SPE Library

The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.

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Polymer Modifiers and Additives

How Poor Selection of Materials, Design, Tooling and Design Errors Affect the Aesthetics of Plastic Parts and What Designers Need to Know About the Science of Color and Appearance - Part 1

Vikram Bhargava, May 2020

Most engineers and designers come from the metal world. Therefore, many of them make assumptions on the predicted performance of plastic properties based on their metals background. Unlike metals, the knowledge of color and appearance is extremely important in the case of plastics. Most plastic parts have dual functions— physical performance and aesthetics. Aesthetics are important since very few of the parts need to be painted or otherwise decorated if designed and manufactured with due diligence. On the other hand, even if we are designing the most aesthetically critical metal components such as exterior automotive parts, we mostly choose the metals and alloys based on the physical properties, weight, and cost. The aesthetics are left to the paint specialist, who will in most cases find a paint system (primer, paint, and application method) that will meet the cost, durability, and cosmetic requirements. In other words, aesthetics and physical properties are quite independent of each other. A vast majority of metal parts meet their aesthetic and environmental requirements just by getting brushed, plated, chromate conversion coated or anodized. Plastic parts not only need to meet the short-term color and appearance requirements, but also need to be resistant to long term color shift and fading. This paper is in two parts. Part 1 - Appearance and Color Factors - Material - Design - Tooling and Processing Part 2 –The fundamentals of Color and Appearance, Specifications, Measurement and Tolerances

Influence of Additive Type On the Properties of Polyolefin Blends

Christoph Burgstaller, May 2020

The aim of this work was to compare the effects of compatibilisation with different additives on the properties of polyolefin blends, made from different PP and PE grades, to mimic the mixed polyolefins found in post-consumer waste and investigate ways to improve the properties of these mixtures. We found, that it is possible to compatibilize such polyolefin blends via the addition of ethylene-octen- or olefinic-block copolymers, where the type of copolymer shows an influence on the properties achievable. Also the blends show differently improved impact behavior, depending on the polyolefin which builds the major phase of the blend. These results show that it is possible to recycle such mixed polyolefin streams towards a suitable material with reasonable properties.

Ship Less Air –Flexible Chip Bag Filling Simulation for Sustainability

Jay Yuan, May 2020

The snack flexible packages on the market today, such as potato chips, pita chips, taco chips, tortilla chips, etc., are typically sold by weight, that is, the packages need to fulfill the label claims by weight. However, the size of the packages is determined by the overall volume of the products. The determination of the overall volume of a given product weight is not trivial. The volume is a function of chip broken rate, chip size distribution profile, bag width, bag film gage and material, production line speed (bag/minute), VFFS machine type, etc. Traditionally, the size of the bag is determined by trial & error process through iterative lab testing and production trials. This approach typically results in unnecessary large bags due to the concerns of sealing contamination induced leakage issues in the case of the bag being too small. This leads to significant sustainability issues in shipping and distribution since the shipping trucks are often cubed out by volume (not by weight) for chip/snack packages. The energy is wasted by shipping more air (thus, less chip/snack packages) during distribution. In this work, authors propose a novel approach of bag size determination by using a virtual simulation of the VFFS chip filling process, where the potential influential attributes, such as chip broken rate, chip size distribution profile, bag width, bag film gage and material, production line speed (bag/minute), and VFFS machine type, can be modeled and their impact on the bag size can be quantified. A progressive 3-case simulation is performed and presented in this paper. The results are directionally correct based on the authors’ observation and past experience. Currently, authors are looking for industry partners (brand owners, co-packers and machine manufacturers) to collect production data and validate the analysis model. The intent of this paper is to bring the awareness of applicability of the simulation technology regarding to the bag size determination and chip/snack filling process, and ultimately help the industry in adopting the technology to make the chip bag filling process more sustainable, i.e., to ship less air.