(US4812545-A)      Polymerisable liq. compsn. for the prepn. of substitutes for optical glass comprises 10-50 wt.% of component (A) 20-70 wt.% of component (B), 5-50 wt.% of component (C) and 1-6 wt.% of a free radical initiator. Component (A) is a monomer prod. of a reaction between diallylcarbonate and diethyleneglycol in a molar ratio of 12:1. Component (B) is an oligomer of formula CH2=CH-CH2-O-C(=O) -O(R-O-C(=O)-)n-CH2-CH=CH2 which is a prod. of a reaction between diallylcarbonate and diethyleneglycol in a mol. ratio of 2:1. Component (c) is a monomer prod. of tris(hydroxyethyl)isocyanurate tris(allylcarbonate) resulting from a reaction of diallylcarbonate with tris(hydroxyethyl)-isocyanurate in a mol. ratio of 10:1.    Prepn. of substitutes for optical glass comprises combining the components (A)-(C) and the initiator and pouring into moulds shaped to produce a mfd. article, maintaining the compsn. at a temp. below the decomposition temp. of the initiator, and polymerising the compsn. at a temp. of 30-120 deg.C for 3-100 hrs..    USE/ADVANTAGE -   The liq. compsn. is used to produce optical glass substitutes with improved optical and mechanical properties. (6pp)a    (EP201978-B1)      A liquid polymerisable allylcarbonate composition for the preparation of optical glass substitutes, consisting of the following components: from 10% to 50% by weight of component (A) which is the monomer product of the reaction between diallylcarbonate and diethyleneglycol in the presence of a basic catalyst and in a molar ratio of at least 10:1; from 20% to 70% by weight of component (B) which is an oligomer product of the reaction between diallylcarbonate and diethyleneglycol in the presence of a basic catalyst and in a molar ratio of 2:1, the oligomer product having the formula CH2=CH-CH2-O-C(O)-O(R-O-C(O)-O)n-CH2-CH=CH2 wherein R is the radical of diethylene glycol and n has a value, or an average value, of from 2 to 5; from 5% to 50% by weight of component (C) which is the monomer product of tris(hydroxyethyl)isocyanurate tris(allylcarbonate) resulting from the reaction of diallylcarbonate with tris(hydroxyethyl)isocyanurate in the presence of a basic catalyst in a molar ratio of at least 10:1, and a free-radical initiator in an amount of from 1% to 6% by weight relative to the total weight of (A), (B) and (C) components, said composition having a kinematic viscosity at 25 deg.C lower than 0.00025 m2/s (250 cSt).    (JP93053806-B)      Polymerisable liq. compsn. (I) contains: (A) 10-50 (15-45) wt.% diethylene glycol bis(allylcarbonate) monomer; (B) 20-70 (30-60) wt.% diethyleneglycol bis(allylcarbonate) oligomer (II); and (C) 5-50 (10-45) wt.% tris(hydroxyethyl) isocyanurate tris(allylcarbonate).    CH2=CH-CH2-O-C(:O)O(R-O-C(:O)O)n-CH2 -CH=CH2 (II) R= radical of diethylene glycol; n = 2-5 (pref. 3).    (I) also contains 1-6 wt.% of free radical initiator (III). A process for prepn. of claimed optical glass substitutes of (I) is also claimed.    USE/ADVANTAGE -   (I) does not show shrinkage, breakage or sepn. from the mould during casting into substitute optical glasses. Such glasses are used in the prodn. of protection shields, solar panels and general lenses. (J61268708-A)