Abstract: Biphosphites of formula I ##STR1## wherein m is 0, 1 or 2,n is 1 to 4 or 6,R.sub.1 is hydrogen or C.sub.1 -C.sub.4 alkyl and, if m=2, the radicals R.sub.1 are identical or different, and A is the radical of an at least n-hydric alcohol or phenol, which radical is attached to the P atom or atoms through the alcoholic or phenolic O atom or atoms, obtainable by reacting a compound of formula II ##STR2## wherein m is 0, 1 or 2, R.sub.1 is hydrogen or C.sub.1 -C.sub.4 alkyl and, if m=2, the radicals R.sub.1 are identical or different and R.sub.2 ' is phenyl, C.sub.1 -C.sub.12 alkylphenyl or C.sub.1 -C.sub.4 alkyl, with a polyether polyol or polyether/ester polyol, the hydroxy functions of said polyether polyol or polyether/ester polyol being partially or completely esterified with the ##STR3## are suitable for use as stabilizers, especially processing stabilizers, for organic polymers, preferably PVC resins, high density polyethylene and propylene.

Abstract: Compounds of the formula I, II, III or IV ##STR1## wherein X is halogen, OH, --OR.sup.1, --OOCR.sup.2, --OOC--R.sup.4 --COOR.sup.3 or --N(R.sup.5)(R.sup.6), or the two X groups together form a group --O--R.sup.9 --O-- or --OOC--R.sup.9 --COO--, Y has one of the meanings given for X, or it is --NHR.sup.5, --NHNH.sub.2 or --NHNH-phenyl, Z has one of the meanings given for X, or is --SR, and R, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.9 and R' are organic radicals having the meanings defined hereinbelow, are thermal stabilizers for chlorine-containing thermoplastics particularly for PVC. Their effect can be further intensified by the addition of co-stabilizers.

Abstract: Copolyesters of terephthalic acid, 1,4-butanediol and an aliphatic dicarboxylic acid of the formula Ihooc--r--cooh (i)wherein R represents a divalent aliphatic hydrocarbon group containing not more than 34 carbon atoms, are eminently suitable as impact modifiers for polyalkylene terephthalates for improving the toughness properties.