Today's KNOWLEDGE Share : The annoying saddle twist warpage of low MFI polyolefin grades

 Today's KNOWLEDGE Share

147. The annoying saddle twist warpage of low MFI polyolefin grades.

If you ever molded extrusion or blow-molding grades of PP or PE, you have certainly experienced a big warpage problem, stemming from the surprisingly higher than usual IN-FLOW shrinkage.

The graph on the right (similar to my previous post nr. 146) shows that moving to a lower Melt Index increases the chance of freezing more molecular orientation in the part, as a result of the longer relaxation time of low MFI grades.

The graph in the center, from the cited article of 2006, shows the trend of increasing parallel to flow shrinkage with increasing molecular weight of a simple unfilled PP homopolymer.

Note that the three grades are all more viscous than typical in Injection Molding, and they all show a strong anisotropic shrinkage (this is measured on a dog-bone classical tensile bar sample) with larger shrinkage in the flow direction, due to strong molecular orientation.

It is the exact contrary of classical higher flow PP grades where perpendicular shrinkage is higher than parallel !

Finally, as seen on the left drawing (by Covestro), a centrally gated part will warp in a “saddle twist” fashion when the In-FLOW shrinkage is larger than the CROSS-FLOW shrinkage (perimeter wants to be larger than the corresponding radius).

When dealing with these viscous “twisty-warpy” grades one could in theory add just a few % GF that create the opposite effect of lower IN-FLOW shrinkage. Magically, you could suddenly mold a perfectly flat disc, by adding just a pinch of GF to the mix !

A higher packing (qualifying probably as OVERPACKING of the part center) would also flatten these part by creating the opposite warp trend, something illustrated in classical MOLDFLOW® literature more than 40 years ago.

What is your own experience with low MFI grades ?

Please comment and share so that we all learn more about this issue.

source : Vito leo

Ground-breaking Ceremony of Air Conditioning Division - Vignesh Polymers India Private Limited at SIPCOT Industrial Park in tamilnadu (INDIA)

Vignesh Polymers, a pioneer in appliance and automotive component and module manufacturing, today marked a historic milestone with the Ground-breaking Ceremony of its #AirConditioning Division, unveiling its 10th Factory Unit at the SIPCOT Industrial Park, Sriperumbudur Taluk.

The new facility will feature a world-class manufacturing unit, reinforcing the company's commitment to innovation, excellence, and global quality standards. The project involves the establishment of a fully integrated air-conditioning manufacturing facility, designed to support end-to-end production under one roof. The plant will encompass sheet metal fabrication, heat exchanger and copper tubing lines, injection moulding and EPS packing operations as well as the in-house production of propeller and crossflow fans.

source: Business Standard

Today's KNOWLEDGE Share : Touchscreen Car controls

Today's KNOWLEDGE Share

Despite having worked on automotive HMI as a product designer, I prefer physical controls in cars over digital infotainment systems. Sometimes it feels like manufacturers are designing for iPad kids and tech enthusiasts instead of regular A-to-B drivers.

Touchscreen car controls are 2-4 times slower than physical buttons.

Touchscreens increase reaction times +30-57%. Legally drunk drivers: reaction time +12%. Car's touchscreen impairs more than a couple of beers.

Physical controls:

- One motion: turn knob left/right

- Works by feel without looking

- Instant response

- Same location every time

- Works with gloves

- Muscle memory kicks in

- Tactile feedback confirms action

Touchscreen controls:

- Multiple taps through menus

- Requires visual attention to locate

- Lag between tap and response

- Interface changes with software updates

- Fails with gloves/wet fingers

- Must relearn after updates

- No confirmation until you look at display (is haptic feedback is enough?)

VW: "We will never make this mistake anymore. It's a car, not a phone."

The best interface is the one you never have to think about. Especially when you're driving the highway at 100+ km/h.

source : Alex Galagan

Today's KNOWLEDGE Share ; Zinc dispersion in zinc-rich Epoxy

Today's KNOWLEDGE Share

Effective zinc dispersion in zinc-rich epoxy (ZRE) coatings requires over 80 wt% zinc, ensuring electrical contact between particles and the steel substrate for cathodic protection. Standards like ISO 12944 define ZREs as having high zinc content, but effective dispersion and continuous electrical paths are critical for performance, often achieved through careful application and sometimes aided by additives like graphene to create conductive networks that prevent isolation of zinc particles.

Importance of Zinc Dispersion

Cathodic Protection:

The primary mechanism of ZREs is cathodic protection, where zinc particles act as sacrificial anodes, corroding preferentially to protect the steel.

Electrical Contact:

For effective cathodic protection, a continuous electrical pathway must exist between the zinc particles and the steel substrate.

Barrier Protection:

The corrosion products from the zinc also fill micropores in the coating, providing a secondary physical barrier effect against corrosive substances.

Standards and Specifications

High Zinc Content:

ISO 12944 defines a zinc-rich coating as having more than 80 wt% of zinc dust in the dry film to facilitate effective cathodic protection.

Active Electric Channels:

The dispersion must ensure that the zinc particles are not isolated by non-conductive binders or corrosion products, which would hinder the formation of active electronic channels to the metal substrate.

Achieving Effective Dispersion

Pigment Grinding:

The manufacturing process involves a grinding stage to ensure uniform dispersion of zinc pigments, often using bead mills.

Binder and Pigment Ratio:

The correct proportion of binder (epoxy resin) to zinc is crucial. An excess of binder can lead to isolated zinc particles, reducing the coating's effectiveness.

Surface Preparation:

A properly prepared, clean, and often sandblasted steel surface is essential for the zinc-rich coating to adhere properly and form the necessary electrical contact with the substrate.

