Showing papers in "Polymer Engineering and Science in 1970"
TL;DR: In this paper, an approximate theoretical treatment for small compressions of bonded rubber blocks is given, where the component of the compressive force arising from the bonded condition at the loaded surfaces is obtained from a pressure distribution within the block, given by the solution of the corresponding torsion problem.
Abstract: An approximate theoretical treatment is given for small compressions of bonded rubber blocks. The component of the compressive force arising from the bonded condition at the loaded surfaces is obtained from a pressure distribution within the block, given by the solution of the corresponding torsion problem. The bending of blocks is treated in a similar way, the pressure distribution in this case being derived from the corresponding bending stress function. The apparent shear of relatively thick blocks is then treated as a combination of shear and bending displacements. The location of an internal rupture and the deformation at which it occurs are also derived from a critical (negative) value of the pressure developed within the block, at which a small cavity increases indefinitely in size. The corresponding critical deformations are calculated for extension and bending displacements. The shear stresses developed at the bonded surfaces under extension, compression or bending displacements are also evaluated.
224 citations
TL;DR: In this article, a mixture of poly(2,6-dimethyl-1,4-phenylene ether) (PPO) and atactic polystyrene (PS) has been prepared by mechanically mixing powders of the two polymers and subjecting the mixtures to three different thermal treatments.
Abstract: Blends of poly(2,6-dimethyl-1,4-phenylene ether) (PPO) and atactic polystyrene (PS) have been prepared by mechanically mixing powders of the two polymers and subjecting the mixtures to three different thermal treatments. Three different compositions were studied by the dynamic mechanical and DSC techniques. The weight fractions of PPO in the mixtures were 0.25, 0.50 and 0.75. The dynamic mechanical measurements indicate that partial mixing took place but that two distinct phases, one rich in PS and the other in PPO, exist in all the mixtures studied. Each phase exhibits a characteristic relaxation peak associated with the glass transition of that phase. DSC measurements, on the other hand, reveal only a single glass transition apparently characteristic of the PS rich phase in each case. The results indicate that a given type of experiment will indicate compatibility or incompatibility depending upon the size of the molecular process it represents.
152 citations
TL;DR: The recent history of planar reinforced plastic resins, including glass flake, high modulus ceramic flake and continuous vapor coated film composites, is reviewed in this paper.
Abstract: The recent history of planar reinforced plastic resins, including glass flake, high modulus ceramic flake, and continuous vapor coated film composites, is reviewed. The theoretical mechanics of both continuous (film) and discontinuous (flake and ribbon) reinforcements are summarized in simple form. A novel set of design curves is presented from which the lower bound requirements for the flake composite constitutents may be read directly. At the same time, the dependence of the composite ultimate strength on the shear strength of the plastic resin matrix is demonstrated.
The mechanical properties of experimental film and flake composites representative of recent work are reported and compared with the theoretical predictions. In conclusion, the potential of planar reinforced plastic resin composites is discussed and found to be significant for applications where low weight and high isotropic stiffness are required, for example in aero-structural, airfoil, or blade components.
136 citations
TL;DR: In this article, the authors derived the residence time distribution (RTD) functions for screw extruders, based on the "parallel plate" and curved channel flow models, and derived the average strain distribution in the fluid across the channel.
Abstract: The residence time distribution (RTD) functions were derived for screw extruders, based on the “parallel plate” and curved channel flow models. The results indicate a relatively narrow distribution, and they explain several characteristics of screw extruders. The strain distribution in the fluid across the channel was also derived. With the aid of these two functions an average strain of the fluid leaving the extruder was defined. The resulting weighted-average total strain (WATS) provides a quantitative criterion to the “goodness of mixing” in extruders.
119 citations
TL;DR: In this paper, a molecular structure approach was used to study the capillary flow instability resulting in extrudate distortion in polyethylene polymer melts, and it was found that the instability initiates at a critical value of elastic strain energy independent of (average) molecular weight.
Abstract: The capillary flow instability resulting in extrudate distortion has been studied for ethylene polymer melts using a molecular structure approach. It is found that the instability initiates at a critical value of elastic strain energy independent of (average) molecular weight for linear polyethylene. Once the flow breaks down, a slip interface within the melt is formed near the capillary wall, causing an abrupt increase in volumetric throughput. The velocity gradient within the melt remains continuous through the instability, however. Low molecular weight species present in the molecular weight distribution of linear polyethylene tend to suppress slip. Blends of linear and branched polyethylene exhibit instability behavior characteristic of both components throughout the entire range of composition. Results are discussed in terms of specific molecular mechanisms.
