Unplasticized Polyvinyl Chloride Research Articles

PVC modification with biobased poly(hydroxyalkanoates)

Supported by numerous calculated and empirical data, a miscibility between polyvinylchloride (PVC) and biobased poly(hydroxyalkanoates) (PHAs), PHAs along with its utilization in plasticization, toughening, and processing improvement is discussed in unplasticized and plasticized (semirigid to flexible) PVC compounds. The long-term thermal stability of PVC stabilized with BaZn salts is shown to be improved in the presence of PHAs and the short-term stability (initial color hold) slightly reduced. The biobased PHAs are also shown to improve UV stability of PVC by offsetting the yellowing of PVC and not causing additional photodegradation. The transparence and durability of PVC are found to be unaffected by the presence of minor phase of otherwise biodegradable PHA. The discussed PHAs offer a new, ecologically attractive, and simplified approach to PVC formulation in which multiple processing and modifying additives could be replaced with a single product, eliminating both undesirable additive interactions and the need to stabilize unstable ingredients. J. VINYL ADDIT. TECHNOL., 21:259–271, 2015. © 2014 Society of Plastics Engineers

Impact of drinking water conditions and copper materials on downstream biofilm microbial communities and Legionella pneumophila colonization.

This study examined the impact of pipe materials and introduced Legionella pneumophila on downstream Leg. pneumophila colonization and microbial community structures under conditions of low flow and low chlorine residual. CDC biofilm(™) reactors containing either unplasticized polyvinylchloride (uPVC) or copper (Cu) coupons were used to develop mature biofilms on Norprene(™) tubing effluent lines to simulate possible in-premise biofilm conditions. The microbial communities were characterized through 16S and 18S rRNA gene clone libraries and Leg. pneumophila colonization was determined via specific qPCR assays. The Cu significantly decreased downstream microbial diversity, approximately halved bacterial and eukaryotic abundance, with some groups only detected in uPVC-reactor tubing biofilms. However, some probable amoeba-resisting bacteria (ARB) like Mycobacterium spp. and Rhodobacteraceae were significantly more abundant in the Cu than uPVC-reactor tubing biofilms. In particular, Leg. pneumophila only persisted (postinoculation) within the Cu-reactor tubing biofilms, and the controlled low chlorine residue and water flow conditions led to a general high abundance of possible free-living protozoa in all tubing biofilms. The higher relative abundance of ARB-like sequences from Cu-coupons vs uPVC may have been promoted by amoebal selection and subsequent ARB protection from Cu inhibitory effects. Copper pipe and low flow conditions had significant impact on downstream biofilm microbial structures (on plastic pipe) and the ability for Leg. pneumophila colonization post an introduction event. This is the first report that compares the effects of copper and uPVC materials on downstream biofilm communities grown on a third (Norprene(™)) surface material. The downstream biofilms contained a high abundance of free-living amoebae and ARB, which may have been driven by a lack of residual disinfectant and periodic stagnant conditions. Given the prevalence of Cu-piping in buildings, there may be increased risk from drinking water exposures to ARB following growth on pipe/fixture biofilms within premise drinking water systems.

Selection of Building External Windows in Different Climatic Zones Based on LCA

The area of building external windows is about 30% of the total area in building envelope, but the energy loss of the external windows accounts for over 50% of the building energy. Building external windows is the weakest parts of insulation performance in building envelope. Based on the method of life cycle assessment (LCA), this article deeply surveys and analyzes the resource consumption, energy consumption and pollutant emissions of bridge-cut-off aluminum alloy windows, unplasticized polyvinyl chloride (PVC-U) windows and aluminum-wood composite windows. This article calculates five main environmental impacts of functional unit (per m2) for the three products including the non-renewable resource consumption, energy consumption, greenhouse effect, acidification and eutrophication. The results show that to meet local design standard for energy efficiency and to achieve the same energy-saving effect, the environmental impacts of different climate zones in external windows from low to high are in the following order: unplasticized polyvinyl chloride (PVC-U) windows with 70 series (4 or 5 cavity), aluminum-wood composite windows with 68 series, un-plasticized polyvinyl chloride (PVC-U) windows with 60 series (3 cavity), bridge-cut-off aluminum alloy windows (55-58 series, the height of PA66 from 14.8mm to16.8mm), and bridge-cut-off aluminum alloy windows (65-70 series, the height of PA66 from 22mm to 35mm). This research provides domestic basic data for building external windows and green building.

