Influence of Polymer Type and Structure on Polymer Modified Asphalt Concrete Mix

Two low‐density polyethylene (LDPE) resins and two ethyl vinyl acetate (EVA) polymers were used to modify asphalt binder, and then mixed with asphalt concrete according to Marshall Method of mix design (ASTM D 1559). Effect of weight average molecular weight (M_w) of LDPE and vinyl acetate (VA) content of EVA was studied by performing Marshall Stability, moisture susceptibility (AASHTO T 283‐89), resilient modulus (M_R) and permanent deformation (rutting) tests. EVA with low VA content showed lower stability loss in Marshall Stability test and improved resistance in moisture susceptibility test in comparison to hot mix asphalt concrete mix (HMA) and other polymer modified asphalt concrete mixes (PMAMs). Higher M_R and better rutting resistance were observed for PMAMs than that of HMA. This elastic behaviour of modified asphalt correlates very well with the M_R and rutting resistance properties of PMAM.     

A simple model for viscosity of powder injection moulding mixes with binder content above powder critical binder volume concentration

A simple model is proposed for the variation of viscosity of powder injection moulding mixes with binder content above Critical Binder Volume Concentration (CBVC), a characteristic of powder. Coarse silica and fine alumina powders are mixed with different types of low viscosity binders at different binder proportions. The viscosities of these mixes are measured by capillary rheometry with a special die at different shear rates. The CBVC values of the powders estimated by the model from the viscosity data of the mixes are matching with those values arrived from the experimental torque rheometry and temperature measurement methods. The proposed model has shown excellent correlation between the calculated and experimentally measured viscosity data at different shear rates, binder contents with different binders and powders. The model also gave precise CBVC values with the viscosity data of the previous authors validating the model to other powders and binders. The model is useful for the prediction of viscosity of PIM mix with known binder content, viscosity of binder and CBVC of the powder.     

On the Improvement of the Processability of UHMW‐HDPE by Adding a Liquid Crystalline Polymer and a Fluoroelastomer

Ultra‐high molecular weight polyethylene possesses many interesting properties but a very bad processability. This material is not usually processed in conventional devices but only by compression moulding and RAM extrusion. Low molecular weight polyethylene can be used to improve the processability. In this work small amounts of a fluoroelastomer and of a liquid crystalline polymer have been used as processing aids to improve the extrudability of this polymer. In fact, the die pressure decreases whereas the output flow rate slightly increases with increasing concentration of the processing aids. Solution viscosity data shows that reduction of the mechanical stress during extrusion decreases the degradation of the polyethylene.     

Ceramic suspension optimization using factorial design of experiments

The influence of organic phases (binder and two plasticizers) on ZnO slip viscosity and the properties of green tape were studied using design of experiments (DOE). Analysis of the results show no significant influence of the three components on slip viscosity and green tape density, but joint influence of two factors—binder polyvinyl butyral (PVB) and plasticizer polyethylene glycol (PEG)—is significant on green tape adhesion to the substrate tape of casting machine.     

载锌抗菌剂在发泡EVA中的应用研究

以铝酸酯、硅烷、硼酸酯偶联剂为改性剂，分别对栽锌抗菌剂粉体进行表面改性，并用吸水性测定法、粘度法、红外光谱法评价抗菌粉体表面改性效果。用扫描电镜观察了抗菌粉体在EVA（乙烯／醋酸乙烯共聚物）基材中的分散性，以及对EVA发泡材料泡孔的影响；同时检测了EVA／抗菌粉体复合发泡材料的力学性能和抗菌性能。结果表明：3种偶联剂中，硼酸酯的改性效果最好，抗菌粉体表面与硼酸酯产生了明显的化学键合；加2％抗菌粉体（硼酸酯处理）的EVA发泡材料，撕裂强度提高28．6％，断裂伸长率提高45．8％，密度降低13．5％，对大肠杆菌和金黄色葡萄球菌具有良好的抗菌抑菌效果。     

