SPE Library

The last decades have seen a rapid development in hard-machining which has encouraged steel manufacturers to develop modern pre-hardened tool steels having leaner chemical compositions when compared with the well-established P20. Use of pre-hardened grades enables faster tool-manufacturing thanks to the elimination of the need for heat treatment (Q&T) in mold manufacturing. Traditional pre-hardened tool steel is commonly delivered in hardness of 300 HBW (P20) and Approx. 360/370 HBW (P20 HH). Today?s modern pre-hardened tool steels are delivered at nominal hardness from 300 HBW up to 450 HBW/45 HRC. Those grades have lower alloy contents than P20 giving much improved machinability. New pre-hardened tool steel grades are also suitable when molding glass-fiber reinforced components as these grades were developed to show good properties after surface engineering (Nitriding, PVD-coating etc.). The tool designer can now tailor-make the mold surface properties required in a given wear situation.

Minimizing weight and size is an important aim in today?s consumer electronics market. Recently nano-molding technology (NMT) is a newer technology wherein plastic resin is injected into metal surface. Therefore high bonding strength between the plastic and metal is important for such applications. Despite significant research and development efforts, there remains a need for blended thermoplastic compositions that effectively address the appropriate balance of properties required in the consumer electronics industry, such as blended thermoplastic compositions that are high stiffness yet have high toughness, while retaining desired color ability. In this paper, we describe a method to manufacture THERMOTUFTM glass filled PBT compounds with high bonding strength and low thermal expansion/shrinkage for NMT application.

The preparation and characterization of a new type of highly efficient pseudo-piezoelectric materials (ferroelectret) based on porous cyclic olefin copolymer (COC) is reported in the study. The quasi-static piezoelectric coefficient of the ferroelectrets can reach exceptionally high level ~1100 pC/N, and the materials retains the high piezoelectric activity for temperature up to 170oC. The sample preparation procedures can be divided into three steps. First, patterns on COC film were prepared using laser cutter. Then CO2 bonding was used to bond different layers together. Finally, contact charging was implemented to obtain desired piezoelectricity. The piezoelectricity was characterized by quasi-static piezoelectric coefficient. Moreover, thermally stimulated discharge was selected to study the thermal stability of the ferroelectret. And hysteresis loop measurements were used to study the charge build up process inside the artificial void. The critical breakdown voltage of the 50?m artificial void sample is about 2500V and agrees with the value calculated from the simplified model. Such material have applications on sensing, actuating and energy harvesting and many other fields.

The dispersion effect has a direct influence upon the rheological behavior of filled blends. This paper aims to study the steady and dynamic rheological properties of different CaCO3 dispersions in LLDPE. A rheological model was chosen to fit the steady viscosity curve. Then the relationship between the dispersed forms and the rheological properties was investigated in order to describe the different filler dispersions via changing the parameters of the equations and consolidating the theoretical support for evaluating the effect of different dispersions based on rheological tests.

A two-step, scalable melt compounding method is used to fabricate carbon nanotube (CNT) / polylactic acid (PLA) and exfoliated graphite nanoplatelet (GNP) / PLA nanocomposite films. The CNT or GNP is dispersed in the PLA melt using a twin-screw microextruder and melt spun fibers are compression molded into films of approximately 110 ?m thick. Fiber & film morphology, investigated using scanning electron microscopy (SEM), shows that the fibers are continuous with a diameter in the range of 60-70 ?m. The thermal and mechanical properties are examined using differential scanning calorimetry (DSC), tensile testing, and dynamic mechanical analysis (DMA). Electrical properties of the films are investigated using impedance spectroscopy.

During the blow molding process of large size drums, string-like defects, which are called worm melt fracture, can be observed on the extrudate surface. Such string-like defects are observed in the capillary extrusion at high shear rate range after the slip-stick transition. It is proposed that the cohesive slip layer which is a failure within the polymer melts inside the die could emerge out as the sting-like defects on the extrudates. The resin having more small chains and lower plateau modulus can be easier to have such an internal failure and consequently exhibit more ?worm? defects.

Currently a new approach for simulating the foam injection molding process is being developed at the Institute of Plastics Processing (IKV) Aachen, Germany. As existing simulation software for foam injection molding works with restrictions and assumptions, especially for the nucleation phase of the foam injection molding. Simulation results often do not correspond with practical tests at the injection molding machine.
In the new approach the influence of the blowing agent on the PVT- and rheological behavior is measured with two injection molds directly on the injection molding machine. The characterization of the material behavior is than prepared as input data to the injection molding simulation software.
In this paper the approach for modeling the rheological behavior of blowing agent loaded melts for simulating the foam injection molding process is described. Step one is to measure the effect of a blowing agent on the viscosity of a polymer melt at different melt temperatures and blowing agent concentrations through an online rheometer. Afterwards the measured data is adjusted, optimized and inputted into the injection molding simulation software.