Microbial diversities (16S and 18S rRNA gene pyrosequencing) and environmental pathogens within drinking water biofilms grown on the common premise plumbing materials unplasticized polyvinylchloride and copper

Drinking water (DW) biofilm communities influence the survival of opportunistic pathogens, yet knowledge about the microbial composition of DW biofilms developed on common in-premise plumbing material is limited. Utilizing 16S and 18S rRNA gene pyrosequencing, this study characterized the microbial community structure within DW biofilms established on unplasticized polyvinyl chloride (uPVC) and copper (Cu) surfaces and the impact of introducing Legionella pneumophila (Lp) and Acanthamoeba polyphaga. Mature (> 1 year old) biofilms were developed before inoculation with sterilized DW (control, Con), Lp, or Lp and A. polyphaga (LpAp). Comparison of uPVC and Cu biofilms indicated significant differences between bacterial (P = 0.001) and eukaryotic (P < 0.01) members attributable to the unique presence of several family taxa: Burkholderiaceae, Characeae, Epistylidae, Goniomonadaceae, Paramoebidae, Plasmodiophoridae, Plectidae, Sphenomonadidae, and Toxariaceae within uPVC biofilms; and Enterobacteriaceae, Erythrobacteraceae, Methylophilaceae, Acanthamoebidae, and Chlamydomonadaceae within Cu biofilms. Introduction of Lp alone or with A. polyphaga had no effect on bacterial community profiles (P > 0.05) but did affect eukaryotic members (uPVC, P < 0.01; Cu, P = 0.001). Thus, established DW biofilms host complex communities that may vary based on substratum matrix and maintain consistent bacterial communities despite introduction of Lp, an environmental pathogen.

Investigation of organic matter migrating from polymeric pipes into drinking water under different flow manners

Polymeric pipes, such as unplasticized polyvinyl chloride (uPVC) pipes, polypropylene random (PPR) pipes and polyethylene (PE) pipes are increasingly used for drinking water distribution lines. Plastic pipes may include some additives like metallic stabilizers and other antioxidants for the protection of the material during its production and use. Thus, some compounds can be released from those plastic pipes and cast a shadow on drinking water quality. This work develops a new procedure to investigate three types of polymer pipes (uPVC, PE and PPR) with respect to the migration of total organic carbon (TOC) into drinking water. The migration test was carried out in stagnant conditions with two types of migration processes, a continuous migration process and a successive migration process. These two types of migration processes are specially designed to mimic the conditions of different flow manners in drinking water pipelines, i.e., the situation of continuous stagnation with long hydraulic retention times and normal flow status with regular water renewing in drinking water networks. The experimental results showed that TOC release differed significantly with different plastic materials and under different flow manners. The order of materials with respect to the total amount of TOC migrating into drinking water was observed as PE > PPR > uPVC under both successive and continuous migration conditions. A higher amount of organic migration from PE and PPR pipes was likely to occur due to more organic antioxidants being used in pipe production. The results from the successive migration tests indicated the trend of the migration intensity of different pipe materials over time, while the results obtained from the continuous migration tests implied that under long stagnant conditions, the drinking water quality could deteriorate quickly with the consistent migration of organic compounds and the dramatic consumption of chlorine to a very low level. Higher amounts of TOC were released under the continuous migration tests.