86 citations
TL;DR: In this article, a numerical simulation of polymer flow is applied to the injection molding fill process to predict fill lengths and fill times of thin constant crossection cavities, and the simulation sensitivity is explored by performing experimental molding trials with two different cavity thicknesses.
Abstract: This paper illustrates a numerical simulation of polymer flow as applied to the injection molding fill process. The simulation model considers heat conduction and viscous heat generation along with the temperature dependence of the flow parameters to predict fill lengths and fill times of thin constant crossection cavities. This simulation is designed for molding situations where fill is difficult, such as thin cavity sections, long flow length requirements, or difficult-to-process materials. The simulation sensitivity is explored by performing experimental molding trials with two different cavity thicknesses. The thinner cavity illustrated a short shot in all cases with the thick cavity completely filling. The simulation accurately distinguishes between the short shot and fill conditions, although significant error is noted for the length prediction of the short shot and the time-to-fill of the full shot condition.
81 citations
TL;DR: In this paper, the authors examined the flow behaviors of a series of polyvinylchloride (PVC) resins covering a broad range of molecular weight and showed that the influence of temperature on viscosity depends on the temperature range and that the activation energy is not constant but can be approximated by two values, one applicable to low temperatures, the other to high temperatures.
Abstract: The flow behaviors of a series of polyvinylchloride (PVC) resins covering a broad range of molecular weight have been examined at several temperatures. It has been shown that the influence of temperature on viscosity depends on the temperature range. That is, the flow activation energy is not constant but can be approximated by two values, one applicable to low temperatures, the other to high temperatures.
The flow activation energy based on viscosities at constant shear rate decreases as the molecular weight increases. In contrast, the flow activation energy from viscosities at constant shear stress increases with molecular weight.
The fact that the activation energy is dual valued does not seem to be associated with the polymer type. Both emulsion and suspension resins exhibit this behavior. Addition of certain modifiers appears to alter the activation energy at lower temperatures. These observations indicate that the shift in the activation energy in the low temperature range is due to a change in the flow mechanism.
69 citations
TL;DR: In this article, a phase inversion occurred from the U-phase particles in A-phase matrix to the "A-phase in Uphase matrix" at A/U ≑ 30/70 as the U phase content increases.
Abstract: Interpenetrating polymer networks of polyacrylate (A) and poly (urethane-urea) (U) were prepared by mixing lattices of self-curing polyacrylate and urethane-urea prepolymer followed by subsequent curing of each network. The structures of the mixtures were analyzed by the dynamic viscoelasticity and the electron microscopy. It was found that a phase inversion occurred from the “U-phase particles in A-phase matrix” to the “A-phase in U-phase matrix” at A/U ≑ 30/70 as the U-phase content increases.
With increasing A-phase content, tensile strength started to increase and elongation-to-break becomes almost constant after the A-phase formed a continuous phase. This implies that the tensile properties are closely related to the morphological features.
59 citations
TL;DR: In this paper, an empirical equation is presented which describes polymer solution viscosity, over the entire concentration range from a knowledge of intrinsic visco-ity, [η], Huggins constant, k′, and bulk flow visosity of polymer, η0.
Abstract: An empirical equation is presented which describes polymer solution viscosity, η, over the entire concentration range from a knowledge of intrinsic viscosity, [η], Huggins constant, k′, and bulk flow viscosity of polymer, η0. The equation is: where solution viscosity, η, is contained in ηsp. No arbitrary parameters are invoked since b can be evaluated at bulk polymer (C = polymer density) where everything else is known. The equation accurately portrays the viscosity of polypropylene oxide (PPG 2025) from infinite dilution to bulk polymer in a very good solvent (benzene) and in a somewhat poorer (∼ θ) solvent (methylcyclohexane). The hydrodynamic consequences of the thermodynamic interactions between polymer and solvent are reflected in the constants. This equation should be applicable to other polymer/solvent systems, and thus be immediately useful to those working with concentrated polymer solutions.
52 citations
TL;DR: A diffusional model was established to study the kinetics of thermally-induced solid state polycondensation of poly(ethylene terephthalate) diffusion through solid polymer is the rate controlling step when temperature is higher than 210°C and particle size is no smaller than 100 mesh.
