JERtech® thermoplastic biocomposite compounds process with little special equipment or tooling. Processing them requires an understanding that cellulose filled resins do not respond well to high shear, high temperature or aggressive process conditions. These materials work best with low compression screws, metering screws, or screws without mixing elements. Eliminating shear and back pressure improves both flow and cosmetics. Screen packs are not advisable nor should processing be forced by increasing pressure of fill speeds. Nozzles should be as large as possible, multiple gates are preferred over singles, although JERtech® formulations have run successfully through single gate molds. Tooling, dies and molds do not require special coatings or metals. In general twin screw extruders are recommended, with screws optimized for processing JERtech® biocomposites or other fiber filled materials.

All cellulose filled polymer composites have moisture in them. The fiber is hydroscopic and will therefore absorb moisture from the ambient humidity in the air. When compounded, JER drives off a significant amount of this moisture and making it easier for our customers to process JERtech® compounds.

It is still recommended that JERtech® compounds be dried prior to processing (injection molding or extrusion) to eliminate any surface moisture that may have accumulated on the pellets. Once molded or extruded, parts may regain some of the moisture driven off during processing as the parts cool and stabilize. Once equilibrium is reached, the parts will not absorb additional moisture.

JERtech® compounds can be colored in line using either color concentrate pellets or liquid concentrates. EVA and PE color concentrates perform very well and give a good even color at let downs of 2 - 4 %. Color granules do not color the fiber in the compounds and allow the fibers to have a distinct color difference in the finished product. Liquid color concentrates also work well and have the added benefit of being able to color the fiber - although the fiber will absorb the color at a different rate than the polymer matrix. The end result is an even distribution of color with excellent aesthetic qualities, but one can still recognize that it is a fiber composite.

JERtech® thermoplastic biocomposites work best with low compression screws, metering screws, or screws without aggressive mixing elements. Tooling, dies and molds generally do not require special coatings or metals. Modifications may be needed to reduce shear points or improve flow characteristics. Single screw systems may be utilized, but twin screws are recommended.

All cellulose fiber filled polymers are hydroscopic and will absorb moisture from the ambient humidity in the air. When compounded, JER drives off a significant amount of this moisture which makes it easier for our customers to process the material with excellent results. However, it is recommended that all wood polymers be dried prior to processing (injection molding or extrusion) to eliminate any surface moisture that may have accumulated on the pellets. For pre-drying, we suggest one to three hours at 88° - 93° C (190° - 200° F) using hot air or one hour at 88° - 93° C (190° - 200° F) using a desiccant dryer.

Each runner system should have a good flow path with minimal obstruction to minimize shearing of the JERtech® compound as it flows to the mold. Gates should be relatively large if the mold permits. Too small of gates will cause excess shear and may cause burning and/or discoloration of the molded component, as well as a polymer-rich appearance at the gate entrance. Use of direct gating into the thick section of the molded component is preferred. Use of an edge gate which is at least 2/3 the thickness of the wall stock through which the material is being gated is also acceptable.

Note that ideal gate dimensions and location(s) will vary based on the wall stock and design of the molded component. Gate location(s) should be placed to minimize joining of flow fronts, as JERtech® compounds are relatively knit line sensitive. Molded components may fracture more easily at joining flow fronts.

Shrinkage is a function of the base polymer used in the JERtech® compound and the level of fiber in its formulation. In general, the higher the fiber loading, the lower the shrinkage. The lower the fiber loading, the more the product will behave and shrink like the base polymer.

JERtech® compounds clean easily and do not require special purge compounds. Simply scrubbing your line with the base polymer of the formulation (PP or HDPE for example) will suffice.

JERtech® compounds clean easily and do not require special purge compounds. Simply scrubbing your line with the base polymer of the formulation (PP or HDPE for example) will suffice.

Molded or extruded products made of JERtech® compounds are better with thicker walls. Depending on the application, parts with wall thicknesses below 90 mils may not be strong enough.

The choice of fiber loading and fiber type is determined by the application and the performance requirements for the finished parts. Lower fiber loadings (10 - 20%) generally give products that perform similarly to the base polymer. Higher fiber loadings (40-50%) provide better tensile properties and lower costs but are not as tough and durable as the base polymer. Mid range products (20-35%) generally provide a mix of some of the fiber properties and some of the properties of the base polymer.

Let down ratios can be easily calculated based on the fiber loading of the JERtech® compound purchased and the desired fiber loading of the finished product. If the master batch contains X% filler (fiber, flour etc), and you want to do a blend to end up with Y% filler in the finished product, the ratio of master batch to polymer is "(X/Y)-1".

For example: You have a master batch with a fiber loading of 50% and you want to end up with a part with a net loading of 10% fiber. The master batch is 50% fiber filled and you want a 10% filled product after molding, the ratio of blend-down polymer is (50/10)-1 = 4. This you blend 4 pounds of polymer to 1 pound of wood polymer and your finished product will end up with 10% fiber.