Investigation of Organic Compounds Migration from Polymeric Pipes into Drinking Water under Long Retention Times

Unplasticized polyvinyl chloride pipes (uPVC), Polypropylene random pipes (PPR) and Polyethylene pipes (PE) for drinking water were tested with respect to migration of total organic carbon (TOC) into water. The investigation was carried out under different long retention times aiming to investigate TOC migration trends of different polymeric pipes over time and the corresponding water quality changes like chlorine decay. Experiment results showed TOC release from all pipes increased significantly over time. PE pipe showed the highest TOC concentrations among all tested pipe materials in this study. Chlorine consumption data observed in this research followed the shape of TOC values.

Geo-Spatial Information for the Location and Maintenance Management of Water Service Pipelines

This study examined the geo-spatial information needed for locating and maintaining water service pipelines. Geo-spatial information about the components of water service pipelines are a sine qua non for their location above, on or under the surface of the earth as well as the effective preventive maintenance of the entire water service pipelines. The Faculty of Engineering water service network in University of Benin, Benin City, was used as a case study. The geo-spatial data of the components of water service pipelines were acquired using Global Positioning System (GPS) receivers, while the attribute data were acquired using a standard checklist. Thereafter, the geo-spatial data (GPS data) were processed, and all the GPS data acquired in geographic co-ordinates were converted to plane rectangular co-ordinates, based on Minna Datum of Nigeria, using INCA GeoMATRIX software. The rectangular coordinates were exported into Autodesk Land development software, and vector model of the water service infrastructure in digital format was produced. A database was designed and created for geo-spatial and attribute information of various components of water service infrastructure (WSI). The study has revealed the locations of the burst pipes and the control valves that were malfunctioning, where the water pumped from the ground level storage reservoir, ooze out and caused artificial water scarcity in the Faculty of Engineering. The burst pipes were replaced with Unplasticised Polyvinyl Chloride (uPVC) pipes since they are nowadays most preferred for water supply piping. The control valves were also replaced with new ones. The GPS coordinates obtained in this study were used to determine the locations of the various components of water service infrastructure (WSI) in the study area. The geo-spatial and attribute information of hydraulic characteristics of the WSI has facilitated the planning, updating, operation and maintenance management of water service scheme in the study area. Furthermore, the study has provided a dynamic water service scheme of the Faculty of Engineering in digital format, which supersedes the existing, static water service scheme that is difficult to update, maintain and in analogue format. The dynamic water service scheme as well as the geo-spatial information of WSI can be updated and maintained regularly.

Characterization of the viscoelastic-plastic properties of UPVC by instrumented sharp indentation

The yielding behavior of glassy polymers may be sensitive to the hydrostatic pressure and also be influenced by the strain rate. Thus, the yield strength is a function of hydrostatic pressure and strain rate instead of a constant. In this paper, using dimensional analysis and finite element simulations, we established a method to estimate the yield strength of glassy polymers by instrumented indentation. Together with the method for determining shear creep compliance proposed in our previous work, the viscoelastic-plastic properties of glassy polymers can be extracted from a single indentation load-depth curve. Applications were illustrated on unplasticized polyvinyl chloride (UPVC). The shear creep compliance and yield strength of UPVC were successfully determined by a single indentation test. Using these parameters, the true stress–strain curves of UPVC under different strain rates were approximately predicted according to a linear viscoelastic-perfectly plastic constitutive description.

Confinement of concrete columns with unplasticized Poly-vinyl chloride tubes

In this paper an experimental study is presented to investigate the effectiveness of UPVC tube for confinement of concrete columns. UPVC tubes having 140 mm, 160 mm and 200 mm external diameters were used to confine the concrete having compressive strength 20 MPa, 25 MPa and 40 MPa. The concrete has been designed using IS code 10262-1982(Reaffirmed -2004) (BIS:10262–1982, Reaffirmed -2004). The testing of the specimens was carried out on a displacement controlled Instron make Universal Testing Machine of 2500 kN capacity. During the experiments mode of deformation and corresponding load-compression curves were recorded and obtained results are compared with the existing models for confined concrete available in the literature. It is found that the predicted capacities of columns using different models are within ±6% of the experimental capacities. It is found that UPVC tubes can be effectively used for confinement of the concrete columns and to enhance their load capacity, ductility as well as energy absorbing capacity.

