氯乙烯共聚弹性体对聚氯乙烯的改性及性能影响

以氯乙烯-丙烯酸丁酯-甲基丙烯酸甲酯共聚弹性体（VCE）增韧改性PVC树脂提高聚氯乙烯（PVC）的抗冲击性能,并与传统抗冲击改性剂甲基丙烯酸甲酯-丁二烯-苯乙烯共聚物（MBS）、ACR及氯化聚乙烯（CPE）改性的PVC材料比较。对改性PVC的流变性能、力学性能、热变形性能及断面结构进行表征和微观观察。结果表明,随着VCE含量的增加,PVC的拉伸强度与弯曲强度逐渐减小,抗冲击强度与断裂伸长率逐渐增加,热变形温度逐渐降低;在相同用量的条件下,VCE对 PVC的改性效果优于ACR及CPE,达到MBS改性PVC的水平,VCE能够增韧PVC,提高PVC的抗冲击性能,是一种性能优异的新型PVC抗冲击改性剂。     

PVC型材断面结构对落锤冲击的影响

通过对PVC异型材断面结构的分析，讨论PVC异型材的不同断面结构在-10℃下落锤对试样冲击的不同结果。     

聚甲基丙烯酸甲酯包覆纳米CaCO3改性聚氯乙烯研究

研究了聚甲基丙烯酸甲酯(PMMA)包覆纳米CaCO3复合粒子填充聚氯乙烯(PVC)复合材料的加工塑化和力学性能，并与未改性纳米CaCO3的改性效果进行比较。结果发现，填充纳米CaCO3使PVC平衡扭矩和平衡熔融温度均会有所提高，填充未改性碳酸钙增加更大，填充PMMA包覆CaCO3使材料冲击性能提高的幅度大于填充未改性纳米CaCO3，而拉伸强度下降幅度较小。当PMMA包覆CaCO3填充量为8％时缺口冲击强度增加到未改性PVC的194％。冲击缺口断面形态分析表明，采用PMMA包覆CaCO3时，纳米CaCO3在PVC基体中分散均匀、团聚少。     

ACR类冲击改性剂的加工性能研究

简单介绍了用冲击ACR改性的PVC干混料的流变、挤出和加工热稳定性能。实验结果表明：与使用CPE改性的PVC干混料相比，使用冲击ACR改性的PVC干混料具有塑化时间短、塑化扭矩大、塑化温度高的特点。     

附聚SBR制备ABS改性剂及其增韧PVC的性能研究

研究了不同粒径SBR制备的ABS改性剂对PVC增韧的影响，发现随着SBR粒径的增大合金的光学性能降低，而缺口冲击强度呈先上升后下降趋势，当SBR粒径为225nm时达到最大值。考察了NaCl与NaOH体系对SBR附聚的影响，发现相同浓度NaOH的条件下，随着5wt％NaCl用量提高，SBR附聚后粒径显著增加。比较了扩径前后SBR制得的ABS／PVC性能发现：扩径后的SBR制得的ABS／PVC冲击强度上升显著，同时与扩径前小粒径SBR制备的ABS／PVC相比较，其光学性能没有明显下降。     

PVC管结构改良

本实用新型涉及管道技术领域，特指一种PVC管结构改良。在PVC管体的外周表面及内周表面附着有涂料层，不仅增加PVC管各种颜色的光泽度及美观度，而且由涂料层给予PVC管相应的内、外保护，提高耐磨性及防腐性，延长使用寿命，降低成本。     

物料压缩比对PVC凝胶化行为的影响

利用转矩流变仪制备聚氯乙烯(PVC)共混物,研究了物料压缩比对PVC凝胶化行为的影响.结果表明:随着物料压缩比增加,PVC凝胶化速度加快,有利于破碎出更多微米级的初级粒子,在相同外部能量作用下,PVC凝胶化度先增加后降低.PVC共混物在扭矩最低点和最高点存在不同的结构和流动机理.     

对PVC共混物冲击性能的研究

文中筛选出了PVC与SBR的优良增容剂-CPE，研究了SBR对PVC的增韧作用，利用微观冲击仪分析了PVC共混物的冲击断裂行为。     

凝胶化对硬质PVC管质量的影响

PVC树脂粉末在一定温度和剪切力作用下发生凝胶化是硬质PVC在挤出成型加工中的基本行为之一,凝胶程度和凝胶速度对硬质PVC管的质量控制,提高生产效率起着关键作用。实验结果表明,PVC的凝胶程度控制在60～70％之间,能够生产出综合性能最佳的高质量管子。PVC挤出成型期间发生的凝胶作用与其高温粘弹性密切相关。利用流变仪测定粘弹性,是迄今测定凝胶度的较理想方法。PVC的凝胶化不仅影响塑料制品的外观和物化性能,对加工能力也有很大影响。在PVC配合料中掺混高分子加工助剂ACR,能有效地促进PVC凝胶化,明显提高硬质PVC管的质量指标。     

