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A manufacturer would love to see progress in the optimization of a production system to maximize profit while maintaining the environmental regulations enacted by a government or society. Thus, a key performance indicator is needed to indicate how the system production is performing in monetary as well as environmental aspects. However, the manufacturer and the regulating body may not be aware of the environmental impacts associated with the production system as a key performance indicator like Overall Equipment Effectiveness (OEE) only implies the monetary aspects of the process. Therefore, there is a need to quantify the carbon emissions of the process and use it as a parameter that indicates profitability and environmental sustainability at the same time. From the public and policy-making body's point of view, they need a proper scale that can be used to track the compliance of the manufacturers with the environmental regulations. In this study, this carbon-based indicator (COEE) aims to discover a way of monitoring the progress of a process with environmental considerations. This study raises key questions that are constructive to each other to build a comparison of the ordinary OEE and environmental COEE. To do so a case study about the plastic process using an injection molding machine is conducted. The data used in this study was provided by the company named Good Solutions. Based on the data provided, the ordinary OEE of the machine for each shift is used to contrast with the result of the new modeled COEE. The RMSE for the given OEE of the machine was 13.424 while for COEE is 12.695. The RMSE of both OEEs indicates that the COEE can be used as an indicator for economic as well as environmental assessments.

The Tissue Engineering Lab at California Polytechnic State University San Luis Obispo focuses on creating tissue-engineered Blood Vessel Mimics (BVMs) designed for the preclinical testing of neurovascular devices. These BVMs are composed of silicone models, representing anatomically accurate neurovasculatures, that are sodded with vascular cell types and then cultivated in bioreactors (which maintain physiologic conditions). These silicone models are currently sourced externally from industry partners, so the primary goal of this thesis was to develop the means and methods for the Tissue Engineering Lab to manufacture silicone models in-house. The first aim of this thesis was to develop and explore injection molding as a possible technique for manufacturing silicone models; this included prototyping various designs of molds, developing a viable workflow for injection molding, then assessing the resulting silicone models through measurement characterization, cytotoxicity screening, and BVM set-ups. The first aim found that injection molding was a viable manufacturing technique for making silicone models. The second aim of this thesis explored an alternative manufacturing method, dip-casting, to produce silicone models. The development of dip-casting was similar to injection molding, where several prototyping stages resulted in a viable workflow for making silicone models; the resulting silicone models were then assessed via measurement characterization and a BVM set-up. The second aim found that, in addition to injection molding, dip-casting was a viable technique for making silicone models, although the overall morphology of the resulting models was less desirable than those made by injection molding. The third and final aim of this thesis compared both manufacturing techniques (i.e., injection molding and dip-casting); this aim established that injection molding was preferable for making simple (less intricate) silicone models, whereas dip-casting was preferable for producing complex (more intricate) silicone models. Although the dip-casting technique requires more development to capture complex shapes and produce models with desirable morphologies, the injection molding protocol was formalized into a prescribed workflow for the Tissue Engineering Lab to reference. Overall, this thesis developed and explored two different manufacturing techniques for making silicone models and found that both were capable of making silicone models that could be used to create tissue-engineered BVMs, with injection molded models being ready to implement as the dip-casting process continues to be refined.

Long fiber reinforced thermoplastic composites are used for creating lightweight, but mechanically sound, automotive components. Injection molding is a manufacturing technique commonly used for traditional thermoplastics due to its efficiency and ability to create complex geometries. Injection molding feedstock is often in the form of pellets. Therefore, fiber composites must be chopped for use in this manufacturing method. The fibers are cut to a length of 13 mm and then fiber attrition occurs during processing. The combination of chopping the fibers into pellets and fiber breakage creates a distribution of mostly short fiber lengths, with some longer fibers remaining. Discontinuous fiber reinforcements are classified as long for aspect ratios greater than 100. For glass fibers, that distinction occurs at a length of 1 mm, and for carbon fibers 0.5 mm. Traditional composite materials and manufacturing processes utilize continuous fibers with a controlled orientation and length. The use of chopped discontinuous fibers requires a method to predict the orientation of the fibers in the final molded piece because mechanical properties are dependent on fiber length and orientation. The properties and behavior of the flow of a fiber reinforced polymer composite during molding are directly related to the mechanical properties of the