Charge localization on a polymer surface measured by triboelectrically induced x-ray emission

The means by which charge is exchanged between two surfaces that have been brought into contact is perhaps the longest standing unsolved problem in physics. To this day, it is debated as to whether charging is due to electrons or ions. Contact electrification is such a singular process that it lies beyond the scope of density functional theory and other ab initio theories of material structure. We present a new method for studying the fundamental processes that underlie triboelectrification, based upon the structure of x-ray emission from the interface of separating surfaces. Our measurement of the x-ray spectrum emitted from lead rolling against various thicknesses of unplasticized polyvinyl chloride (uPVC) on top of a grounded conductor indicate that triboelectrification, like turbulence, extends over a broad range of length scales. We observe millimeter-scale charge-patching, which indicates the feasibility of building MEMS x-ray sources.

Failure analysis of a PVC sewer pipeline by fractography and materials characterization

Sewer rising mains are an integral part of wastewater network and convey sewage under pressure between gravity fed systems or from gravity systems to treatment plants. The failure of a rising main can result in significant volumes of sewage being discharged to sensitive environments, significant clean-up costs and severe indirect consequences being incurred.This paper describes the analysis of an Unplasticised Polyvinyl Chloride (PVC-U) pressure sewer (sewer rising main), nominal diameter 200mm, pressure class 12, that failed prematurely after 34years of service considering the design life of >100years. It was hypothesised that the root cause of pipe failure was either material degradation from exposure to an aggressive environment (the conveyed sewage) or an inherent defect in the pipe. To test this hypothesis, a thorough visual examination of the exhumed failed section and the fracture surface was undertaken, followed by Fourier Transform Infrared Spectroscopy, micro-scale examination of the fracture surface using Scanning Electron Microscopy and Energy Dispersive X-ray Spectrometry. Fourier Transform Infrared Spectroscopy showed no evidence of material degradation due to contact with sewage. Visual and micro-scale examination revealed that failure occurred in two major stages initiated at an inherent defect (foreign inclusion) in the pipe wall that was attributed to the original manufacture. In addition to the initiating defect in the pipe wall, numerous other potential stress risers were also identified. The application of an established crack growth model predicted pipe failure close to the observed lifetime. Application of the staged methodology presented is recommended to establish relationships between manufacturing eras of PVC pipes and severity of inherent defects.

Effect of woodstack structure on invertebrate abundance and diversity

Reduced quantities of dead wood in managed forests have resulted in a reduction in the abundance and diversity of saproxylic invertebrates to the extent that many are now considered red list species. To mitigate against this loss, one conservation measure is the provision of dead wood, in the form of piles of chopped logs, i.e. ‘woodstacks’. The heterogeneity and volume of dead wood habitat is considered to be an important component of habitat suitability. However, the value of different wood stack types to invertebrate conservation has rarely been quantified and there is little consensus on how to best to survey the invertebrate fauna of woodstacks. This study used both sticky traps and pitfall traps to sample the invertebrate fauna of three types of sycamore woodstack. Woodstacks were made from 10 logs, 20 logs and 10 scorched logs plus a control woodstack made of unplasticised polyvinyl chloride (uPVC) plastic piping and observed over a 4-week period. A total of 1446 invertebrates from 16 orders, including 127 Coleoptera, were caught during the sampling period. A generalized linear model was used to analyse invertebrate abundance between woodstack and between trap types, and diversity was determined using Shannon diversity indices and analysed using a two-way Analysis of Variance (ANOVA). The woodstack type had no effect on the abundance of invertebrates. However, Shannon diversity was highest on the scorched woodstacks, with little difference between the 10 and 20 log stacks and the control uPVC woodstacks. However, closer inspection of orders revealed the uPVC woodstacks to have the lowest abundance and diversity of Coleoptera. This study suggests that constructing woodstacks can provide suitable habitat for a variety of invertebrates. However, these invertebrates may have simply used the structures for shelter and the true value with saproxylic invertebrates could not be measured in this 4-week study. To fully appreciate the conservation value of woodstacks will require longer term studies that examine how and when saproxylic invertebrates use dead and decaying wood.

