both surface sorption and intraparticle diffusion contributes to the rate limiting step.     

Fracture behavior of NR and SBR vulcanizates filled with ground rubber having uniform particle size

The use of recycled rubber including ground scrap vulcanizates in rubber compounds was studied. When ground rubber was incorporated into rubber compounds, the physical properties, especially the tensile strength, were deteriorated compared to the virgin rubber compound. Also, incorporating ground rubber caused a change of the cure behavior via migration of sulfur or an accelerator between the virgin rubber matrix and the ground rubber vulcanizate. In this study, the fracture behavior and abrasion property of carbon black‐filled SBR and NR compounds containing ground rubber vulcanizate were investigated. Also, the effect of the particle size or loading volume of ground rubber powder on those properties was studied. Four different sizes, 420–600, 177–250, 125–150, and 75–88 μm, of ambient ground rubber powder recycled from waste tire were selected and used in the compounding. The loading amounts of ground rubber powder were 10, 30, and 50 phr. The flex crack growth of SBR‐ and NR‐based compounds was altered by the addition of ground rubber particles. More delayed crack growth was observed with an increasing loading volume and decreasing particle size of the ground rubber powders, and this behavior was more prominent in SBR than in NR compounds. Tangent delta, a direct measure of internal energy dissipation, increased with an increasing loading volume of the ground rubber particles. The abrasion rate of ground rubber‐filled compounds was more dependent on the size of the abrasion pattern than on the loading level or particle size of the ground rubber powders. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2491–2500, 2002     

Production of Tomato Powder by Refractance Window Drying

The aims of this work were to investigate the drying of tomato pulp by refractance window (RW) and the effects of process conditions on the drying rates and characteristics of the dry powder. Different heating water temperatures (65, 75, 85, and 95°C) and pulp thickness (2 and 3 mm) were studied for drying 4.8–5.2 °Brix pulps. The powder characteristics were assessed from its solubility, dispersion time, water sorption isotherm, and color. Shorter drying time (17 minutes) was observed to the lower pulp thickness and higher drying temperature. The solubility of tomato powders was approximately 80%, and the dispersion time was lower than one minute. The color change (ΔE) of rehydrated powder showed an increase with increasing process temperature. These results indicate that RW is an adequate procedure for the production of tomato powder.     

废旧轮胎橡胶的常温粉碎及性能研究

采用盘式磨设备对废旧轮胎胎面胶颗粒进行常温粉碎,研究胶粉性能及其对丁苯橡胶(SBR)硫化胶物理性能的影响,并与胎面胶颗粒进行对比。结果表明:常温粉碎胶粉的粒径比胎面胶颗粒降低了一个数量级,形状更加不规则且表面粗糙;动盘和定盘相对转速对常温粉碎胶粉粒径及其分布影响不大,但动盘和定盘间隙影响较大;常温粉碎胶粉的热稳定性比胎面胶颗粒低,且交联密度减小一半以上;与胎面胶颗粒相比,添加常温粉碎胶粉的SBR硫化胶的拉断伸长率有很大提高,但邵尔A型硬度、100%和300%定伸应力以及拉伸强度有所减小。     

碱土金属氧化物含量对模拟高放废液玻璃固化体析晶行为的影响

以硼硅酸盐玻璃作为基础玻璃基材,通过熔融法制备了含16%(质量分数)模拟高放废液的玻璃固化体,探究了碱土金属氧化物含量对玻璃固化体析晶行为的影响,以期在保证玻璃固化体性能要求的前提下,通过控制碱土金属氧化物的含量抑制玻璃固化体的析晶倾向。结果显示:碱土金属氧化物(CaO+MgO+BaO)含量在7%~19%(质量分数)时,玻璃固化体析晶上限温度和析晶率随碱土金属氧化物含量的降低而逐渐降低;玻璃网络聚合度的增加能够显著增强玻璃固化体的抗析晶性能,当碱土金属氧化物含量低于11%(质量分数)时玻璃固化体中硫酸盐的溶解度明显下降。基于包容0.7%(质量分数)SO₃的要求,碱土金属氧化物含量适宜组成应控制在11%(质量分数)以上。     

废旧橡胶循环利用技术进展

介绍废旧橡胶循环利用技术现状和进展。废旧橡胶循环利用方式主要为制造再生胶、胶粉和轮胎翻新。国内再生胶制备新工艺主要为常压动态硫化工艺、常压中温塑化脱硫工艺及低温连续再生工艺,可以解决传统再生工艺的二次污染和高能耗问题;胶粉制备的3种主要方法为常温粉碎法、低温粉碎法和溶液粉碎法,其中常温粉碎法技术经济性较好。轮胎翻新技术主要包括传统的热硫化翻新方法(热翻法)和较新的预硫化翻新方法(冷翻法),冷翻法效率较高,可以延长轮胎使用寿命。     

Impact modification of polypropylene‐based composites using surface‐coated waste rubber crumbs

Blends of maleated polypropylene (MAPP) with high contents of waste rubber powder, namely ground tire rubber and waste ethylene propylene diene monomer (EPDM) powder, were used as impact modifiers for polypropylene (PP) based composites with different reinforcements (hemp, talc, and milled glass fiber). Adding reinforcements led to increase in modulus (tensile, flexural, and torsion moduli) of PP, while its impact strength decreased noticeably. Impact modification of PP‐based composites was successfully performed via inclusion of MAPP/waste rubber compounds, especially compounds containing waste EPDM powder. Inclusion of such impact modifiers increased impact strength of composites over 80%. The effects of impact modification were more significant for hemp‐ and glass‐filled composites compared to composites containing talc. However, slight decrease in tensile, flexural, and torsion moduli (up to 30%) of the composites was also observed after inclusion of impact modifiers. POLYM. COMPOS., 35:2280–2289, 2014. © 2014 Society of Plastics Engineers