Plastification of poly(vinyl chloride) by polymer blending

Blends of poly(vinyl chloride) (PVC) with different copolymers have been studied to obtain a plasticized PVC with improved properties and the absence of plasticizer migration. The copolymers used as plasticizers in the blends were acrylonitrile butadiene rubber, ethylene vinyl acetate (EVA), and ethylene-acrylic copolymer (E-Acry). Blends were studied with regard to their processing, miscibility, and mechanical properties, as a function of blend and copolymer composition. The results obtained were compared with those of equivalent compositions in the PVC/dioctyl phthalate (DOP) system. Better results than PVC/DOP were obtained for PVC/acrylonitrile butadiene rubber blends. The plasticizing effect on PVC of EVA and E-Acry copolymers was similar to that of DOP. It is shown that crosslinking PVC/E-Acry blends or increasing the vinyl acetate content in PVC/EVA blends, are alternatives that can increase the compatibility and mechanical properties of these blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1303–1312, 2000     

Melt rheological and thermodynamic properties of polyethylene homopolymers and poly(ethylene/α-olefin) copolymers with respect to molecular composition and structure

Various types of polyethylene homopolymers and copolymers, including linear high-density polyethylene (HDPE), branched low-density polyethylene (BLDPE), poly(ethylene vinyl acetate) copolymer (EVA), heterogeneous linear poly(ethylene/α-olefin) copolymer (het-LEAO) or commonly known as linear low-density polyethylene, homogeneous linear poly(ethylene/α-olefin) copolymer (hom-LEAO), and homogeneous branched poly(ethylene/α-olefin) copolymer (hom-BEAO), were evaluated for their melt rheological and thermodynamic properties with emphasis on their molecular structure. Short-chain branching (SCB) mainly controls the density, but it has little effect on the melt rheological properties. Long-chain branching (LCB) has little effect on the density and thermodynamic properties, but it has drastic effects on the melt rheological properties. LCB increases the pseudo-plasticity and the flow activation energy for both the polyethylene homopolymer and copolymer. Compared at a same melt index and a similar density, hom-LEAO has the highest viscosity in processing among all polymers due to its linear molecular structure and very narrow molecular weight distribution. Small amounts of LCB in hom-BEAO very effectively reduce the average viscosity and also improve the flow stability. Both hom-LEAO and hom-BEAO, unlike het-LEAO, have thermodynamic properties similar to BLDPE. © 1996 John Wiley & Sons, Inc.     

A study on the applicability of vibration in fresh high fluidity concrete

The introduction of superplasticizers (Sp) in the production of concrete has produced highly flowable mixtures with enhanced viscosity. In cases of optimum flowability and viscosity, for example self-compacting concrete (SCC), no vibration is necessary for placement. However, such ideal conditions are not practically easy to achieve and deviations are possible. This paper reviews the results of a study to investigate the vibration of such high fluidity concrete. Two criteria were used to characterize the fresh mix, that is, slump flow and V-funnel time (V-time). Firstly, the feasibility of vibration on such mixes was studied. Then, the significance of flowability and viscosity was determined. Next, the relationship between workability and its segregation tendency was investigated. Finally, concrete mixes that missed SCC criteria were vibrated. Three different scenarios of vibration were concluded: namely, mix that accept vibration freely, mix that required controlled vibration and mix that needed prior treatment of viscosity enhancing agent (VEA) before vibration.     

Simultaneous extrusion process of projector carbons

The importance of viscosity in the control of wet mixing of both shell and core mix used in projector carbon is discussed. It has been shown that the parallel plate viscometer can be used to control the wet mixing by subjecting random samples of the mix to plastic viscosity and yield stress test. This test is more important for core mix than for shell mix. It is always desirable to use binder content less than the optimum for coremixes. One can use slightly more than optimum for the shell mix to obtain a proper case of extrusion. Under these conditions simultaneous extrusion of both core and shell mixes is feasible.     

