Today's KNOWLEDGE Share:molecular orientation in molded parts

Today's KNOWLEDGE Share

I often get questions in my seminars about molecular orientation in molded specimens.People often get a bit confused about the layers that could possibly show some degree of molecular orientation, potentially observed as birefringence for transparent grades.

- The very skin is coming directly from the fountain flow and freezing, so it is not very oriented at all since it never experienced much flow in the main direction.

- The "frozen skin" below it is extremely oriented since, by definition, it freezes UNDER FLOW. As a result it is very oriented, almost regardless of the polymer relaxation time / molecular weight.

- Other layers below, approaching the center line can show orientation induced during the second stage of the molding process, the packing phase. This flow stress is active at later times, thus acting on deeper layers.

- Although thick parts should show little orientation below the frozen skin, high molecular weight materials could still show significant orientation if their relaxation time exceeds the overall cooling time of the specimen. Try molding a blow-molding grade and see for yourself !

- Strictly speaking, the very center line should not show orientation since the shear-rate and shear-stresses are zero at all times during the process.

A quick test to assess the degree of average orientation (which really works perfectly for opaque crystalline polymers) is to examine the degree of (post-)shrinkage in the flow direction when annealing the specimen at the appropriate temperature (just below Tg for amorphous, just below Tm essentially for semi-crystalline).

Orientation is not strictly speaking a "residual stress" given the weakness of the entropic force at play. Upon reheating or softening with a solvent (PVC and acetone for instance reveal flow induced orientation), such tiny force can produce this significant post-shrinkage.

source: Vito leo

Today's KNOWLEDGE Share :Plastic films from abaca plant

Today's KNOWLEDGE Share

Eco-friendly plastic being developed from abaca fiber

A research initiative is paving the way for eco-friendly bioplastic films using nanocellulose extracted from a hybrid of the local abaca plant.

The project, spearheaded by the Forest Products Research and Development Institute of the Department of Science and Technology (DOST-FPRDI), is being funded the DOST Philippine Council for Agriculture, Aquatic, and Natural Resources Research and Development (DOST-PCAARRD).

It is making use of fibers from the Bandala abaca hybrid developed by the Institute of Plant Breeding of the University of the Philippines Los Baños (UPLB) which made use of abaca and banana tissues to create a hybrid that is resistant to the Bunchy Top Virus.

This project aims to leverage Bandala's unique properties to produce bioplastic films, offering a value-added product that extends beyond traditional fiber uses.

Led by Dr. Anniver Ryan P. Lapuz, the project team is exploring various processes, including pulping and bleaching, to derive cellulose pulp from BANDALA fibers. They will also characterize the properties of extracted cellulose nanocrystals (CNC) and test different CNC amounts in starch-based bioplastic films.

According to Dr. Lapuz, an essential aspect of the project involves assessing the production costs of CNC and CNC-reinforced bioplastic films, ensuring the feasibility of large-scale production.

Long considered as the world’s strongest natural fiber, abaca is the preferred raw material for making ship and power transmission ropes, car interiors, well-drilling cables, furniture, texture, and even security paper being used in money.

The Philippines holds a significant position in the global abaca industry, being one of the top producers of abaca fiber. In 2019, the country produced approximately 85,000 metric tons of abaca fiber, accounting for around 87% of the world's total production. The abaca industry provides livelihoods for over 200,000 Filipino families in over 50 provinces and contributes significantly to the country's economy.

Dr. Lapuz emphasized the potential environmental benefits of the bioplastic film, which could serve as an alternative to synthetic, petroleum-based plastics. This innovation is particularly timely, given the urgent need to reduce plastic waste and greenhouse gas emissions globally.

The commercial application of the project lies in the development and production of bioplastic films. These can be used as an eco-friendly alternative to traditional petroleum-based plastic packaging. This application is particularly valuable in the food packaging industry, where there is growing demand for biodegradable and compostable materials.

Due to its flexibility and strength, the bioplastic film can be used for the packaging for a wide range of products, including snacks, fresh produce, and consumer goods. It can be used as mulch films in agriculture to help retain soil moisture, suppress weeds, and improve crop yields. Being biodegradable, these films do not require removal at the end of the growing season, reducing labor and disposal costs.

The materials can also be used to produce biodegradable seed coatings and nursery pots, which can be planted directly into the soil, reducing transplant shock and plastic waste. And the bioplastic can be utilized in manufacturing disposable items such as plates, cutlery, cups, and straws, which are commonly used in the foodservice industry. These items can offer an environmentally friendly alternative to single-use plastics.

Dr. Lapuz said the growing global concern over plastic pollution and the increasing demand for sustainable materials present a significant market opportunity for bioplastic products. The use of locally sourced materials, like BANDALA abaca, not only supports local agriculture but also reduces reliance on imported raw materials, promoting economic resilience.