Abstract: A diffusional model was established to study the kinetics of thermally-induced solid state polycondensation of poly(ethylene terephthalate) Diffusion through solid polymer is the rate controlling step when temperature is higher than 210°C and particle size is no smaller than 100 mesh The activation energy is 30 Kcal/g mole In polymerizing powders (20-200 mesh), the crystallinity of prepolymer and its changes during the polymerization affect the diffusivity and thus the polymerization rate The diffusivity was found to be linearly proportional to the mass fraction of the amorphous phase in PET polymer
50 citations
TL;DR: In this paper, a new quantitative thermal analysis technique was attempted on ABS and Noryl-type polyblends, where a particular component within a polyblend was identified by its glass transition temperature and the amount of the component was determined from the increase in specific heat at the transition temperature.
Abstract: A new quantitative thermal analysis technique was attempted on ABS and Noryl-type polyblends. A particular component within a polyblend was identified by its glass transition temperature and the amount of the component was determined from the increase in specific heat at the glass transition temperature.
Two commercial Noryl resins were determined to be blends of high impact polystyrene and polyphenylene oxide in 47-47 and 69-17 proportions by weight, respectively. Polystyrene appears to be cosoluble with polyphenylene oxide without the formation of any complex. The PS-PPO polyblends yield single sharp glass transitions which are a function of concentration.
TL;DR: In this article, the transport kinetics and equilibrium concentrations of n-pentane at high penetrant activities in cast, annealed polystyrene were determined and compared with similar measurements in biaxially-oriented poly styrene.
Abstract: The transport kinetics and equilibrium concentrations of n-pentane at high penetrant activities in cast, annealed polystyrene were determined and compared with similar measurements in biaxially-oriented polystyrene. The rate of Case II (relaxation-controlled) sorption in biaxially-oriented polystyrene is three to four times faster than the sorption rate in cast, annealed polystyrene. The Case II sorption process in biaxially-oriented polystyrene is more highly temperature dependent than in cast, annealed film. The higher activation energies coupled with the larger relaxation-controlled sorption rates in biaxially-oriented polystyrene imply the involvement of larger polymer segments in the rate controlling polymer relaxations. The sorption in cast, annealed polystyrene was a position-dependent relaxation controlled transport process; in contrast the sorption in biaxially oriented polystyrene, albeit relaxation-controlled, was not position dependent. The position dependence of the Case II sorption appears to be a consequence of the presence of residual benzene in the film which accelerates the rate-determining relaxations. Desorption measurements at very low penetrant activities were quite similar for both biaxially oriented and cast, annealed polystyrene. The desorption kinetics were Fickian and were only a weak function of polymer orientation at these low activities.
TL;DR: In this paper, the authors measured the impact strength of a series of two-phase polymer systems over a wide range of temperatures, including polyvinylchloride (PVC) and ABS polymers.
Abstract: Notched Charpy impact strengths of a series of plasticrubber two-phase polymer systems were measured over a wide range of temperatures. Blends of polyvinylchloride and rubbers with varying chemical structures, and several ABS polymers were investigated.
In all systems, Charpy impact strength began to increase near the Tg of the rubber component followed by a logarithmic increase with increasing temperature. The trend is expressed by the following empirical relation:
where I is Charpy impact strength, A and B are constants, and T is the absolute temperature. This equation is applicable between the Tg's of the plastic and the rubber components. The increasing tendency of impact strength, i.e. the B value of the above equation, is depressed mainly by the decrease of the compatibility and/or the interfacial adhesive force between the two phases. Toughening mechanism and the ways of increasing toughness are discussed based on the craze formation mechanism.
TL;DR: When plastics are used for outdoor applications, they often deteriorate fairly rapidly Theoretical explanation is based upon absorption of ultraviolet energy, raising some bonds to an energy level which exceeds their stability, and thus initiating their breakdown, usually involving atmospheric oxidation and sometimes hydrolysis as mentioned in this paper.