偶联剂与等离子体协同表面处理对聚乙烯木塑复合材胶接性能的影响

采用硅烷偶联剂涂覆与等离子体协同处理的方法,对聚乙烯木塑复合材料进行表面处理以改善其胶接性能。研究了硅烷偶联剂浓度、等离子体处理时间、等离子体喷头距试件的处理距离对胶接强度的影响,优化了协同处理工艺。利用接触角测试、红外光谱分析研究了协同表面处理前后材料的表面性质变化,并对胶接接头的耐水性能进行了测试。结果表明:利用偶联剂涂覆和等离子体的协同处理,可以既提高胶接强度,又改善胶接接头的耐水性能。协同处理受偶联剂涂覆和等离子体处理的工艺因素影响较大,选取的优选处理工艺为偶联剂浓度为5%、等离子体处理时间为30s、处理距离为30mm。     

Shape memory effect of ethylene–vinyl acetate copolymers

Crosslinked ethylene–vinyl acetate (EVA) copolymers with VA content of 28% by weight were prepared by a two‐step method by evenly dispersing the crosslinking agent (dicumyl peroxide) into the EVA matrix and then crosslinking at elevated temperatures. The crosslinking features of the samples were analyzed by Soxhlet extraction with xylene and dynamic mechanical measurements. All the samples were crystalline at room temperature, and the chemical crosslinks seemed to have little effect on the melting behavior of polyethylene segment crystals in the EVA copolymers. The shape recovery results indicated that only those specimens that had a sufficiently high crosslinking degree (gel content higher than about 30%) were able to show the typical shape memory effect, a large recoverable strain, and a high final recovery rate. The degree of crosslinking can be influenced by the amount of the peroxide and the time and temperature of the reaction. The response temperature of the recovery effect (about 61°C) was related to the melting point of the samples. The EVA shape memory polymer was characterized by its low recovery speed that resulted from the wide melting range of the polyethylene segment crystals. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1063–1070, 1999     

中间包碱性干式振动料的研制与使用

以电熔镁砂或中档镁砂为主原料(骨料与基质料的质量比为65∶35),研究了有机结合剂、烧结剂以及改性剂的种类和数量对碱性干式振动料性能的影响。结果表明:分别以电熔镁砂或烧结中档镁砂为主原料,加入6%的酚醛树脂结合剂JA,2%的偏磷酸盐烧结剂SA和3%的含Al2O3的改性剂GB,研制的碱性干式振动料使用性能优良,并在多家钢厂的中间包上得到成功试用,最高使用寿命达55h,能较好地满足中间包长寿化的要求。     

Study of interphase in glass fiber–reinforced poly(butylene terephthalate) composites

It is well known that application of a coupling agent to a glass fiber surface will improve fiber/matrix adhesion in composites. However, on commercial glass fibers the coupling agent forms only a small fraction of the coating, the larger part being a mixture of processing aids whose contribution to composite properties is not well defined. The interfacial region of the composite will therefore be affected by the coating composition but also by the chemical reactions involved in the vicinity of the fiber and inside the surrounding matrix. The main feature of this study consists in dividing the interface region into two separate regions: the fiber/sizing interphase and the sizing/matrix interphase. A wide range of techniques was used, including mechanical and thermomechanical tests, infrared spectroscopy, gel permeation chromatography, carboxyl end group titrations, extraction rate measurements, and viscosity analysis. Experiments were performed on poly(butylene terephthalate) composites and results indicate that the adhesion improvement is due to the presence of a short chain coupling agent and of a polyfunctional additive, which may react both with the coupling agent and the matrix. According to the nature of this additive, it may be possible to soften the interphase and then to increase the composite impact strength.     