The project will be implemented for two years and will benefit abaca farmers, traders, researchers, and the pulp paper and plastic industries. It officially kicked off during an inception meeting organized by DOST-PCAARRD led by Deputy Executive Director for Administration, Resource Management and Support Services Melvin B. Carlos, along with Crops Research Division Director Leilani D. Pelegrina in UP Los Baños.

source:https://mb.com.ph/DOST-PCAARRD/(DOST-FPRDI)

Polymer patch made from dynamic polymer networks

Today's KNOWLEDGE Share

From aviation to orthopedics: Polymer patch made from dynamic polymer networks

Researchers at the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM have developed a new polymer patch that can significantly accelerate and simplify previously laborious, expensive, and time-consuming repair processes on damaged lightweight aircraft components.

The thermoformable, recyclable repair patch is pressed onto the damaged area and fully sets in just 30 minutes. The innovative fiber-reinforced plastic is so versatile that it can be used in a wide range of different industries, from aviation to orthopedics.

Repairing lightweight fiber composite components like those used in aircraft wings, fuselage sections, tail surfaces, and doors is a time-consuming and costly process with multiple work steps. The damaged area is typically repaired using a painstaking wet lamination process or by applying fiber-reinforced polymers (FRPs) or aluminum structures known as doublers to the surface. However, these methods involve a long curing time and require additional adhesives.

Researchers from Fraunhofer IFAM have now developed a repair patch made from dynamic polymer networks—also known in the trade as vitrimers—that shortens the previously lengthy and laborious repair process to just 30 minutes.

What is really special about the innovative material which is based on benzoxazines, a new class of thermosetting material known as a thermoset is that the polymerized plastic does not melt or otherwise behave like a traditional resin system used in wet lamination.

The polymer's dynamic networking processes make it possible to heat the material locally. The fully cured patch adapts to the repair site in its heated state. At room temperature, the polymer has thermosetting properties, so the patch is not sticky and is stable when stored. This saves energy, as the patch can be stored at room temperature and does not require refrigeration, which reduces storage costs.

The patch is applied to the lightweight component requiring repair using pressure and thermally induced exchange reactions. It enables rapid repairs, fully setting within 30 minutes. There is no need to work with reactive hazardous materials, as is necessary with traditional resin systems. The vitrimeric properties make it possible to remove the patch as and when needed, without leaving any residue behind.

"Our adhesive-free, storage-stable fiber-reinforced patch enables direct repairs to damaged composite materials and hybrid structures. Because the polymer is a vitrimer by nature, the patch behaves like a conventional thermoset composite material during storage, but it also bonds cleanly and easily when simply heated, without any need for additional adhesives," explains Dr. Katharina Koschek, head of the Adhesive Bonding and Polymeric Materials section at Fraunhofer IFAM in Bremen.

The versatility of the benzoxazine-based vitrimers opens up potential applications in various industries, even beyond the mobility sector. In orthopedics, for example, the thermoformable material could be used to realize individually adjustable orthoses and prostheses in the future. At present, custom fabrication of lightweight devices like these is a highly laborious process, as conventional fiber composite materials do not permit much adjustment once the resin cures.

"Prostheses are custom-made for individual patients. But they don't always fit. The slightest imperfection in the fit or physiological change can mean that the prosthesis or orthosis causes the patient pain or discomfort, interfering with their treatment. Previously, that meant that a new prosthesis would have to be made, and due to the demand and amount of detailed manual work involved in orthopedics, that can take up to several months," Koschek explains.

Using thermoformable materials could eliminate the need to remake these kinds of medical aids. In the CFKadapt project, researchers from Fraunhofer IFAM joined forces with orthopedics and prosthetics firm REHA-OT Lüneburg Melchior und Fittkau GmbH, E.F.M. GmbH, and the Leibniz Institute of Polymer Research Dresden (IPF) to develop a novel fiber-reinforced polymer that is based on dynamic polymer networks and can be adjusted in various ways.

The key difference between the new material and commercial matrix systems for orthopedic devices made from fiber composites is the possibility of readjusting and modeling the new material to the appropriate pressure or support points, which permits dynamic adjustment to the patient and their changing needs over the course of treatment. The trick is that the new polymer fiber composite mix can be heated locally and individually adjusted.

"The benefits lie in the great design and configuration freedom and significant reduction of waste during production, along with longer service life for these devices, as they can be adjusted on an ongoing basis during treatment. For patients, the main factor is that they can get a custom-fitted orthopedic device as soon as possible," Koschek says.

Standardized production of components with subsequent individual adjustment also has the potential to yield cost benefits and improve the efficiency of the production process.

source:https://phys.org

Today's KNOWLEDGE Share :Carbon fiber sheet used portable Displays VAIO Vision

Today's KNOWLEDGE Share

Tenax™ TPCL and Teijin's Panlite® Sheet are Used for the Housing of the World's Lightest Portable Displays VAIO Vision

Teijin Limited announced today that Teijin’s Tenax™ TPCL, a carbon fiber intermediate material, and its Panlite® Sheet, a polycarbonate (PC) product, the housing of the world's lightest portable displays developed by VAIO Corporation (hereinafter VAIO). The VAIO Vision+™ 14 and the VAIO Vision+™ 14P, subsequently referred to collectively as VAIO Vision+™, were launched by the VAIO in Japan in early July.