Preferential colonization and release of Legionella pneumophila from mature drinking water biofilms grown on copper versus unplasticized polyvinylchloride coupons

Legionella occurrence in premise drinking water (DW) systems contributes to legionellosis outbreaks, especially in the presence of suitable protozoan hosts. This study examined L. pneumophila behavior within DW biofilms grown on copper (Cu) and unplasticized polyvinylchloride (uPVC) surfaces in the presence of Acanthamoeba polyphaga. One year-old DW biofilms were established within six CDC biofilm reactors: three each containing Cu or uPVC coupons. Biofilms were then inoculated with L. pneumophila (uPVC-Lp and Cu-Lp), or L. pneumophila and A. polyphaga (uPVC-Lp/Ap and Cu-Lp/Ap) and compared to sterile water inoculated controls (uPVC- and Cu-Control) over a 4 month period. L. pneumophila appeared more persistent by qPCR within Cu biofilms in the presence of A. polyphaga compared to uPVC biofilms with or without A. polyphaga, but maintained their cultivability in uPVC biofilms compared to Cu biofilms. Also, persistent shedding of L. pneumophila cells (assayed by qPCR) in the effluent water implied colonization of L. pneumophila within Cu-coupon reactors compared to no detection from uPVC-coupon reactor effluent 14 days after inoculation. Hence, L. pneumophila appeared to colonize Cu surfaces more effectively and may be shed from the biofilms at a greater frequency and duration compared to L. pneumophila colonized uPVC surfaces with host amoebae playing a role in L. pneumophila persistence within Cu biofilms.

Optimization‐driven design of dies for profile extrusion: Parameterization, strategy, and performance

AbstractA computational design optimization environment is developed, handling, for the first time, streamline dies used for profiles in unplasticized polyvinyl chloride (uPVC) having multiple complex features, as well as simpler designs. Die cavity cross sections are described by planar contours, such as the cutting paths for wire electrical discharge machining of the plates from which streamline profile dies are constructed. Contours are parameterized using key points, and by joining the contours with ruled surfaces, the three‐dimensional geometry can be reconstructed. For the optimization a developed flow analysis on each die cross section is used with the avoid‐cross‐flow strategy. Cross sections are partitioned and the die is balanced to obtain the required flow rate through each. A robust and efficient parallel decoupled optimization strategy is developed. In application to a uPVC window profile, five cross sections were optimized. The number of design variables on each ranged from 2 to 46, and the cross section optimizations converged within one to seven cycles. Compared with the work of an experienced designer making manual changes to the computer‐aided design model, guided by computational fluid dynamics analyses, the design quality was comparable or better and computational demands similar; however, the time required from the designer was reduced seven times. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Computer-aided design and optimization of profile extrusion dies for thermoplastics and rubber: a review

A review is provided of issues and techniques in design and optimization of profile extrusion dies for thermoplastics and rubber, with particular emphasis on unplasticized polyvinyl chloride and rubber compounds. Traditional profile die design methods are contrasted with computer-based ones, with respect to efficiency and economic benefits. The main types of die construction are outlined. Physical phenomena relevant to the design and performance of dies are summarized, including: rheology and kinematics of the flow, wall slip, extrusion instabilities, residence time and degradation, extrudate swell, draw-down, and thermal effects. Approaches and strategies for die design are explained, including: flow balancing – with guidance from analytic flow results, the Avoid-Cross-Flow strategy, use of flow separators, and designing for extrudate swell. Published computer simulations of die flow used to assist with design are reviewed. Introducing automatic die design, the structure and elements of a computerized design optimization environment are set out. Key components and options within this are described, including: objective functions, constraints, design variables, optimization algorithms, design parameterization and flow domain meshing, and optimization strategies. Published implementations of computerized profile die design optimization are described. Automatic design optimization is compared with the work of a designer assisted by flow simulations in the industrial environment, showing how substantial reductions in demands on the designer's time are possible. The nature and potential of robust design is outlined, with techniques for its implementation. Conclusions are drawn as to the present state of the art in computer-assisted profile die design and optimization, and potential advances.