Abstract: When plastics are used for outdoor applications, they often deteriorate fairly rapidly Theoretical explanation is based upon absorption of ultraviolet energy, raising some bonds to an energy level which exceeds their stability, and thus initiating their breakdown, usually involving atmospheric oxidation and sometimes hydrolysis as well This theory is satisfactory for many polymers, but does not explain the instability of some polymers which are transparent to ultraviolet, nor the stability of some polymers which contain ultraviolet-absorbing and/or unstable groups Plastics are often stabiliized by addition of ultraviolet reflectors, absorbers, or deactivators, increasing stability sufficiently for outdoor use; theoretical explanation of their protective action is satisfactory when they work, but does not explain their specificity or their failures
TL;DR: Polymeric materials flow at tube entrance, discussing pressure drop and flow birefringent patterns at tapered and sharp entrances as discussed by the authors, and discussing flow patterns at tube entrances.
Abstract: Polymeric materials flow at tube entrance, discussing pressure drop and flow birefringent patterns at tapered and sharp entrances
TL;DR: In this article, the non-Newtonian viscosity of concentrated solutions of a styrene-butadiene-styrene, SBS, block copolymer was measured with a novel capillary viscometer.
Abstract: The non-Newtonian viscosity of concentrated solutions of a styrene-butadiene-styrene, SBS, block copolymer was measured with a novel capillary viscometer. Polymer concentrations ranged from 0.165 to 0.306 g/cc. Apparent shear rates ranged from 1 to 105 sec−1. Five different solvents were employed. All of the flow curves can be reduced to a single master curve with the same shape exhibited by monodisperse polystyrenes and the Graessley theory. The shift factor for the shear rate axis, τ0, approximately parallels the Rouse relaxation time, τR, but shows a residual concentration and solvent dependence not predicted by the Rouse form. For different solvents at the same concentration, better solvents show a minimum relative zero shear viscosity, η0/ηs, and a maximum ratio τR/τ0. It is concluded that all solvent effects are not adequately incorporated into the zero shear viscosity for the purposes of constructing master plots; however, the shape of the master plot is not affected by the solvent or the polymer block structure.
TL;DR: In this article, the retractive force in pure gum elastomers is largely entropic in origin, while reinforcement in silicone rubber-silica systems appears to arise by greatly augmenting the deformational free energy change stored in energetic modes.
Abstract: Increases in modulus, tensile strength, and swelling caused by reinforcing silicone rubber with silica filler were correlated with the thermoelastic parameter, fe/f. A new semiempirical equation of state, containing a generalized front factor, was derived to explain the experimental results. While the retractive force in pure gum elastomers is largely entropic in origin, reinforcement in silicone rubber-silica systems appears to arise by greatly augmenting the deformational free energy change stored in energetic modes.
TL;DR: In this article, the authors compared relaxation modulus curves for monodisperse and polydisperse polystyrenes and showed that the significant effect of molecular weight distribution on these curves is shown.
Abstract: : Relaxation modulus curves for monodisperse and polydisperse polystyrenes are compared and the significant effect of molecular weight distribution on these curves is shown. An empirical three-parameter equation is shown to describe well the stress relaxation behavior of monodisperse polystyrenes. New data for high molecular weight monodisperse polystyrenes are presented and used to extend the applicability of previous quantitative relations for higher molecular weights. The stress relaxation technique is shown to be sensitive to the type of plasticizer used at low concentrations. (Author)
TL;DR: In this article, the dynamic mechanical properties of low-density polyethylene melts were measured as a function of frequency and temperature using the Orthogonal Rheometer and the results were expressed in terms of the components G′ and G″ of the dynamic modulus and the components η′ and η″ of dynamic viscosity.
Abstract: The dynamic mechanical properties of low-density polyethylene melts were measured as a function of frequency and temperature using the Orthogonal Rheometer. These results were expressed in terms of the components G′ and G″ of the dynamic modulus and the components η′ and η″ of the dynamic viscosity. The functions J′, J″, η*, and G* were also calculated from the results.
The method of reduced variables or time-temperature superpositions was attempted on the results. The classical method was found to require modification to be applied to these low-density polyethylenes. From this modified form of the reduced variables technique, the temperature dependence of the elastic and viscous parts of the response could be separated.
The experimentally determined temperature dependence of the elastic part of the response was found not to be in accord with the accepted theory of rubber elasticity.
The temperature dependence of the viscous part of the response is discussed in terms of the concept of flow activation energy, and clarification of this term is explored. It is concluded that the temperature dependent properties of polymer melts are best compared at equivalent time scales of response in the non-Newtonian region. In order to do this the temperature dependence of the elastic part of the response must be included explicitly in the reduction scheme.
