• Plastic ( soft or malleable) at normal ambient temperatures
• A melting point above approximately 45 °C.
• A  relatively low viscosity when melted (unlike many plastics)
• Insoluble in water
• Hydrophobic

We shall be discussing here on the waxes which are only being used in the rubber and plastic industry. Beeswax, perhaps , is the first wax which used by human in the beginning of our civilization, was one of the important renewable source of fuel. The honey comb formed by bees has typical hexagonal geometric pattern (Fig.1). Bees wax is used in tire building drum, if the rubber is too sticky, it can also be used in two roll mill to take care of rubber sticking to the rolls. It is frequently being used in the BC, MC, PC, TB  inner-tube making industry during pre-forming operation in the green stage when inner-tubes are expanded under mild air pressure just before curing in mold.

The main commercial source of wax is, however, crude oil but not all crude oil refiners produce wax. "Mineral" wax can also be produced from lignite. Plants, animals and even insects produce materials sold in commerce as "wax". There are five categories of waxes being used in rubber industries :

• Bees Wax
• Paraffin Wax - made of long-chain alkane hydrocarbons
• Microcrystalline Wax - with very fine crystalline structure
• Chlorinated Paraffin Wax
• Polyethylene Wax
• Chlorinated Polyethylene Wax

The major uses of petroleum based waxes are in rubber, cosmetics and in Candle industry. They are generally white in color but show usual brown color (Fig.2) due to contaminated with oil traces. Two types of waxes, in general, are used in rubber industry, Paraffinic wax and Microcrystalline wax. Its normal dose is 1-3 phr and high level of wax impairs low temperature flexibility and compression set. Rubber compounder considers wax as a very important processing aid because it has following advantages:

• Improves mixing properties

  

   

• Improves dispersion of filler and other ingredients
• Improves extrusion properties
• Improves upon extrudate and calendared surface finish
• Protects surface and acts as antioxidant /antiozonate

Paraffin and Microcrystalline waxes are derived from petroleum. They are easy to recover and offer a wide range of physical properties that can often be tailored by refining processes. Most producers offer two distinct types of petroleum waxes: paraffins, which are distinguished by large, well formed crystals; and microcrystallines, which are higher melting waxes with small, irregular crystals. Microcrystalline wax contains substantial proportions of branched and cyclic saturated hydrocarbons in addition to normal alkanes.

Some producers also sell "intermediate" wax, in which the boiling range is cut where the transition in crystal size and structure occur. Petroleum wax producers also characterize wax by degree of refinement; fully refined paraffin has oil content generally less than 0.5% and fully-refined micro-crystalline less than 3%. Paraffin wax produced from petroleum is essentially a pure mixture of normal and iso-alkanes without the esters, acids, etc. found in the animal and vegetable-based waxes.

Paraffin wax (or simply "paraffin") is mostly found as a white, odorless, tasteless, waxy solid, with a typical melting point between about 47-64 °C  and having a density of around 0.9 g/cm³. It is insoluble in water, but soluble in ether, benzene, and certain esters. Paraffin is unaffected by most common chemical reagents, but burns readily. Paraffin wax is generally unbranched hydrocarbon having carbon above C₁₇ and  are solid at room temperature. Their carbon atoms typically ranges between C₁₇ - C₃₀ and having typical melting point around 60°C. All paraffinic wax are recovered from fractional distillation of petroleum.The name paraffin implies that it contains straight hydrocarbon structure but it has branch also. Branched paraffins are called ‘Isoparafins’ and cyclic parafins are called ‘Cresines’ or ‘Isoceresies’.

Pure paraffin wax dose in rubber compounding varies from 1-3 phr. Pure paraffin wax is rarely used these days in rubber industry as it has oozing character and in excess it causes blooming on green rubber components, that results in reduction in compound tack. They are frequently blended with microcrystalline wax in rubber compounding therefore.

Pure paraffin wax is an excellent electrical insulator, with an electrical resistivity of between 10¹³ and 10¹⁷ ohm meter. This is better than nearly all other materials except some plastics (notably teflon or polytetrafluoroethylene). It is an effective neutron moderator and was used in James Chadwick's 1932 experiments to identify the neutron. Paraffin wax (C₂₅H₅₂) is an excellent material to store heat, having a specific heat capacity of 2.14–2.9 J g^–1 K^–1 (joule per gram per kelvin) and a heat of fusion of 200–220 J g^–1(joule per gram). This property is exploited in modified drywall for home building material.

Microcrystalline waxes: This is produced by de-oiling petrolatum, as part of the petroleum refining process. Microcrystalline wax contains a higher percentage of isoparaffinic (branched) hydrocarbons and naphthenic hydrocarbons. It is characterized by the fineness of its crystals in contrast to the larger crystal of paraffin wax. It consists of high molecular weight saturated aliphatic hydrocarbons with comparatively higher melting point than paraffinic wax. It is generally darker, more viscous, denser, tackier and more elastic than paraffin waxes. The elastic and adhesive characteristics of microcrystalline waxes are related to the non-straight chain components which they contain. Typical microcrystalline wax crystal structure is small and thin, making them more flexible than paraffin wax. It is commonly used in rubber formulation and cosmetic formulations.

