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   In the previous article, we discussed flame retardant (FR) regulations and how they might be expected to change. Nevertheless, the market is still strong for non-halogenated flame retardants. Therefore, the objective of this second part article is to summarize notable experimental results obtained with commercial Flame Retardants, and approaches that are likely to be important over the coming decade. New Flame Retardants chemistries and approaches will also be discussed.

  Fire safety is crucial to our modern society. Flame retardants play an important role in the fire protection strategy.  In recent years, regulatory demands have put enormous pressure on developing environments friendly flame retardants for thermoplastics. The aim of this series of articles is to review new flame retardant technology and trends in their use with thermoplastics.  It describes advances in non-halogenated flame retardant technologies, new polymeric flame retardant additives, and advances in testing and fire risk evaluation.

         Here we go again. After intercalated compounds of graphite (1974), fullerenes (1985), and carbon nanotubes (1991), it is time for another allotrope of elemental carbon to be at the forefront of scientific curiosity (Boehm 2010). The allotrope is: “graphene”. By graphene, we mean the basal plane of graphite, a one atom thick two dimensional honeycomb layer of sp2 bonded carbon. Conversely, when many graphene layers are stacked regularly in three dimensions, graphite is created.

 

In the introductory chapter of the book, Graphite, Graphene, and Their Polymer Nanocomposites; editors have laid out their vision for this nascent and exciting area of research. They have also briefly described the contents of the each of the chapters and explained the logic that binds them into a compelling book. This allows the readers to derive the maximum benefit from the developing story of the most sought after carbonaceous nanomaterial, graphene. Clearly, there are a very large number of both challenges and opportunities in the area of graphene research. Plasticstrends is pleased to provide to its readers a revealing look at the contents of this book. 

 

 

  Part 1 of this paper discussed the origins of the injection molding process and the development and use of the helical screw for conveying and melting polymers.

The plasticating unit used for melting and mixing on an injection moulding machine performs the same basic functions as the plasticating unit of an extruder. The difference lies in the fact that the screw moves backwards in injection moulding and thus the plasticating unit in an injection moulding machine can be considered to be a reciprocating extruder.

While screw design was considered to be important in extrusion, it was often considered to be less import in injection moulding. The major difference is that in a reciprocating system, the process is cyclic instead of continuous and the screw design plays a key role in maintaining cycle to cycle consistency for the resulting, molded plastic parts.

This second part of this paper discusses the use of barrier / mixing screw technology for the plasticating of polymers in the injection molding process from the early 1960’s to today’s sophisticated injection molding equipment.                                                          

  The screw is the heart of an injection molding process. Over the past several decades, screw design for the injection molding process has played a vital role in delivering high quality and value added plastics parts. That’s where the story begins.

The origins of Injection Moulding

In 1868, John Wesley Hyatt invented a way to make billiard balls by injecting celluloid into a mold, perhaps in response to a request by billiard ball maker Phelan and Collander. By 1872, John and his brother Isaiah Hyatt patented the injection molding machine. This paper will discuss the evolution of the use of barrier / mixing screw technology in the injection molding process for the plasticating (melting and mixing) of polymers from early plunger machines to today’s sophisticated injection molding equipment. Although John and his brother Isaiah Hyatt patented the injection molding machine that was primitive yet it was quite suitable for their purposes. It contained a plunger to inject the plastic into a mold through a heated cylinder.

Fillers have been in use since the early days of plastics.  Today’s enormous growth of the polymer industry is due to the unique properties of fillers they impart to polymers.  Glass bubbles (low density hollow glass microspheres) as fillers have been incorporated into thermoset polymers for decades.  They are tiny hollow spheres and are virtually inert.  These glass bubbles are are compatible with most polymers.  Until recently, their use with thermoplastic polymers has been limited because of high rates of bubble breakage from the high shear forces to which they are exposed during such thermoplastic processing operations as extrusion compounding and injection molding.  At issue has been the strength of the glass microspheres.

3M have recently developed innovative glass bubbles which offer resistance to extremely high compressive and shear forces.  This allows compounders, thermoformers and injection molders to use them to achieve significant weight reductions without restoring to costly equipment modifications.  This article will showcase how plastics processors could exploit the advantages of these novel glass bubbles while improving the end-product properties.

