The Photodegradation of Copolymers of 2,2-Chloroacrylonitrile With Styrene and With Methyl Methacrylate

Methyl methacrylate/2,2-chloroacrylonitrile and styrene/2,2-chloroacrylonitrile copolymers of various molar ratios have been prepared by free-radical, addition polymerisation and characterised by nuclear magnetic resonance spectroscopy and microanalysis. The photodegradation by 254nm radiation of thin copolymer films has been studied at ambient temperatures. Spectroscopic examination of the residual films, separation of degradation products by a recently developed, low-temperature, thermal volatilisation analysis technique, cumulative, quantitative product analysis and product identification by spectroscopic techniques have enabled the photodegradation processes to be studied in depth. The results indicate that, as the proportion of 2,2-chloroacrylonitrile in the copolymer with methyl methacrylate is increased, the well-established degradative behaviour of poly(methyl methacrylate)--- a rapid decrease in molecular weight and formation of products from ester decomposition--- is gradually replaced by crosslinking, unsaturation, insolubility, the production of hydrogen chloride from 2,2-chloroacrylonitrile units and methyl chloride from both monomers. Around the 1 : 1 molar ratio a highly absorbing surface layer begins to be formed. The effect of 2,2-chloroacrylonitrile units on polystyrene photodegradation is less marked. The major reaction is hydrogen chloride formation. For the same molar ratio, the rate of formation of hydrogen chloride from 2,2-chloroacrylonitrile copolymers with styrene is considerably greater than with methyl methacrylate. This is attributed to the different absorption coefficients of radiation of the two co-monomers. Solvent participation in photodegradation reactions is indicated by anomolous molecular weight measurements on the methyl methacrylate system and by post-irradiation absorption spectra of copolymer films of both systems. The effect of pre-irradiation on the thermal degradative behaviour of copolymer films has been studied. The nature of the degradation products remains unchanged but the effects of crosslinking and unsaturation on the methyl methacrylate system are reflected in thermogravimetric analyses and differential condensation thermal volatilisation analyses on the system. The initiation processes involved, the scissioning reactions, the development of unsaturation in the copolymers and the related discoloration of copolymer films are discussed in the course of the work. Comparisons are drawn with studies on similar polymer systems and various references are listed which have been found relevant to the present study

Mersenne Numbers: consolidated results

This document provides and comments on the results of the Lucas-Lehmer testing and/or partial factorisation of all Mersenne Numbers Mp = 2^p-1 where p is prime and less than 100,000. Previous computations have either been confirmed or corrected. The LLT computations on the ICL DAP is the first implementation of Fast-Fermat-Number-Transform multiplication in connection with Mersenne Number testing. This paper championed the disciplines of systematically testing the Mp, and of double-sourcing results which were not manifestly correct. Both disciplines were adopted by the later GIMPS initiative, the 'Great Internet Mersenne Prime Search, which was itself one of the first web-based distributed-community projects

The Implicit Relational Assessment Procedure (IRAP) and the malleability of ageist attitudes

The current study examined the malleability of implicit attitudes using the Implicit Relational Assessment Procedure (IRAP). In Experiment 1, “similar” and “opposite” were presented as response options with the sample terms “old people” and “young people” and various positive and negative target stimuli. Results showed significantly faster response latencies for consistent (e.g., Similar- Positive-Young People) compared to inconsistent tasks (e.g., Similar-Positive-Old People). Explicit measures did not correlate with this IRAP effect. Experiment 2 determined whether prior exposure to pictures of admired and disliked old and young individuals had an impact on IRAP performance. Results revealed that pro-old exemplars reduced the pro-young IRAP effect, but reversed the anti-old effect, and this held for 24 h; explicit measures were largely unaffected. The findings suggest that the IRAP provides an informative measure of attitudechange following pro- versus anti-exemplar training

The Implicit Relational Assessment Procedure (IRAP) as a response-time and event-related potentials methodology for testing natural verbal relations: A preliminary study

The current article reports the first attempt to test the Implicit Relational Assessment Procedure (IRAP), as a group-based measure of natural verbal relations, using both response-latency and event-related potentials as dependent variables. On each trial of the IRAP, participants were presented with 1 of 2 attribute stimuli (“Pleasant” or “Unpleasant”), a positive (e.g., “Love”) or negative (e.g., “Murder”) target stimulus, and 2 relational terms, “Similar” and “Opposite,” as response options. Participants were required to respond as quickly and accurately as possible across blocks of trials, with half of the blocks requiring responses that were deemed consistent (e.g., Pleasant–Love–Similar), and the other half inconsistent (e.g., Pleasant–Love–Opposite), with natural verbal relations. Shorter mean latencies were predicted for consistent than for inconsistent blocks. Two separate experiments supported this prediction. Event-related potentials, gathered during the second experiment, also proved to be sensitive to the IRAP, yielding more negative waveforms for inconsistent relative to consistent blocks of trials. A theoretical interpretation of the IRAP effect is offered, and important directions for future research are highlighted