Its usual carbon atom ranges from C₄₀–C₇₀ , having comparatively higher melting point (Fig.4) between 80-105 ⁰C because they have higher number of carbon. Common dose in rubber compounding is between 1-3 phr. Some time higher dose of  100% Micro crystalline wax is difficult to process and as a result they are often blended with paraffinic wax for rubber use. Blending is also done for economical reasons as microcrystalline wax is comparatively costlier. Paraffinic wax, having smaller molecular weight bleeds faster in cured rubber article, whereas, 100% micro crystalline wax  will have inherent resistance to faster volatilization and eventually, blended wax will have an intermediate property. Refineries may also utilize blending facilities to combine paraffin and microcrystalline waxes. This type of activity is prevalent especially for industries such as tire and rubber industries.

Higher dose of antioxidant and anti ozonates are always advised to add along with microcrystalline wax because the later help slower migration of antioxidant and antiozonates on the product surface and thereby increase on the product durability against ageing process. Tire curing bladder is often blended with 1-3 phr of microcrystalline wax.

Chlorinated Paraffin Wax

Upon chlorination of paraffinic wax we get Chlorinated Paraffin Wax(CPW). This is available in batch process that is processed from effective exothermic reaction. This reaction generates a by-product hydrochloric acid that is later removed out of the solution. Finally stabilizer and solution is mixed that provide the required final product, which is used in various industrial applications. With 30 to 70% chlorine and insolubility in water, these CPWs have low vapor pressure. Chlorinated Paraffin Wax is highly inert, insoluble in water and they have low vapor pressure. Generally used as plasticizers in plastic and elastomers, where flame retardant property is important.

Polyethylene waxes (PE-Wax)

Polyethylene waxes or PE-Wax is same familiar polyethylene chemical structure (Fig.5) but with lower molecular weight , generally around or less than 3000.This is a processing aid in elastomer and plastics but basically they are a form of synthetic resins. It is a white solid product (Fig.6) appears in the market as powdery, lumpy, or flaky product. It is a non-toxic product having concentrated distribution of molecular weight of 1500 with specific gravity about 0.94 with high softening point but low fusion viscosity with melting point; 112 - 118°C, melt peak 110 °C, flash point 210°C, minimum. It has excellent stability against polishing, scratch resistance, metal mark resistance, scuff resistance. PE-Wax is resistant to water and chemical materials.

The Rubber Board, which is observing its 77th anniversary this year, organised a press conference to showcase a novel method developed by the Rubber Research Institute of India (RRII) for recovering high-quality rubber from skim latex.

The new technique creates rubber lumps by treating the skim latex with a specific chemical mixture for 24 hours, then allowing the acid to coagulate. After that, these lumps may be dried and turned straight into skim crepe. About 3–4 percent of the rubber used to make Centrifuged Latex (Cenex) is skim latex, a by-product of the process. Cenex is frequently used in the production of goods including balloons, condoms, and gloves. About 10 percent of the natural rubber produced in India is converted into Cenex via centrifugation, which is accomplished at more than 40 centrifuging facilities.

The current method for recovering skim rubber is the acid coagulation of skim latex, which produces a slurry of skim rubber. After being packed into many plastic sacks, this slurry is allowed to solidify and dewater for two weeks. Skim crepe is made by further processing the resultant skim powder. But this traditional approach is labour-intensive, unrefined and results in bad odours, and it only generates rubber of poor grade. It has also caused public outcry and legal conflicts in the vicinity of Cenex enterprises, and it presents difficulties for wastewater treatment facilities. With the innovative method created by RRII, plastic bags are no longer used and processing takes only twenty-four hours. In addition to improving environmental sustainability and guaranteeing full recovery of premium rubber from skim latex, it drastically reduces offensive odours.

The Federation of Latex Processors (FLP), a group of owners of centrifuged latex factories, has been granted access to this technology on a fee basis. Other organizations and Cenex units can also purchase it. The product is marketed as Indian Purified Skim Rubber (IPSR) by the Rubber Board, which is also working on a patent for the concept. Rubber companies nationwide have expressed a strong interest in employing IPSR in product manufacture as it provides a competitive edge because of its improved quality and reduced cost.

Several efforts to solve various problems that exist in the rubber value chain were also addressed at the press conference. At the press conference, it was revealed that a nationwide celebration of the Silver Jubilee of the National Institute for Rubber Training (previously the Rubber Training Institute) would be organised, with participation from all relevant parties. M Vasanthagesan IRS (Executive Director, Rubber Board), Dr T Siju (Rubber Production Commissioner), Dr M D Jessy (Director-in-Charge, Rubber Research Institute of India) and representatives of the Federation of Latex Processors were in attendance.