Thermoplastic elastomers (TPEs) have been traditionally compounded and manufactured from raw materials based on fossil fuels.  Current trends in marketplace abounds sustainability programs. TPEs are no exception to this trend.   In a recent editorial, the authors stated “Through research and application, sustainability can evolve from a catchphrase to a societal one”¹. More than two decades ago the Brundtland Commission (formerly the World Commission on Environment and Development, WCED), deliberated sustainable development issue and gave a definition of sustainability:

“Sustainable development meets the needs of the present without compromising the ability of future generations to meet their own needs.^1a

GRAPHENE is the thinnest known material and has the highest intrinsic strength of any material ever measured. We are posting an article to describe some of the interesting research on graphene and graphene-based  polymer nanocomposites (GPNC) that is occuring. This article reviews how graphene is made, explain how single sheets can be dispersed in a polymer matrix to give plastics with interesting properties and where these works are being carried out.

May 05, 2009

Expressing the rationale for pursuing a green environment along with the movement toward pursuing the same has brought about terms such as peak oil, greenhouse gases, and sustainability. Are these terms indicative of an upsurge in green-chemistry research?  Indeed they are: the plastics research community is up and running in developing “green” polymers.  Manufacturing plastics from carbon dioxide, sugarcane, corn, and switch grass are in high gear.  Traditional petrochemical-resin companies such as Braskem and Dow are getting ready to produce bio-polyethylene while Solvay is focusing on “green” polyvinylchloride (PVC).  In fact, Braskem made bio-ethylene consisting of 100% renewable carbon and then polymerized into “green” polyethylene*.  And we can say the same about the list of growing bio-polymer related industry standards (including EN 13432, ASTM D6866, D6868, D7075, D7081, D5511, D5271). We see fibres and packaging products made from corn on the grocers' shelves.  Of course, there is science behind transforming a kernel of corn into lactic acid and into poly-lactide molecules (PLA).  Technically, however, to make PLA plastics as a viable and a cost-effective alternative to conventional plastics is another story.  This is our rationale for publishing Dr. Zuzanna Cygan’s work on PLA, a work that shows how scientists are tackling challenging processing issues to improve PLA properties.

* More on innovation and industrial trends of bio-plastics are available in the issue of Journal of Macromolecular Science, Part C: Polymer Reviews, volume 49, 2009.

This site is all about plastics.  Polymers are the backbone of plastics.  The giants of the molecular world.  They can be built from simple molecules.  Understanding polymers' behaviour and building it accordingly is a fascinating science.  Only the education of polymers in young and brighter minds could open up new material ideas and technologies for a brighter tomorrow. Our mission is to bring plastics education and its news to everyone.

 

Since graphene was isolated by a group of physicists from Manchester University, UK in 2004, interest in graphene research throughout the world has skyrocketed.  This huge activity stems from graphene’s unusual and extraordinary electrical, thermal, and mechanical properties.  Professor Geim, who was instrumental in the separation of graphene, recently commented, “Graphene is a wonder material with many superlatives to its name”.  Why such glorification of graphene as a material?  Because it is the thinnest known material in the universe and its strength is the highest ever measured¹. Prior to its separation into platelets, graphene was a controversial material and the subject of much speculation.  Many believed that graphene could not exist as a freestanding sheet, and yet it was studied theoretically for over 6o years. The results of this intense work over the years have been comprehensively documented in an article by Geim and Novoselov².  Particularly noteworthy is the research, at MIT, of Gene Dresselhaus and Mildred Dresselhaus who began work with graphite (multi-layered graphene) several decades ago.  The results, until 1980, of the Dresselhaus team on graphite intercalated compounds have been described by these authors themselves³.  Today graphene’s unique structure allows for a wide spectrum of applications in a variety of fields while giving researchers an unprecedented opportunity for fundamental physical science. Picture on the top left show false-color 3-D rendered TEM image of isolated hydrogen atoms (purple-tipped) and an isolated carbon atom (red-tipped) on a graphene membrane ("Courtesy Zettl Research Group, Lawrence Berkeley National Laboratory and University of California at Berkeley"). This article aims to capture and convey in a few words the excitement provided by some of the interesting trends observed in research on graphene and graphene-based polymer nanocomposites (GPNC).

 

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