Effect of inorganic fillers in binary processing aids on the rheology of a metallocene linear low‐density polyethylene

Inorganic fillers including porous diatomite, flaky talc, and spherical calcium carbonate were blended with polyethylene glycol (PEG) to prepare binary processing aids, and the effect of varied binary processing aids on the melt flow properties and extrudates distortion of a metallocene linear low‐density polyethylene (mLLDPE) was studied. It was found that the binary processing aids exhibit better effect on viscosity reduction of mLLDPE than that obtained when PEG was added alone. The morphology of inorganic fillers influences the effect of binary processing aids. The diatomite/PEG binary processing aid shows the most noticeable effect, followed by the talc/PEG binary processing aid, and then the calcium carbonate/PEG binary processing aid. The influence of particle size of the diatomite on the effectiveness of the diatomite/PEG binary processing aid was also studied. The mechanism for the improved effect of binary processing aids on reducing viscosity of mLLDPE was proposed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1824–1829;2005     

中频感应炉用刚玉质干式捣打料烧结性的研究

分析了某进口刚玉质干式捣打料的化学组成、粒度组成及相组成 ,对比研究了该干式捣打料与添加不同烧结剂的自配试样的烧结性能。结果表明 :此种刚玉质干式捣打料不能单纯追求高强度 ;烧结剂以高温烧结剂为宜 ,加入量不能太高 ,烧结层的扩展和强度的升高应缓慢进行 ,这样才有利于提高材料的使用寿命     

Rheological and mechanical performance of ethyl‐vinyl acetate/poly(vinyl chloride) formulations

A range of powdered ethyl‐vinyl acetate (EVA) copolymers and poly(vinyl chloride) (PVC) formulations were compounded at PVC:EVA ratios of 100:0, 60:40, 50:50, 40:60, and 0:100. Two grades of EVA with 20% and 27% of vinyl acetate (VAc) (EVA I and EVA II) and two grades of PVC with K values of 56 and 71 (PVC I and PVC II) were used in the investigation. Mechanical analysis was performed on injection molded samples of these blends, and the results showed that the tensile and flexural moduli decreased significantly with increasing EVA concentration. Rheological analysis was performed by using dual capillary rheometry, and the results showed only slight changes in shear viscosity with increasing EVA content, even at lower shear rates. Dynamic mechanical thermal analysis showed partial miscib lity of the PVC and EVA over the range of concentrations studied.     

Determination of pressure drop for concentrated suspension in a capillary flow

The rheological behavior of concentrated suspension melts in a capillary die is investigated. Particle migration and wall slip are two major factors affecting the flow behavior. A numerical model is proposed to describe the coupling effect of particle migration and wall slip in a capillary tube flow, incorporating a power‐law model for binder viscosity and a concentrated suspension viscosity model proposed by Krieger. Wall slip of a non‐Newtonian concentrated suspension is characterized by a modified Mooney method for which the conventional Mooney method is not applicable. We characterized the flow behavior of a concentrated suspension of a non‐Newtonian binder, EVA 460 (ethylene vinyl acetate), mixed with spherical glass beads of 40% by volume. Predicted results were compared with experimental observations, with good agreement. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Understanding the Compatibility of the Energetic Binder PolyNIMMO with Energetic Plasticizers: Experimental and DFT Studies

The development of energetic binders with suitable energetic plasticizers is required to enhance the mechanical properties and to reduce the glass transition temperature of propellant and explosive formulations. The compatibility of the energetic binder poly(3‐nitratomethyl‐3‐methyloxetane) (polyNIMMO) with five different energetic plasticizers viz. bis(2,2‐dinitro propyl)acetal (BDNPA), dinitro‐diaza‐alkanes (DNDA‐57), 1,2,4‐butanetriol trinitrate (BTTN), N‐N‐butyl‐N ‘(2‐nitroxy‐ethyl) nitramine (BuNENA) and diethyleneglycoldinitrate (DEGDN) was studied by differential scanning calorimetry (DSC), rheology, and DFT methods. The results obtained for the pure binder were compared with the results obtained for the binder/plasticizer blend in regard of the decomposition temperature and the format of the peak indicated the compatibility of polyNIMMO with the plasticizers. The glass transition temperatures of the blends were determined by low temperature DSC and showed desirable lowering of glass transition temperature with single peak. The rheological evaluation revealed that the viscosity of the binder is considerably lowered by means of flow behavior upon addition of 20 % (w/w) plasticizer. The addition of BuNENA and DEGDN has maximum effect on the lowering of viscosity of polyNIMMO. The predicted relative trend of interaction energies between plasticizer and binder is well correlated with the corresponding trend of viscosity of binder/plasticizer blends. These experimental studies verified by theoretical methods are valuable to design practical blends of new plasticizers and binders.     