The characteristics of the Teijin materials have made it possible to achieve the world's lightest portable display, which weighs approximately 325 g and is approximately 3.9 mm thin at its thinnest point.

Tenax™ TPCL intermediate, used for the VAIO Vision+™ housing’s top and bottom layers of the sandwich construction, is a sheet-like material made of woven carbon fiber impregnated with thermoplastic resin. It is lightweight, resistant to heat and impact, strong and rigid, and also meets flame retardancy requirements for electrical products. In addition, Panlite® Sheet, made from PC resin and used for the middle layer, has excellent dimensional stability, is lightweight, and has impact resistance.

Reduced CO2 and Easier Manufacturing:

Conventional housings use metal parts for assembly, which need to be installed during the manufacturing process. However, the housing of the new displays, which has a structure that sandwiches Panlite® Sheet between Tenax™ TPCL layers, achieves the shape and strength of the connections necessary for assembly without the need for metal parts. This material solution makes it possible to manufacture complex, three-dimensional shapes in a single molding step, which helps reduce the number of steps required to manufacture the housing and also cuts CO2 emissions.

The Teijin Group aims to become "a company that protects the global environment," embodying its long-term vision of becoming "a company that supports the society of the future," and will continue to utilize a wide range of highly functional materials to provide solutions in a variety of fields.

source:Teijin/azom.com

Today's KNOWLEDGE Share :Replacing steel cylinders with composite cylinders in India

Today's KNOWLEDGE Share

Indian Govt is planning to replace steel cylinders with lightweight composite Cylinders:

There are 32.68 crore active domestic LPG consumers served by public sector Oil Marketing Companies (OMCs) as on 01.07.2024. To ensure a steady supply of refills and accommodate new LPG connections, OMCs currently have over 50 crore cylinders in circulation which are predominantly steel cylinders. To meet replacement and fresh future demand, OMCs regularly review their inventories and issue tenders for the procurement of new cylinders.

Composite cylinders are a recent offering of PSU OMCs and are still in limited circulation. These cylinders have a three-layered construction. The cylinder is made up of a blow-molded High-Density Polyethylene (HDPE) inner liner, covered with a composite layer of polymer- wrapped fibre glass and fitted with a HDPE outer jacket. These cylinders are costlier than regular steel cylinders but are lighter in weight, rust-free, translucent and safer.

Oil Marketing Companies (OMCs) procure composite cylinders through competitive bidding process from any manufacturer meeting the tender requirements. Currently, there is no proposal to set up any manufacturing facility by OMCs anywhere in the country.

OMCs promote composite cylinders through various methods viz. generating awareness in consumers, display of banners and standees, distribution of pamphlets during home delivery and other marketing initiatives etc.

source:Ministry of Petroleum & Natural Gas-India

My speech at Ahmedabad University on 11th August 2024

Join me on 11th August (coming sunday) on Day 3 of #CINCE2024 Conference in Ahmedabad University to hear my speech on Composites in the Hydrogen Economy that addresses significant challenges in the composites storage systems and the future of the hydrogen economy that is going to enhance our lives through zero carbon emission on the earth.

There are quite a number of presentations from the Peers in the Polymer Composites Industry and attend the sessions on various technologies and interact with leading experts in the field of composites.”

Register here https://lnkd.in/gTnt9JGX

Offering process efficiency solutions for the environmental impact emission reduction.Looking forward to seeing everyone at the conference.

#polymers #type4cylinders #composites #plasticsindustry #hydrogen #compositematerials #cince2024 #hydrogeneconomy #storagetank #conference2024 #india #cgd #pipeline #naturalgas #gas #greenhydrogen #electrolysers #ccus #alternativeenergy #renewableenergy #netzero #carbonfiber

Today's KNOWLEDGE Share : Fatigue test on a Glass filled polymer

Today's KNOWLEDGE Share

Let's imagine we do a fatigue test on a 40% GF filled polymer. Visually, such material will always show what appears to be a brittle failure.

Even a less severe quasi-static tensile test will typically show failure at 1 or 1.5 % strain, which we mentally associate with "BRITTLE FAILURE".

However, you'd be surprised to see to what an extent such failures are largely due to plasticity/ductile mechanisms.

If we do our fatigue test (with a classic stress ratio R=0.1 ) at 1 Hz and then we repeat it on a fresh sample at 2 Hz, very often we will observe that life-time is the same, despite doubling the number of cycles ! This indicates that failure is essentially controlled by the underlying creep and accumulated plastic strain. A totally ductile mechanism !

If we were to observe failure two times faster, i.e. at the same number of cycles, this would point towards a dominant crack growth/brittle mechanism.

In real life, we may also find something in between, demonstrating that failure mechanisms are often the result of concurrent damage mechanisms involving plasticity and cavitation. This is what modern "progressive damage" models (e-Xstream engineering, part of Hexagon’s Manufacturing Intelligence division for instance) will implement.

source:Vito leo