Modification of Poly(Vinyl Chloride) for Biocompatibility Improvement and Biomedical Application-Review

Poly(vinyl chloride) is widely used in biomedical devices. This review deals with various applications of PVC and modified PVC in the medical field. Blended, grafted, and plasma-treated modified PVCs are described for various medical applications. Plasma treatment of PVC devices is a versatile and useful method for changing the surface properties, as compared to blending and grafting.     

Ultra-high molecular weight PVC resins

Ultra-high molecular weight PVC resins have properties similar to conventional homopolymer resins, except for a few significant differences. Compounds utilizing these polymers display improved toughness qualities and utility in a wider temperature range. These upgraded properties, combined with the usual advantages of PVC such as colorability, processability, and chemical resistance, should permit these PVC compounds to enter markets previously excluded. New potential markets suggested are footwear utilizing the lighter weight advantage of these tougher compounds, automotive under-the-hood applications that employ the broader temperature properties, and replacements for elastomers in gasket and compounds used in automotive and appliance applications.     

PVC新型改性剂AS的合成与应用

本文主要介绍ＰＶＣ新型改性剂ＡＳ树脂的合成方法、产品性能及其在ＰＶＣ异型材、管材、注射、压延片等加工领域中的应用。实验结果证明：该产品完全可以代替ＡＣＲ加工助剂，并有很好的经济效益。     

An innovative plasticizer for sensitive applications

Di(isononyl) cyclohexane‐1,2‐dicarboxylate (HEXAMOLL® DINCH) is a new plasticizer for PVC. In the tests used, it has no indication of toxicity or genotoxicity; it is biodegradable; and it has low sensitizing properties. Its properties in PVC compare favorably to those of other plasticizers having well‐balanced properties. This plasticizer should be well‐suited for sensitive applications.     

Antioxidants and UV stabilizers: A summary of their utilization in PVC

With the ever increasing demand for better performing products has come the enhanced use of stabilizers and stabilizer systems in both the production and processing of poly(vinylchloride). Antioxidants and chain terminators are commonly used in teh resin manufacturing to improve the initial color and overall quality of the polymer isolated from production. Hindered phenolics and organophosphites have been found to boost the performance of thermal stabilizers for PVC processing. Additionally, as both rigid and flexible PVC compounds have found greater and more demanding weatherable applications both indoors and outdoors, the utilization of UV stabilizers has grown proportionally. For most outdoor applications the UV stabilizer system is essential for the maintenance of color and mechanical properties of the PVC product. This paper attempts to review and discuss stabilizer usage for specific PVC formulations and applications and answer questions as to how and why they are used.     

Glutarimide acrylic copolymer: A new route to high heat PVC

PVC is the second largest polymer produced and used in the U.S. It is a self-extinguishing material with excellent chemical resistance and good dimensional stability. It's greatest asset, however, is it's versatility. By specifically formulating PVC with the numerous types of additives available, a balance of properties can be tailored for a wide range of applications. The most serious disadvantage of PVC is it's low heat resistance which limits the service temperature of finished articles to about 70°C. Now an additive is available that can be formulated with PVC to form miscible, transparent blends with increased service temperature. With proper formulating, the higher HDT can be achieved without sacrificing other properties. It is especially important in clear PVC applications where no increase in haze was noted with the addition of the acrylic imide copolymer. Indications are that substantial market opportunities exist for a high heat PVC. Major market segments include clear packaging with it's need for hot-fill containers, building products where the desire to use darker colors provides the driving force, and in custom injection molding applications where improved heat resistance would allow vinyl to compete more effectively with FR-styrenics.     

稀土改性的PVC加工助剂应用研究

披露了一种稀土改性的新型PVC加工助剂(WAC)。比较了WAC和ACR等加工助剂的加工性能,机械力学性能。在管材、注塑件方面等进行了应用试验。WAC合成工艺先进,性能优异,可广泛用于PVC制品的各种加工。结果表明WAC比ACR塑化能力强,并兼具热稳定性、润滑性及偶联、增容作用,可改善制品的初期白度及表面光洁度。     

The all-acrylic weatherable impact modifier for PVC

Rigid poly (vinyl chloride), PVC, is finding increasing use in outdoor applications as a replacement for conventional materials such as wood, aluminum, steel, and other materials. Formulating PVC for outdoor applications requires special attention to several essential properties in order to achieve the high-quality standards needed over a long period of time. One area that needs modification in a rigid PVC formulation for outdoor applications is toughness. Impact modifiers used to improve the toughness of PVC in outdoor use are CPE, EVA copolymers, and acrylates. The all-acrylic weatherable impact modifier is designed especially to modify PVC for outdoor use and ease of processability. We will review its key performance features with special emphasis on the processing advantages of the all-acrylic impact modifier. The study of the influence of processing conditions on the physical performance of weatherable PVC compounds in a Ba/Cd stabilized window profile shows an acrylic modifier to give consistently high toughness over a wide temperature range and shearing friction.     