Polyethlene-modified bitumen for paving applications

In cold regions, transverse cracking of asphaltic paving materials is a serious problem which has not been completely resolved despite much effort. In this investigation, the low temperature stress–strain properties of bitumen containing dispersed polyethylene were measured over the temperature range from ?40 to 0°C and compared with unmodified bitumen in an attempt to develop a tougher, more ductile crack-resistant binder for paving materials. Several grades of polyethylene were individually dispersed in liquid, heated bitumen to produce therein colloidal suspensions of polyethylene. The viscosities of these suspensions were determined at various temperatures and concentrations for each grade of polyethylene. Despite rather large differences in composition, molecular weight, and crystallinity of the polyethylenes, the differences in viscosity at the same concentration were relatively minor. However, the viscosity was very sensitive to the polyethylene concentration and the mixture became difficult to process at concentrations greater than 10 percent by weight. Thesee hot mixtures were then cast into rectangular beams for flexural testing at temperatures below zero degrees Celsius. Near the optimum polyethylene concentration of 8 percent by weight, the bitumen mixture possessed increased flexural strength, increased flexural modulus, increased elongation, and increased fracture energ at temperatures near ?30°C. In one example the energy to fracture was increased ninefold compared to a standard 80/100 pen. bitumen control at ?20°C. Mix design results are presented for a typical aggregate and compared with a MTC HL4 hot-mix paving formulation which is used extensively throughout Ontario. The polyethylene-modified asphalt concrete mix displayed a curious increases in both the Marshall flow and the Marshall stability values. Dynamic mechanical measurements confirmed the expected increase in resilient modulus at temperatures above zero degrees Celsius. The Marshall briquets containing polyethylene also exhibited slightly greater wet strength retention after prolonged immersion in water. These observations are consistent with the published data for commercial Novophalt paving materials developed in Austria and predict that the use of polyethylene in asphaltic hot-mix paving materials can extend service temperature range at both high and low temperatures, thereby simultaneously reducing both pavement distortion (rutting) and low-temperature cracking, so that pavement lifetimes can be more than doubled. The cost of such modification can be substantially reduced if scrap or reclaim polyethylene is employed instead of virgin polyethylene. Dispersing agents, such as Shell Chemical Kraton G block copolymers were advantageously employed to control the emulsion stability, particle size, and compatibility of the dispersed polyethylene phase.     

i-PP/HDPE blends. III. Characterization and compatibilization at lower i-PP contents

The mechanical properties of high-density polyethylene (HDPE)-rich i-PP/HDPE blends were studied. Two grades of HDPE were investigated, one with a melt viscosity close to that of the polypropylene (PP) and the other having a much lower melt viscosity. Compatibilization of the 10/90 i-PP/HDPE blend with three copolymers (an ethylene/propylene/diene [EPDM] copolymer and two ethylene/vinylacetate [EVA] copolymers, differing in their VA content) was also investigated. Blends of PP with the low melt viscosity HDPE displayed poor mechanical properties. It was not possible to improve these properties sufficiently with EPDM or EVA. In the case where viscosity matching was achieved between PP and HDPE, addition of i-PP (up to 30%) to HDPE resulted in a large drop in the impact strength of the blends, compared to that of the neat HDPE. A large drop (>50%) was also observed in the ultimate tensile elongation. However, the flexural modulus, yield stress, and ultimate tensile strength all increased with the introduction of i-PP into HDPE. Modification of these blends with an EPDM resulted in the return of all properties to values very close to those of the neat HDPE. The ultimate tensile elongation of the EPDM-modified i-PP/HDPE blend even exceeded that of the virgin HDPE. It was also found that although EVAs can be used to compatibilize these blends these additives were not as effective as was the EPDM. © 1996 John Wiley & Sons, Inc.