Process at lower temperature profiles than normally used with pure polymers or other polymer blends. For example, we recommend the following temperature ranges for polypropylene-based JERtech® formulations:

• Rear zone: 340° to 370° F (171° to 188° C)
• Middle zone: 360° to 390° F (182° to 199° C)
• Front zone: 380° to 410° F (193° to 210° C)
• Nozzle tip: 390° to 410° F (199° to 210° C)

Obviously, there is an added cost benefit to processing at lower temperatures in the form of energy savings. Depending on the equipment used and the JERtech® formulation, energy savings can be as much as 30%.

The primary difference is the source of the fiber. Wood flour is a post industrial waste stream that JER has specially processed for use in our compounding operation. This flour is made of pine, oak or maple. Rice hulls are a true agricultural waste stream that is normally burned to dispose of it. JER has the rice hulls processed into a flour that we use in our compounding. Rice hull flour also contains higher levels of silica that has some benefits in physical properties not available to wood flour.

The cavity size will depend on the clamp size, mold design, gating, sprue size and fiber concentration you are seeking to use. Generally, larger parts may be possible if the machine is large enough, the gates and nozzles are located properly and large enough to encourage even flow and pressure across the mold and the chosen loading of fiber is keyed to the product design and the mold thickness.

The look of the final product will depend on the fiber loading and the type of processing you choose. Molded parts tend to have a smoother surface - similar to the base polymer - with elements of fiber visible throughout. The more fiber, the more of these elements that are visible. An extruded part tends to have a rougher surface, with more fiber visible on the surface, again this is dependent on the JERtech® formulation.

On some of the extruded pieces a "wood grain" appearance may be possible with color concentrates and/or post-extrusion sanding, staining, etc. Most molded parts do not display a "wood grain" look. Typically, embossing is used on an extrusion line to create a wood grain appearance.

Any of JER's JERtech® formulations can be "cut" in line with additional polymer. Adding polymer will reduce the overall fiber content and lower the specific gravity closer to that of the base resin. Let down ratios can be easily calculated based on the fiber loading of the base JERtech® formulation purchased and the desired fiber loading of the finished product.

Stiffness can be related to the base polymer and the level of fiber used in the JERtech® compound. Polypropylene products will be stiffer than some of the polyethylene products. Polystyrene is also stiffer that other olefin-based compounds. JERtech® compounds with higher levels of fiber are stiffer than low levels. Fiber is less flexible than polymer and therefore stiffer. Adjusting fiber levels and considering other polymer bases are options to address this issue. Thinner product walls may also help.

Impact strength is key to improving shatter resistance. Fiber is a filler that tends to lower impact strength. Improving impact strength will require proper polymer selection and careful consideration of fiber loadings to achieve the desired performance.

Poor fill of the molds is often a function of the processing of the JERtech® material and the set up of the molding equipment. The runner system should have a good flow path with minimal obstruction to minimize shearing of the JERtech® compound as it flows to the mold. Gates should be relatively large if the mold permits. Too small of gates will cause excess shear and may cause burning and/or discoloration of the molded component, as well as a polymer-rich appearance at the gate entrance. Use of direct gating into the thick section of the molded component is preferred. Use of an edge gate which is at least 2/3 the thickness of the wall stock through which the material is being gated is also acceptable. Note that ideal gate dimensions and location(s) will vary based on the wall stock and design of the molded component. Gate location(s) should be placed to minimize joining of flow fronts, as the thermoplastic biocomposite material is relatively knit line sensitive. Molded components may fracture more easily at joining flow fronts.

JERtech® compounds can be safe for these applications depending on the choice of base polymers and manufacturing of the materials. Complying with FDA regulations requires 3 basic steps 1) the use of FDA-approved raw materials 2) prevention of contamination from non-FDA elements (you may need a clean line or dedicated production line for FDA type materials) and 3) good manufacturing processes (with documentation to prove you comply with the first 2 steps).

Cost for JERtech® compounds will depend greatly on the choice of polymers in the formula, fiber selection, the final ratio of materials, as well as any required additives. In general, compounding with virgin polymers and fiber are more expensive that the non-compounded virgin polymers. Master batch formulas - generally those with more than 50% fiber - are less expensive than fully let down compounds. Fully let down products are competitively priced compared to other filled or compounded polymer products.

JER offer injection molding grades of our JERtech® formulations in PP, HDPE, PS and TPO and can formulate a unique blend for your organization. JER also offers a range of extrusion grade formulations based on PP, HDPE and PS formulas. These products range in fiber concentrations between 10 and 45%. These formulas are optimized to provide excellent processing results without requiring additional polymer to achieve the desired fiber levels. The fully compounded formulas can be made with virgin polymer bases or can be compounded using recycled polymers if available