Resins, properties scrap

Superior Environmental Products, Inc. introduced a product based on liquid poly sulfide containing 40% of a surface-modified scrap tire mbber. The product, ER-IOOR, is a coating that can temporarily contain chemical, oil, and gasoline spills. Rodriguez [97] reported that an unsaturated polyester resin containing silane-treated CGR showed better mechanical properties than that containing untreated CGR. 

Organic Extenders. Organic extenders are primarily of two types (1) fillers derived from organic materials and (2) low-cost, naturally occurring or synthetic resins. Of the first type, wood flour, shell flour, and other cellulosic fillers are the most common. They also provide a margin of mechanical property reinforcement because of their relatively high aspect ratio. Of the resinous types these are petroleum-based derivatives as well as soluble lignin and scrap synthetic resins. 

It should be remembered that additives used for one type of resin may have detrimental effects on another resin and/or on its additives. It was reported that the interfacial properties in PA/PO blends can be seriously affected by incorporation of unsuitable additive into a blend. When PA scrap was mixed with PO containing phosphite stabilizers, a rigid membrane was formed at the interface by a chemical reaction between -NH groups of PA and phosphite acidic functionality [Luciani et al., 1997]. The membrane has two serious effects it increases the melt viscosity (thus, it reduces the throughput), and it makes dispersing the PO in PA much more difficult (what reduces the performance). The detrimental effects are most likely when heat and light stabilizers are present in the recyclates. 

Impregnated resins for the selective adsorption of noble metal ions obtained [108] by loading TOA onto macroreticular hydrophobic resins were proposed. Au(lll), Pt(lV), and Pd(Il) are adsorbed on the resins as anionic chloro complexes. The adsorption efficiency of the resin was closely related to the specific surface area, the hydrophobic property of the resin matrix, and the amount of TOA loaded. The distribution coefficients of the resin for Au(lll), Pt(lV), and Pd(ll) are higher than 10 in 1 M HCl solutions. The selective recovery of gold and platinum by column operation from the acid-leaching solutions of industrial scraps has been demonstrated. Different from the case of conventional anion exchangers, the adsorbed chloro complexes were readily released from the resin as ion pairs with TOAH" by elution with 4-methyl-2-pentanone. 

Economics. An advantage of coextrusion is the capability of combining layers of high performance resins with low cost resin layers to produce high per-formance/low cost composite structmes. The use of recycled and scrap resins in buried layers further improves economy. Multilayer extrusion economic considerations have been calculated (89). The effect of recycle on film properties, eg, tensile strength, impact, and elongation, depends on the degree of compatibiUty of polymers in the recycle layer. Often the tie-layer polymer acts as a compatibi-lizer for recycle. Recycle of incompatible polymers with different refractive indexes usually causes haziness and cannot be used when excellent optical properties are required. 

New processing techniques offer another way to recycle PVC scrap. One example is the production of window frames by coextrusion. The regenerated PVC is used in core whereas virgin resin is used as the skin. In this process only 1/3 of new material is necessary to obtain the same properties as a window frame from 100% virgin PVC. The coextrusion process is also feasible for the production of pipes where the inside and the outside layers are made out of a new resin and the old material is used for the thick middle layer. ... 

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