Thermoplastic polyurethane (TPU) possesses many special characteristics. The flexibility, rigidity, and elasticity can be adjusted by controlling the ratio of soft and hard segments. Additionally, the chemical properties of TPU can be varied by using different starting monomers. Due to its versatile physical and chemical properties, TPU is commonly used in transportation, construction, and biomaterials. The technique of foaming TPU by CO2 is still under investigation. To avoid the effect of additives that are found in commercially available polymer, we synthesized TPU ourselves using a pre-polymer method. In addition, graphene was added as the nucleation agent. The synthesized TPU was foamed by batch foaming using super critical CO2 as the blowing agent, and the effect of saturation temperature on the cell morphology of TPU foam was examined. The average cell size of TPU foam decreased from 1.8 ?m to 800 nm, after only 0.1 wt% of graphene being added.

Today, your products may be excluded from a project simply because you do not have an HPD (Health Product Declaration). This presentation will not advocate for, or against, Health Product Declarations (HPDs) and/or other instruments for demonstrating ingredient transparency. Rather, the goal of this presentation is to examine the evolution of Health Product Declarations, determine the true impact these mechanisms are having on buying decisions today, and discuss the likely impact in the future. Most importantly, we will discuss the ?as is? of ingredient transparency initiatives and the relative merits of defending and/ or embracing these initiatives, for building material manufacturers and raw material suppliers

Topics will include:
What is a Health Product Declaration?
Growing influence of green building rating systems (such as LEED) and how this is changing product development
Who?s on board? Who are the stakeholders driving change?
Ingredient Disclosure: Hazardous Chemical lists vs. Risk & Exposure Assessment
How do I decide if an HPD is right for my company?
Now that you?ve decided?what?s next?

The tubes melt-extruded of a commercially-available segmented polyurethane block copolymer based on the soft segment chemistry of poly(1,6-hexyl 1,2-ethyl carbonate) diol (namely BionateTM 75D) were found to exhibit structural relaxation and phase demixing (or ?cold crystallization?) phenomena upon thermal exposure at low temperatures. To prevent these phenomena for practical engineering applications, a series of post-extrusion annealing experiments were conducted at temperatures from 50 to 150 øC within durations from 15 to 240 min. To reveal the correlative process-structure-property relationships, the annealed tube samples were then analyzed using differential scanning calorimetry (DSC) methods. It was observed that despite initial morphological states of the extruded tubes, their thermal properties are largely tunable via solid-state annealing processes. Dependent of annealing conditions, the extruded tubes could be renewed to a desirable phase-separated morphology exhibiting the desirable thermal properties that are deemed to be thermally stable.

Business corporations? emphasis on sustainability is ever increasing which is evident by the increase in sustainability spending. Each year, companies are spending more on sustainability. This research is an attempt to understand if the sustainability spending depends upon the size of the company as measured by its revenue. Moreover, the paper focuses on the relationship between sustainability spending and size of the company in plastic industry. The study is the second survey of its kind and is based on the global inquiry with the members of the Society of Plastics Engineers (SPE). Based on the results of Chi-square test for independence, we found that there is no relationship between sustainability spending and the size of the company.

Scratch and mar damages can critically impact the aesthetics of polymeric surfaces. Improving scratch and mar visibility resistance of polymers is of big interest for academic and especially industrial arenas. In this paper, we investigate the influence of surface brightness, color and transparency on scratch and mar visibility resistance in polymers. A new psychophysical test based on Multidimensional Scaling (MDS) statistical method was utilized to determine mar visibility resistance onset. It has been found that scratch visibility resistance decreases with greener, lower brightness and higher transparency samples. Preliminary results show that MDS is a powerful tool to disseminate the psychophysical evaluation of mar damage. This research paves the way for a standardized methodology to reliably quantify scratch and mar visibility resistance in polymers.

The tradition packing way is that the injection unit holds the high pressure in a few seconds, which is highly energy-consuming. Gas Assisted Injection Molding (GAIM) refers to injecting gas into the short shot melt in the packing stage, the compressed gas is used as the medium to push melt and maintain pressure, which can save the material and energy. Therefore, the hollow area and penetration length are mostly required in end product quality. This study visualizes molding flow, and uses gas counter pressure mechanism in the gas assisted molding process, the melt flow behavior is influenced by controlling the counter pressure, so as to discuss the effect of counter pressure mechanism on the hollow area and the penetration of gas assisted molded articles. This study designs in-mold visible mold, and uses clip-shape cavity for experiment on gas assisted injection molding with counter pressure mechanism. The flow field of two phase fluid and fountain effect in different counter pressure conditions are observed by high-speed photography and adding particles, the relationships among the penetration length of finished product, hollowed evenness and molding parameters are analyzed by mold flow analysis software, and the database of gas assisted injection molding under counter pressure mechanism is created. The experimental results show that the gas counter pressure is applied to gas assisted molding, the hollow area is reduced and the penetration length of finished product can be increased, so as to uniform the hollow quality. And the result of mold flow analysis software will verify the experiment.