completed part. Flow affects the orientation of the fibers within the polymer matrix and at locations within the mold cavity. The ability to predict, and ultimately control, flow properties allows for the efficient design of safe parts for industrial uses, such as vehicle parts in the automotive industry. The goal of this work is to test material characterization techniques developed for measuring and predicting the orientation of fiber reinforced injection molded thermoplastics using commercial grade long carbon fiber (LCF) reinforced nylon 6,6 (PA 6,6). Forty weight percent LCF/PA 6,6 with a weight averaged fiber length of 1.242 mm was injection molded into center gated disks and the orientation was measured experimentally. A Linux based Numlab flow simulation process that utilizes the finite element method to model the flow and orientation of fiber reinforced materials was tested and modified to accurately predict the orientation for this composite and geometry. Fiber orientation models used for prediction require the use of empirical parameters. A method of using non-lubricated squeeze flow as an efficient way to determine the strain reduction factor, , and Brownian motion like factor, CI, parameters for short glass fiber polypropylene orientation predictions using the strain reduction factor (SRF) model was extended to use with the LCF/PA 6,6 composite. The 40 weight percent LCF/PA 6,6 material was compression molded and underwent non-lubricated squeeze flow testing. The flow was simulated using finite element analysis to predict the fiber orientation using the SRF model. The empirical parameters were fit by comparing the simulated orientation to experimentally measured orientation. This is a successful method for predicting orientation parameters that is significantly more efficient than optimizing the parameters based on fitting orientation generated in injection molded pieces. The determined orientation parameters were then used to reasonably predict the fiber orientation for the injection molded parts. The authors proved that the experimental and simulation techniques developed for the glass fiber reinforced polypropylene material are valid for use with a different, more complex material. / Doctor of Philosophy / Fibers reinforce thermoplastic polymers to create lightweight, but mechanically sound, automotive parts. Thermoplastics flow when heated and harden when cooled. This work compares two of the commonly used thermoplastics, polypropylene (plastic grocery bags, food storage containers) with a glass fiber reinforcement and a form of nylon called PA 6,6 with a carbon fiber reinforcement. Injection molding is a manufacturing technique commonly used for un-reinforced thermoplastics due to its efficiency and ability to create complicated shapes. Injection molding feedstock is often in the form of pellets. Therefore, fiber composites must be chopped for use in this manufacturing method. The fibers are cut to a length of 13 mm and then fiber breakage occurs in the injection molder. The combination of chopping the fibers into pellets and fiber breakage creates a range of lengths. This distribution consists of mostly short fiber lengths, with some longer fibers remaining. Discontinuous fiber reinforcements are classified as long for aspect ratios (the ratio of length over diameter) greater than 100. For glass fibers, that distinction occurs at a length of 1 mm, and for carbon fibers 0.5 mm. Traditional composite materials and manufacturing processes utilize continuous fibers with a controlled orientation and length, such as the weave pattern one might see in a carbon fiber hood. The use of chopped fibers requires a method to predict the orientation of the fibers in the final molded piece because mechanical properties are dependent on fiber length and orientation. The way that the plastic flows during molding is directly related to the mechanical properties of the completed part because flow affects the way that the fibers arrange. The ability to predict, and ultimately control, flow properties allows for the efficient design of safe parts for industrial uses, such as vehicle parts in the automotive industry. The goal of this work is to test the techniques developed for measuring and predicting the orientation of fiber reinforced injection molded thermoplastics using commercial grade long carbon fiber (LCF) reinforced nylon 6,6 (PA 6,6). LCF/PA 6,6 with an average fiber length of 1.242 mm was injection molded into a disk and the orientation was measured experimentally. A computer flow simulation process that utilizes the finite element method to model the flow and orientation of fiber reinforced materials was tested and modified to accurately predict the orientation for this composite and geometry. Fiber orientation models used for prediction require the use of parameters. There is no universal method for determining these parameters. A method of using non-lubricated squeeze flow as an efficient way to determine the parameters for short glass fiber polypropylene orientation predictions was extended to use with the LCF/PA 6,6 composite. The LCF/PA 6,6 material was compression molded and underwent non-lubricated squeeze flow testing. The flow was modeled to predict the fiber orientation. The empirical parameters were fit by comparing the simulated orientation to experimentally measured orientation. This is a successful method for predicting orientation parameters. The determined orientation parameters were then used to reasonably predict the fiber orientation for the injection molded parts. The authors proved that the experimental and simulation techniques developed for the glass fiber reinforced polypropylene material are valid for use with a different, more complex material.