TL;DR: In this paper, the use of a thermomechanical analyzer (TMA) operated in its isothermal mode is illustrated for studies of polymer-swelling and dissolution in liquids.
Abstract: The use of a commercially available thermomechanical analyzer (TMA) operated in its isothermal mode is illustrated for studies of polymer-swelling and dissolution in liquids. Results for a variety of polymer-swelling agent systems demonstrate that information usually requiring more sophisticated experimental techniques can be readily obtained with the TMA. In particular rates of swelling and penetrant diffusion coefficients can be determined for selected systems. Dissolution measurements, exemplified here for polystyrene in three different solvents, can be utilized to obtain steady state rates of solvent penetration and rough estimates of the interdiffusion coefficient for a system. The experimental limitations involved in both types of measurement are discussed.
TL;DR: The two main flow defects which appear to originate in the processing machine or die are melt fracture and sharkskin, which are associated with the elastic nature of the polymer melt.
Abstract: The two main flow defects which appear to originate in the processing machine or die are melt fracture and sharkskin. Both are associated with the elastic nature of the polymer melt. Processing variations that decrease the elastic nature of the melt diminish the severity of the effects of melt fracture. These include increased die length and temperature and shear at temperatures at which polymer segmental mobility is not too high. The sheared, less elastic melt structure may sometimes be stabilized by polymeric additives. A simple model is presented to account for this behavior, which is illustrated with examples of polyethylene and plasticized PVC.
TL;DR: In this paper, a more reliable analysis must be based on a knowledge of the factors in the weather which affect plastic properties and of the modes of interaction between these factors and the plastic material, and some new techniques are proposed for more reliable predictions of long-term outdoor weatherability on the basis of laboratory studies.
Abstract: In most instances, the study of the weatherability of plastics follows empirical schemes that show little correlation with the actual effects of outdoor exposure. A more reliable analysis must be based on a knowledge of the factors in the weather which affect plastic properties and of the modes of interaction between these factors and the plastic material. It is shown that both the factors of the weather and the kinetics of polymer degradation may be expressed in a quantitative manner suitable for analytical treatment. Furthermore, it is shown that the analytical approach yields predictions which are in qualitative agreement with the results of actual outdoor exposure. Finally, some new techniques are proposed for more reliable predictions of long-term outdoor weatherability on the basis of laboratory studies.
TL;DR: The extursion melting model of Tadmor et al. as discussed by the authors has been modified to include the effects of screw channel curvature and melt leakage through the screw flight-barrel clearance.
Abstract: The extursion melting model of Tadmor et al. (1967) has been modified to include the effects of screw channel curvature and melt leakage through the screw flight-barrel clearance. An alternate coordinate system was used in modifying the model to simplify the addition of curvature corrections. Also proposed is an improved method of computing solid bed velocity. A substantial number of typographical errors and truncations appeared in the original data published by Tadmor et al., and verification of their computations with corrected data was successful in all cases. Channel curvature corrections and the improved method of computing solid bed velocity increased the predicted rate of solid bed width decrease by approximately 14% during the initial stages of melting. Addition of leakage flow to the model tended to offset this effect completely or in part. Leakage flow effects always predominated during the later stages of melting, however. These effects may interact differently for other extruder sizes or screw designs; therefore, the modified melting model should be a more accurate model for use in the design of extruder screws and in studies of extruder performance.
TL;DR: In this article, the spectrum of relaxation times of five samples of polypropylene have been calculated from swelling measurement in the molten state and from flow master curves, as suggested by Ferry.
Abstract: The structure of isotactic polypropylene, obtained by means of Ziegler-Natta catalysis, can be characterized only by molecular weight distribution. The mechanism of stereospecific catalysis eliminates other variables, i.e., short and long branching. In this case it is possible to develop a rheological study dependent only by polydispersity. The spectrum of relaxation times of five samples of polypropylene have been calculated from swelling measurement in the molten state and from flow master curves. The molecular weight distribution of the samples has been calculated by means of the relaxation spectrum, as suggested by Ferry. This information has been compared with that obtained by a fractionation method. There is a good agreement between the calculated and measured polydispersity curves.
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TL;DR: In this paper, the solubility parameter of polyisobutylene has been determined from intrinsic viscosity measurements in a single solvent as a function of temperature, where Vs, the molal volume, changes with temperature.
