Vol. 18, No. 3, Page 2

TECHNICAL NOTES

PROCESSING OF LLDPE BLOWN FILM

According to Mobil Chemicals, LLDPE can be more readily processed if small amounts of an organic peroxide are incorporated. It results in dramaticincreases in melt strength and bubble stabil- ity. The organic peroxide appears to work as a polymeric pro- cessing aid, increasing the branching of the chain and effectively causing the LLDPE to process more like LDPE.

BLOWING AGENTS Foamed polycarbonate has good potential for use in a number of FOR ~LYC~~NAT~ industries, including automotive, packaging, and the construction

industry. One of the problems associated with current blowing agents is the need to eliminate byproducts such as ammonia and moisture which significantly reduce the impact strength of the blown polycarbonate. A further requirement is a blowing agent that will be stable at the high processing temperatures associa- ted with polycarbonate, A number of companies are actively devel- oping blowing agents which will satisfy all these requirements. Bee Chemical in the US has had limited success with hydrazene derivatives and hydracerol compounds. Olin Chemicals in the US is focussing its attention on modified 5-phenyltetrazole com- pounds in its Expandex range.

STRESS CORROSION Glass-fibre reinforced plastics with epoxy resin matrix are known CRACKING OF to respond with high sensitivity to a combined stress imposed GLASS-FIBRE by mechanical forces and mineral acids, The phenomenon is com- REINFORCED EPOXY parable with the stress corrosion cracking usually observed with RESINS metallic materials and is therefore also characterized as such

in the case of glass reinforced epoxies. In this paper the stress corrosion cracking of typical insulators made from such compo- sites is determined quantitatively by fracture-mechanical experi- ments. From the obtained results material characteristic values are derived which can be used for the mechanical dimensioning of components and structural parts.

Kunststoffe, 1987, 7J, (Nov.), 1161-1167

EFFECT OF SELECTED The concept is that high-IR-reflecting pigments can be effective

PIGMBNTS ON HRAT in reducing heat build of plastics subjected to solar exposure

BUILD OF RIGID and that this should translate into improved physical-property PVC SIDING retention and reduced buckling due to thermal expansion. Data

are given for a high-IR black pigment in grey, pastel, and brown vinyl siding.

Plast. Compound, 1987, (Nov./Dee.), 23 Cont./......

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