Poly(vinyl chloride) in medical device and packaging applications

Poly(vinyl chloride) (PVC) is the leading polymeric material used in medical device and packaging applications in terms of total volume consumed. It offers a uniquely broad range of properties for a wide variety of applications in the medical and health care industry. It fulfills an extensive range of performance and processing requirements such as gloss, transparency, chemical resistance, scuff resistance, flexibility, bondability, sterilizability by steam, ETO, or high energy irradiation. This paper examines fundamental chemsitry and physical structure of PVC to provide a clear insight and a better understanding on how versatile properties and performance are rendered. The paper also illustrates how specific mechanical and thermal properties can be tailored via compounding and fabrication processes to serve specific purposes in medical applications.     

PVC wood: A new look in construction

As a result of the increasing environmental concern for forest protection, there is a rapidly growing demand for alternatives to wood products. PVC wood, which includes PVC foam and PVC/wood flour composite, shows improved performance over wood in the following properties: termite resistance, weathering aging, less moisture absorption, and ease of installation. It can be nailed, screwed, sawed, cut, and glued like wood by conventional tools without any special skills required. Although the bending strength of PVC wood is lower, it can be used for decorative applications, i.e., cornice, door, and siding.     

Mass polymerized PVC in wire and cable applications

Mass (bulk) polymerized PVC is used extensively in rigid extrusion applications on a worldwide scale. However, relatively small quantities are used in flexible products such as wire and cable. This is surprising considering the uniformity of the resin, its highly accessible porosity, and its consistency batch-to-batch. There was concern that mass polymerized PVC would not meet existing specifications. A study was undertaken to determine if mass resin could be used in various wire and cable applications. The results show mass resin compounds may have slightly lower electrical properties but still within specification. Selected physical and aging properties are also satisfactory. Independent testing has confirmed our results. Based on this study, major wire and cable producers are now routinely using mass resin with excellent results.     

Dielectric and electromechanical studies of plasticized poly(vinyl chloride) fabricated from plastisol

Poly(vinyl chloride) (PVC) plastisol is used in many industrial applications and is considered an electrically inactive material. To explore the potential of plastisol as an electroactive material, the dielectric properties, space charge distribution, mechanical properties, internal structure and electromechanical behavior of plasticized PVC (PVC gel) prepared from plastisol by heating were investigated. The gel exhibited a large dielectric constant at low frequencies (1–1000 Hz), an asymmetric charge distribution and excellent mechanical properties. Various DC electric fields were applied to the gel placed parallel between two electrodes and the electrostatic adhesive force to the anode was measured. The results of small‐ and wide‐angle X‐ray scattering suggested that the electromechanical properties of the gel originated from the characteristics of the physical crosslinking distance (ca 20 nm) of PVC in the gel structure. Considering the dielectric properties, space charge density and adhesion force to the anode, PVC gels prepared from plastisol using the heating method have potential for use as electroactive materials. © 2013 Society of Chemical Industry     

Application of Poly(butylenes 2-methylsuccinate) as Migration Resistant Plasticizer for Poly(vinyl chloride)

The bio-based and biodegradable polyester poly(butylenes 2-methylsuccinate) (PBM) was successfully used as a polymeric plasticizer to modify poly(vinyl chloride) (PVC) in this work. The tensile properties, plasticization efficiency estimated by the lowered glass transition temperature and the enhanced elongation at break of the PVC/PBM blends and the migration stability of the PBM were investigated. It was indicated that the migration-resistant property of PVC plasticized with PBM was greatly superior to that with dioctyl phthalate (DOP). Furthermore, the tensile properties were comparable to that of PVC/DOP, indicating that the environmentally friendly PBM can be used as an alternative plasticizer to remove the potential health risks from migrating phthalates during applications.     

Coated metals compatible with PVC jackets for bonded sheath cable applications

Mechanical strength in the cable sheath is particularly valuable for both fiber optical and copper pair cable. By bonding a PVC jacket to a coated metal tape, a mechanically strong sheath construction is obtained. Changes in PVC jacket technologies have created the need for PVC compatible coated metals with greater tolerance for variations in PVC jacketing materials. This need has been met by the development of a variety of coated metals having thermoplastic coatings which adhere to PVC. As a consequence of this development, new cable sheath designs for use in a variety of applications, such as riser cable and direct buried cable destined for local area networks, are possible. These cables may utilize both copper conductors and/or optical fibers for signal transmission. Data will be provided in the paper to show the effects of extrusion process conditions on adhesion for a variety of PVC resins. The properties of a variety of coated metals—aluminum, copper, and steel—will be discussed. Data on environmental tests of adhesion will be presented. Relationships between adhesion, metal characteristics, jacket properties, and mechanical performance of the sheath will be discussed. Cable applications for the PVC compatible metals will be discussed. Data on the performance of the bonded sheath in riser cable and buried local area network cable will be presented. New cable applications where coated metals in the sheath can provide lightweight armoring will also be discussed.     