A non-destructive testing method ? ultrasonic birefringence ? employing ultrasonic transverse waves and their polarization dependent velocity and attenuation is proposed to monitor fatigue damage in laminated CFRP and damage induced by tensile loading of braided CFRP. A calculation approach is presented to predict the measurement results in laminated CFRP. The method exploits the inherent elastic anisotropy of fiber reinforced plastics to characterize damage. The increase in attenuation and decrease in velocity which is induced by the transverse matrix cracks in fatigued laminated CFRP is matched with simulated results to estimate the shear moduli of each fiber direction in the laminated CFRP and hence characterize the fatigue state in each fiber direction. In the braided CFRP case the method is used in a preliminary attempt to demonstrate the anisotropy of damage induced during tensile testing.

There are no ?all encompassing? sterilization studies which combine all available sterilization methods at varying intensities comparing polystyrene to other polymers commonly used in medical packaging and devices. This paper will show physical property data over a two year time span using multiple general purpose polystyrene (GPPS) and high impact polystyrene (HIPS) grades, comparing them to seven other polymers, including high density polyethylene (HDPE), polypropylene (PP), polyethylene terephthalate (PET), copolyester (PETG), acrylonitrile butadiene styrene (ABS), impact acrylic (PMMA), and styrene butadiene copolymer (SBC). The sterilization methods used include two intensities each of Gamma, E-Beam, and Ethylene Oxide (EO or EtO).

Virtually any industry that makes use of colored thermoplastic compounds whether made from master batch or compound has the potential to be negatively impacted by the movement of color from the manufactured item to the surrounding environment, eg; hands, clothing, or other objects. Industries where this may be of critical importance include but are not limited to fiber (clothing, upholstery and carpet), food packaging, toys, automotive, and household appliances. No one appreciates the color of their new clothing transferring to their couch, or the color of a child?s new favorite toy transferring to their face because they fell asleep laying on it. This paper attempts to review the above phenomenon, many of which have similar definitions, but may indeed have different mechanisms. In some of the above instances mechanisms for their occurrence are proposed and methods hypothesized as to how to predict and therefore how to mitigate their presence.

Co-continuous polypropylene (PP)/polystyrene (PS)=53/47 vol% blends containing 0.7 vol% multi-walled carbon nanotubes (CNTs) were obtained by melt-mixing in a conical twin-screw micro-compounder. To study the influence of melt viscosity ratio, PS with different viscosities were selected. With decreasing viscosity ratio, the better uniform co-continuous structure and higher electrical conductivity could be obtained. The compounding parameters, including the mixing time and the sequence of incorporation have been investigated. The results indicated that high melt viscosity ratio could not hinder the migration of CNTs from PP into PS phase. Higher rotation speed, mixing simultaneously and shorter mixing time lead to the better uniform co-continuous morphology and higher electrical conductivity

Foaming behavior of polypropylene/nitrogen system in microcellular foam injection molding was investigated by using a 50-ton injection molding machine equipped with Mucell? gas injection unit. The evolution process of cell morphology was obtained by regulating the filling ratio. Both the filling ratio and the injection velocity have significant effects on cell morphology. To maximize the cell density, lower injection velocity should be used and the filling ratio should be controlled in the reasonable level of about 80%. With an extremely large filling ratio, cells formed in filling stage can be dissolved back into polymer melt and the special cell morphology with longitudinal cells can be obtained.

A low-temperature saturation pathway to create thermoplastic nanofoams is presented. We conducted saturation by CO2 to a temperature as low as -30 øC and successfully fabricated PC nanofoams (cell size 20-30 nm, void fraction up to 60%), PMMA nanofoams (cell size 30-40 nm, void fraction up to 86%), and PSU nanofoams (cell size 20-30 nm, void fraction up to 48%). Cell nucleation densities exceeding 1015 cells/cm3 were achieved.
Lowering the saturation temperature results in a significant increase in solubility, which is essential for creating nanofoams. Cell nucleation density increases with CO2 concentration and average cell size decreases with CO2 concentration. All three polymers exhibit very similar behaviors. At sufficiently high CO2 concentrations, cell nucleation densities reach the range of 1012 - 1015 cells/cm3, and corresponding cell sizes fall below 1 æm into the nanometer range. The CO2 concentration for generating nanofoams is above 18.9%, 32.6%, and 12.3% for PC, PMMA, and PSU, respectively. Representative processing conditions for creating nanofoams with cells below 100 nm are presented. The method of lowering saturation temperature can be applied to create nanofoams in other polymers, polymer blends, copolymers, and polymer nanocomposites.

Effects of injection speed on the experimental orientation of long, semi-flexible glass fiber-reinforced polypropylene composites using an end-gated plaque geometry exhibiting a complex 3-dimentional flow field were quantified. Three injection speeds were considered with constant mold and screw temperatures. Samples were subsequently used to obtain experimental orientation and fiber length distribution data. Orientation data was obtained using a slightly modified version of the Method of Ellipses, which is used for rigid fibers. Injection speeds of 1, 2, and 4 seconds were used with a mold temperature of 79oC. Orientation data along the center plane and also images along the composite width were obtained and compared. Preliminary data suggests that the orientation at these injection speeds does not change considerably along the center plane from one mold fill time to another. More data is needed to conclude whether orientation is changing significantly along the width of the part.