CPE-g-VC共聚树脂结构与性能的关系

采用悬浮溶胀接枝共聚方法合成不同CPE含量的CPE - g -VC共聚树脂 ,对其加工性能和力学性能进行了研究 ,并与PVC、PVC/CPE共混物进行比较。结果表明 :接枝共聚物的加工性能优于PVC和PVC/CPE共混物 ,且其加工性能随CPE含量增加而逐渐改善 ;在CPE含量相同时 ,CPE - g -VC共聚物的冲击强度大于PVC/CPE共混物 ,冲击强度随CPE含量的增加而增强 ;当CPE含量相同时 ,CPE -g -VC共聚物的冲击强度随接枝率增加而增强 ;相近CPE含量的接枝共聚物的屈服强度大于共混物。     

Increasing the flexural modulus of rigid PVC at elevated temperatures

The use of PVC building products in hot climates has demonstrated the need for formulations that exhibit increased stiffness at elevated temperatures. Talc has been used as an additive to increase flexural modulus but this approach can produce an unacceptable drop in impact strength. This report presents the results of laboratory work designed to find ways to increase the stiffness of rigid PVC compounds at elevated temperatures while maintaining their room temperature impact performance. J. VINYL. ADDIT. TECHNOL., 12:37–40, 2006. © 2006 Society of Plastics Engineers     

The performance of ultrafine talc in rigid PVC

This paper demonstrates how ultrafine talc can be used in a rigid PVC formulation to design a compound with increased stiffness and high impact strength. The talc's shape and particle size, combined with the affects of increased levels of impact modifier, produce a PVC material with an outstanding impact stiffness balance. Although more expensive than conventional PVC formulations, it can compete with other resins, such as ABS, in high performance applications.     

Rheology,morphology, and mechanical and thermal properties of recycled PVC pipes

This article demonstrated the possibility of recycling PVC pipes by investigating the effect of adding PVC pipes (varying from 0 to 80 % wt) into two commercial PVC virgin grades on the rheological, morphological, mechanical, and thermal properties of the PVC blends. The results obtained showed an increase in the melt viscosity and no change in the die swell ratio as the concentration of the recycled PVC was increased. The die swell ratio was observed to increase with temperature, this being associated with the presence of gelation that occurred at high temperature. The optimum tensile and impact strengths were detected, the impact strength being explained by use of SEM micrographs of the fracture surface. The hardness result corresponded well to the density of the compounds. The glass transition, degradation, and heat-deflection temperatures were also found to shift with the recycled PVC loading. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2478–2486, 2001     

An introduction to toughened polyamide-4,6

Impact modified polytetramethylene adipamide (polyamide-4,6) has recently been introduced. The author compares this compound to a toughened polyamide-6,6 and a toughened polyamide-6 in selected impact resistance and elevated temperature tests. Based on the results, toughened polyamide-4,6 promises similar impact strength; and, better retention of stiffness, creep modulus, and toughness at elevated temperatures. Apparent improvements in melt stability make it suitable for extrusion, as well as injection molding applications.     

Cell morphology and property relationships of microcellular foamed pvc/wood-fiber composites

Wood-fiber composites make use of cellulose fibers as a reinforcing filler in the polymer matrix and are known to have a lower material cost and a higher stiffness than neat polymers. However, the lower material cost and enhanced stiffness of wood-fiber composites are achieved at the expense of other properties such as the ductility and impact strength. Since microcellular plastics exhibit a higher impact strength, higher toughness, and increased fatigue life compared to unfoamed plastics, microcellular foaming of wood-fiber composites will improve the mechanical properties of the composites and therefore increase the usefulness of the materials. In this paper, microcellular foamed PVC/wood-fiber composites with unique cell morphology and material composition are characterized. Microcellular structures are produced in PVC/wood-fiber composites by first saturating the composite samples with CO₂ under high pressure followed by rapidly decreasing the solubility of gas in the samples. The void fraction of the microcellular foamed PVC/wood-fiber composites is controlled by tailoring the composition of materials and the foaming process parameters. The results indicate that tensile and impact properties of microcellular foamed PVC/wood-fiber composites are most sensitive to changes in the cell morphology and the surface modification of fibers.     