Effect of injection molding conditions on creep rupture and flex fatigue of rigid PVC

Rigid PVC is used in applications requiring long term performance and is sometimes produced under non-optimal conditions, so that an understanding of the processing variables that affect long-term performance needs to be obtained. In this study, injection molding parameters were varied according to a statistically designed plan to permit construction of predictive equations for creep rupture, flexural fatigue, and environmental stress cracking. The results show that these properties are strong functions of melt temperature, PVC compound formulation, and of the polymer structure formed during molding.     

Reduction of time-releasing ammonia from polymer foam using low acidic polymers

Polymer foams are used in everyday life for industrial and household applications. However, the time-releasing ammonia is environmentally harmful that becomes attractive. Here, we introduce a technically advanced synthetic process for the polyvinyl chloride (PVC) foam, in which the emission of ammonia gas is significantly reduced by using the polymeric acids. The PVC foam has processed with azodicarbonamide (ADCA) as a chemical blowing agent after the solid type polymeric acid is mixed as supporting agent. While the characteristic properties such as specific gravity (density) and chromaticity of PVC foams are not critically changed, the reduction of time-releasing ammonia is up to 85% compared to the PVC foam without polymeric acid. This is attributed to the cell structure with small sub-cells and lots of connecting channels and the chemically capturing ammonia of polymeric acids.     

Poly(vinyl chloride)/styrene-butadiene rubber blends prepared by dynamic vulcanization with nitrile rubber as the compatibilizer

A new kind of thermoplastic elastomer is obtained by dynamic curing of PVC/SBR blends. A compatibilizer is necessary, and of three tested—NBR and two ABSs—NBR-18 is the best. Sulfur and Dicumyl peroxide were chosen as the two different curing agents for the blends. The curing agent and its concentration have a dramatic effect on the mechanical properties. Di(2-ethyl hexyl)phthalate was used as the plasticizer for PVC. Variations in the PVC and di(2-ethyl hexyl)phthalate concentrations can produce materials having a wide range of hardness and strength to meet the needs of different applications. The effects of processing parameters such as blending time and processing temperature and the effect of filler in the blend on the mechanical properties were also investigated. The material, after processing five times, showed no significant changes in physical properties. © 1995 John Wiley & Sons, Inc.     

Highly filled polyolefin plastomer formulations for possible PVC replacement in flooring

Calcium carbonate highly filled composites of a polyolefin plastomer (POP), and its blends with postconsumer linear low‐density or high‐density polyethylene (PC‐LLDPE or PC‐HDPE) were prepared and evaluated. The mechanical properties of compounded POP and its blends were compared with those of a PVC–calcium carbonate formulation used for flooring applications. Tensile and impact properties of calcium carbonate‐filled POP composites compare very favorably to the PVC‐based formulation at filler loadings as high as 200 phr. Moreover, postconsumer LLDPE or HDPE can replace at least 50% of the POP in these composites without affecting their main properties. DSC analyses indicate that the synergism occurring in mechanical properties for some of the blend compositions, may be related to the ability of the individual polymers to cocrystallize in the respective blends. This article presents the results of a preliminary study. Continued research is expected to contribute toward a complete characterization of the compounded POP/postconsumer PE blends to establish if they can replace plasticized PVC compounds in some or all flooring applications. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1156–1168, 1999     

Understanding the functions of acrylic processing aids in rigid PVC injection molding

Poly(vinyl chloride) (PVC) compound use is growing in specialty injection molding applications such as appliances, business equipment, and electrical enclosures. A key factor in determining the appearance and physical properties of the molded parts is the processability of the PVC compounds, which can be improved through the use of acrylic processing aids. Processing aids promote PVC fusion, modify the melt rheology, and/or provide lubrication. Some processing aid products are designed to serve one of these functions while others provide a combination of functions. Each of these functions and its major benefits in rigid PVC injection molding are described. Some guidelines for selecting appropriate processing aid products for applications are provided.     

Factors influencing PVC resin apparent bulk density

Bulk density is one of the easiest measured and most practical physical properties of PVC resins and compounds, especially those used in rigid applications. The paper addresses the importance of bulk density of rigid PVC resins, both regular and antistat, and their compounds. The negative influence of static electricity on bulk density measurement of PVC resins is studied and discussed. Effective static removal and accurate, consistent bulk density measurement is explored through various methods such as compacted bulk density and conditioned bulk density (either by addition of silica, methanol or carbon black, or by treatment with an ionizer).