Kraton Corporation, a leading global sustainable producer of speciality polymers and high-value bio-based products derived from pine wood pulping co-products, has expanded its CirKular+ product line with the launch of CirKular+ Paving Circularity Series C5000 in line with its long-term vision to create innovative solutions for a sustainable tomorrow.

The CirKular+ Paving Circularity Series addresses the changing demands of the paving industry to use more reclaimed asphalt and lower greenhouse gas (GHG) emissions. It allows for the addition of up to 50 percent or more reclaimed asphalt to the asphalt mix in surface layers while enhancing performance and processability. It increases the modified asphalt's resilience while maintaining resistance to permanent deformation and lowering the pavement's lifetime carbon footprint.  C5000 satisfies requirements for asphalt surface materials and is compatible with Warm Mix Asphalt technology.

Pedro Lopes, Kraton Global VP of Strategic Marketing, Product Management and Supply Chain, said, “Launching the Paving Circularity Series is a testament to our commitment to sustainability and innovation. In Europe, the paving industry is actively working to increase circularity and reduce GHG emissions in alignment with the European Green Deal and the EU’s 2050 climate neutrality goals. The new series helps unlock value-added circularity by enabling polymer-modified bitumen (PMB) producers and contractors to increase the reuse of reclaimed asphalt, thereby reintegrating it back into the road surface layer.”

Perth-based CTS Tyre Recycling is forging ahead with its plans to reshape the options for disposal of end-of-life tyres in Western Australia.

The company, a part of the wider Cometti Group, a family-owned business with more than 40 years of experience in the tyre industry, has invested more than USD 40 million in a state-of-the-art recycling plant at Neerabup, north of Perth, that processes waste tyres into crumb rubber, tyre derived products, reusable high tensile steel wire and reusable textile. The company also made some additions to its management ranks and expanded its links with industry associations as it moves forward with its strategy. These tyres, along with all other sizes, will be remanufactured in the new Neerabup factory into new, high-value goods like load-restraining matting, gym matting, equestrian and farm matting and acoustic underlay.

Leigh Cometti, the company’s Managing Director, identified a potential to diversify into the recycling of end-of-life tyres, concentrating on some of the huge off-the-road tyres utilised in the mining services and agricultural industries. Over 90 percent of the bigger OTR tyres now in use in Western Australia are thought to end up in landfills. Tyres are commonly buried in pits left behind during excavation, which results in the greatest landfill disposals in the Pilbara area. The recycling programmes will lessen the need for more virgin products in addition to decreasing landfill discharge.

Cometti has brought on two seasoned senior level managers to support him as the company grows. Joseph Jeevaraj has joined as Chief Financial Officer, while Darren Rodwell has been named Chief Operating Officer. Both positions work for the Cometti Group, which also owns the Bunbury Trucks Sales and Service dealership, CTS People and Mechanics Recruitment.

Continental and the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH have extended their project to improve sustainability in smallholder natural rubber farming by three years. About 5,000 indigenous smallholders in West Kalimantan, Borneo, Indonesia, have already received training since 2018 on how to grow premium natural rubber in accordance with well-defined sustainability standards. Co-funded by Continental and the German Federal Ministry for Economic Cooperation and Development (BMZ), the initiative aims to engage an additional 1,000 smallholders by 2027.

Lack of knowledge and low farmer income are two major issues in natural rubber farming that are addressed by the Continental and GIZ initiative in the region of Kapuas Hulu, which is home to a UNESCO biosphere reserve. Farmers are taught sustainable agriculture practices and cultivation techniques through the training offered by Continental and GIZ. This enhances the rubber's quality, boosts yield, streamlines the supply chain and raises rubber producers' profits. Additionally, this aids in putting into practice the crucial subject of preserving or reviving biodiversity in the project region. Transparency is also guaranteed across the natural rubber supply chain, from the rubber tree to its usage in Continental's manufacturing, thanks to the implementation of a digital tracking system.

In addition to increasing local capacity, both the companies are actively assisting in enhancing smallholders' quality of life and encouraging environmentally friendly methods of growing natural rubber. The objectives of the EU Regulation on Deforestation-Free Supply Chains (EUDR) are clearly supported by Continental, which has long been actively dedicated to increased supply chain sustainability and transparency. In addition to Continental's tyre facilities, other manufacturers can purchase the sustainably sourced natural rubber produced as part of the project, and more partners are being invited to join.

Dr Michael Radke, Head of Sustainability in Purchasing, Continental, said, “As one of the largest tyre manufacturers in the world, we have a particular responsibility in the natural rubber supply chain. That is why we are committed at all levels and are building capacity locally. Over the past few years, together with GIZ, we have shown that we can make the natural rubber supply chain transparent and at the same time increase farmers’ incomes. Now we want to reach even more smallholders and create the framework conditions for the successes achieved to be sustained.”