This work is concerned with the processing of pellets of polypropylene (PP) containing pregenerated microfibrils of thermotropic liquid crystal polymers (TLCPs), referred to as microcomposites. The processing methods used are injection molding, sheet extrusion, and extrusion blow molding. The TLCPs used are HX6000 and Vectra A950. The microcomposites are produced by drawing strands of PP and TLCPs generated by means of a novel mixing technique and pelletizing the strands. The work was undertaken in an effort to improve on the properties observed for in situ composites in which the TLCP fibrils are generated in elongational flow fields that occur during processing. In situ composites usually exhibit highly anisotropic mechanical properties and the properties do not reflect the full reinforcing potential of the TLCP fibers. Factors considered include the effect of in situ composite strand properties on the properties of the injection molded composite, the melt temperature used in injection molding, TLCP concentration, and the melt temperature of the TLCP. It was found in this work that microcomposites can be processed by means of injection molding, sheet extrusion, and extrusion blow molding. It was necessary to process the materials at low temperatures to maintain the TLCP fibrils. However, HX6000, the higher melting TLCP allowed higher processing temperatures than Vectra A. When the TLCP fibrils were maintained, the properties of the TLCP reinforced composites did show reduced anisotropy as compared to an in situ composite. The tensile strength of the composites produced by all three methods was about equal. The modulus of the injection molded composites was slightly higher than that of the composite sheets, but the composite sheets showed a lower degree of anisotropy. In all three processing methods the modulus of the TLCP reinforced composite was a function of the modulus of the in situ composite strand used to produce the microcomposite. Therefore, it is recommended that to improve the properties of the microcomposites the properties of the in situ composite strands should be improved. Furthermore, the mechanical properties of the composites increased with increasing TLCP composition. To provide a basis of comparison the properties of the extruded sheets and the injection molded composites were compared to both the predictions of composite theory and the properties of glass reinforced composites. It was found that the modulus of the 10 wt% composites approached the predictions of composite theory, but at higher TLCP loadings the modulus showed negative deviations from the predictions of composite theory. This is believed to be the result of a reduction of fiber aspect ratio due to poor fiber distribution and fiber breakup. The modulus of the TLCP reinforced composites was about the same as the modulus of the glass reinforced composites produced by both sheet extrusion and injection molding. The tensile strengths were slightly lower than that of the glass reinforced composites. It is expected that as the modulus and strength of the reinforcing TLCP fibrils are improved the properties of the TLCP reinforced composites should exceed those of glass reinforced composites. It was concluded that the processing of microcomposites is a viable means of producing composites based on TLCPs and thermoplastics with good mechanical properties and low degrees of mechanical anisotropy. / Ph. D.

Methods of processing polypropylene (PP)/ liquid crystalline polymer blends to obtain high mechanical properties from injection molded samples were investigated in this dissertation. Three liquid crystalline polymers (LCPs), two liquid crystalline (LC) copolyesters and one LC poly(ester-amide), were used. The PP/LCP blends were compatibilized with a maleic anhydride grafted polypropylene (MAP) to enhance the mechanical properties. The effect of increasing MAP content on the mechanical properties, morphology, and interfacial tension of injection molded tensile bars and plaques made from blends with 30 wt% LCP was investigated. It was determined that MAP enhances both the tensile strength and modulus, but the tensile strength is increased to a greater degree than the tensile modulus. For the LC copolyesters, the tensile strength appeared to reach a maximum while for the LC poly(ester-amide) the tensile strength increased without limit in the range of MAP contents studied. Simultaneously, a finer dispersion was created as the MAP content was increased. Calculation of the interfacial tension from contact angle measurements indicated that the interfacial tension decreased as MAP was added to the PP matrix. Analysis of the MAP concentration after blending indicated that MAP did not react with the LCP, but enhanced tensile properties resulted from physical interaction such as hydrogen bonding. This mechanism is consistent with the greater property improvements found in the LC poly(ester-amide) blends where the amide group is expected to undergo stronger hydrogen bonding than the ester group. Analysis of the injection molding of these blends found that heat transfer and solidification significantly affected the flexural modulus of these blends. Injection molding conditions such as fill time, mold thickness, mold temperature and melt temperature were investigated in three molds of different thicknesses. Different processing relationships were found between the LC copolyesters and the LC poly(ester-amide). For the former LCP blends, the highest moduli were obtained from the thinnest mold in a manner parallel to that of the moduli of neat LCPs. For the latter LCP blends, the highest moduli were obtained in the intermediate thickness mold. The differences between the copolyester and LC poly(ester-amide)s processing / property relationships were related to the melt rheology of the LCPs. For the LC copolyesters, maximum mechanical properties were obtained when the melt temperature was selected so that the storage and loss moduli of the LCP were nearly equal. This equality of storage and loss moduli could not be achieved with the LC poly(ester-amide). In addition, upon cooling, the storage and loss moduli of the LC poly(ester-amide) indicated that rapid solidification occurred while a much lower rate of solidification was indicated for the LC copolyesters. In addition the mechanical properties were sensitive to the rate of cooling as indicated by the Graetz number. It was speculated that attainment of the highest mechanical properties was related to the LCP being deformed during the filling stage followed by rapid solidification of the LCP morphology upon cessation of flow. / Ph. D.