Factors Affecting Dispersion and Performance

Zinc Particle Size:

While not explicitly a dispersion metric, the particle size of zinc dust is relevant.

Coating Additives:

Materials like graphene can enhance dispersion by promoting the formation of conductive networks within the coating, which improves electrical contact and extends the lifespan of the sacrificial protection.

Curing:

Proper curing conditions after application are necessary for the coating to fully harden and form the necessary barrier and conductive properties.

source : Hussien Elkaluoby

Fibaplast Inspired by Nature – masterbatches with colors and effects inspired by nature

A modern interpretation of natural beauty – with the new Fibaplast – Inspired by Nature product series, we are bringing the fascinating textures and colors of nature into the world of plastics. Inspired by the variety of fine wood grains, the powerful appearance of stone structures and the warm nuances of natural earth tones, high-quality effects are created that give products an distinctive identity.

Extended variety of materials:

Until now, nature-inspired masterbatches have mainly been used in #polyolefins. Finke is now expanding its portfolio to include solutions for #styrenics, enabling even more applications in different material systems. All variants are not only visually impressive, but also technically: they offer good to very good light fastness and therefore guarantee durable, high-quality surfaces.

The targeted play with flow lines, the use of special pigments and additional finishes such as laser marking allow impressive, nature-like structures and a special feel to be achieved. This turns every surface into an experience authentic, unique and high-quality.

Diverse applications with strong designs:

Head of Development and Application Technology Dr. Martin Fritsch explains: “We are noticing that customers are increasingly asking for natural designs in order to visually highlight their products and differentiate themselves more strongly in the market. The first successful applications are already in the cosmetics and furniture industries, where natural effects are particularly appreciated. Our nature-inspired masterbatches are also being used successfully in the toy sector: the special effects give the products a unique look that visually enhances them and makes them stand out from the crowd suitable for children, individual and with a high recognition value.”

Sustainability is also a focus here: many #Fibaplast – Inspired by #Nature masterbatches are already based on recycled materials. On request, we can produce all variants entirely from #recycledrawmaterials – without compromising on quality or aesthetics. In addition, all #Masterbatches are food-safe and therefore open up further application possibilities.

There are also no limits to the imagination when it comes to color design: our experienced colorists develop tailor-made shades and effects that are precisely matched to the customer’s ideas.

source : Finke

Today's KNOWLEDGE Share : Biofoam boxes for Seafood Industry

Today's KNOWLEDGE Share

Biofoam boxes greening WA’s lucrative seafood industry

Western Australia is known for many things from its beautiful beaches to its vast outback, and, famously, its fresh and tasty seafood.

The WA seafood industry brings in around $1billion of revenue each year, making it one of the state’s most lucrative industries. However, with that revenue comes packaging waste. 

To transport seafood from the ocean to the markets or the shelves, it has historically been stored in #expandedpolystyrene boxes. These have now been banned in WA and are being phased out around the world.  

While some greener, #recyclablepackaging options have been introduced, a new and collaborative local project is looking to move from recyclable, to fully #biodegradable.  

The Bioplastics Innovation Hub (BIH), a joint venture between #MurdochUniversity and #CSIRO, has partnered with #CassMaterials, a Perth biotechnology company, to develop #biofoam #seafoodboxes made from wheat straw.  

“In WA, approximately 10million tonnes of #wheatstraw per year is retained on the farm and, with no tillage systems, most is burnt,” Cass Materials CEO Gary Cass said.  

“With the Bioplastics Innovation Hub, we can convert this agricultural waste into new fossil-free biofoam boxes for fresh food and seafood markets.

Traditional polystyrene boxes take more than 500 years to decompose in landfill, and form microplastics as they break down. 

Biofoam boxes fully break down within a few months and improve the organic matter content of soils. 

This is particularly poignant, as a recent review by Murdoch University discovered that agricultural soils now hold around 23 times more microplastics than oceans.  

The boxes are also lightweight, hydrophobic (able to retain ice and water) and home compostable.  

BIH director Professor Dan Murphy said the Hub’s research is directed by what industry needs and aims to solve real-world problems.  

“We want to improve single use items in the food industry by having biodegradable and compostable materials that replace things like synthetic plastics,” Professor Murphy said.  

By developing these items that can replace synthetic plastic in food transportation, storage and packaging we can help to both lower environmental impacts and address incoming plastic bans. 

The biofoam boxes are currently at TRL4, meaning the laboratory prototypes have been validated. Cass Materials is currently raising capital to scale this technology. 

In preparation for this upscale, BIH researchers are working to develop the entirely waterproof barrier needed to meet final requirements. We are confident that upon scaling-up this product, it will become a commercial success and meet the consumer and industry demand for convenient and environmentally friendly packaging.”  

source : Murdoch University

Today's KNOWLEDGE Share : Sustainable Graphites

Today's KNOWLEDGE Share

Imerys introduces SU-NERGY™ , a novel #graphite series featuring biomass-derived raw materials. This innovative product is the first of its kind at industrial scale, representing a significant leap forward towards more #sustainablegraphite manufacturing.

SU-NERGY™ incorporates biomass in its production process and is manufactured using exclusively low-carbon energy sources. The result is a powerful and more sustainable alternative to traditional fossil -based graphites.

Key advantages are:

-->Excellent electrical conductivity

-->Superior thermal management capabilities

-->Up to 60% reduction in CO2 emissions compared to traditional graphite materials from fossil fuel-based raw materials

-->Increased isotropicity and springback

-->High purity and crystallinity

-->Incredible versatility, meeting the needs of a wide range of industries, including:

-->Mobile Energy Solutions

-->Energy Storage and Conversions

-->Conductive Polymers

-->Powder Metallurgy

-->Engineering Materials and others 

source : Imerys