Abstract: The solubility parameter of polyisobutylene has been determined from intrinsic viscosity measurements in a single solvent as a function of temperature. The change in solubility parameter of the solvent as a function of temperature was calculated form the equation where Vs, the molal volume, changes with temperature. The vlaue for the solubility parameter thus obtained compares well with values reported in the literature for intrinsic viscosity measurements in a series of solvents. Similar measurements were made with an ethylenepropylene copolymer. The solubility parameter of 87 mole % C2 ethylene-propylene copolymer was determined to be 8.1-8.6 in either toluene or methylcyclohexane.
TL;DR: In this article, the in-phase and out-of-phase moduli were measured over the range of composition and at frequencies between 10−4 and 10 revolutions/sec.
Abstract: The dynamic mechanical properties of blends of polymer melts were measured using the orthogonal rheometer. Two-phase blends, polyethylene-polystyrene, polyethylene-poly-(methylmethacrylate), and polystyrene-polymethylmethacrylate, were studied. The in-phase and out-of-phase moduli were measured over the range of composition and at frequencies between 10−4 and 10 revolutions/sec.
The out-of-phase modulus increases in a monotonic manner with composition. The in-phase modulus, however, shows a maximum with composition in two cases. Examination of the relaxation spectra of these blends shows that when no maximum occurs it can be written as an additive function of the spectra of the components. In the case where a maximum is observed in the modulus the measured spectrum of the blend is shifted in frequency relative to the calculated one. This is tentatively attributed to slight interpretation and solubility of one phase in the other in these cases.
TL;DR: A detailed study of the physical properties of alternating block copolymers of polydimethyl siloxane and bisphenol-A polycarbonate is presented in this paper, where the results suggest that the mechanical and optical properties of such materials are dependent upon the presence of associated regions as well as the nature of the chain between such regions.
Abstract: A detailed study of the physical properties of alternating block copolymers of polydimethyl siloxane and bisphenol-A polycarbonate is presented. The results suggest that the mechanical and optical properties of such materials are dependent upon the presence of associated regions as well as the nature of the chain between such regions. Dielectric, infrared, and DSC data as well as the stress and birefringence strain behavior are presented.
TL;DR: In this paper, a method for determining the melt elasticity of polyethylene and polypropylene is presented, which requires the measurement of axial pressure distribution in a capillary and makes use of the extrapolated value of the pressure at the exit of the capillary, the so-called residual pressure.
Abstract: A method for determining the melt elasticity is developed. The method requires the measurement of axial pressure distribution in a capillary and makes use of the extrapolated value of the pressure at the exit of a capillary, the so-called “residual pressure.” The same measurement also provides data for determining the flow curve. Measurements were taken with polyethylene and polypropylene. The results are presented and discussed with particular emphasis on the application of the method to various ways of processing polymers.
TL;DR: In this paper, a method for measuring the rate of water vapor transmission through thick sections of polyethylene used as insulation on electrical conductors of pure sodium metal is described, which is useful for materials which do not react with sodium, and for cylindrical samples which can be filled with molten sodium in a dry box.
Abstract: A method is described for measuring the rate of water vapor transmission through thick sections of polyethylene used as insulation on electrical conductors of pure sodium metal. The technique could be generally useful for materials which do not react with sodium, and for cylindrical samples which can be filled with molten sodium in a dry box. For samples with uniform dimensions the results are extremely precise because sensitive electrical measurements are used. Specimens of products in final form can be employed to determine the effects of variations in processing.
TL;DR: In this article, four types of packaging applications for a new polybutylene resin based on butene-1 monomer are described: industrial film, easy opening tear packages, shrink film, and rotationally molded tanks.
Abstract: The unusual physical properties of polybutylene are ascribed to details of morphology and a unique crystalline transformation. Inherent properties important for industrial film uses include toughness, low creep, relatively high temperature resistance, stress crack resistance and flexibilty. Four types of packaging applications are described for a new polybutylene resin based on butene-1 monomer. These include industrial film, easy opening tear packages, shrink film, and rotationally molded tanks.
A polybutylene shrink film is described having a combination of optical and shrink properties similar to vinyl shrink film, but with mechanical properties typical of polyolefin shrink films.
Rotationally molded parts exhibit an unusual degree of toughness, stress crack resistance, and low crystallization stresses in thick parts.