At a conference 'Polyolefins 2005' at Houston, USA, organized by SPE, several new developments on additives for Polyolefins were presented. We summarize some of these developments here:

Coupling Agents for PP- Woodflour composites
Dyenon has developed functional hydrocarbon-based block copolymers, based on proprietary "controlled-architecture materials" (called CAM ) for PP woodflour composites and polymer nanocomposites. These compatibilizers for wood-plastic composites (WPC) are aimed to improve processing and surface aesthetics, reduce edge tear, and raise stiffness and tensile strength.
Dupont has introduced a new Fusabond coupling agent W PC-567D for PE/wood composites that is said to significantly boost strength and reduce water absorption at very low use levels. Fusabond W PC-567D is possibly based on ethylene copolymer with anhydride functionality incorporated in its backbone.
Crompton has pursued a similar goal of adding greater MA functionality with its new technology for producing MA-functionalized PP. With this process, the company has produced developmental maleated PP coupling agents that reportedly overcome the limitations of current commercial products in that they allow molecular weight and functionality to be varied independently. Moreover, the molecular-weight distribution of the starting resin is more closely preserved because of reduced chain scission during the functionalization reaction.
These coupling agents increase flexural properties almost by 100% compared to the conventional coupling agents. Coupling agents made with Crompton's new technology appear to be less adversely affected by lubricants. PP/wood composites made with these additives retained 90% of original flexural strength when a 75/25 blend of fatty acid ester and fatty acid amide was added, compared with 76% retention for the reactive-extrusion coupling agents

Nano-compatibilizers
Dyneon is currently exploring "controlled-architecture," hydrocarbon-based block copolymers as compatibilizers and coupling agents for polyolefin and styrenic nanocomposites made by melt compounding montmorrilonite clay.
Current additives that enhance the exfoliation and dispersion of organically modified clays include copolymers such as MA-grafted polyolefins for use with organically modified clays. Their main drawback is inefficiency: A fairly high level of additive is needed to exfoliate the clay. Dyneon has been developing a broad range of new, more efficient block copolymers containing amine, epoxy, anhydride, and acid functionality for use with a variety of clays.
For example, composites consisting of 5% of a CAM coupling agent, 5% of an organoclay (three were tested), and 90% PP were compounded in a twin-screw extruder. These nanocomposites were then compared with similarly prepared blends of PP with clay and 5% maleated-PP random copolymer.
X-ray diffraction studies reportedly showed that CAM nanocomposites were more efficient in aiding exfoliation of the clay and at significantly lower loadings (only 1%). In addition, the CAM-coupled compounds had 40-50% higher tensile modulus than the MA-PP composite.

Fluro surface modifiers
D yneon has also developed migratory additive packages that can modify polyolefin surface properties at low loading levels. These additives include block copolymers of a fluorinated butenesulfonamide ethyl methacrylate, which can render polyolefinic surfaces hydrophobic or hydrophilic to impart anti-fogging, static dissipation, adhesion, compatibilization, paintability, printability, dyeability, and moisture wicking. Applications include carpet fibers, agricultural films, nonwovens, auto bumper fascias, packaging, hygienic products, incompatible resin blends, laminated articles, and eyewear.

Light Stabilizer
Researchers at Cytec have found that recently developed hindered hydroxybenzoate (HB) light stabilizers (non-basic forms of phenolic antioxidant) offer significant advantages in combination with primary and secondary antioxidants plus high-molecular weight (HMW) HALS light stabilizers. These stabilizer systems reportedly give polyolefins long-term thermal stability as well as moderate to very high light stability.
Polynox Corp. has developed a new class of high-performance antioxidants for polyolefins that boast significantly higher activity and lower migration than conventional antioxidants, resulting in longer service life for finished products. Albermale has another novel approach for minimizing phenolic discoloration. Researchers discovered that a small amount (as little as 300 ppm) of Albemarle 's "Poly A" polyhydric alcohol is an effective color-reducing additive when used with phenolic antioxidants in PP and HDPE.

Silicone flow enhancer
A novel pelletized silicone gum from Wacker Chimie based on an ultra-high-MW (UHMW) polydimethylsiloxane, is very effective in improving the processing and flow properties of a range of thermoplastics, particularly filled polyolefins. With a higher concentration of UHMW silicone gum than conventional solid silicone additives, Genioplast Pellet S has also been shown to improve impact and tensile strength as well as surface smoothness and abrasion resistance.

Beta Nucleating Agent for PP
A new type of nucleator masterbatch for PP has been developed by Mayzo Inc. It produces unique properties in OPP film and enhances properties and processability of moulded and extruded products. The conventional agents nucleate the alpha-crystal phase, the most common crystal form of PP. In injection molded or extruded PP, the alpha type accounts for over 95% of the crystals.
A less common form is the beta crystal form, which produces improved impact strength and ductility but lower tensile yield strength.
While there are many commercially available grades of alpha-nucleated PP, there are no beta-nucleated PP resins commercially available in the U.S. and only two fractional-MFR grades are produced in Europe for pipe.
Mayzo introduced two commercial beta-nucleant masterbatches last year. Both have a PP homopolymer carrier and contain only ingredients acceptable for food contact. They are priced competitively with high-performance alpha-nucleating agents. One grade, BNX BetaPP-LN, contains a lower level of the company's proprietary beta nucleating agent and is suitable for non-pigmented film and thermoformable sheet. It is typically added at a 2% to 3% loading.
The other grade, BNX BetaPP-N, contains a higher level of beta-nucleant and is also designed for use at 2% to 3% in situations where weak alpha-nucleating agents, such as certain pigments and additives, may be present in the PP and could interfere with beta-nucleation. This product is also suitable for compounders and polymer prod ucers.
Extruded PP sheet containing this masterbatch has very high levels of beta crystallinity. When subsequently stretched into monoaxial or biax film, the beta crystals transform into alpha crystals and develop microvoids. These microvoids scatter light, resulting in an opaque film whose density is reduced by 12% to more than 40%, depending on process conditions.

In thermoforming, beta-crystalline PP sheet has a broader processing window than conventional PP sheet, according to Jacoby. Beta-nucleated sheet has been formed into white/ opaque containers (Fig. 6), which are advantageous for dairy products because less TiO2 is needed to produce a uniform white color.

FR additive
J.M Huber Corp. has been developing new grades of magnesium hydroxide (abbreviated MDH) with various particle characteristics and surface treatments to optimize low-smoke, non-halogen, flame retardant polyolefin compounds such as EVA wire and cable jacketing. One new grade is Vertex 100, a 0.8-micron MDH with an intermediate particle-size distribution. When treated with a vinyl silane and used in EVA cable jacketing, the product reportedly outperforms existing MDH products with either silane or fatty-acid surface treatment.
Competitors that were tested include a 1-micron grade with narrow particle-size distribution, a 1.5-micron MDH with broad particle-size distribution, and a 4.5-micron size with intermediate particle-size distribution. All were compared by measurement of heat-release rate in a cone colorimeter (ASTM E1354)
In these tests, the Vertex 100 compound displayed a lower heat-release profile and also showed a later and lower second heat-release peak, suggesting more potent FR efficacy.