Effect of Low Molecular Weight Additives on Immobilization Strength, Activity, and Conformation of Protein Immobilized on PVC and UHMWPE

Horseradish peroxidase (HRP) was immobilized onto both plasticized and unplasticized polyvinylchloride (PVC) and ultrahigh molecular weight polyethylene (UHMWPE). Plasma immersion ion implantation (PIII) in a nitrogen plasma with 20 kV bias was used to facilitate covalent immobilization and to improve the wettability of the surfaces. The surfaces and immobilized protein were studied using attenuated total reflection infrared (ATR-IR) spectroscopy and water contact angle measurements. Protein elution on exposure to repeated sodium dodecyl sulfate (SDS) washing was used to assess the strength of HRP immobilization. The presence of low molecular weight components (plasticizer, additives in solvent, unreacted monomers, adsorbed molecules on surface) was found to have a major influence on the strength of immobilization and the conformation of the protein on the samples not exposed to the PIII treatment. A phenomenological model considering interactions between the low molecular weight components, the protein molecule, and the surface is developed to explain these observations.

Properties of Kenaf Filled Unplasticized Polyvinyl Chloride Composites

Combination of lignocellulosic fiber with thermoplastic is leading to the new areas of research in plastic composite field. Due to the problem of petroleum shortages and encouragement for reducing the dependence on fossil fuel products, thus increased the people interest in maximizing the utilize of renewable materials like kenaf fiber. By adding optimum natural fiber to thermoplastics could provide some cost reduction to the world of plastic industry as well as to dominance the agro-based industry. With a view to identifying the effect of fiber content and effect of coupling agent in kenaf fiber reinforced unplasticized poly (vinyl chloride) (UPVC) composite on the mechanical properties, the fiber and matrix mixture were mixed with poly [methylene poly (phenyl isocyanate)] (PMPPIC) using thermal mixing process followed by compression molding technique for the composite preparation that required for tensile characteristic (ASTM D638). The fiber loading were 10%, 20%, 30%, and 40% in weight. Since the kenaf fiber and UPVC are chemically different, the compatibility and dispersability of kenaf fiber in UPVC can be improved by lowering the surface energy of the fiber to make it less polar, consequently more similar to the plastic matrix. Generally, PMPPIC act as a bonding agent that facilitates the optimum stress transfer at the interface between fiber and matrix which gives an optimal mechanical performance of kenaf fiber reinforced UPVC composites. Meanwhile, the addition of 30% fiber contents with PMPPIC was successful to enhance the tensile properties and the efficiency of PMPPIC was verified using Fourier Transform Infra-Red (FTIR) spectroscopy.