Antiplasticization and transition to marked nonlinear viscoelasticity in poly(vinyl chloride) (PVC)/poly-ε-caprolactone (PCL) blends

Measurements of mechanical damping (tan δ) in the temperature range of ?120° to +120°C at 110 Hz, of uniaxial tensile creep at 25.0° ± 0.5°C covering creep times from 10 to 1000 sec, and of impact strength at 21°C have been carried out for a series of physical PVC/PCL blends in the composition range of 0%–12% by weight of PCL in the blend. With increasing PCL content in the blend, the α-peak of PVC was shifted to lower temperatures and became broadened. The β-peak of PVC was also shifted to lower temperatures and was markedly suppressed. The tensile creep compliance of approximately linear viscoelasticity showed a maximum decrease of 10%, and the impact resistance was reduced 3.5 times when 5% and 12% by weight of PCL, respectively, was blended with PVC. There was also a considerable increase (25%) in stress level at which the transition from approximately linear to markedly nonlinear viscoelasticity occurred when up to 5% by weight of PCL was added to the PVC. These results are attributed to the antiplasticizing effect of PCL on PVC. They support the importance of β-mechanism in the stress-activated processes proposed to be responsible for the appearance of nonlinear viscoelasticity in glassy polymers, and they are in agreement with the pseudocrosslinking concept of antiplasticization. By comparing the antiplasticization behavior of PVC/PCL blends with that of PVC/DOA and PVC/DOS from reported data, it was possible to obtaing an idea of the level of compatibility in the PVC/PCL blends. The results suggest that PCL is partially compatible with PVC.     

Effects of compounding and extrusion variables on degree of fusion and impact strength of PVC window profile

The effects of temperature in twin screw extrusion of a window profile compound have been studied. Compounds were made with and without an acrylic impact modifier. Fusion levels of the extruded profiles were rated from values of the rubbery plateau modulus at temperatures near 110°C. Impact strength was measured at room temperature using notched tensile specimens at 1 m/s jaw separation rate. The impact strength of these materials does not increase with fusion level once an adequate degree of gelation has been achieved. The impact-modified compound shows a dramatic improvement in impact strength when the melt temperature was increased from 319°F to 343°F. A further increase to 365°F had no effect. The compound without impact modifier exhibited no improvements in impact strength over the whole extrusion temperature range. Conflicting reports in the literature on effects of fusion level on impact strength of PVC articles probably reflect different interactions between extrusion conditions and compound composition.     

The appearance retention properties of poly (vinyl chloride) compounds during weathering

Damage to poly (vinyl chloride) (PVC) compounds due to thermal degradation during processing has an important influence on its subsequent weatherability. High melt temperatures and/or high residence times cause white PVC to become more yellow and colored PVC to fade and bleach more upon weathering. If high melt temperatures are used, then short residence times are needed to maintain excellent weatherability. In addition to careful consideration of extrusion conditions, stream-lined equipment is necessary to produce extrudate of uniform thermal history. Also, relatively high thermal stabilizer levels help reduce thermal damage and, therefore, improve weatherability. Impact resistance is better retained when processing occurs at higher melt temperatures. A reasonable compromise between extrusion rate and temperature must be reached to provide for adequate color and impact retention.     

Mechanical,thermal, and water uptake characteristics of woodflour‐filled polyvinyl chloride/acrylonitrile butadiene styrene blends

Woodflour‐filled composites based on polymeric blends of polyvinyl chloride (PVC) and super high‐impact grade ABS were developed. Mechanical, thermal, and water uptake characteristics of the PVC/ABS matrix and their wood composites were evaluated. In the case of PVC/ABS matrix, the blend at a mass ratio of 50/50 rendered the impact strength with a very high value of up to 65 kJ/m², noticeably higher than those of the parent resins, that is, 6 kJ/m² of PVC and 35 kJ/m² of ABS. Dynamic mechanical analysis thermograms showed two distinct glass transition temperatures (T_gs) that shifted toward each other indicating partial miscibility of the blends. Water absorption of the blends after 24 h immersion was low, that is, within the range of 0.04–0.2 wt % and exhibits a behavior closed to pseudo‐Fickian type. The obtained PVC/ABS wood composites exhibited an increase of flexural modulus as well as T_gs with an increase of woodflour content. Finally, impact strength of the PVC/ABS composites was significantly higher than those of PVC composites or polyethylene composites comparing at the same woodflour content. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Reaction injection molding of mica reinforced polyurethane

Reaction injection molded polyurethanes are reinforced with inorganic materials to improve stiffness and structural integrity at elevated temperatures and to reduce the coefficient of thermal expansion. This work describes the reinforcement obtained with an experimental grade of mica designed to achieve low viscosity of mica suspensions in polyol. The effect of mica on properties is essentially identical to that of glass flake (i.e., improved stiffness at the cost of reduced impact strength). Compared to hammer milled glass fiber, mica and glass flakes yield more isotropic, albeit weaker, materials. The study of unreinforced polyurethane shows that mechanical properties (tensile and impact strength, flexural modulus) are approximately proportional to the square of foam density.