Implicit Attitudes to Work and Leisure Among North American and Irish Individuals: A Preliminary Study

The current article reports the findings from two preliminary experiments investigating the Implicit Association Test (IAT) and the Implicit Relational Association Procedure (IRAP) as measures of implicit attitudes in the domain of work and leisure among North American and Irish individuals. The IAT and IRAP tasks involved responding under time pressure on a computerized task, with response latency as the dependent variable. The IAT required participants to categorize positively or negatively valenced words with stimuli associated with either Work or Holidays. The IRAP required that participants confirm or deny that Work and Holidays are similar or opposite to positively and negatively valenced words. Participants also completed an explicit measure consisting of a Likert-based questionnaire. In both Experiments, citizens of the United States of America produced performances on the IAT and IRAP that indicated more negative attitudes to work and more positive attitudes to holidays than both Canadian and Irish citizens. Responses on the explicit measures did not accord with this overall pattern of group differences. The results support the use of the IRAP as a measure of implicit attitudes and furthermore the findings appear to be generally consistent with a recent large-scale survey of attitudes to work across 23 countrie

Exploring Screen Presentations in the Implicit Relational Assessment Procedure (IRAP)

The current study attempted to systematically manipulate stimulus presentations in the Implicit Relational Assessment Procedure (IRAP) to determine the potential impact of this variable on implicit responding. The study comprised of four conditions that systematically manipulated the positions of the sample stimuli and the response options. Specifically, the Random-Random Condition randomized both sample stimuli and response options; Random-Fixed randomized sample stimuli, but response options remained in fixed locations; Fixed-Random Condition fixed sample stimuli but randomized response options; and Fixed-Fixed Condition fixed both sample stimuli and response options. The results demonstrated strong and predicted IRAP effects in all four conditions. Although the Random-Fixed presentation generated the strongest D-IRAP score, the randomization of the sample stimuli and response options were both critical to producing strong and significant D-IRAP scores because the Random-Random and Fixed-Random Conditions were only marginally smaller. The implications of the findings for existing and future research with the IRAP are discussed

A sketch of the Implicit Relational Assessment Procedure (IRAP) and the Relational Elaboration and Coherence (REC) Model.

The current article outlines a behavior-analytic approach to the study of socalled implicit attitudes and cognition. The Implicit Relational Assessment Procedure (IRAP), the conceptual basis of which was derived from relational frame theory, is offered as a methodology that may be used in the experimental analysis of implicit attitudes and beliefs. The relational elaboration and coherence (REC) model provides a possible relational-frame account of the findings that have emerged from the IRAP. The article first outlines the research history that led to the development of the IRAP, followed by a description of the method. The REC model and how it explains a range of IRAP data are then considered. The article also outlines how both the IRAP and the REC model overlap with, and differ from, similar research found in the non-behavior-analytic literature. Key words: Implicit Relational Assessment Procedure, relational frame theory, network, elaboration, coherence, attitude

Implicit Attitudes to Work and Leisure Among North American and Irish Individuals: A Preliminary Study

The current article reports the findings from two preliminary experiments investigating the Implicit Association Test (IAT) and the Implicit Relational Association Procedure (IRAP) as measures of implicit attitudes in the domain of work and leisure among North American and Irish individuals. The IAT and IRAP tasks involved responding under time pressure on a computerized task, with response latency as the dependent variable. The IAT required participants to categorize positively or negatively valenced words with stimuli associated with either Work or Holidays. The IRAP required that participants confirm or deny that Work and Holidays are similar or opposite to positively and negatively valenced words. Participants also completed an explicit measure consisting of a Likert-based questionnaire. In both Experiments, citizens of the United States of America produced performances on the IAT and IRAP that indicated more negative attitudes to work and more positive attitudes to holidays than both Canadian and Irish citizens. Responses on the explicit measures did not accord with this overall pattern of group differences. The results support the use of the IRAP as a measure of implicit attitudes and furthermore the findings appear to be generally consistent with a recent large-scale survey of attitudes to work across 23 countrie

A sketch of the Implicit Relational Assessment Procedure (IRAP) and the Relational Elaboration and Coherence (REC) Model.

The current article outlines a behavior-analytic approach to the study of socalled implicit attitudes and cognition. The Implicit Relational Assessment Procedure (IRAP), the conceptual basis of which was derived from relational frame theory, is offered as a methodology that may be used in the experimental analysis of implicit attitudes and beliefs. The relational elaboration and coherence (REC) model provides a possible relational-frame account of the findings that have emerged from the IRAP. The article first outlines the research history that led to the development of the IRAP, followed by a description of the method. The REC model and how it explains a range of IRAP data are then considered. The article also outlines how both the IRAP and the REC model overlap with, and differ from, similar research found in the non-behavior-analytic literature. Key words: Implicit Relational Assessment Procedure, relational frame theory, network, elaboration, coherence, attitude