Plastic pipe pressures in siphonic roof drainage systems

Siphonic roof drainage is a highly efficient type of drainage system that is particularly suitable for large buildings and other structures over approximately 4 m in height. Although siphonic roof drainage systems are enjoying ever-increasing popularity with architects, there is still some uncertainty regarding the minimum pipe pressure class required for siphonic pipework, especially in tall buildings. This is particularly the case in warmer countries since higher temperatures can drastically decrease the strength of the pipework material used in siphonic systems – typically unplasticized polyvinylchloride (PVC-U) and high-density polyethylene (HDPE). However, there is very limited information available on how plastic pipes behave under the sub-atmospheric pressures that occur under operating conditions in siphonic systems. This paper describes experiments conducted to investigate sub-atmospheric pressures in siphonic systems and how they may be controlled by injecting air into vertical downpipes. Recommendations for minimum pipework pressure classes are provided together with methods for limiting the minimum pressures without significantly decreasing the system capacity. This paper will help engineers design siphonic systems with more confidence so that such systems will continue to perform adequately over their intended design life. L’évacuation siphonique des eaux de toit est un type de système d’évacuation des eaux hautement performant, qui est particulièrement adapté aux grands immeubles et autres structures dépassant 4 m de hauteur environ. Bien que les systèmes d’évacuation siphonique des eaux de toit bénéficient d’une popularité sans cesse croissante auprès des architectes, il existe encore quelque incertitude quant à la classe de pression minimale des tuyaux nécessaire pour les tuyauteries siphoniques, surtout dans les grands immeubles. Ceci est tout particulièrement le cas dans les pays plus chauds, dans la mesure où des températures plus élevées peuvent considérablement réduire la résistance du matériau utilisé pour les tuyauteries dans les systèmes siphoniques – généralement du polychlorure de vinyle non plastifié (PVC-U) et du polyéthylène haute densité (PEHD). Les informations disponibles sont cependant très limitées concernant la manière dont se comportent les tuyaux en plastique soumis aux pressions sub-atmosphériques qui se rencontrent dans les conditions de fonctionnement des systèmes siphoniques. Cet article décrit des expériences conduites afin d’étudier les pressions sub-atmosphériques dans les systèmes siphoniques et la façon dont elles peuvent être contrôlées en injectant de l’air dans les tuyaux de descente des eaux pluviales. Des recommandations concernant les classes de pression minimales des tuyauteries sont fournies, ainsi que des méthodes pour limiter les pressions minimales sans abaissement significatif de la capacité des systèmes. Cet article aidera les ingénieurs à concevoir avec plus d’assurance des systèmes siphoniques de façon à ce que ces systèmes puissent continuer à fonctionner convenablement tout au long de leur durée de vie nominale prévue. Mots clés: pression critique de flambage, pression négative, évacuation siphonique des eaux de toit

Influence of Temperature on Compression, Impact Strength and Barreling in Recycled Polyvinylchloride

Izod-type impact and compression tests were carried out on virgin and recycled unplasticized polyvinylchloride (uPVC) for different temperatures, T; from 25oC to 130oC at intervals of 15oC, to determine and compare their impact strength and axial compressive stress (&sigma;z)a, respectively. Appropriate formulae available in literature were used to determine the barreling correction factor; C, and the effective stress at fracture with respect to C; &sigma;eff. Comparison was made between (&sigma;z)a and &sigma;eff to determine the effect of barreling on (&sigma;z)a at fracture for virgin and recycled uPVC. Empirical equations were developed to describe the relationship between T, (&sigma;z)a and &sigma;eff. The results show that under dynamic loading, recycled uPVC exhibit greater impact strength at 70oC (142.86 and 171.43J/m for virgin and recycled uPVC, respectively) and temperatures above 85oC; while 85oC to 100oC is the transition temperature range for change in appearance of break in specimen. Compression test show that except at 85oC, recycled uPVC show greater (&sigma;z)a. Softening temperature (Ts = 85oC) of uPVC was discovered to have significant effect on the impact and compressive behaviour of uPVC. Barreling causes reduction in &sigma;eff for virgin and recycled uPVC by a mean C of 1.2474 and 1.7404, respectively. The relevance of the model was discussed.Keywords: Virgin uPVC, Recycled uPVC, Barreling, Correction factor, Softening temperature

Dynamic Mechanical Behaviour of Banana-pseudostem-filled Unplasticised Polyvinyl Chloride Composites

The dynamic mechanical behaviour of unplasticized polyvinyl chloride (UPVC) and its composites reinforced with banana pseudostem (BPS) fibres has been studied, with special reference to the effect of filler loading and temperature. Dynamic properties such as the storage modulus (E’) and damping behaviour (tan d) were evaluated as a function of BPS volume fraction. It was found that the storage modulus increased with increasing BPS content in the samples. At lower temperatures (in the glassy region), the E’ values of the samples were highest in both unmodified and acrylic-modified BPS/UPVC composites with 40% fibres. The glass transition temperature (Tg) associated with the damping peaks of BPS/UPVC composites reached its highest value at 94.9 °C with 20% fibre loading for unmodified BPS/UPVC composites, whereas, in the case of acrylic-modified composites, CA4 had the highest Tg at 98.7 °C.